[carusoracer]

Jolida 302b number 3 socket has stopped providing current to the socket.  The other 3 tubes are working and the amplifier is playing music despite number 3 not working.   Swapped out tubes and even bought a new quad...should have swapped first. However music is still playing.  Any test or diy help? Do not know how to self repair, Bias is stable to the 3 pots for old tubes as well as new. 

Any suggestions or advice is welcomed.


Thanks.





 

[FullRangeMan]

Jolida 302b number 3 socket has stopped providing current to the socket.  The other 3 tubes are working and the amplifier is playing music despite number 3 not working.   Swapped out tubes and even bought a new quad...should have swapped first. However music is still playing.  Any test or diy help? Do not know how to self repair, Bias is stable to the 3 pots for old tubes as well as new. 

Any suggestions or advice is welcomed.


Thanks.

Not sure what do you mean say. Seems the tube or socket are damaged.
This amp are PCB?

[carusoracer]

The 3rd EL34 tube of 4 is not working. I though it was a blown tube however it is not the case. New quad inserted and number 3 El 34 power tube socket does not send voltage to the tube.  Sound still plays but only three of four power tubes are working.

[FullRangeMan]

Seems this socket gone or the heater circuit.
Change sockets in PCB not funny.

[S Clark]

Jolida 302b number 3 socket has stopped providing current to the socket.

Does this mean that you have gone into the amp and put a volt meter on the wire with incoming current and it's dead, or that the tube is simply not powering up?

[carusoracer]

Yes, correct.  I put a volt meter on the factory tube bias trim pot. No voltage to that specific socket.

[carusoracer]

Seems this socket gone or the heater circuit.
Change sockets in PCB not funny.

What’s typically required if that’s the case?

[FullRangeMan]

Need a experiencied tech in some cases adjacent tracks are too close and all the area get hot.

[S Clark]

IF you are very comfortable tracing it back to find power, then I'd trouble shoot it.  But tube amps can bite you in a bad way.  If there is any doubt about your abilities, I'd follow Gustavo's advice and seek a tech. 

[carusoracer]

Any techs or repair shops in mind?  I’m in Ohio. I’m sure this takes a backseat to global issues , just trying to help the audio industry people.

Thank you.

[carusoracer]

Any forum members or recommendations?

Thanks.

[beeah]

If you don't have a firm grasp of what you're doing - and no offense, but it seems that you don't - I implore you NOT to poke around inside the amp, whether it's powered up or not.

There are hundreds of volts, both AC and DC present all over the place, and one false move or slip with a meter probe (or anything else conductive) could literally be deadly. 

Even with the power switch off, the power supply capacitors can keep a charge of several hundred volts.  Again, all it takes is one wrong move.

I'd be happy to take a stab at it, for the cost of parts and shipping both ways, with no guarantee other than I won't give it back to you in worse condition than I got it.  Building and fixing has been my main hobby for over 20 years.

[FullRangeMan]

Correct only 30V DC already can stop a heart of a man.

[Colnagofan]

The bias pots are on the outside of the amp, and not a danger. They are there for use with a meter as he is doing.

Call Jolida, they are great and will help you out to diagnose the problem. You can also send it in for repair. I’ve done that once with a 302B.

If you do, they have reasonably priced cap and resistor upgrades. I also suggest having the slow start circuit added to protect your tubes.

It’s a great amp.

-Steven