Nasty hum when you turned up the 'reverb' control. Not the pan or the cables!
Пікірлер: 130
@DennisVanderklompen2 ай бұрын
The skills are being passed on! I'm going to show my kid the bit about "legend up" on the caps. He's not into this kind of thing but it's wisdom that can be generalized. Thanks for these videos, very helpful.
@stuartukguitarampguy58302 ай бұрын
Hi Dennis. Great idea!
@fiddlix Жыл бұрын
Those IC filter caps on Fender amps have been a dogs breakfast for amp techs. Great fix to an all too common problem.
@stuartukguitarampguy5830 Жыл бұрын
Thanks David.
@martinreid1740 Жыл бұрын
Great diagnosis, guys like you are tremendous asset. I hope your skills have been passed on.
@stuartukguitarampguy5830 Жыл бұрын
Hi Martin. Alas no but my main reason for doing these vids is to help aspiring amp techs.
@zbaby82 Жыл бұрын
Fender uses glue that will last about thirty years to hold in electrolytic capacitors that will last about four years. Nice job Stuart.
@stuartukguitarampguy5830 Жыл бұрын
Cheers Zack!
@wuldntuliktonoptb68619 ай бұрын
Warranty is 5 years so the caps are specifically chosen to last 5 years and a day. They save 50 cents per cap using them.
@michaelevans3852 Жыл бұрын
Fantastic show here. I have one just like this from 2017. I have not had this issue, but it's good to see potential problems. It's always nice to seethe simple stuff again as a reminder. Thanks again for your expertise in the use of schematics. Always entertaining/educational. Wonderful job Stuart.
@stuartukguitarampguy5830 Жыл бұрын
Cheers Michael
@alexdeleon7135 Жыл бұрын
Well deduced, Stuart! I give full marks for the brilliant modality in diagnosing this odd issue. To confess, it is one I have never seen occur. I am elated the customer agreed to the replacement of the caps in the doghouse. F&T are very reputable, and rarely if ever, fail. Since Leo's death, Fender has become a corporation who is single-minded of purpose to value profit far above quality. He must be spinning in his grave. Since he started with radio repair, his entire mantra was to design his amps to be serviceable. It is shameful that his legacy has been bastardized to the degree it currently resides. Thank you for posting this. I raise a pint to your health. Cheers!
@stuartukguitarampguy5830 Жыл бұрын
Thanks Leon, yes I've not come across this before either but if you see elwrongo comment above it's apparently quite common.
@goodun2974 Жыл бұрын
Some of the other techs I subscribe to on KZfaq are also using MOD capacitors and have had good results with those so far.
@stuartukguitarampguy5830 Жыл бұрын
@@goodun2974 Ok. JJ also now produce a range of HT caps. I wonder what they are, really. Hard to believe they make them in house. But they could, I guess.
@goodun2974 Жыл бұрын
@@stuartukguitarampguy5830 , TAD [Tube Amp Doctor] also sells their own line of capacitors.
@BradsGuitarGarage Жыл бұрын
@@goodun2974 That's "Tube Amp Doctor"
@edwardhannigan6324 Жыл бұрын
Nice clean fix Stuart, very interesting...Love the way you sneak around the amp and show practical examples of why these faults occur. Like the tea towel, cool info..Thanks for sharing,..Ed.UK.😀
@stuartukguitarampguy5830 Жыл бұрын
I'm never without my tea towel!
@edwardhannigan6324 Жыл бұрын
@@stuartukguitarampguy5830 😂😂
@pda49184 Жыл бұрын
Great video Stuart.. Faultless diagnosis and a valuable lesson in reading a schematic. I wont repeat my mantra about Fenders production policies as I'm sure by now we're all aware of them. We must remember that Leo Fender was a skinflint and cut every cost he could on his product production, but the one thing he wouldn't do was sell you short term reliability.
@elwrongo Жыл бұрын
I've seen the issue on 3 Deluxes Reverb Reissues, great diagnosis, well done! Everybody always thinks its the pan , tube or leads.
@stuartukguitarampguy5830 Жыл бұрын
Damn I wish you'd been around to ask! I spent WAY longer than the video shows chasing hum loops etc.
