[PeterR]

Quote:

Originally Posted by Madcat05 I'm pretty sure it was AC. On my meter I used the scale with the capital A with a line and two dots above it.

Yeah, sorry if I make you feel like being talked to like a retard, I'm just trying to nudge you into some precision in your reports, makes helping you a lot easier
(but since there's no smiley, you ARE kidding, right?)
Quote:

I've measured from the pads where the battery straps are soldered and I get about 8.75V on each pad which is about 18V. And I'm using two 9v batterys.

Ok, what about after the switch?

 

[Madcat05]

yes I was kinding.

what do you mean by "after the switch"?

 

[Madcat05]

A few days ago I was putting the amp in the case for a few mins and I had to bend back the headphone wires and the LED wires. Could that have damaged them?

Should I replace them?

 

[PeterR]

You said you got 0V on all pins of the 8620, and I assumed that was in response to me asking whether you'd checked the voltage at the ICs' supply pins (4 and 8 BTW). If that is the case, the chips don't get any power and you have a problem to fix. If you've used the pads provided on the board for the power switch, the next step would be to verify that there is voltage at the power switch pad next to C4- when the switch is closed.

Quote:

Originally Posted by Madcat05 A few days ago I was putting the amp in the case for a few mins and I had to bend back the headphone wires and the LED wires. Could that have damaged them? Should I replace them?

Very unlikely. You should check if you've broken any bad solder joints in the process, though.

 

[Madcat05]

I measured at the switches pads and I got 0V.

Should I have measured from virtual ground?

 

[Madcat05]

All the joints look the same as when the amp was working.

One of the battery straps looks loose, so I resoldered it. But it didn't fix anything, but I thought I'd try anyway.

 

[Pars]

Quote:

I've measured from the pads where the battery straps are soldered and I get about 8.75V on each pad which is about 18V. And I'm using two 9v batterys.

You need to trace thru the schematic from the batteries to the switch, crowbar diode etc. to find out where the problem lies. It sounds like you are getting power to the board itself at least at the battery pads? But no power to the opamp (and I would also assume the buffers, etc.)? These measurements should be from virtual ground to the pins, etc. that you are trying to determine power status to. The lack of LED would seem to indicate that if power is indeed getting to the board itself, it isn't making it very far as the LED and other circuitry should be immediately on the other side of the switch. I might instead remove the batteries and then ohm everything out along the way (with the power switch on) instead of subjecting your somewhat expensive opamps and other active circuitry to unknown conditions.

Just my $0.02,

Chris

 

[tangent]

Quote:

I used the scale with the capital A with a line and two dots above it.

That sounds like DC amperes, to me. You want to set the meter to the V with the wavy line over it.

If I'm right, you got a 0 reading because you didn't move the red probe to the amperes jack. If you had, you would have been measuring the maximum amperes your source could put out.

It's time that you read your meter's manual.

 

[Madcat05]

Ok I put the red probe in the AC jack. I measured from PG to the lugs of my input jacks and I still got a reading of 0.

 

[tangent]

...and the meter is set to what?

 

[Madcat05]

AC

 

[Madcat05]

If the amp is getting power to the opamps, buffers, etc. should I just measure from PG to various spots starting from the power pads?

 

[tangent]

Sure. DC volts, this time.

But I'd still like to know why you're getting 0V AC at the input jack. I realize that it doesn't explain the LED, but it is just as worrying as the LED symptom.

 

[Madcat05]

I measured some things.

From PG to the power switch lugs I got 0.08V

From the diode to PG I got 0.08V again

I then measured from all the power pads to PG starting at the - pad closest to the C2/C3 caps. I got these readings

1st - pad = 0.03V
1st + pad = 8.70V
2nd - pad = 8.65V
2nd + pad = 0.07V

 

[tangent]

That suggests damage to the ground channel. All three ICs along that path are suspect.