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Rowe JBM, Amplifier re-cap question

Posted: Tue Feb 23, 2010 9:17 pm
by TinkerV2
Hello fellow enthusiasts,

I'm re-capping the power amp (R2652-2). I didn't buy a cap kit since I had most of the cap's needed. My question is about the cap across the mute relay contacts. My schematic shows it as 0.047 uf. There is a 4.0 uf electrolytic in that place. Before I replace it with a 0.047uf like the schematic shows, could there have been a service bulletin or upgrade having the operator putting in this bigger cap? It's not even close to the designed value. Could this big cap be better at eliminating a "pop" when the contacts open or close? Any ideas?

Thanks

Re: Rowe JBM, Amplifier re-cap question

Posted: Sun Feb 28, 2010 7:05 pm
by Ron Rich
Just a WAG since no one else has answered--I think the 4.0 was someone's "misteak".
Ron Rich

Re: Rowe JBM, Amplifier re-cap question

Posted: Mon Mar 01, 2010 12:55 pm
by ami-man
Hi TinkerV2,

Yes the manual shows the mute relay no 1 switch N.C. has a .047uF across the 20k 10 watt resistor and contacts. I can understand why a larger capacitor may have been fitted to suppress the arc on those contacts, but why a electrolytic was fitted is something else.

Regards
Alan Hood
ami-man
UK

Re: Rowe JBM, Amplifier re-cap question

Posted: Tue Mar 02, 2010 3:51 pm
by TinkerV2
Thanks Ron and Alan,

I went ahead and put a 0.047uf cap in. As soon as I finish with the control amp re-cap, I'll give her a try. I'll report back on the progress. Thanks again!!

Re: Rowe JBM, Amplifier re-cap question

Posted: Wed Mar 31, 2010 8:09 pm
by TinkerV2
Update: The 0.047uf cap worked perfectly. No pops or hiss when the mute relay activates. I'm a happy guy. :) And so is the "JBM". This tube amp sounds soooooo much better then the other solid state jukes I have.

Re: Rowe JBM, Amplifier re-cap question

Posted: Thu Apr 01, 2010 10:49 am
by ami-man
Hi TinkerV2,

Glad to hear that the amp is now ok with your bonus that it sounds great. I still think that you can not beat the sound of a Rowe Ami jukebox or am I opening a can of worms!

Regards
Alan Hood
ami-man
UK