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    Building, troubleshooting and testing of these amplifiers should only be
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    the safety precautions around high voltages.

Jolida FX-10 repair

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tacit_tactix

Member
Joined 2005
Jolida FX-10 is redplating the tube.

A different power tube redplates each time I turn it on. By redplate I mean the tube glows extra red than other tubes.

I read online that some resistors failing would cause this. Grid plate resistors or something like that.

I spoke to jolida and they said their protection circuit would turn the unit off if this were the case, and that it must be loose tube sockets. They told me to retention the tube sockets, and try again. Each time I do a new tube glows red hot.

Does anyone have a schematic? Or advice about replacing resistors of this type?

Thanks

-Jason
 
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tacit_tactix

Member
Joined 2005
I have swapped tubes. I haven't done repairs but I have built electronics. I have built electrostats, voltage multipliers, built solid state amplifiers in engineering school. I do need a schematic but can't find one, don't think Jolida will release publicly. I will not send this to Jolida there turn around time is bad, shipping is bad, customer service reportedly bad. I have a few amps piling up that need repair, and I have chosen to thoroughly learn how to troubleshoot.

Any resources recommended would be appreciated.

Thanks

-Jason

last time I took amplifiers to parts connection they charged me $300 to replace a pot, and "trouble shoot" my other amp, which they never diagnosed, but charged me $150 for nothing.

considering I have an engineering background and a vested interest in learning I don't want to take these amps to a technician.

I would be willing to pay for mentorship to learn the trade.

Currently the amp still play music without distortion, and the red plating only occurs in a single tube ( which tube is different every time) about 3-5 min after turning on the amp.
 
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tacit_tactix

Member
Joined 2005
If it were a grid resistor it would be the same tube socket every time I think. the time delay makes me think it could be a loose connection moving after heating and expanding, or a capacitor charging. Because I tightened the sockets I don't think its those. The red plating changing each tube socket each time makes me think it has to be something up stream. I looked inside, theres some IC's not sure what they are for. Could those be for the autobias?
 
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Tjj226

Member
Joined 2012
tacit_tactix said:
I will not send this to Jolida there turn around time is bad, shipping is bad, customer service reportedly bad.
Click to expand...

Their customer service is actually pretty good.

I actually know the guys at jolida ( I see them every year at DC audio fest) and they are some of the nicer and more patient people in the audio world. The only catch is that they don't have patience for BS. So as long as you play nice with them, they will bend over backwards for you.

If you are dead set on fixing it yourself, I would call them back and let them know that you tried setting the tube back into place and that you would like to know where else you can check for problems.
 
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