C64 Black Screen Repair (MT RAM Chips)

Рет қаралды 21,590

Күн бұрын

I'm troubleshooting and repairing another black/blank screen Commodore 64 board in this episode. // Kindly sponsored by PCBWay - Get your first PCBs free! - www.pcbway.com/
Commodore PCB Reproductions at Bob's Bits Tindie Store: www.tindie.com/stores/bobsbits/
Boelle's 326298 C64 Board Replica on GitHub: github.com/boelle/326298-Rev-...
bwack's KU-14194HB C64 Board Replica on GitHub: github.com/bwack/KU-14194HB-R...
Here's some handy resources I refer to when troubleshooting and repairing C64s:
The Pictorial C64 Fault Guide is here: derbian.webs.com/c64diag/
Ray Carlsen's troubleshooting and repair guides are here: personalpages.tds.net/~rcarlse...
You can get the .bin files for various C64 diagnostics cartridges from World of Jani (in case you want to make your own or try in an emulator): blog.worldofjani.com/?p=164
Here's the GitHub with Sven's diagnostics harness: github.com/svenpetersen1965/C...
Time stamps:
0:00 Introduction
2:38 Inspection & Checking Voltages
7:08 Populating the Board
8:33 The Difference between Dead Test & Diagnostic Cartridge
10:55 Finding a faulty RAM IC
12:53 Replacing RAM (with Soldering tips)
17:20 Finding and replacing more faulty RAM
19:41 Finding even more faulty RAM
21:03 Still more broken RAM?
21:36 Replacing ALL the RAM ICs
23:45 Testing the repaired Board
27:30 Thank you and Good Night!
--------------------------------------------
Music by Focus 10 / user-993847645
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#JanBeta #Commodore #C64 #PCBWay

Пікірлер: 176

@tvirkki 4 жыл бұрын

It is always satisfying to see the dead computer come back to life.... Blue-gray screen is quite pleasing. Good job!

@JanBeta 4 жыл бұрын

Thanks Topi! I still feel great whenever I manage to fix one, too. :)

@videolabguy 4 жыл бұрын

16:30 - Good job! You used a machined pin socket. After 40 years in the industry, I have come to despise stamped pin sockets. I call them guaranteed failure points. The Machined sockets cost a few cents more. But, replacing the socket again costs your time which is very valuable.

@gertsy2000 4 жыл бұрын

Good video Jan. You're very patient. Well done.

@tubeDude48 4 жыл бұрын

Had to chuckle! I'm 72 and I have *NEVER* used a wrist ground strap, and have *NEVER* destroyed an IC!!

@JanBeta 4 жыл бұрын

I destroyed a SID chip a while back with ESD, using a strap ever since.

@leemackenzie549 4 жыл бұрын

Great to see another C64 saved Its a shame that the details on the custom chips has not been made available so the chips and be remanufatured to save more of these amazing machines

@JanBeta 4 жыл бұрын

There's quite a few modern recreations of the custom ICs now, I have a video coming up about that soon. :)

@MrChrisRP 3 жыл бұрын

Yep. I watched enough C64 repair videos that I knew straight away it was the RAM, same as you did. Awesome video. Thanks!

@SeaJay_Oceans 4 жыл бұрын

It's June 16th, 2020 A.D. - and thank you for still loving and repairing the original Commodore 64 ! :-)

@JanBeta 4 жыл бұрын

Haha, thank you. My love for the Commodores is everlasting. ;)

@awilliams1701 4 жыл бұрын

When I got my C64 I wasn't going to fix it originally. It was going to be a U64 system. But after I cleaned up the case and keyboard and motherboard, I noticed that my 425 board looked pristine BRAND NEW!! No wavyness in the ground plate like the one in this video. I'm like this thing is beautiful and it would be a shame to let it go to waste. So I decided to fix it up. But after that, the next thing I noticed was MT ram. lol I was shocked when it powered up to BASIC, but then I noticed 429 bytes free. lol I'm like yeah.....I'm surprised it worked at all. I ordered 8 new ram chips and proper round sockets. While I was waiting on those, I found a BASIC program that would identify the faulty RAM chip(s). It sets about 32K to 0 and shows any differences. Then it sets the same 32K to 255 and shows any differences. In 32K I had 39 errors. Most of them were 127 instead of 255, but I had a couple 128s instead of 0s in there as well. That's U12. So when the RAM came in, I swapped U12 first and sure enough 38911 bytes free. Afterword I replaced the other 7 chips anyway. And later on I recapped it. Unfortunately I'm not done some games glitch graphically, but play fine. Either my color sram is bad or my vic-2 is bad. I feel like since I wan't to do a vic^2 mod I should get a PAL chip and see what happens. If the PAL chip doesn't help, then I'll know its the sram.

@francoisleveille409 4 жыл бұрын

Bad power supplies is what destroys DRAM in a C64.