@Tyler75D Жыл бұрын
Great channel! I have very little experience with amps but like to fix electronic devices in general. Your channel gives me access to so much experience (that I lack) which makes troubleshooting that much easier! So thank you so much for sharing these videos!
@_alexsams Жыл бұрын
Another channel to look into - Psionic Audio - Highly recommended!
@vintageguitaramp_guitarteacher Жыл бұрын
I see you have the 4 x 12 Marshall cab under the bench. A mandatory workshop tool. I have one too. Another good video Stuart. Thank you.
@stuartukguitarampguy5830 Жыл бұрын
Cheers. Yes I bought it cheaply because the actual cab is in shocking condition.
@waynewayne37093 ай бұрын
Skiled repair by very time served electronics engineer.
@stuartukguitarampguy58303 ай бұрын
Thanks Wayne
@1paparico3 ай бұрын
My Deluxe reissue reverb works fine but not with the vibrato, its one or the other even after changing the pedal! seems these should be called fender electronic issues.. Great diagnostic BTW!
@electrolytics Жыл бұрын
Thanks Berkshire Amp Repair. Rock and Roll.
@stuartukguitarampguy5830 Жыл бұрын
Glad you enjoyed it.
@theoloutlaw Жыл бұрын
Funny you talk about solder braid, I've also gone back to using it as my mine solder removal. I have the pumps, and even a good vacuum solder station, but I still like the 'wick' for the most part, especially on older gear with fragile traces.
@stuartukguitarampguy5830 Жыл бұрын
Exactly the ame for me. I have all the other gear but default to braid.
@soupforare Жыл бұрын
Lovely, helped me down the road with my Twin. Bless
@stuartukguitarampguy5830 Жыл бұрын
Glad to have been of service!
@jerryogle8798 Жыл бұрын
Great Job Stuart ‼️
@stuartukguitarampguy5830 Жыл бұрын
Thanks Jerry.
@GreboGent10 ай бұрын
I always find it funny that the capacitor outline on the pcbs better matches the caps you fit than those horrible ic caps, maybe whoever designed it had the better caps in mind originally? Then the budget department stepped in during production
@stuartukguitarampguy583010 ай бұрын
Hi I've never really noticed that before, but now you point it out...
@5barkerstreet Жыл бұрын
brilliant Stuart!!!!
@stuartukguitarampguy5830 Жыл бұрын
Thanks Paul.
@dennismasterton38348 ай бұрын
Good detective work Stuart.
@stuartukguitarampguy58308 ай бұрын
Cheers Dennis.
@gingercat777 Жыл бұрын
Nicely done, but you gave me the yips when you have the cap in the wrong orientation in the prep 😉
@bjornstromberg797511 ай бұрын
great fix. as usally I learnt something new
@stuartukguitarampguy583010 ай бұрын
Thanks Bjorn
@davescupper5789 Жыл бұрын
After watching your videos i think i might get the capacitors changed after buying a fender tube amp. Id quite like a vibrolux reverb or deluxe reverb. They are pretty expensive,you would think fender would use better capacitors. Brill video again,im learning a bit more each time i watch your videos.
@stuartukguitarampguy5830 Жыл бұрын
Thanks Dave I'm pleased you are enjoying them.
@user-rf9me7xm1w Жыл бұрын
Back in the day I was an examiner for City and Guilds electronic servicing courses, we always recommended the use of de-soldering braid. I find your videos fascinating and really useful as I use a 1973 pro reverb which has the dreaded turret board leakage problem. I’ve yet to try cleaning it in an attempt to reduce a bit of slight crackling. I’ve been into the doghouse (haven’t we all) and changed all the capacitors and received a shock (not electrical) as to how expensive the replacements were. Now Maplins are no longer in business, are there any similar retail companies in existence?
@goodun2974 Жыл бұрын
Psionic Audio on KZfaq has done a number of videos on measuring for, and removing conductive residue from Fender eyelet boards.
@user-rf9me7xm1w Жыл бұрын
@@goodun2974 Thanks very much, I’ll have a look, much appreciated.
