So just to clarify, it seems the Silver version of this amp doesn’t have a zobel network - which I think is ok because I’m pretty sure the speakers I’m using have compensation in the crossover. But I learned something today!
All the passive resistors measure ok, as do the diodes. It could be leaky transistors.
But while researching replacements I found this interesting thread and will look on the other boards as well: https://audiokarma.org/forums/index.php?threads/repalacement-for-2sc1775-dc-offset.186869/
It won’t be tonight though as I’ve had a few red wines and don’t’ want to play with electricity….
But while researching replacements I found this interesting thread and will look on the other boards as well: https://audiokarma.org/forums/index.php?threads/repalacement-for-2sc1775-dc-offset.186869/
It won’t be tonight though as I’ve had a few red wines and don’t’ want to play with electricity….
There may not be anything wrong with Q423. Probably there's a transistor junction shunting the resistance measurement--- you've already confirmed 100 ohm out-of-circuit. Be sure to measure R453 with both ohmmeter polarities--- if the reading differ, there's a transistor junction shunting the measurement. Both Q423 and Q419 are tied to R453, so in may not be possible to find a polarity that doesn't cause junction conduction, and thus no 100 ohm in-circuit. Compare with behavior at R454 for reassurance.
I'm traveling, so my replies may be erratic. Good luck.
I'm traveling, so my replies may be erratic. Good luck.
Confirmed Q423 was faulty. Not open, not short, but giving low readings when measured with a multimeter diode tester and also reading values when it shouldn't.
I had replaced the SA1111/SC2591 pair on the right channel way back at the start because they had blown, I just did the ones on the left channel recently with the other pair that I had bought at the time, but I wasn't sure if they were genuine. I would love to know if there was a modern replacement that will work. For now the originals have gone back in as they measured ok.
Haven't hooked up again to test yet, I ran into some issues with a stripped thread on the earth lead and then broke the mounting tab off the heat sink...time to go to bed!
I had replaced the SA1111/SC2591 pair on the right channel way back at the start because they had blown, I just did the ones on the left channel recently with the other pair that I had bought at the time, but I wasn't sure if they were genuine. I would love to know if there was a modern replacement that will work. For now the originals have gone back in as they measured ok.
Haven't hooked up again to test yet, I ran into some issues with a stripped thread on the earth lead and then broke the mounting tab off the heat sink...time to go to bed!