AQ 2200

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I did a quick recheck of all the PS IC voltages... here they are:

KA7500BD
Pin 1: 6.01 (high)
Pin 2: 2.519
Pin 3: 4.25
Pin 4: 3.574 (high?)
Pin 5: 1.546
Pin 6: 3.658
Pins 7, 9, 10 & 16: 0.000v
Pins 8, 11 & 12: 12.64v
Pins 13,14 & 15: 4.95v

IL393
Pin 1: 6.60 (high)
Pin 2: 2.473
Pin 3: Started out @ 4+v and as I held the lead on it, the voltage slowly went down to 2.43v (lower than pin 2) then will jump up above to around 2.6or 2.7v then slowly go back down over and over. climb and drop, climb and drop. Whats up with this?
Pin 4: 0.00v
Pin 5: 1.025v
Pin 6: 3.096v
Pin 7: 0.118v (low?)
Pin 8: 12.64v

Pin 3 of the IL393 (IC2) appears to go to Pin 11 of the PS card and out to pin 2-1 on IC 201 (output card) via D206. They all share this voltage fluctuation problem.
 
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The anode has 0.000v, the cathode is doing the fluctuation thing from 2.81 (sometimes much higher) to 2.4??? then back up again. So if the anode isn't being driven high, then I can rule out the Q225/226 circuit?

R263 & 264 should be 22K but I'm only getting 18.5K...
 
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Yes I did, however I just went over them all again.

They all have high resistance through all pin configurations.

The transistor readings set to diode check were as follows:

All IRF640N: 1-2: 0.961v, 1-3: 0.540v, 2-3: OL
leads reversed - 1-2: OL, 1-3: 0.586v, 2-3: 0.454v

All IRF9640: 1-2: OL, 1-3: 0.67v, 2-3: 0.440v
leads reversed - 1-2: 0.942v, 1-3: 0.539v, 2-3: OL

The amp looks brand new. Clean, no smells or obvious signs of damage. What should I look at next? Thanks
 
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With or without the jumper? Without the jumper both have 0vdc across the resistors. If I measure from one to the other I get 9.5vdc. If I hold the leads there, voltage slowly drops. It dropped down to 5.5v before my arms got tired, lol

I did check them earlier for resistance. They are both good. R4A = 46.9K (47K) and R29B = 4.69K (4.7k)
 
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Both R4A and R29B have approx. 0.020v across them with the jumper installed.

The Pin 2 on IC 2 is still 2.473v, pin 3 was 3v and again as I hold the lead on the pin it slowly drains until it hits pin 2 voltage. Then it jumps down to 2.23v, then flashes to 2.34v, then jumps back to 2.49 and slowly goes back down to 2.42 and back to 2.49 over and over. IF I leave the lead off the pin for awhile and then reattach it, it shows that the voltage slowly rises on its own to over 3v again (depending on how long its powered up and the pin is not connected to ground through the meter).
 
OK! I have the following readings with IC2 removed and the jumper from pin 4 to pin 14.

Pad 1: 8.42v (high?)
Pad 2: 2.473v
Pad 3: 0.028v (not fluctuating like it was, but every time I check it, keeps climbing. .058v, .090v, .126v, .151 right now - about 15 min powered up with no IC2)
Pad 4: 0.000v
Pad 5: 1.233v
Pad 6: 3.270v
Pad 7: 8.41v (high?)
Pad 8: 12.5v

For easy comparison... my old readings with IC2 installed were:

IL393
Pin 1: 6.60 (high)
Pin 2: 2.473
Pin 3: Started out @ 4+v and as I held the lead on it, the voltage slowly went down to 2.43v (lower than pin 2) then will jump up above to around 2.6or 2.7v then slowly go back down over and over. climb and drop, climb and drop. Whats up with this?
Pin 4: 0.00v
Pin 5: 1.025v
Pin 6: 3.096v
Pin 7: 0.118v (low?)
Pin 8: 12.64v

So basically Pin/pad 1 went even higher and pad 7 went from low to just as high as pin 1??? and pin/pad 3 dropped drastically. I just checked the voltage on pad 3 again, now its up to 0.370v and if I hold the lead on it, it does start to drain down the voltage... :(
 
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