@wsscott724 ай бұрын
Stu-Love your projects, and some of your shortcut methods that you have learned from experience and that seem to work so well. I saw the video of you using a Megger to test a capacitor in circuit for leakage, and thought that would be a great tool to have, so I bought a BM100/4 off of eBay, and now I'm trying to learn how to use it. I have its manual. I wanted to start by testing some old caps that have been removed from the circuit, and I didn't know if the Megger can be used to test out of circuit or not. The manual implies that the testing is done in circuit. Anyway, could you help me with this to get me up and running! Thanks again.
@stuartukguitarampguy58304 ай бұрын
No you can definitely test out of circuit. Check what DC voltage it produces though. You don;t want to put 1000V across a 400V cap!
@wsscott724 ай бұрын
Thanks. It's just a 20uf 300VDC electrolytic cap. So I wanted to do the insulation testing that you did. The Spec Sheet indicates that the Insulation Test Voltage for the Megger is 500 VDC. Since my cap is old, it's from a 1975 Fender Music Master amp, and is only 300 VDC, it looks like the Megger's test voltage would be too high, and it would blow the cap. Am I correct?
@wsscott724 ай бұрын
I've just learned that you cannot test electrolytic caps for leakage with a Megger! But its still handy for coupling caps where we don't want any DC leakage to pass through with the AC.
@stuartukguitarampguy58304 ай бұрын
@@wsscott72 Defintely not! Coupling caps only - and higher voltage ones at that.
@katherinemacdonald99099 ай бұрын
Thanks very much great to see , I have this hum/ buzz on my fender stage 100 it gets louder n louder and you can’t turn anything down to stop it. Turning it off at the mains is the only way , only happens if played load or distortion is switched on , any advice would be greatly appreciated as I’m about to take it apart to find this 4 year old fault.
@katherinemacdonald99099 ай бұрын
Annoyingly I have a schematic drawing I got when this first happened and just can’t find it.
@katherinemacdonald99099 ай бұрын
This is Craig Macdonald not my wife Katherine 😂
@johnbravo7542 Жыл бұрын
Thanks Stuart
@stuartukguitarampguy5830 Жыл бұрын
Glad you enjoyed it John.
@paulp2033 Жыл бұрын
H Stuart. Really enjoying your channel and working my way through all your videos. As I really enjoy your teaching style I wondered if you might be prepared to do a tutorial on using an oscilloscope with guitar amps. I have watched loads of these but haven’t been totally convinced by any. Best regards, Paul
@stuartukguitarampguy5830 Жыл бұрын
Hi Paul I'm pleased you are enjoying the channel. Thanks for the suggestion, I might do that video at some point.
@BryanClark-gk6ie11 ай бұрын
65 DRRI ' when the reverb is turned on 10 it sounds like it's on 1 ' barley any reverb. It wasn't like that until I got it back from having it worked on. Has new tubes and supposed to have been recapped. Any idea?
@stuartukguitarampguy583011 ай бұрын
Hard to say. Low revern is a tougher problem than no reverb. Long shot make sure the phono plugs are pushed firmly into their sockets. Sorry can;t help much more.
@krauz11110 ай бұрын
great stuff
@stuartukguitarampguy583010 ай бұрын
Thanks!
@miguelrichartmellado2834 Жыл бұрын
Good job frend. Allways.
@stuartukguitarampguy5830 Жыл бұрын
Cheers Miguel.
@jerrymcgeorge4117 Жыл бұрын
The 220uf/100v cap is not the bias cap, it’s part of the odd Fender asymmetrical power supply caps, 47/500 + 220/100. All done to give the power supply 600v capacity.
@stuartukguitarampguy5830 Жыл бұрын
Hi Jerry Okay, wow I didn't know that and didn;t check the schematic for this amp. Thanks for the info. I did wobder why it was 220uF which seemed high for the bias cap.
@goodun2974 Жыл бұрын
Yeah, I noticed that on the schematic and wondered "what the hell was Fender thinking"? Dissimilar series-wired capacitors not only increase the voltage handling of the pair, as one would expect, but also form a capacitive voltage divider, where the voltage inbetween those two caps isn't exactly half of the total B+ voltage, which might be handy if they wanted to tap off say 50 or 60 volts or so, whatever the difference might be at that point between the two caps, but it's not being used. (Also note the two different values of bleeder/balancing resistors). Or perhaps they just had a surplus of inexpensive 220 mfd, 100 volt caps. Otherwise, you'd expect to see a series pair of 47 mfd or even 100 mfd caps rated for 350 volts each.
