I've never seen one fail on an Amiga PSU, and I've also never seen one where both the live and neutral connections fail at the same time either! In this case I am sure it was just corrosion that did it.

Yes, that's a good idea for sure!!!

Do you think it might be a good idea to put one of those mini heatsinks meant for a raspberry pi around that hot resistor?

The problem would be mounting it to the two resistors (without shorting anything). The better solution might be to replace the resistors with ones that handle twice as much current (instead of 1/4 watt, go with 1/2 watt), and leave the legs longer so they sit further away from the PCB. You would need to put insulation or heat shrink around the extended legs though.

Thanks =D

Thanks lol =D

Thanks! There are 2 reasons to remove the fuse - 1) To test it 2) to make sure its 3A and not 5 or 13A...

Check the switching transistor and bridge rectifier before you power it back up to make sure they aren't shorted.

Cheers mate! Long time no see - really miss videos on your channel!!!!!

Hehe, thanks mate! Sorry it's not mega interesting content this week, but I do have a number of Amiga repairs coming up!

@@GadgetUK164 We can all learn from the simplest of things. I dare say there's peeps out there that do not realise bulbs need to be replaced, for example.

Cheers =D

Thanks

Haha =D

To my knowledge Commodore's factory in Braunschweig didn't build PSUs?

@@danielmantione The backside of the plastic cover has an imprint: "Made in W.-Germany" which, in 1987 and further on, was Braunschweig. I'm sure they just put it all together but "LOTSEITE" is definitely german.

@@DerMartexus That's true, but... the sticker on the transformer says that is made by Ismet, which was one of Commodore's power supply manufacturers. If you look at some of the documents we have from Ismet, such as the Commodore 128 power supply schematic, it says "Schwenningen": www.zimmers.net/anonftp/pub/cbm/schematics/computers/c128/power/ps-128.gif Ismet still exists and if you visit their website, you will still see that they are still situated in Schwenningen today. As far as I understand it, Commodore Werk Braunschweig did assembly of the computers: Mainboard, keyboard, floppy drive were installed into the cases, then combined with assesories such as the power supply and packaged. It looks like the vast majority of computers made in Braunschweig have the Ismet power supply, but it is not a rule: It looks like some of the West-German Amigas got shipped with power supplies from Dee Van.

@@danielmantione Aaah, thanks for researching! :) That's an interesting backstory.

Great idea!

OMG £8 !!!

My last 500+ was £8 too lol - mum and dad picked it up from a car boot sale.

There are different versions of the PSU! Some of the UK ones are probably similar (if not almost identical) to the one you have! I might get chance to look at others in future!

@@GadgetUK164 I will try to put up some photos on instagram later of mine and tag you

Commodore had several manufacturers of the PSUs: I know Ismet, Dee Van and Mitsumi. There is a sticker on the transformer that says "Ismet", so this was a PSU manufactured by Ismet. The PSUs between different manufacturers look identical from the outside, are electrically very comparable, but the construction is completely different. Besides this, there are 2.5A Amiga PSUs and 4.5A PSUs. Both types were made by the different manufacturers. And there are also different voltage versions. So all in all, there are quite a few different PSUs out in the field and it is always a bit of a surprise what you get. However, Ismet seems to be most common in Europe.

Conformal coating is just a coating they sometimes cover a PCB with, to protect connections from corrosion or the elements.

Which game?

@@GadgetUK164 the one shown in video. Packland?

I thought it was a completed game? Pacland!

Yes, a nice tip someone else just posted too was to perhaps replace and leave longer legs on them!

Thanks! I used to work in the industry, but way back in 1994 ish I moved into Software Development (not through want but need at the time, and just ended up spending most of my career in the software side rather than hardware).

Thanks! Yeah, I did mention it might be used by the audio stuff but couldn't quite remember on this boards.

When you use a fuse larger than it needs (and it needs a 3A), that means if the device develops a short, it could pull up to the capacity of the fuse. So for example with a 13A fuse that means the cables and PSU could get super heated whilst 10A is drawn due to a direct short somewhere. Next thing you know you have a fire!

It's ages since I looked at an A2000 PSU, so off the top of my head I am not sure. You might want to re-inspect it to make sure the cap solder points are correct. I am not sure if the -12v comes from a 7912 or something similar on there, it could just be a failing regulator.

