I think if you talked to the people at Jolida they could tell you exactly which resistor to check. I don't want to give you any wrong info on that, as it was a few years ago, I did not do the repair myself, and I can't remember exactly which resistor it was.
Jolida JD1000A 1 tube will not Bias
I have a jolida JD1000A tube amp that i bought a few years ago, and replaced all the tubes and found that when i was biasing them all one tube will not bias, reads only .001V anywhere you adjust the pot.
I swapped tubes around thinking it was the tube, but it does the same with a different tube, I pulled the amp board out to inspect solder points, traces and ohmed out some resistors and the biasing pot and all looked good.
Posted this problem several months back and had someone recommend checking the tube socket, i bent all the contacts in a bit so they would get a tight fit, and it still fails to bias.
I noticed that when you turn the bias pot clockwise or "Bias down" on that bad tube sector the amp puts out a mild humming out of the speaker that is hooked to that side and when you turn the pot CCW the humming goes away at about the 10 oclock position (fully CW would be about 5 Oclock and fully CCW would be about 7 oclock) all the while the volt meter still does not read over about 1mV on its test point.
also, just to make sure that im on the right Biasing pot and Biasing test point, all the other 7 power tubes are biased and are reading the correct voltage around 30 mV DC i think it was.
Any ideas? i havent found any local tube audio repair shops in the Kansas City area.
I swapped tubes around thinking it was the tube, but it does the same with a different tube, I pulled the amp board out to inspect solder points, traces and ohmed out some resistors and the biasing pot and all looked good.
Posted this problem several months back and had someone recommend checking the tube socket, i bent all the contacts in a bit so they would get a tight fit, and it still fails to bias.
I noticed that when you turn the bias pot clockwise or "Bias down" on that bad tube sector the amp puts out a mild humming out of the speaker that is hooked to that side and when you turn the pot CCW the humming goes away at about the 10 oclock position (fully CW would be about 5 Oclock and fully CCW would be about 7 oclock) all the while the volt meter still does not read over about 1mV on its test point.
also, just to make sure that im on the right Biasing pot and Biasing test point, all the other 7 power tubes are biased and are reading the correct voltage around 30 mV DC i think it was.
Any ideas? i havent found any local tube audio repair shops in the Kansas City area.
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- 10 posts total
- 10 posts total