@BradsGuitarGarage Жыл бұрын
@@goodun2974 I'm thinking the surplus was the case. Otherwise, I don't know what they were smoking that day. I just jumper it and use a 500V axial with capacitance value to user's taste.
@markwhitney56679 ай бұрын
It's not needed, since the voltage is less than 400 volts. Some folks take the 220uF a and the
@markwhitney56679 ай бұрын
And the 100k resistor out. Jumper where the 100k was.
@davidsimpson3380 Жыл бұрын
Thanks again for the tips Stuart! Also, I really like your theme music and logo! Did you play/write it?
@stuartukguitarampguy5830 Жыл бұрын
Thanks David. No I got it done on one of these creative websites where freelancers pitch. Cost about £50 from memory!
@davidsimpson3380 Жыл бұрын
@@stuartukguitarampguy5830 Thanks Stuart, I get a kick out of it every time I hear it :)
@MattAnthony-rq3cf2 ай бұрын
Hi Stuart - thanks for that. I notice you replaced C31 which was 100V 220uf with a new 100V 100uf. Obviously works from the video - but is that a normal thing to do. Thanks!
@stuartukguitarampguy58302 ай бұрын
Hi Matt I can;t recall tbh, but the correct value is 220uF 100V. Maybe I made a mistake? It wouldn;t make a huge difference.
@MattAnthony-rq3cf2 ай бұрын
@@stuartukguitarampguy5830 Thanks Stuart
@datamouth7 ай бұрын
man i wish i could do this to my Fender Twin. i have horrible noise coming thru the reverb channel.
@stuartukguitarampguy58307 ай бұрын
I hope you manage to get it sorted!
@michaelevans3852 Жыл бұрын
Stuart, I'm looking for a good capacitor tester, could you make a recommendation please. Thank you, Mike
@stuartukguitarampguy5830 Жыл бұрын
Hi Mike. Loads of them in eBay at about £30. They're all pretty much the same.
@fernandocesarmartins515 Жыл бұрын
Hi Stuart, I have a Fender Hotrod Deluxe that the reverb volume is very low, you can hardly hear it. I already replaced the Potentiometer, I already tested the pan, I already reviewed the coax cables and I can't find the problem. Can you give me any more ideas please?
@stuartukguitarampguy5830 Жыл бұрын
Hi Fernando. Seems like you've tried the obvious stuff. I'm afraid you're going to need a tech to take this further. I hope you get it sorted.
@richwallace6854 Жыл бұрын
I bet there are a number of your viewers that would like to build t.heir own "Stuart's Orininal capacitor box". What doe you say, Stu? Would you show a little schematic?
@stuartukguitarampguy5830 Жыл бұрын
Hi Rich. Ok it's quite simple. Put a 100uF 500V cap in a box and bring out two wires, ground and positive. Across the cap put a 220K 2W resistor. This discharges the cap (slowly) if you happen to leave it charged, so next time you go to use it, it won't be 'live'.. Now put a momentary push switch in series with a 1K 5W resistor across the cap. Pushing the button connects this resistor across the cap, discharging it in a few seconds. Note there is a certain danger with this item. If you put the probes across a live cap in an amp, then removed the probes, then grabbed hold of the end of each probe you'd get a nasty shock as the internal 100uF cap discharges through your body! So you need to treat it with respect. I hope that helps.
@_alexsams Жыл бұрын
You might like the YT channel - Psionic Audio. Lyle an Amplifier Tech from Memphis Tennessee. Thanks for the upload Stuart!
@stuartukguitarampguy5830 Жыл бұрын
Thanks Alex, yes that's one of the channels I watch.
@clintronicsrva Жыл бұрын
Yeah the gray IC caps are defective. Should always replace them when you see them. They sold the company and the new owner corrected the defect and changed the color to blue.
@stuartukguitarampguy5830 Жыл бұрын
Interesting, so were the new blue caps better?