@JanBeta 4 жыл бұрын

As Francois says, the DRAM is often destroyed by overvoltage from the original wonky power supplies. MT brand RAM chips seem to die even in storage without ever being used in my experience though so it's always a good idea to replace them in my opinion. The VIC-IIs can develop all kinds of weird glitches caused by overheating or overvoltage, too. I have one that displays some random $ signs on screen for example but otherwise works fine. There are some strange effects with sprites, too, sometimes on some VIC-IIs.

@brianv2871 4 жыл бұрын

While I don't immediately swap out MT ram (just like i don't swap out capacitors unless they're actually bad), they're definitely my first go to when there's a problem. I've experienced exactly what Jan mentioned where the MT ram will go bad just sitting there but being used.. They're not even being stored in bad conditions. I don't swap them out immediately because i have about 6 (usually) working boards but i have two complete cased c64s and those definitely have the MT ram and the crappy silver/gold vic chips swapped out... They're also the same board in this video which i prefer even though the 8701 chips are also a bit temperamental.

@awilliams1701 4 жыл бұрын

@@JanBeta I think it is the Vic, but the way it glitches it could be the sram too. It glitches in 8x8 blocks. The pattern is correct but the colors are wrong. It recently started doing it in Sam's journey. I don't know enough about when color ram is or isn't used but I believe Sam's journey is a game that doesn't use it. Which would make it the Vic. Also affected, giana sisters, impossible mission 1 and 2, Congo bingo, and project space station. Everything else was fine, but I hadn't had time to test again lately and Sam wasn't affect originally. So maybe it's all games now.

@awilliams1701 4 жыл бұрын

@@brianv2871 I actually did keep my working mt ram in the tube the new ram came in. But since i know its going to fail i swapped all 8 chips with the new brand. I can use mt as spares now, but it seems unlikely. Why put off changing all of them if they're going to fail anyway? I can replace them all at once or wait for it to break again. As for the caps, they can and will leak and that will damage the board. Also I did get a slightly cleaner picture after recapping. It didn't cost much to do and it should help with the longevity.

@maxsmarts8210 4 жыл бұрын

Nice work Jan , congrats!!!

@JanBeta 4 жыл бұрын

Thanks Max!

@JoeMcLutz 4 жыл бұрын

Great (and hard) work Jan! I've never seen all the RAMs' substitution! :)

@JanBeta 4 жыл бұрын

I think in this particular case it was best to just replace all the RAM. Too many wonky chips. ;)

@jasmijndekkers 8 ай бұрын

Great job Jan Beta. Greetings from Steven from the Netherlands

@tiemanowo 4 жыл бұрын

I really like your working desk. "Crowded" as mine :). Nice video as always.

@JanBeta 4 жыл бұрын

It always looks like that, even when I tidy it up... :D

@vince_martyn 4 жыл бұрын

Hi Jan, thank you for another informative video. It's thanks to you that I bought one of those desoldering machines and yes I find it gets blocked down at that end of the intake pipe. On the subject of pcbWay, I gave them a chance to quote for some boards I recently ordered but they were quite a bit more than another PCB maker that also sponsors KZfaq creators, so the order went elsewhere. Keep up the great work, from the UK.

@JanBeta 4 жыл бұрын

Thanks! Yes, PCBWay are not the cheapest, never had any quality issues with them though and the service they provide is great. You're free to choose obviously. :)

@brianv2871 4 жыл бұрын

I've used both pcbway and "the other China pcb maker", and there are times, depending on what type of board your making (specifically color options) where pcbway can be the faster and/or cheaper option.

@mrkingston2001 4 жыл бұрын

Great video Jan! Thanks

@michelloenneberger8146 Жыл бұрын

the dead test manual states that if after replacing the culprit ram chip for the one flash, and the dead test still flashes one time after replacing, it is usually the ram associated with data bits 0 and 1 (flashing 8 and 7 times)...which would be inline with your first test where the dead test flashed 6 times (because, if the dead test flashes 6 times I think it indicates that the rams according to 1 to 5 flashes are fine. The dead test stops at first failure).

@macdaniel6029 4 жыл бұрын

C64 videos = best videos :)

@leojrgensen2819 4 жыл бұрын

Nice video Jan 👍

@ChinFu535 4 жыл бұрын

Thanks for the tip with MT ram chips. Got a Breadbin with a black screen a couple weeks ago and the main chips work fine in another C64. Maybe it has these suckers, too

@ingmarm8858 4 жыл бұрын

Hey Jan, happy new Patreon member here to help you over this hill. Cheers from Canberra (like those other two retro ratbags on Twitter ;-) ). Ich kann auch noch deutsch sprechen!

@JanBeta 4 жыл бұрын

Thank you Ingmar, vielen Dank für die Unterstützung! I actually have some relatives in Australia, parts of my family (great aunt/uncle) flew the Nazis to Tasmania and they multiplied down under. Lots of family I don't even know there, I have to visit some time. :)

@jmboyd78 4 жыл бұрын

Heck yeah, Jan c64 video!

