Hello, everybody!
If you remember me, i posted several months ago regarding a 12 year old Vox Cambridge 30 guitar amplifier which kept loosing it's reverb. The thread is here:
http://forum.allaboutcircuits.com/showthread.php?t=62541&highlight=vox
That issue was successfully resolved thanks to the kind people over here (it was only a matter of cleaning some jacks with a contact spray).
However, now i'm facing a new problem and i came back here, maybe someone can help me out with this one as well
So, here it goes: for about i year i started experiencing a random loss of volume while i was playing. It happened very rarely and it automatically resolved itself after a couple of seconds, so i blamed it on power fluctuations.
However, the problem got a whole lot worse lately. The random volume drops appeared more often these last few weeks, and once they appear, they will not go away. Now it happens every time i play the amp. The problem usually happens after i play the guitar a bit. If i let the amp rest 30 minutes and start it up again, the problem is gone but reappears after 15-30 minutes or even sooner. Also, i noticed i am able to generate the appearance of the problem if i crank the amp at maximum right after i turn it on.
I tried cleaning all jacks and volume pots with contact spray and i replaced the preamp tube with a new one but to no effect. Also, the problem is not related to the guitar or the cables as i tested them on my second amp and they're fine
I though that maybe the volume pot is bad, but i have two volume pots on 2 channels and they both exhibit the same problems (and i very rarely use channel 2, the pot there was almost untouched the past 2 years so no reason for it to go bad at the same time as the channel 1 pot).
Could it be that a solder got bad and when the amp gets hot or is pushed too much the solder fails and the signal is getting weaker?
I would be much obliged if anyone could tell me what would most likely cause this problem (what solders should i fix, what components might need replacing etc.).
I have attached the schematics to the amp. Thank you again!
If you remember me, i posted several months ago regarding a 12 year old Vox Cambridge 30 guitar amplifier which kept loosing it's reverb. The thread is here:
http://forum.allaboutcircuits.com/showthread.php?t=62541&highlight=vox
That issue was successfully resolved thanks to the kind people over here (it was only a matter of cleaning some jacks with a contact spray).
However, now i'm facing a new problem and i came back here, maybe someone can help me out with this one as well
So, here it goes: for about i year i started experiencing a random loss of volume while i was playing. It happened very rarely and it automatically resolved itself after a couple of seconds, so i blamed it on power fluctuations.
However, the problem got a whole lot worse lately. The random volume drops appeared more often these last few weeks, and once they appear, they will not go away. Now it happens every time i play the amp. The problem usually happens after i play the guitar a bit. If i let the amp rest 30 minutes and start it up again, the problem is gone but reappears after 15-30 minutes or even sooner. Also, i noticed i am able to generate the appearance of the problem if i crank the amp at maximum right after i turn it on.
I tried cleaning all jacks and volume pots with contact spray and i replaced the preamp tube with a new one but to no effect. Also, the problem is not related to the guitar or the cables as i tested them on my second amp and they're fine
I though that maybe the volume pot is bad, but i have two volume pots on 2 channels and they both exhibit the same problems (and i very rarely use channel 2, the pot there was almost untouched the past 2 years so no reason for it to go bad at the same time as the channel 1 pot).
Could it be that a solder got bad and when the amp gets hot or is pushed too much the solder fails and the signal is getting weaker?
I would be much obliged if anyone could tell me what would most likely cause this problem (what solders should i fix, what components might need replacing etc.).
I have attached the schematics to the amp. Thank you again!
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