@clintronicsrva Жыл бұрын
@@stuartukguitarampguy5830 yes I haven't had a bad one show up yet of the blue ones
@mackk294Ай бұрын
I just got mine B-Stock from Thomann, and the issue is idle hum noise, not super loud but still wish it was reduced, do you think replacing the tubes would be a good idea to start off?
@stuartukguitarampguy5830Ай бұрын
My view is that it wouldnt help. Hum can be caused by so many things, alas.
@mackk294Ай бұрын
@@stuartukguitarampguy5830 what about other models? 65 or 68 custom pro,same issues?
@stuartukguitarampguy5830Ай бұрын
@@mackk294 I can;t recall tbh!
@mrunit7261 Жыл бұрын
Hmmm, dunno. (Pardon the pun) I've got two of these amps and they are dead quiet at idle. Don't think your noise floor is correct yet.
@stuartukguitarampguy5830 Жыл бұрын
Hi Yes it was fine when I finished.
@user-dz1fq2di1g Жыл бұрын
😄😎 thanks Stuart
@stuartukguitarampguy5830 Жыл бұрын
Glad you enjoyed it.
@user-dz1fq2di1g Жыл бұрын
@@stuartukguitarampguy5830 I'm always learning about amps
@christopherbennett252 Жыл бұрын
Are the probes switched wrong way round at 14:13?
@stuartukguitarampguy5830 Жыл бұрын
Yes well spotted. But it doesn;t matter as my meter can read negative voltage.
@waynegram8907 Жыл бұрын
STUART, why do they call it the ZED Supply? for the values that feeds the reverb springs
@stuartukguitarampguy5830 Жыл бұрын
Hi Wayne. Not sure but it's just another letter, e.g. the is an X and a Y HT supply so I guess Z follows. No real reason. Oddly the negative bias vvoltage is always called 'C'. Go figure! Sometime the HT is called B+.
@goodun2974 Жыл бұрын
@@stuartukguitarampguy5830 , The A, B, and C designations correspond to the batteries used for 1920s American radio sets, back in the days when all tubes were directly heated, 3-element triodes at most, and there were no "screen-grid" tetrodes nor indepently-heated cathodes. You couldn't run these tube types off of AC house current because there would be way too much hum (1920's filter capacitors weren't up to the job, as they were big, expensive, and of low capacitance value), and so the radios were powered by an A battery for the filaments, a B battery for the plates, and a C battery for the grid bias.
@stuartukguitarampguy5830 Жыл бұрын
@@goodun2974 Very interesting thanks I didn;t know that.
@goodun2974 Жыл бұрын
@@stuartukguitarampguy5830 , Just a few decades after those early battery radios were prevalent, the convention and nomenclature changed somewhat, so that when you look at a power supply from something built in the late forties or 1950s the highest voltage is usually called the A supply, the 2nd voltage/filter node is the B supply, and then the nodes are named C, D and E going down the line as the voltages are further dropped and filtered. And yet we still use B+ to refer to the highest voltage supply because of those "B" batteries 100 years ago!
@waynegram8907 Жыл бұрын
@@stuartukguitarampguy5830 Yes it goes back to the old radio days in the 30s and 40's for WWII those letters meant something. Its looks like the voltage is Unregulated voltage and also no power conditioning meaning less power filtering for the reverb unit which I'm not sure why they are use less power conditioning for the reverb circuit stages?
@RearviewMirror-ij2pr11 ай бұрын
At 23:47, what is that noise emanating from? Thanks.
@stuartukguitarampguy583011 ай бұрын
Do you mean that clanging sound? I probably just knocked the amp and it rattled the reverb pan. I had the reverb full up.
@RearviewMirror-ij2pr10 ай бұрын
@@stuartukguitarampguy5830 The "sh" sound. Very faint. Is this normal?
@stuartukguitarampguy583010 ай бұрын
A certain amount of noise is normal. It's a tough line though to decide when something is 'too noisy'.
@tomfoolery2082 Жыл бұрын
Do u use a variac to power an amp up ?
@stuartukguitarampguy5830 Жыл бұрын
Very rarely and only if the amp is blowing fuses on switch on.