@zuimelanieforno4654 4 жыл бұрын

I would say. "Heck No! Where is the Amiga 2000?"

@SeaJay_Oceans 4 жыл бұрын

11:39 Thank you Hong Kong for making C>64s !

@JanBeta 4 жыл бұрын

I'll get back to that soon! :)

@TheDefpom 4 жыл бұрын

Nice work Jan

@JanBeta 4 жыл бұрын

Thank you sir! :D

@SolitaryBro 4 жыл бұрын

Great vid!

@PlasmaHH 4 жыл бұрын

For those desoldering guns, what I usually use is a pair of pliers holding a just fitting small allen key, then heat that one up with one of these mini blowtorches for the kitchen and shove it in. Repeate a few times and its clean, much easier and probably also better for the plastic than poking around in it with a sodlering iron

@artur3edd 4 жыл бұрын

Ah, those MT ram chips) Last e-bay bought C64 had classic black screen, I assumed the PLA could be the problem. Replaced it with Plankton and to my surprise machine started up but with incorrect bytes free. I don`t have a dead test so I tried to load C64 diagnostics program from 1541 test disk and it worked! Program pointed 2 faulty ram chips, after replacing them the repair was done)

@fallofmanbrand 4 жыл бұрын

amazing video

@miked421 4 жыл бұрын

Good Video, as allways. And also very helpful. If my C64 will Show a blinking screen I now know that the ram Chips are the reason. Thx a lot.

@RetroMarkyRM 3 жыл бұрын

sometimes but not always. could be the multiplexers or many other LS chips

@douro20 4 жыл бұрын

I have a drill the size of the bore in those desoldering guns specifically for clearing hard clogs.

@JanBeta 4 жыл бұрын

That makes sense. I'll consider it. Usually I clean the gun part after each use and it works okay, forget it sometimes though. ;)

@kundenbetreuung4921 4 жыл бұрын

I have gotten into the habit of using the cleaning wire on the desoldering gun every time before switching it off. Makes life a lot easier.

@JanBeta 4 жыл бұрын

That makes sense, maybe I should make that a habit, too.

@Oem5 10 ай бұрын

Hi, I would like to socket the chips on my board, can you tell me what the two types that are used (I believe it is only two types for width), obviously I would have to order them according to amount if pins as well. I also seen there are the round hole types. do they work with these and if so are they better?

@PaulinesPastimes 4 жыл бұрын

Another one saved. Cheers.

@JanBeta 4 жыл бұрын

Thanks! It always makes me happy to bring a C64 back to life. :)

@johnharmer394 4 жыл бұрын

Jan, a tip I read about was to place a 5 cent US or similar into the spring in the Glass chamber of the solder sucker gun. All the Solder then splashes against the coin,and doesn't clog the holes. You can then clean it easier as most of the solder is on the coin.

@brianv2871 4 жыл бұрын

I didn't notice his, but they actually do come with a little metal bit the shape of a plus for this exact purpose. I'm not sure if the coin would be better then what comes with it since less air would get through. Of course, it's easy to lose that metal piece during the cleaning process, i didn't realize until i had to replace the glass on mine that i had that it was where this little metal piece i had sitting around was supposed to go.. must have taken it out on a cleaning and forgot to put it back 😁

@JanBeta 4 жыл бұрын

As Brian points out, mine also came with a little metal bit that serves that purpose. I heard about the coin trick, too. I think that applies to some earlier versions of the desoldering gun that didn't come with the metal part.

@bwack 4 жыл бұрын

Thanks for link to my github ! :) Oh, nice, the youtube video chapters on the timeline are great. Did you make them by writing Time stamps: and then a list with timestamps ? or do we need to make the table in the youtube studio ? great work, wow so many dead RAMs.

@JanBeta 4 жыл бұрын

You're very welcome! I have a couple of videos about the various C64 board recreations/replicas coming up soon and am going to show your board in more detail, too. The sections are added to the video timeline automatically if you just put the x:xx time codes in the description. Very useful new KZfaq feature in my opinion. :)

@richardblack5710 4 жыл бұрын

You can Piggyback a RAM chip on top to help troubleshoot. Also it could be the Multiplexer chip for that row.

@JanBeta 4 жыл бұрын

Yes, I've done both in previous videos. The MT RAM chips are almost always the culprit if they are present so I didn't bother this time. :)

@brianv2871 4 жыл бұрын

I've done the piggyback method, but the thing about it is that it can either positively tell you the chip is bad, or it can tell you nothing at all. especially in a situation like this board where multiple ram is bad. I've also had bad ram chips where the piggyback method didn't work on it, presumably there are different levels of bad. 😁

@SaintKaede 4 жыл бұрын

Commodore wooooo~ na really anythin' you do is fine, thank you for pointing out that MT chips fail a lot I'll have to keep that in mind. Danke Jan!