Alice! - Who the f*ck is Alice? (Roy Chubby Brown)

Indeed lol - Who the f*ck is Alice? It's Alison!!!!

@@GadgetUK164 My bad, I'm terrible with names Bob :/

@@Neffers_UK No problem Dave!

@@GadgetUK164 Haha, good old Trigger :D That scene where Rodney is sat with him in the town hall and Rodney explains it nice and slow. So brilliant.

There are a few things to consider when you are struggling to desolder. The first is temperature - if the solder is just not coming out of the hole at all I would suspect you aren't using enough heat, or an iron with not enough power. Flux does help, but often I just use leaded solder containing a flux core. You can use separate flux, something like Chip Quik or Amtech. Regards the Amiga not reading the CF card HDD, it could be a damaged connection on the motherboard where the old capacitors have leaked. Clean up leaked electrolyte with white vinegar, and then IPA. You may then need to work out where traces are damaged using connectivity test on a multimeter, and bridge any broken connections with kynar wire or something similar.

@@GadgetUK164 Oh through-hole are no problem, I use a solder station so I can turn up the heat on stubborn componants and add fresh solder to the old stuff before drawing it off with a solder vacuum, but the caps in the amiga are just a pain because of the way the pads are positioned. It makes it hard to desolder one side and lift it so you can desolder the other side. My solder is all flux cored, but I have a pot of waxy flux too which I've only recently started to use. Honestly, I didnt know what it even was, as all the flux I've seen people use has been liquid. As to the IDE, I was afraid that this would be the case, I cant SEE any track damage but that could all be around the pins of the IDE header. There was I think a little fuzzing of surface componants but it sure did stink of fish so the leak may be worse than it appears. I didnt know that pain white vinegar and IPA would clean it out though, I'll get some as soon as I can. Any damaged tracks I tend to use lines from an old IDE ribbon cable, small and flexable, and not much thicker than the original tracks in many cases. I and my 'miggies thank you ^_^

There isn't! And it's not as essential as that type of failure is a lot less on Amiga Power Supplies. You can get more modern PSUs for the Amiga.

It filters high frequency noise from the mains there! The name is a clue - it kind of "chokes" the connections so only lower frequency can pass through.

@@GadgetUK164 Ah. That makes sense. Thanks Chris. Learned something.

@@GadgetUK164 It is the other way around! Allthough it is true that the choke stops high frequency noise in both directions, the goal in a switched PSU is more to prevent high frequency noise from escaping *to* mains. The mains wires in building are fantastic radio transmitters, therefore noise generated inside power supplies is better kept inside.

Ah, I never knew that and actually that makes perfect sense!

Good point! We used to have a coal fire! In this case it was from cigarette smoke though - you could smell it when cleaning the PCB. Nice and clean at the end though!

Thanks, yes, I gathered I could just have bypassed it but didn't want any noise problems!

I see no need to install a Meanwell in there! They might be more efficient, but these things have lasted 30 years so far, I expect they will last another 30 once fixed.

@@GadgetUK164 probably true but id rather be om the safe side replacing internals for my daily driver 👍

One thing you cannot be sure of - how will the meanwell fail, will it spike one of the voltage lines, will one line go higher than it should (eg. 10v instead of 5v). One thing with these old Amiga PSUs is at least you know how they've been failing over the last 30 years - in predicable ways that often just means you need new caps or a resistor and your Amiga didn't die as a result of the failure. The other problem is they don't seem to use decent caps - how long they will last is anyones guess.

Not all transistors are heat sinked! This design didn't rely on a heat sink!

@@GadgetUK164 Thanks for the info, I came to the same conclusion while watching the video. This transistor looks different to those I have in my PSUs. Good to know :). BTW, the bottom side of the board comes with a thick coat of flux from the factory. Probably that's why it picked up all the dirt during the decades. Awesome video BTW, I'm glad to see another Amiga PSU repair video! Thanks!

To be fair, a heat sink could help with the life of the transistor, so it's certainly a way to help extend its life perhaps!

The tolerance marking on caps indicates that they can be a % lower or higher than they are rated! You can swap out smoothing caps on a PSU like this with a higher capacity. Sometimes it helps! On the ST PSU for example, uprating the 2200uF caps to 4700uF caps gives better stability. Any capacitor used as a filter, or for timing, coupling signals etc should be replaced like for like, but smoothing supply rails you can generally uprate.