Access and abilities differ across the world, that is why forums like ours exist. Berating other for lack of tools does not befit us, and is not useful.
If the system works momentarily, per post #7, and then the resistor burns after a transient, it's pretty much something in the output side. Else it would be destroyed on power-on. The best bet is to replace the entire Zobel chain with properly rated parts. A 1/2w resistor and tiny 100v caps is asking for trouble. After one fails, the second one will also fail.
If the system works momentarily, per post #7, and then the resistor burns after a transient, it's pretty much something in the output side. Else it would be destroyed on power-on. The best bet is to replace the entire Zobel chain with properly rated parts. A 1/2w resistor and tiny 100v caps is asking for trouble. After one fails, the second one will also fail.
Throwing parts at problems without testing is called "shotgunning" and is about the WORST "repair" technique possible.
In this case, oscillation is about 1000 times as probable as a shorted cap.
Call it 10000 times less possible, because TWO caps should short at the same time, what´s the probability of that?
This is a Tech Forum and Tech answers rule.
I am quite worried that a Moderator applies his own subjective judgement ("berating" indeed!!!) on Tech answers offered here.
In this case, oscillation is about 1000 times as probable as a shorted cap.
Call it 10000 times less possible, because TWO caps should short at the same time, what´s the probability of that?
This is a Tech Forum and Tech answers rule.
I am quite worried that a Moderator applies his own subjective judgement ("berating" indeed!!!) on Tech answers offered here.
Two caps didn't short at the same time. One failed short, and after that the other. An extremely common scenario. Oscillation is also a possible issue, and both have to looked at. Oscilloscopes aren't the only way to detect oscillation. There is a very handy circuit described on the forum that detects oscillation.
But #21 is a follow up to #7, where the circuit works fine when power is applied initially. It's an educated guess, and there's no merit in promoting either problem as the predominant cause. I haven't ruled out oscillation, and would be curious to know what your 0.00001% probability comes from.
Moderators are also regular members, and when in a discussion we are posting as regular members. FYI, 99% of repair techs in India do NOT have oscilloscopes and never did. Not every country in the world has, and sometimes you have to adjust your expectations. This is why the community has engineered solutions like the oscilation detector, and why many members started threads on designing crossovers without measurements. That is sufficiently off-topic for now. we should direct our energies towards finding solutions and being helpful.
But #21 is a follow up to #7, where the circuit works fine when power is applied initially. It's an educated guess, and there's no merit in promoting either problem as the predominant cause. I haven't ruled out oscillation, and would be curious to know what your 0.00001% probability comes from.
Moderators are also regular members, and when in a discussion we are posting as regular members. FYI, 99% of repair techs in India do NOT have oscilloscopes and never did. Not every country in the world has, and sometimes you have to adjust your expectations. This is why the community has engineered solutions like the oscilation detector, and why many members started threads on designing crossovers without measurements. That is sufficiently off-topic for now. we should direct our energies towards finding solutions and being helpful.
Solution to this problem is to resolder all joints, test-better replace electrolytics on the AMP IC board and add bypass caps to GND on power supply pins.
This is my suggestion and I am pretty sure that this amp self oscilate because of bad caps.
This is my suggestion and I am pretty sure that this amp self oscilate because of bad caps.