@JanBeta 4 жыл бұрын

Thanks! Yes, MT RAMs are evil, they even seem to die in storage without ever being used. :)

@GoWstingray 4 жыл бұрын

Thanks

@stefanocrespi5424 4 жыл бұрын

4:58 where can I download the full album?

@arjanvanraaij8440 4 жыл бұрын

Hi Jan did you know that you can do ram repairs without a deadtest cardridge. by piggyback a good ramchip on existing chips or by looking at what caracter/letter is random in the screen +nummer of ram in the screen. And google that.

@Lee_Adamson_OCF 4 жыл бұрын

I have that same desolder station, but I had to extensively modify the gun to be able to get the glass cylinder in and out. Have you had trouble with yours? Its like my glass tube is too long.

@JanBeta 4 жыл бұрын

It's not easy to do on mine but I got used to it. It might very well be that there are slight variations though.

@RobA500 4 жыл бұрын

Another 64 lives, great work Jan. Where do you get the Focus 10 music, I really like that type of stuff.

@JanBeta 4 жыл бұрын

Thanks Rob! There's a link to the Focus 10 music in the video description for free listening. One of the songs is also available on CDBaby for purchase. Øystein who makes the music generously provides it for free use in my videos. :)

@DanielSchneller 4 жыл бұрын

Have you ever thought about opening one or more of the failed RAM chips to see if the damage you are suspecting is actually visible (under a loupe or microscope)?

@UpLateGeek 4 жыл бұрын

I recently saw a video going around on the tweeters showing the laser decapsulation of an Apple A11 chip. It was originally from phonefixcraft.ie in Ireland, here's the link: twitter.com/realMaxMeier/status/1271740807637282817. It'd be cool to send them a dead chip and a working one to see if they could spot the difference!

@JanBeta 4 жыл бұрын

That would be interesting but I doubt that I have the equipment to open them in a way that there would be anything to see. Maybe worth a try to use the Dremel or something though...

@DanielSchneller 4 жыл бұрын

Jan Beta that’s exactly what I had in mind. Nothing fancy, just crack it open. If the inside is to small to show the defect, nothing was lost. But maybe you see corrosion or similar obvious things.

@simontay4851 4 жыл бұрын

@@donnied8127 You have to use concentrated fuming nitric acid to disolve the plastic. Its really nasty stuff. You need a fume hood, face mask and protective gloves. Acetone won't do it.

@SimonZerafa 4 жыл бұрын

@@JanBeta Some of the EEPROM programmers will also test 74 series chips and RAM chips. I've often wondered what they would show for an alleged faulty RAM chp 😁

@retrocomputerskarachi6158 3 жыл бұрын

Nice Job. Greetings from Karachi, Pakistan.

@Atari2600_Dude 4 жыл бұрын

Great video, just wondering where you get your ram chips from? Cheers.

@JanBeta 4 жыл бұрын

I found them on eBay a while ago. There was a seller in Germany who sold a lot of salvaged 4164s and I bought some, I don't think there's any stock left at the moment though.

@IanRomanick 4 жыл бұрын

Classic C64 bad RAM whack-a-mole. Fun for the whole family!

@JanBeta 4 жыл бұрын

Lol, indeed! :D

@mertuckan 4 жыл бұрын

you have a green floppy diskette too close to the speaker. I hope nothing very important on it. :) I love your videos. I love the way you are not trying to look cool. very sincere. and I love that you are not trying to make new things. there is nothing wrong with ordinary repair videos. I watch them day and night. but next time don't give away the ending too soon :)

@JanBeta 4 жыл бұрын

Haha, well spotted! That disk was dead when I got it, it's only there for decoration at the moment. :)

@TimothySCarlson 4 жыл бұрын

MT is short for Micro Technology, a memory producer founded in 1978. They were popular in the 80s/90s in computer systems. We used them for a while in GRiD Systems laptops, but found they were junk and we went elsewhere. So sad that 1) they are causing grief some 40 years later and 2) they seem to still be around, probably still selling crappy memory.

@schutz85 4 жыл бұрын

I think micron got eaten up by crucial. Crucial still makes sub-par memory though.

@TimothySCarlson 4 жыл бұрын

From Wikipedia: "Its consumer products are marketed under the brands Crucial and Ballistix." So I guess Micron consumed Crucial at some point. So it's Micron who still makes sub-par memory, as you said.

@awilliams1701 4 жыл бұрын

I've had their memory in DIMM form and never had any issues. But it wasn't a 38 year old computer either. lol

@nickolasgaspar9660 2 жыл бұрын

Freaking MT Drams. I always replace them ALL before starting testing an 8bit machine.

@PLOBEXRIME 4 жыл бұрын

6:30 it goes through a 6.8V diode, I get around 6V on my boards which is expected. Isn't 6.9V a bit too high?

