It is currently Mon Mar 16, 2020 4:49 pm

All times are UTC - 7 hours



Post new topic Reply to topic  [ 24 posts ]  Go to page Previous  1, 2
Go to page Previous  1, 2
Author Message
Post subject:
Posted: Thu Jun 03, 2010 2:40 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
I agree with you aclempoppi about the stanby switch could be not needed with GZ34, but the more tube is warm (heated) before power on best is.

So IMO I keep the standby switch


Top
Profile
Fender Play Winter Sale 2020
Post subject:
Posted: Thu Jun 03, 2010 2:10 pm
Offline
Hobbyist
Hobbyist

Joined: Sun May 02, 2010 6:05 pm
Posts: 16
I have tried the amp with the swich bridged, no standby.
It still popped. Would you suggest that maybe the problem is with
the choke?
thanks,
Barry


Top
Profile
Post subject:
Posted: Thu Jun 03, 2010 9:35 pm
Offline
Professional Musician
Professional Musician

Joined: Fri Jun 26, 2009 6:53 pm
Posts: 2252
Location: Harvard IL
OK, at this point the standby switch is taken out of the equation, if it still pops, when just using the on-off switch, right? So there is arcing somewhere in the power supply. My first suspects would be the carbon comp power(dropping) resistors, then the plate load resistors. Of course I could be totally wrong and the choke may have developed a short in it's insulation. But I've always considered them as being very sturdy. At any rate, you've already narrowed down the problem to the Vib channel. And in this amp, that is one big channel ! The ceramic caps should be fine. IMO They are resonant and add to the amp's tone. BTW Don't change the way you've been using the standby. I used to warm my amps up for 3 min. I've only changed my thinkng over the past year, due to reading and research. Art

_________________
None of Us are free, if One of Us is chained !


Top
Profile
Post subject:
Posted: Fri Jun 04, 2010 2:33 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
aclempoppi, more I read what you said more I see that you know very well amplifiers and more.
I have a lot to learn from you.


Top
Profile
Post subject:
Posted: Fri Jun 04, 2010 11:21 am
Offline
Hobbyist
Hobbyist

Joined: Sun May 02, 2010 6:05 pm
Posts: 16
Thanks Art
By power dropping resistors I assume you mean the ones between
the filter caps? Most have been changed but I'll try the rest.
I don't see any plate resistors on the 5881s only the 1w resistors on
the grids and I changed these to 5w.
I might take a chance and fork out $40. on a Mercury Magnetics
choke. I'm also thinking of changing the tube sockets of the 5881s.
I really appreciate the help you and Stratele52 have given me.
thanks very much,
Barry


Top
Profile
Post subject:
Posted: Fri Jun 04, 2010 8:31 pm
Offline
Professional Musician
Professional Musician

Joined: Fri Jun 26, 2009 6:53 pm
Posts: 2252
Location: Harvard IL
Yeah man, it's cool ! You are correct on both counts, about the resistors. The 5 watt screen grid resistors are an excellent choice. New power tube sockets are another good idea, but be sure to go with a high grade mil-spec socket(ie Belton). The choke is a hard call without an inductance test. I put Merc iron in my '68 Bassman, PT,OT, and choke. And they work fine. But I was trying to bring the amp into a '63 Bassman realm. Any way, the arcing is going to be tough to run down. There are so many possibilities ! But all the work you're putting into the amp, is all good ! BTW Stratele, I've learned from your contributions. The more folks working on a problem, makes for lighter work. Art

_________________
None of Us are free, if One of Us is chained !


Top
Profile
Post subject:
Posted: Fri Jul 02, 2010 7:11 pm
Offline
Hobbyist
Hobbyist

Joined: Sun May 02, 2010 6:05 pm
Posts: 16
Hi aclempoppi and stratele52 it's me again.
I just found the problem wth the popping!
You're not going to believe this.
I was inside the cap pan and trying to figure which cap was which
on the circuit diagram. The 2 caps furthest from the end, closest to the
transformers are wired in parallel and charge before the standby switch
is closed. Checking for continuity at the + ends of these caps I found
that one cap was not connected to the other. So I checked under the
fiber board and found that the jumper wire was disconnected at one
end. This probably happened when the amp was recapped long
before I bought it. I installed a jumper on top of the board and
no more popping. Maybe you can use this info and
thanks for your comments and concern.
Barry


Top
Profile
Post subject:
Posted: Fri Jul 02, 2010 10:06 pm
Offline
Professional Musician
Professional Musician

Joined: Fri Jun 26, 2009 6:53 pm
Posts: 2252
Location: Harvard IL
Barry, that's great news!!! Guess there's no substitute for the hands-on work and investigation. All your work will be worth the effort well into the future. Keep Pickin' ! Art

_________________
None of Us are free, if One of Us is chained !


Top
Profile
Post subject:
Posted: Sat Jul 03, 2010 3:41 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14049
Location: Province de Québec, Canada
Thank's cpbarry for the information.

So, the two 20 mfds caps after the rectifier and before the standby switch, only one was in the circuit !

This information could be very useful for me. I appreciate you come back with


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 24 posts ]  Go to page Previous  1, 2
Go to page Previous  1, 2

All times are UTC - 7 hours

Fender Play Winter Sale 2020

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum

Search for:
Jump to: