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Wasting my time and money? WTF? What would you do if you thought the original chip was bad? Throw the unit out? I'm looking for constructive help. Not judgemental BS.

Ebay and Aliexpress

Yes, I replaced the PA0016 many times. I'm almost convinced the last batch were bogus. I've also tested and/or replaced every transistor on the board more than once. I've looked at pictures of the boards posted on the internet and convinced myself both of those diodes should not be installed...

Yes many times.

8v So, you don't know if there supposed to be populated or not? Geez, I thought you had pictures. I honestly didn't think this question would be so hard to answer.. There are no 'positions' on my schematic.

Thanks for the quick reply! I'm consistently getting bad readings at PA0016 pin 14. But the reason I posted was to find out if D137 and D139 are supposed to be populated on the PCB. They do not appear on the schematic, but appear across R139 and R141. I've attached a photo, with the two...

D137, D139 positions on left driver board AWZ1025 for Pioneer M90

I've been working on this M90 for way to long. Components were missing and charred when I received it. I'm having a great deal of trouble getting the PA0016 bias correct. I've replaced that IC numerous times without correcting the problem. Bottom line is; on the 1025 Driver Bord there are...

Definately a scam. STAY AWAY FROM THIS SUPPLIER. I ordered a recap kit for AU717 on March 26th of this year, and still have not received it. They replied only once with a BS answer saying supply chain issues. Second reply they said they'd send it "soon" with a tracking number - a month ago - and...

Hi Jack - I could really use the owner manual with schematic for the Cambridge 2500. Can you share? cbkoerner@hotmail.com

Good point. But it does have trouble starting and stopping. I thought it might be related.

Hi folks, I just came across an Elac Miracord model 40. After removing the turntable from the plinth, I noticed a tiny part loose in the bottom of the plinth. It's brass, and about the size of a BB. It's not spherical, but round and smooshed, with a tiny hole in the center. Where would this part...

The HVPS is defective.

I have two on the bench right now and they sound awesome. Amazing how much punch they have. If they've never been worked on, you must replace the electrolytic cans and bias filter caps.

Good job! Don't worry about those big yellow input lowpass filter caps - they're fine. I have several of those Chinese meters and they're fabulous! Mosfets like to fail shorted, so the quick test is short the gate to source and use your ohmmeter to measure high resistance source to drain. I'm...

Almost forgot - when I said capacitors I meant electrolytes. Don't worry about the others - they'll likely be fine. But a s a matter of practice electrolytic caps this old should be replaced - especially since that are crap brand. All 3 of mine were very high ESR, and way off capacitance value...

You'll find the driver board schematic in one of my prior posts. My unit had all good transistors, lousy capacitors, and a bad (open) 100K resistor (yup!).

yes the brown is center tap. nothing will be biased properly if it is open. don't connect the amplifiers until you figure that out. also - the breaker on these units are very prone to failure. try clipping in a 15a fuse and see if it handles the caps.

I've been struggling with this for way to long. My Anthem MRX300 powers up with Front Left DC offset of about 100mV which causes it to power down into protection mode a second or so later. Gut told me it should be a problem with the driver, so I proceeded to trace the schematic. The latter takes...

Oh, almost forgot; I also replaced all 3 electrolytic capacitors on each board with nice new Nichicon pieces as they were trashed. Those were bound to be part of the HF oscillations as well...

I purchased a 2450 on ebay for $20 and drove to the pawn shop to pick it up which saved shipping. I have a weakness for power amps and couldn't pass this one up. Failure turned out to be two resistors. One of them looked brand new, and set the gain on the differential amplifier. The second was a...

just to be clear, I never said -no connection between circuits'. you can connect what you want provided what I mentioned holds true.

that does sound right. but does it have a grounded ac cord or just 2-prong?

ditto regarding the solid state comment. you really need a tube amp to take advantage of them.

I see no reason why you can't do what your asking, providing the circuits you are referring to use a full wave bridge. stated differently, the ac portion of the two circuits must not ground either of the two ac inputs.