1961 Reverberocket Pops. Help?

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1961 Reverberocket Pops. Help?

Postby ceeya68 on Wed May 25, 2016 3:56 am

I have a 1961 R12R Reverberocket that has a problem with Pops. I have replaced the electrolytic caps and most coupling caps and most resistors. I replaced the tubes with NOS Tubes. Ones that I know are good. Yet the same result happens. So I put the originals back in. No change. I have resoldered the connections on the sockets and cleaned and resized the socket pin connections. I have tapped around with a chopstick and can not find a change in the symptom tapping around. I am just not finding the source of the problem. The amp works and sounds good except for the Pops problem. The trem works great the reverb works great. Pots are smooth and quiet. I am starting to think I may have a cap in the wrong polarity but I'm not seeing it. Please see video link and listen close. To the popping. Maybe someone can help? Thanx!!

https://youtu.be/R4oWsOkVR4Q
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Re: 1961 Reverberocket Pops. Help?

Postby slider313 on Wed May 25, 2016 7:20 pm

Is the first bypass cap, to the far left looking at the back, installed with the positive end toward the tube? I can't tell from the angle of the camera. Have you checked your voltages?
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Re: 1961 Reverberocket Pops. Help?

Postby ceeya68 on Wed May 25, 2016 9:11 pm

Yes, Yes it is positive end toward the tube. And the voltages seem to be correct and within tolerances.
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Re: 1961 Reverberocket Pops. Help?

Postby slider313 on Wed May 25, 2016 10:18 pm

Try re-tensioning the tube sockets and check for bent or broken contacts.

Also check your power supply caps. I've had a bad section in a cap can more than once.
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Re: 1961 Reverberocket Pops. Help?

Postby ceeya68 on Wed May 25, 2016 11:17 pm

OK. I went and checked with my capacitance meter the 4 x 20uf @ 450V can and the readings were between (20.45uf and 24.36uf). The lugs on the can that has the 1 watt 22K ohm resister tied to it reads 20.26uf at one lug and the other side of the resister at the lug reads 2.84uf). with the the multi cap just above the can I believe it is supposed to be a 2 x 20uf multi cap and it reads (37.05uf) on the meter. It's value is supposed to be 33uf written on the side of the can. I had cleaned and retensioned all the tube connections in the sockets before I posted this help posting. I want to Thank You for trying to help me. It is Apreciated. I am beating my head against the wall here. :dumass:
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Re: 1961 Reverberocket Pops. Help?

Postby slider313 on Wed May 25, 2016 11:26 pm

Try crossing a single 20uf or 40uf @ 500v cap to each section. You'll have to do it with the amp on "live". Take a tester lead and ground the negative to the chassis then touch the positive to each tab on the can. Even a new can may have a faulty section. It sounds like you have a bad electrolytic somewhere.
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Re: 1961 Reverberocket Pops. Help?

Postby ceeya68 on Thu May 26, 2016 3:17 am

Will do. I'll keep plugin away at it. Thanx!! Stay tuned for another day. I may be back on the forum again. I'll will post what I discover.
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Re: 1961 Reverberocket Pops. Help?

Postby ceeya68 on Thu May 26, 2016 3:51 am

Ok. slider313. I did what you said. The result was that when I touched 4x20 can at the lug marked with a square indication the amp got a lot quieter. It did not totally go away but it was significantly reduced. this is also one of the lugs tied to the 22k 1 watt resister. When I touched the other lugs the amp remained the same as before. Only when I touched the square lug did it make a change. The multi can itself is only a month old from Fliptops Ampeg website. I will imagine that you will advise me to change the can again. I will say that it was expensive. I believe it was around the $40.00 mark plus shipping. I am wondering if it could be the resister that is tied in with the lug. I have not changed that particular one. It is the original 50 plus yr. resister. Thanx again for your help! at least I found something because of your help. :shock:
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Re: 1961 Reverberocket Pops. Help?

Postby slider313 on Fri May 27, 2016 2:43 pm

What was the value of the cap you were using to test the can? Is the square lug on the can going to the first node; the rectifier? You could always add a cap to that lug; positive to the lug and negative to a ground point, if you have enough room.
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Re: 1961 Reverberocket Pops. Help?

Postby ceeya68 on Sat May 28, 2016 1:23 am

The value of the cap I used was an IC cap 22uf @ 500V. The wire from the lug we are talking about goes from lug to the Neg. side of the board where it ties in with another 120K 1/2 watt resistor. Also I have made a mistake on the 4x20 can lug in my description. It is not the square lug but the - (dash Indicated) lug. Sorry bout that. I could possibly tie in another cap. But I probably would just purchase another can and try that rather than try to fit another cap in there. I have a new 22K 1 watt resister on order now. waiting on the post. But also to answer your question the square indicated lug on the 4x20 can does have a wire that leads to the rectifier tube socket at the #8 lug. Nothing is attached to the #1 lug at all. I have been following this schematic I found on the internet. Please see Link: http://s93105080.onlinehome.us/61-R12R/61-R12R.htm) Joe Piazza's back stage. Thanx.
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Re: 1961 Reverberocket Pops. Help?

Postby ceeya68 on Sat May 28, 2016 2:25 am

I wish someone had a Layout diagram drawing of a 1st version R12R reverberocket. I am not very good at making heads or tails of the schematic. I can get a little but not very much. The intersections of a schematic confuse me. I need a point to point diagram. That would make things much easier.
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Re: 1961 Reverberocket Pops. Help?

Postby Unit_1 on Sat May 28, 2016 6:29 pm

carbon comp resistors do go bad with time. they can crack and make noise or drift out of spec. I would definitely suspect that before a new electrolytic. Replace with carbon fiber resistors which have the same sound qualities, but don't fade or crack.
Good Luck! :cheers:
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