@JanBeta 4 жыл бұрын

It might be a bit high on mine because my power supply provides a slightly higher voltage, also no load might be an issue. I think it's okay. I'll have to compare it with other boards though. Good point!

@senilyDeluxe 4 жыл бұрын

I have a Plus/4 with MT RAMs. I left them in just to see how long they'll last. Last time I used the machine (a year ago...) they were all working fine... to my surprise... I wonder if the Plus/4 uses them in a way that they last longer* but I probably just got lucky, because I keep getting C64s (and a 128) with weird problems and/or not the full 38911 bytes and I don't even need to open it up to know which brand of RAM chips is used... (the 128 was a nightmare as it has 16 of 'em) I also used an MT RAM to fix a Fairchild Channel F video RAM. I only need most of 4 consecutive kilobits working. And since the CPU can only ever write to video RAM, it won't crash if dead pixels start piling up. I see it as a long time test. For desoldering on double sided boards I heat the pins from the other side with a regular soldering gun. I got a bag of random chips from Pollin and while most of them were next to useless to me, it hat a bunch of 6164 RAMs made in GDR! And guess what, they all work! Like 40 or 50 of them! *)maybe higher refresh frequency

@bhstone1 4 жыл бұрын

Jan, can you do a video where you take a stock C64 board and populate it with all aftermarket chips?

@JanBeta 4 жыл бұрын

Yes, I actually have plans for a video like that in the very near future. :)

@bhstone1 4 жыл бұрын

@@JanBeta cool.

@jaycee1980 4 жыл бұрын

ZD915's are awesome but it's annoying when they clog! I use a straightened out paperclip to clean down the barrel as well, and have had to clean a blocked nozzle using a drill bit. Still, much better than using those spring loaded pumps!

@JanBeta 4 жыл бұрын

Definitely a step forward from the "manual" solder suckers. I got used to cleaning mine often but sometimes I forget to do it after use. :)

@pierrerocky 4 жыл бұрын

Great Videos. Ein paar Deutsche trobleshooting und Erklärungsvideos für den C 64 wären nicht schlecht. (Mein C64 möchte nicht mehr so richtig. ) Greetings

@UpLateGeek 4 жыл бұрын

Yeah, I'm worried that other rarer MT memory might start failing. I was recapping my Mac SE/30 the other weekend and noticed it uses MT branded dual port memory for the video RAM. It's pretty rare stuff, only a couple of other manufacturers made compatible products back in the day, and they're hard to come by these days. The SE/30 is a lot more rare than C64, so it'd be a real shame if they start dying just sitting in people's collections! Especially if we can't easily find replacement chips.

@necronom 4 жыл бұрын

My C64 doesn't have them, and I've just checked my SE/30, and I can't see any, though I'm not sure where to look on that.

@JanBeta 4 жыл бұрын

Yes, definitely have seen MT RAMs die just sitting in storage without ever being used, too. But only the 4264s as of yet. I guess they got some of the chemicals wrong and they just degrade over time.

@deborahberi3249 4 жыл бұрын

Is that the right method to Clear up Clogs on the ZD-915? I have one that got clogged before I moved and I couldn't quickly unclog it before packing it up for the move...but I'm gonna have to deal with it this weekend and those 'de clogging' pins didn't do the trick this time...arghh. I figured you have been using yours for some time and should be a good source for really useful tips on cleaning out the clogs that occur. Thanks, Mark.

@UpLateGeek 4 жыл бұрын

The method that Fran Blanche uses is to prop up the stand so the barrel of the gun is vertical with the tip facing downwards and leave it to heat up for at least 15 minutes, then pull the trigger and that should clear the clog.

@jameshearne891 4 жыл бұрын

They normally only clog there if you use the gun too soon after switching it on. The tip has heated up but the tube end is still cold so the molten solder sets in the cold end of the tube. I find it needs at least 10 mins to heat up and you don't have this problem.

@JanBeta 4 жыл бұрын

It's one method I guess, a quick one. I often use the poking thing that came with the desoldering station but sometimes that's not enough and I have to heat the rear end of the gun. Then it's easier to just knock it on the table slightly so the solder falls out. Probably not the best idea for not damaging the heating element though.

@ArthLud 4 жыл бұрын

Good morning 🌞

@JanBeta 4 жыл бұрын

Good afternoon (sorry, I'm late!). :D

@Ikrananka 4 жыл бұрын

I see you have Jupiter Lander on your Dead Test cart. I vaguely remember you saying before that it's good for testing but can't remember what. Could you remind me. Thanks.

@awilliams1701 4 жыл бұрын

If I recall correctly it plays fine on a functional system with bad ROMS. So it's a decent test if your basic or kernal roms are bad.

