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No voltage on pins 8-19 on SX-1050 awr 103 board????!!!!

Mark , new d2
voltages now are:
pin3 -80.1
pin7 -12.87
pin8 -59.1
pin9 -30.1
pin10 -24.95
pin11 -24.95

Need a new 470mF 100V cap for 104 board.
 
Steve 1050 said:
Mark , new d2
voltages now are:
pin3 -80.1
pin7 -12.87
pin8 -59.1
pin9 -30.1
pin10 -24.95
pin11 -24.95

Need a new 470mF 100V cap for 104 board.
Click to expand...

:D:thmbsp::D We're getting there!!!

When the cap is in, we should have a functional regulator board. Before that we can attack the power amp transistors. I will start gathering diagrams and thoughts on it in preperation.

I vanquished a lingering problem of my own tonight, (well then I discovered more, but that's the way it goes) I was practicing on a sx-3800 in preparation of starting work on an AK'ers sx-3900... The power supply had to be completely rebuilt, but an undocumented factory mod was done to the entire unit's protection circuits, and once the power supply looked good, it still wouldn't come out of protect. It turned out there was a mod on the power supply too, with a reversed diode and 2.2uf cap generating a positive bias for the ac sense input of the protect circuit instead of a negative one. Took a LOT of reverse engineering of the modifications to figure THAT out!! My rebuild/recap MISSED the reversed cap on removal....ouch... now it FINALLY comes out of protect... to discover preamp problems.. hopefully deoxit will clear THEM up.

You would NOT have believed how I had the guts of the thing spread ALL over the bench (and LIVE) to work on it...

edit: I don't believe how much I am slipping, I THOUGHT I had already given you parts numbers for the caps, but apparently NOT:
mouser part # 140-XRL100V470-RC 470uF 100v @ $1.03 ea in stock 85 degree c part ( get two, do them both )
-- or --
mouser part # 140-HTRL100V470-RC 470uF 100v @ $1.34 ea in stock 105 degree c part ( get two, do them both )
-- -- --
you may want to get the high temperature version, since we did have a failure of the old part, PLUS CHECK the old part to see if it is marked as an 85 or 105 degree part. If it is 105 already it IS a high temperature part.
 
I Was hoping you'd say that.
Sometimes the simplest of problems are the hardest to find, undocumented,that's just another way of saying, FUN! I can only say one thing in response to your patience,and expertice, YOU DE MAN!


when I get the caps replaced I will let you know. next step power amp trans tests.
gotta get to bed work comes in 7 hrs.
 
We just had an earthquake. 5.6 mi NE of San Jose. Shook for what felt to be about15 seconds! No damage here, just shook nerves.
 
Sounds like fun, hope there were no plumbing leaks and everything stayed on the shelves.

I rode the universal earthquake ride years ago and that convinced me I didn't want to experience the real thing.

edit: hey my post shows the RIGHT time (for me....)
 
I replaced the caps on 104 and all my - voltages seem to be slightly low now, just as an aside I put my pos mm lead on the case of C10(104) and measured -78.8Vdc???!!!
 
Steve 1050 said:
I replaced the caps on 104 and all my - voltages seem to be slightly low now, just as an aside I put my pos mm lead on the case of C10(104) and measured -78.8Vdc???!!!
Click to expand...

Welcome back, hope the quake didn't do too much of a "shake and bake" on you and yours.

If the regulated voltages are within 10 percent of the schematic you are FINE...
If they are closely symmetrical you are BETTER than fine.

The case is the negative terminal, no sweat. It's mostly insulated by the covering, right? C9 case is ground, but the -78 supply dictates the POSITIVE is grounded.
 
It has been a day, I had to replace a starter.on one car and fix a mirror that the owner had knocked off of a brand new 2008 Mercury, by clipping a pole while parking,FUN!
 
Probably a shift in the weather. I've been feeling out of sorts lately myself figure it's the chainge in the weather.
 
After diode checking all the transistors on the amp board I decided to reconnect pins 16,17 and 8. and apply power. all is good except the protection circuit is not working. there is signal at pins 8,11 but not at pins 9,10. protection relay not being energised.
 
Steve 1050 said:
After diode checking all the transistors on the amp board I decided to reconnect pins 16,17 and 8. and apply power. all is good except the protection circuit is not working. there is signal at pins 8,11 but not at pins 9,10. protection relay not being energised.
Click to expand...

ALL the transistors on both channels were ok? And ALL transistors are re-installed?

What are the DC voltages on 8, 11 with no audio signal ?

If they are less than a volt, more like millivolts, then the protection circuit needs analysis. In that case I need emitter base and collector voltages on Q5, Q6 & Q7, as well as the cathode voltages of D6, D7 & D8.

If the amplifier output voltages are elevated, the amplifier still has problems and the protection circuit is doing it's job.
 
Steve 1050 said:
Which board?
Click to expand...

The protection board awm-090.

edit: if the protection clicks on , DON'T connect the speakers until you have dialled that offset voltage as close to zero as you can, 0.28v is too high, also adjust the 0.028 closer to zero if possible and then JUST CHECK the bias current (voltage across the emitter resistors) on each amp as per the manual's procedure.
 
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