Classic 50, no sound, burned smell, glowing EL84 plates
Re: Classic 50, no sound, burned smell, glowing EL84 plates
OK, I have to see if I have 22s, if not I'll order them, I have new JJs and a passle of fuses (could only find 2 today) coming in the mail.
One last question, is there any benefit to replacing the 2200V35 with a higher voltage cap? I'll order that as well, but there are 35V and 63V 2200s listed.
One last question, is there any benefit to replacing the 2200V35 with a higher voltage cap? I'll order that as well, but there are 35V and 63V 2200s listed.
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Re: Classic 50, no sound, burned smell, glowing EL84 plates
Not really. Higher voltage caps usually have lower internal impedence but they get bigger. Make sure the cap you order is squat enough to fit in the amp.wilsonsk wrote:OK, I have to see if I have 22s, if not I'll order them, I have new JJs and a passle of fuses (could only find 2 today) coming in the mail.
One last question, is there any benefit to replacing the 2200V35 with a higher voltage cap? I'll order that as well, but there are 35V and 63V 2200s listed.
Re: Classic 50, no sound, burned smell, glowing EL84 plates
Those are on the way, I'll take the board out tomorrow and remove cap and finish trouble shooting.
Thanks!
Thanks!
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Re: Classic 50, no sound, burned smell, glowing EL84 plates
You're welcome and good luck! Let's hope the Classic 50 NoFX rocks again! BTW, I have a Classic 50 2x12 NoFX as well. Welcome to the brotherhood.
Re: Classic 50, no sound, burned smell, glowing EL84 plates
Thanks for all of the help, I have parts on the way. I picked this up cheap as a spare amp, I love the thing, I played a Koch TwinTone for 12 years, traded it off after playing this. Spose I should buy a spare.
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Re: Classic 50, no sound, burned smell, glowing EL84 plates
There's one on GC website listed as a "Classic 120/120 power amp" that I'm pretty sure is a black tolex Classic 50 for $299... I have two, a 2x12 and a 4x10. Been playing the 4x10 a LOT lately. It's brighter and chimier without being harsh. But the 2x12 has a thump factor the 4x10 can't match. I keep thinking if I was A/Bing them I'd use the 2x12 for clean channel / light breakup stuff and the 4x10 for lead stuff.
Re: Classic 50, no sound, burned smell, glowing EL84 plates
i modded a Bell Carillon 30 a few years ago, other than playing it in the basement here and there, I've never gigged with it. The C50 being down forced me into it last saturday. It went well. I played it through the stock speakers in the C50, sounded great. I have been playing it at home though an old Hammond JR20 through the 4 10s. I really like that and have started building a cabinet and will install the Hammond speakers in it to start with as I like them in the basement. IN the JR 20 those are the bass speakers, so they are not overly bright. We'll see once I get it on stage, everything is different when the rest of the band is playing.
I'm attaching the last schematic I made for the mods, two major changes, the two channels going through V1A&B are now a single channel paralleled through both and combined at the 1M volume pot.
I also remove the 12AV6 as I had added a 12AX7 and it was too much for the PT, I pulled the 12AV6 and everything works fine, too fat on the OD channel, but I can change those caps and brighten it up, for now I back the bass off on the tone control. Overall I dig it, I wired an effects loop and run through a Behringer reverb pedal for verb.
I'm attaching the last schematic I made for the mods, two major changes, the two channels going through V1A&B are now a single channel paralleled through both and combined at the 1M volume pot.
I also remove the 12AV6 as I had added a 12AX7 and it was too much for the PT, I pulled the 12AV6 and everything works fine, too fat on the OD channel, but I can change those caps and brighten it up, for now I back the bass off on the tone control. Overall I dig it, I wired an effects loop and run through a Behringer reverb pedal for verb.
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- Bell Cad 20091026.jpg (104.15 KiB) Viewed 6333 times
Re: Classic 50, no sound, burned smell, glowing EL84 plates
OK, I removed the C43, R61 and R62. I read 54 ohms across where the two legs of C43 were in the board, does this sound right? Looking at the schematic, it looks to me like it should be 200 K, but not sure how the cap affects that reading. Thoughts?
Re: Classic 50, no sound, burned smell, glowing EL84 plates
How do I test that 2200uF cap? My meter doesn't go that high.
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Re: Classic 50, no sound, burned smell, glowing EL84 plates
Check it for being shorted first. If it measures anything less than an open circuit after a few seconds it's broke. Note that for a few seconds it can measure low, but should climb and go to an open circuit.wilsonsk wrote:How do I test that 2200uF cap? My meter doesn't go that high.
Re: Classic 50, no sound, burned smell, glowing EL84 plates
Awesome, thanks, definitely reads short.
What do you think about my other question?
"OK, I removed the C43, R61 and R62. I read 54 ohms across where the two legs of C43 were in the board, does this sound right? Looking at the schematic, it looks to me like it should be 200 K, but not sure how the cap affects that reading. Thoughts?"
What do you think about my other question?
"OK, I removed the C43, R61 and R62. I read 54 ohms across where the two legs of C43 were in the board, does this sound right? Looking at the schematic, it looks to me like it should be 200 K, but not sure how the cap affects that reading. Thoughts?"
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Re: Classic 50, no sound, burned smell, glowing EL84 plates
Yeah that does seem low looking at the schematic, but I'm not sure where that -27V goes before it gets to the bias circuit input. OK I whipped out my multimeter and measured. From the bottom of the pair of resistors to ground I measured 47ohms and from the top of the pair to ground I measure 37 ohms. This is with fuses and EL84s all plugged in.
Re: Classic 50, no sound, burned smell, glowing EL84 plates
Sounds like I'm in the ballpark then?
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Re: Classic 50, no sound, burned smell, glowing EL84 plates
Sounds like. I'd replace that cap and put fuses in it and see what happens.
Re: Classic 50, no sound, burned smell, glowing EL84 plates
I replaced the 22 ohm resistors and the 2200V35 cap, put back together, new fuses, smoke from the 2200V35 cap again, this was only with the power not, not the high voltage.
What's next?
What's next?