Took a chance on a CR1040

61sprite

ROACHED
Got it for 40 Bucks dirty and untested. Took it home and gave it a little cleaning and can tell after a good detailing this will be a beautiful piece:drool:! The guy said all he did was turn it on and it lit up. I got no speaker relay action:thumbsdn: I pulled the relay just to see if the contacts looked fried up and they look great, i pulled a piece of clean paper threw them a few times gave it a shot of Deoxit and re installed it. The pre driver chips look good on the backsides, no dark or burnt looking spots? Are the transistors and caps in the protection circuit the ones that activate or send voltage to the relay or is it the power supply board? I am thinking of recapping the power supply board and C810 C812 TR806,807,808,809 in the protection circuit. Any advice on this is greatly appreciated! Just trying to save its life, its such an elegant looking piece i hate to part it out:tears:
 

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Well, the most common cause of protection relays not engaging, at least in this series, is that there is excessive DC offset at the outputs. Have you tried checking that? There are test points provided near the predrivers.

This is a little more plain-spoken that I usually am, but just to be clear: I think it would be a tragic waste of time to go shotgunning parts in the protection circuit.

Cheers,

chazix
 
i adjusted Left TP1 to around 1mv. Right TP2 is off the chart:thumbsdn: 55V, OL MV and the pot doesnt change the voltage at all.
 
i adjusted Left TP1 to around 1mv. Right TP2 is off the chart:thumbsdn: 55V, OL MV and the pot doesnt change the voltage at all.

Check voltages on the amplifier chips. You have a very good chance of having a shorted one.
 
The 55V offset means, with pretty good confidence, a bad output module. It may have damaged the predriver, and the emitter resistors (the ceramic parts near the output module). The emitter resistors can be checked with an ohmmeter. You can find a procedure for checking the predriver (with the output module removed) in a thread with "ongoing saga" in the title.

Good luck,

chazix
 
Measured voltages on the 2 pre driver chips. Chip closest to the front, Pin 15-51.2
Pin 14-3.4
Pin 13-3.2

Chip #2 Pin 15-51.2
Pin 14-22.6
Pin 13-2.6

These are with the output module still in place. My guess is chip 2 aint looking good.

I am going to study the schematics and that super duper saga thread and work my way back to the output modules. Pic of meter is on Pin 14 on chip 2. Is that a crappy soldier job on the output modules or is that normal?
 

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Your guess is correct.Excellent soldering don'tcha think.:D

Yeah thats pretty bad:scratch2:

I got Left channel tunes! I pulled the right output module and she booted right up, relay clicked and she was singin.

I had bad voltages on the right output module and was hoping that was causing the high voltage on pin 14 of the pre driver. Not the case i got high voltages on pre driver pin #13- 50.8V & #14- 50.3V with the module removed:thumbsdn: (i think i read somewhere Merrylander said if ya got anything over 5V you were no good, the left side measures around 3V )

Ya think the pre driver got toasted also?

You guys have ant idea where i can find a pre driver chip? I know i can get the output transistor (stk0080ll)

Thank you Chazix and AV so much for not letting me shotgun parts and pointing me in the right direction:thmbsp:
 
I don't think it's really possible to evaluate the health of a predriver with the output module removed. Unless, that is, you tack in a couple of resistors to complete the overall feedback loop around the amplifier section - there's a description of that technique somewhere in the saga thread.

You'll want to check the emitter resistors - the white ceramic parts near the output module. I believe they are 1/2 ohm. Sometimes they fail when the output module fails.

chazix
 
Chaz, i removed the emitter resistors and they both check good at .6

I saw in the saga thread where 4seatpilot tacked in those resistors, what do you think if i just swap in the good output module from the left channel?
 

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Well, that would be a good test, but it would mean a risk of damaging the good output module. It's a very small risk, though - the more I think about it, the less risk I see. I can say that I've never personally seen a predriver fail in a way that I believe could damage an output.

If it's not convenient for you to use the resistor technique, I'd say go ahead with the swap. Put the emitter resistors back in for the test.

chazix
 
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Chazix, i put the resistors back and moved the output from the left to the right and was hoping to hear the relay click and it never pulled in. Put it back in the left channel to make sure nothing happened to the output module and the left channel pulled the relay in and was fine. I read in the saga thread you examined a IG02950 from Utsource and deemed it satisfactory. They offer a IG02930, do you think it is a satisfactory replacement for the 1040? I would rather have one of your reproduction boards (or maybe 2 and just replace both predriver chips, no heatsinks needed) but i dont know if you are still offering them? I realize you would want to make sure the chip that it was replacing was absolutely bad instead of just shotgunning parts. Can we be pretty confident at this point the output module and the pre driver are bad? I am willing to spend a little time saving its life recapping that board with a new output module and pre driver if ya think that will do it? Thanks
 
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Alas, 61sprite, I think you're right to concude that you've got both a predriver and output bad.

I don't know whether the IG02930 predrivers from UT on ebay are copacetic. Another AKer bought some, but turned out not to need them. He did report that they were new, though. That is, they weren't "pulls". I don't think it's known whether they are NOS or are somehow being newly produced. To be honest, I can't imagine how they can sell them so cheaply in either case.

I'll send you a PM about my repros shortly.

Cheers,

chazix
 
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