It won't do anything with the 1-2 jumper on the servo op-amp.
You can install the outputs and check the drive. If you do, you can either remove the rectifier or just power up for a few seconds and then remove remote. The low-voltage supply will keep running for about 15 seconds during which time you can check the drive signals.
You can install the outputs and check the drive. If you do, you can either remove the rectifier or just power up for a few seconds and then remove remote. The low-voltage supply will keep running for about 15 seconds during which time you can check the drive signals.
If one is grounded, it won't have anything.
If the other is the input and it's shorted to the output, you won't see a signal.
Everything is likely OK. Power it up after removing the jumper and see if it's OK. Of course, be careful as you would powering up any amp after a repair.
If the other is the input and it's shorted to the output, you won't see a signal.
Everything is likely OK. Power it up after removing the jumper and see if it's OK. Of course, be careful as you would powering up any amp after a repair.
Isnt there just a single TO-220 case fet driving the LV standby supply? It doesn’t appear to be doing anything, and like I said I would expect a bipolar supply on the various opamps in this chassis but I have next to nothing. That tells me it’s not actually running.
Drive for what, the outputs?
Drive for what, the outputs?
The drain of the FET driving the LV transformer should be swinging about 24v. It drives pin 1 of the transformer. Pin 10 of the transformer goes to 12v.
Does the 5v regulator have output?
I wouldn't expect there to be drive voltage without the LV operating but I don't know the 250 very well and there may even be different revisions like in the 500.
Does the 5v regulator have output?
I wouldn't expect there to be drive voltage without the LV operating but I don't know the 250 very well and there may even be different revisions like in the 500.
Doesn’t it have to at least attempt to start up to go into OC protect though? I can’t even get a single pulse out of the thing, but I’ll check that resistor when I get back home.
I looked into the COMP pin as well since it can be used for shutdown (either at ground or 5v), it’s right at .6v does that sound right?
I looked into the COMP pin as well since it can be used for shutdown (either at ground or 5v), it’s right at .6v does that sound right?
There is a low-value resistor connected to its source leg. If it's out of tolerance, the IC will go into over-current protection.
That 1-ohm resistor on the standby FET read infinite in the circuit. Attempted to remove it, and one of the legs fell clean out. I swear, this amp has more failure modes than I’ve ever seen.
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