@JanBeta 4 жыл бұрын

Yes, as Ashley says both the Jupiter Lander and Dead Test carts override the ROMs and work without them. Both use the Ultimax mode (which is a legacy compatibility mode for the Commodore Max which didn’t have any ROMs).

@Ikrananka 4 жыл бұрын

@@JanBeta Brilliant, thanks for reminding me Jan :) Keep up the great work with the videos and I wish you all the best.

@Liberty309 4 жыл бұрын

Just bought a new 64 board :-)

@BilisNegra 4 жыл бұрын

That speaker connector board just happened to be there by chance, or is it intendedly showing as a cliffhanger for a future video?

@JanBeta 4 жыл бұрын

Oh, that indeed is a salvaged part for a project I'm working on. Might very well end up in a video, too. ;)

@francoisleveille409 3 жыл бұрын

My solution to faulty DRAM ICs: www.melon64.com/forum/viewtopic.php?f=34&t=8779 There is even one for the C128 too: www.melon64.com/forum/viewtopic.php?f=34&t=12439

@jaycee1980 4 жыл бұрын

I concur on the Micron chips.. often seen failed... its a bit strange as Crucial (who are Micron!) are one of the best brands of PC memory you can buy :)

@JanBeta 4 жыл бұрын

Yes, they even seem to die in storage without ever being used. My guess is they got the chemicals slightly wrong, similar to some earlier MOS chips and they just degrade over time.

@wesleymoyer5530 Жыл бұрын

Funny - I opened up a dead C64 (black screen) and saw MT RAM, so I pulled all of them, socketed the board, and put new RAM in.. And.... It still had a black screen!! Ended up being the 8701! Oh well - they're socketed now...

@JanBeta Жыл бұрын

Haha, I‘ve been there, too. C64 repair is always good for a surprise. Doesn’t hurt at all to have socketed RAM, even if it works currently. :D

@holleholl3057 4 жыл бұрын

As for the C64 spare parts: concerning the PLAs (which are pretty prone to failure as well) you might want to follow Mr. Adrian Black´s stunning tip to build a PLA out of two cheapo GAL Chips from china , maybe for another video with the help of your sponsor ? ;)) (Auf gut deutsch: mache aus 2 billigen GAL-Chips einen teuren PLA ;))

@JanBeta 4 жыл бұрын

Yes, I already have some circuit boards and GALs for that, but that's for another video. :)

@brianv2871 4 жыл бұрын

yeah, those gal pcbs work great, and the nice thing about them is only one of those cheap gal chips get fried when you accidently stick it in the SID socket because you're swapping chips between two different board types and not paying attention 😁

@catriona_drummond 4 жыл бұрын

All those bent little yellow capacitors trigger me. The cute little blokes are supposed to stand upright T.T

@thomassmith4999 4 жыл бұрын

Not in a C64, they are always laying over after being covered with a RF shield for decades

@JanBeta 4 жыл бұрын

As Thomas said, they often get knocked over by the cardboard shields in the C64s. In some other Commodores they can even short out parts of the circuitry (particularly Plus/4s and C16s), didn't see that in C64s yet though.

@bluetonic9538 4 жыл бұрын

MT Ram, the curse of the Atari XE, if it isn't dead it will be soon

@andrewclegg9501 4 жыл бұрын

All the XEs I've seen have had a NEC in the first position. Seems like if that was MT it would fail during warranty period.

@JanBeta 4 жыл бұрын

Yes, the MT 4264 chips seem to be particularly bad, I've seen many fail, even in storage without ever being used.

@bluetonic9538 4 жыл бұрын

@@andrewclegg9501 I think that Atari did that to get them through QC at the factory. 40 years later all of the Mt ram is suspect

@christianberthelette299 4 жыл бұрын

Hi . Nice video.I have dead test card and my last week repair on c64 black screen say one blink ...all ram test ok on another board ,multiplexer ok! I have take out PLA and yes problem is PLA first for have good screen picture and next bad chip CPU cause don't load big program and screen,picture problem....so the dead test card say one blink u12 or another ram 🤥🤥🤥🤥🤥🤥.....lol!!!!!!

@olegkostoglotov8800 4 жыл бұрын

According to what I could find the RAM chips are still available, are these RAM chips 4164s? If any are getting hot that means they are shorted inside and have to go, but what may have caused the failures could have been a defective original power supply. An interesting web page I found on this subject: neperos.com/search.php?a=pt7298fccd6145e6 . All this reminds me of a retired TV repairman I knew who fixed up C64s and C128s back in the 1990s, and even later, people bought them off of him for use as word processors. He used to remove the defective chips by cutting the legs with a wheel in a Dremmel tool, and then desoldered, and removed them individually, after which he installed sockets for their replacements.

@Kasi11 4 жыл бұрын

Ja ohne MOS nix los!

@Roman_Comrad 4 жыл бұрын

Today, a computer can be repaired in 5 minutes. In the years 80-90 it was difficult ...

