It is currently Mon Mar 16, 2020 7:46 am

All times are UTC - 7 hours



Post new topic Reply to topic  [ 8 posts ] 
Author Message
Post subject: Silverface Vibrolux Reverb - S.O.S.
Posted: Sun Feb 04, 2018 10:13 pm
Offline
Amateur
Amateur

Joined: Sat May 25, 2013 10:02 pm
Posts: 197
I am pulling my hair out trying to figure what it gives a nice sharp defined POP after 40 minutes.

6L6's are new
Bias is set at 25MA
Pre Amp Tubes have been swapped out
Tube Socket cleaned / Deoxed
Tube Sockets Retensioned
Filter Caps are newer from the looks and they test within spec

Any one ever have this kind of mystery?


Top
Profile
Fender Play Winter Sale 2020
Post subject: Re: Silverface Vibrolux Reverb - S.O.S.
Posted: Mon Feb 05, 2018 2:28 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14045
Location: Province de Québec, Canada
Ryan41018 wrote:
what it gives a nice sharp defined POP after 40 minutes.



Can you say more ?

1- Check, reheat solders.
2- Need new stanby switch ?

Post picture inside the amp and filter caps in dog house,


Top
Profile
Post subject: Re: Silverface Vibrolux Reverb - S.O.S.
Posted: Mon Feb 05, 2018 7:11 am
Offline
Roadie
Roadie

Joined: Sat Dec 13, 2014 7:34 am
Posts: 245
Maybe the "chop stick" test in order after the amp is warmed up. A cold/bad solder joint expands with heat. I recently serviced a early 70's Princeton Reverb with occasional popping noises, sometimes it would be weeks before it acted up. Pushing on the board revealed the problem area, even though the solder joints looked good to the eye. I re-flowed the joints in that area and it's never had a problem since. Just an idea.

UN


Top
Profile
Post subject: Re: Silverface Vibrolux Reverb - S.O.S.
Posted: Mon Feb 05, 2018 11:22 pm
Offline
Rock Star
Rock Star
User avatar

Joined: Sat Jul 03, 2010 2:18 pm
Posts: 6544
Also, use wooden chopsticks to check solder points on the sockets. I've had cold solders cause loud enough pops to wake the dead. :lol:


Top
Profile
Post subject: Re: Silverface Vibrolux Reverb - S.O.S.
Posted: Tue Feb 06, 2018 10:06 am
Offline
Professional Musician
Professional Musician

Joined: Thu Aug 07, 2014 3:25 pm
Posts: 1022
If you pull the phase inverter tube, it will split the amp in half. If it still pops, its in the power supply or power stage. If it quits, its in the preamp, reverb or vibrato stage.
The pop comes from a sudden change in dc level. A bad solder joint can explain it, but a bad capacitor is just as likely from that vintage of an amp. Bad coupling caps sometimes betray themselves with a sizzling noise before the pop.
If the problem seems to be in the power supply, filter caps can sometimes pop, but more likely its coming from the vibrato/bias circuitry.
The 40 minute time frame sounds like a function of indirect heating, not a hot component, but one indirectly heated by overall warm temps in the amp. I'm thinking a cathode capacitor. Bypassing them one at a time with a clip lead is safe and will prevent a cathode cap from popping
Opening up the amp may allow enough cooling to chase the problem away, but a hair dryer on the board might help identify the offender. Good luck.


Top
Profile
Post subject: Re: Silverface Vibrolux Reverb - S.O.S.
Posted: Sat Feb 24, 2018 10:12 am
Offline
Amateur
Amateur

Joined: Sat May 25, 2013 10:02 pm
Posts: 197
TimsAudio - I think I will do that test at this point. Reflowing all solderjoints did not seem to help with the problem. In reference to the caps under the dog house everything test within spec, solder is clean???

Tim can you detail this in practice? **Bypassing them one at a time with a clip lead is safe and will prevent a cathode cap from popping

Somebody noted "new standby switch"??? Can this symptom be related to a switch ?


Top
Profile
Post subject: Re: Silverface Vibrolux Reverb - S.O.S.
Posted: Sun Feb 25, 2018 3:37 am
Offline
Rock Icon
Rock Icon
User avatar

Joined: Fri Feb 05, 2010 4:31 am
Posts: 14045
Location: Province de Québec, Canada
Ryan41018 wrote:

Somebody noted "new standby switch"??? Can this symptom be related to a switch ?


Somebody name is stratele52 :lol:

Just bypass switch with a wire , you see


Top
Profile
Post subject: Re: Silverface Vibrolux Reverb - S.O.S.
Posted: Mon Feb 26, 2018 9:09 am
Offline
Amateur
Amateur

Joined: Sat May 25, 2013 10:02 pm
Posts: 197
stratele52 wrote:
Ryan41018 wrote:

Somebody noted "new standby switch"??? Can this symptom be related to a switch ?


Somebody name is stratele52 :lol:

Just bypass switch with a wire , you see


Thanks Strattele52.....I'llgive it a shot.


Top
Profile
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 8 posts ] 

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: