What is a TCR504? As used in an Arcam Delta 290
I have used the ol mighty search engine but I cannot find a Datasheet. I assume it is some kind of CCS?
I have used the ol mighty search engine but I cannot find a Datasheet. I assume it is some kind of CCS?
Looks like an N-channel JFET used as a current source. If it has only two pins, the gate is probably internally connected to the source.
It is an N channel JFET used as a current source. Looks to be 0.6ma
https://www.mouser.co.uk/datasheet/2/676/jfet_j503_j504_j505_interfet-2887914.pdf
Are you sure it is faulty?
https://www.mouser.co.uk/datasheet/2/676/jfet_j503_j504_j505_interfet-2887914.pdf
Are you sure it is faulty?
Thank you. I swapped the channels devices around and nothing had changed. The left channel is still faulty even though all the semiconductors are good as well as the diodes and resistors.
Both the FETs turn on to the point of destruction. I have used a Variac to turn it on slowly and thus prevent damage. Less than 8v per rail.
I would begin by linking out the bias generator Q14. That will force zero bias current providing the driver transistors surrounding circuitry is good.
If you are sure the drivers are good and the output FET's are good and you have shorted the bias generated out then the FET's should NOT be able to conduct. That will allow you to check the rest of the amp.
If the FET's still conduct in the above state, then you still have a problem around that stage.
The amp should work normally with the bias generated linked out and just slightly higher distortion.
If the FET's still conduct in the above state, then you still have a problem around that stage.
The amp should work normally with the bias generated linked out and just slightly higher distortion.
I have replaced the IRF240s because the originals were toast and the drain resistor pair was cooked. Cleaned everything up and replaced the offending parts and still no luck. But let me remove the bias transistor and observe the state of the circuit from there on.
Thanks for the advice.
Thanks for the advice.