@ArjanvanVught 4 жыл бұрын

Today repaired in 5 minutes? It is replacing very expensive parts today, no solder iron needed. Not really repairing.

@schutz85 4 жыл бұрын

Repairing a modern computer is more than just taking out an expansion card and replacing it. There could also be underlying software and other hardware problems. Especially if you use windows.

@Roman_Comrad 4 жыл бұрын

@@ArjanvanVught I use an infrared soldering station and I see no problems with this. Laptops, video cards, motherboards and other modern devices are easy to repair, and also including reprogramming using a programmer (for me this is not a problem, today)

@painkillergko 4 жыл бұрын

My MT Ram Chips was bad one week after repair:(

@JanBeta 4 жыл бұрын

Yes, I literally saw MT 4264 chips die in storage without ever being used. No idea what's wrong with those chips, I guess a similar chemical problem like with some of the earlier MOS chips. They seem to just be degrading over time.

@daddlertl3 4 жыл бұрын

Erste Frage im Forum64, wenn jemand ein kaputtes Board hat "Mach mal ein Foto von den Chips" oder "Sind da MT-RAMs drin ?" :P (ja, diese MT-RAMs sterben wie die Fliegen; auf einem Retrotreffen hatte auch mal jemand einen C64 mit RAM-Fehlern, die sich in falschen Zeichen auf dem Bildschirm geäußert haben - ich habe in den Rechner geschaut und MT-RAMs gesehen und ihm gesagt, dass er die tauschen sollte und es dann wahrscheinlich wieder geht)

@JanBeta 4 жыл бұрын

Ja, nach meiner Erfahrung sterben die MT RAMs sogar als NOS Chips, ohne dass sie jemals benutzt werden. Vermutlich gibt es da ein Problem mit der chemischen Zusammensetzung bestimmter Layers, ähnlich wie bei einigen frühen MOS Chips. Die zersetzen sich anscheinend mit der Zeit selbst und werden zu Kurzschlüssen.

@francoisleveille409 4 жыл бұрын

DRAM of that kind is not made anymore. What you need is Saruman-64 ! A single chip replaces all 8 DRAM ICs. www.melon64.com/forum/viewtopic.php?f=17&t=8779

@brianv2871 4 жыл бұрын

It might not be made, but it's still plentiful and cheap. That DRAM alternative might be required one day, but for now it seems like buying NOS ram chips would be the easiest and cheapest option, especially if only a couple are bad.

@francoisleveille409 4 жыл бұрын

@@brianv2871 Another advantage of the Saruman-64 board is that it consumes less than 10mA, half the power on an LED for all the RAM a C64 needs except the color RAM so there is much less load on the power supply.

@francoisleveille409 4 жыл бұрын

@@brianv2871 I don't know where you find old 4164 and 41464 'plentiful and cheap' but I can tell you just about everything you find on eBay that's from China are fake chips that don't work. Here in Montreal Canada, Abra Electronics used to have a large supply of these but they are now mostly gone.

@psteier 4 жыл бұрын

"I would not recommend to use a screwdriver..." ... *putting screwdriver twice under the chip* ... :) ... Jan, you have to follow your spoken rules... :D

@JanBeta 4 жыл бұрын

I know, I know... :D I do it all the time, just won't recommend it because you easily damage traces if you don't do it carefully...

@brianv2871 4 жыл бұрын

amusingly i have the same puller as jan and also a few regular chip pullers, but i also predominantly use a screwdriver as well. While you have to be careful with the screwdriver, i actually would recommend it if the chip has been in there since the 80s since you can better wedge the chip out without breaking it (which I've seen happen with the chip pullers).

@psteier 4 жыл бұрын

@@brianv2871 I did it also with a screwdriver for some reasons, but I've tried now tools from iFixit and they are nondestructive, because not out of metal. The best tool I've saw was a bent screwdriver with a shrink tube covering the metal tip. Worked very well. I've also used the standard chip puller and once damaged the chip, because of pressure - it slides away and some legs were gone... chipped them off.

@teufelslama5496 4 жыл бұрын

i do have the same desoldering-station... and you know what... it SUCKS! :-) "leg thumper" (Schenkelklopfer *g*)

@JanBeta 4 жыл бұрын

Lol, yes, it sucks pretty badly... ;)

@jeffm2787 3 жыл бұрын

Just call them Micron chips, not MT. MT is Micron Technology. OK, I've pointed this out in enough video's now. 😎

@transilvanischervampir666 4 жыл бұрын

Ich hätte gleich von Anfang an alle RAM Chips ausgelötet und gesockelt..wenn man schon dabei ist ....spart man sich irgendwann wieder das rumlöten...

@JanBeta 4 жыл бұрын

Ja, ist bei den MT RAMs auf jeden Fall meistens die beste Idee. Habe ich am Ende ja dann auch gemacht. ;)

@SeltsamerAttraktor 4 жыл бұрын

You know, there is not much point in making a riddle out of it, if you put the answer in the title.

@JanBeta 4 жыл бұрын

Good point! I wanted to warn people about the MT RAMs very prominently though... ;)

@eightbit1975 2 жыл бұрын

C64 MT RAM = Shit. If you have this memory, get rid of it!

@catriona_drummond 4 жыл бұрын

"We have a CIA problem" - Terrorists and C64 users.

@JanBeta 4 жыл бұрын

Lol, yes. I wonder if they had that in mind when they named the chips. Some of the Commodore/MOS engineers seem to have quite a good sense of humor in general. :)

@simontay4851 4 жыл бұрын

9:15 The back of your hand is very hairy. have you ever considered trimming/shaving the backs of your hands ?

@JanBeta 4 жыл бұрын

You should see my legs!

@catriona_drummond 4 жыл бұрын

No shaving! He looks good the way he does! :P

@gerdbaier9437 2 жыл бұрын

Wäre schön wenn du Deutsch sprechen würdest. Es gibt schon 1000 andere Englisch sprachige Videos, da wäre ein Deutsches irgendwie schöner. Verstehe es zwar so auch, aber müsste ja nicht sein.

@JanBeta 2 жыл бұрын

Yo. Ich mache die Videos auf englisch, damit mehr Menschen die verstehen können (du ja auch). Ich möchte mich nicht auf die deutschsprachige Retroszene beschränken und finde die internationalen Kontakte sehr spannend. Das Internationale war auch von Anfang an mein Hauptziel. Anfangs dachte ich mal blauäugig, dass ich eventuell die Videos sowohl auf deutsch als auch auf englisch veröffentlichen könnte, aber das ist leider bei weitem zu viel Aufwand.

@gerdbaier9437 2 жыл бұрын

@@JanBeta ja so gesehen hast du schon recht, aber man findet leider immer weniger Deutsch Sprachiges in diesem Segment, aber ich versteh deine Einstellung da schon. Trotzdem danke für deine Rückmeldung. Glaub du benutzt eine Weller WS81 Lötstation, oder? Wie zufrieden bist du mit der?

@johnsweda2999 4 жыл бұрын

I just don't see the logic of using old boards slow processes where you could use a Raspberry Pi or Arduino and just burn the ROMs onto that ,,

@catriona_drummond 4 жыл бұрын

It's a matter of taste. Some people like the old Hardware, the feel, the smell, the sounds. Some people love their old cars precisely because they don't have modern features. And emulation does have an input lag problem. If anything then FPGA based solutions.

@johnsweda2999 4 жыл бұрын

@@catriona_drummond you can still put it in the original case connected up to the original peripherals connectors just the motherboard would be replaced, and you limit the appeal to the Next Generation who might take the baton on and go further with it. Just having an Commodore emulator is not the same. That's what I'm saying there is no emulation! in this process, You're not emulating by doing it this way! your programming with the original program software in ROM the only difference is the hardware chips that would act as the original but with more features scope be added if somebody wanted to write the program for this purpose. you just making another generation of Commodore carrying on from where it left off it's like having ms-dos Mac Linux, could be Commodore Unix I think that's what it's based off. I don't know is it based off Unix or is it Pascal? A whole new generation of software games other functions could be brought be bought back to life, could come a mainstream operating system and hardware once again for the modern world If enough Enthusiasm for it people with the know-how, but just seems like people scratching around in the dark instead of getting together as a community and you have a big workforce could be done just the same as Linux open source but can't be done on old ancient hardware. Has anybody laid out the ROMs the original on a database that's what needs to happen. If you've got these for all the machines you can program any type of board chip computer to act like a Commodore even your phone

@thomassmith4999 4 жыл бұрын

While the BMC emulator on a Rasberry pi is by far the best C64 emulator the world has ever seen it's still not quite as fast as a real c64 (it's very good though). Also it only has composite output to a CRT and not S-video (or RGB which you get on the U64). So it depends how good you want your setup. Emulation is still a clear 3rd place thing.

@svivs 4 жыл бұрын

Hi. 🙂 The whole point of emulators is to emulate the hardware (the 6510 cpu, the sid chip, the pla, etc), but it will always be imperfect, at least because of the analog circuits and also because it’s difficult to reverse engineer some of the chips perfectly. Then there are all the obscure bugs and quirks in the hardware that are used by some software like fast loaders and the demo scene. The hardware is the whole point of this really. It’s making the hardware work today and perhaps do even more than before with new and modern software. 🙂 The commodore 64 machines ran microsoft basic, not unix btw. Of course emulators are great and easy to use, and is probably what will preserve the commodore machines for posterity. If you want new hardware in an old looking enclosure I would suggest 3D printing and a raspberry pi like board inside. 🙂

@barnabas5688 4 жыл бұрын

I think maybe this channel isn't for you, John.