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CA-1000 Rebuild Issues

jandajr said:
TR 605 E: -52.3 C: -52.3 B: -52.3
TR 606 E: -51.9 C: 48.8 B: 51.1
TR 608 E: 0.3 C: -51.5 B: -51.5
TR 609 E: 0.3 C: 52.5 B: 48.7
TR610 E: 0.3 C: 52.5 B: 51.9
Click to expand...
Suggests R622 (680) is open

You've been reflowing solder, plz post hi-res pic of solder side

EDIT: Can you source another MM to try
 
jandajr said:
B to Jumper 12.19K
Click to expand...
Wanted to see OL to indicate open component/burnt track... though 12k is not a great result either.
Jumper is at R620, R617 node, so measuring to wire B should be measuring R617(470) and the VR603/R616 combo, VR603 (is it still set fully CCW/zero ohms?) typically being 1-2k so ballpark maybe 2k expected, so why 12K, open path?

Plz resistance check between red-red then blue-blue, yellow-yellow, green-green
upload_2022-2-7_9-14-18.png

yellow-yellow is across VR603, may not be zero ohms, others should be short.
 
I have 2 Fluke 8010A Measurements are identical.

After some reflowing of mentioned, I when back and re-checked:
VR603 0.0 ohms
R617 (one lead pulled from PCB) 475 ohms
R617 (in circuit) 377 ohms

Wire B Normal - 50.9
Wire B Class A - 51.0

B to Jumper 376 ohms
Red/Red 00.1 Blue/Blue 00.1 Yellow/Yellow 00.1 Green/Green 00.1

Checked TR605/606 same measurements as last tested.
At this point I’m going to unsolder all the leads to the board (again), so that I can easily re-test all the components, and check all tracks, and reflow everything
without being concerned about braking the leads.


IMG_1961.jpeg
 
Wire C is at +50V, this is a brown wire, the +50 supply wire is also brown... impossible that someone connected the +50V supply wire to point C??? Check continuity between power amp point C and point C on the operations board, marked in blue.
upload_2022-2-9_12-17-46.png

Otherwise, there is a near short between wire C and the +50V supply?
Measure resistance between
wire C and +50V wire
wire C and -50V wire
wire C and +B wire
wire C and -B wire
 
Possibly TR609 has failed c-b short, if you replace TR609 with a 1N4148 diode connected between b-e, do you still have 48V at point C?
 
I checked the resistance at C on the operation board to the C on the main board 00.0 ohms

wire C and +50V wire = 00.0 ohms
wire C and -50V wire = 00.0 ohms
wire C and +B wire = 00.0 ohms
wire C and -B wire = 00.0 ohms

I removed the TR609 when it failed the DBT. Yes I added a 1N4148 diode connected between b - e.
I have -50.7 at C on the main board.
 
jandajr said:
wire C and +50V wire = 00.0 ohms
wire C and -50V wire = 00.0 ohms
wire C and +B wire = 00.0 ohms
wire C and -B wire = 00.0 ohms
Click to expand...
Sorry but that should be "impossible". Measuring the resistance between wire C and other wires on the power amp board. Perhaps MM incorrectly set to volts???
 
mbz said:
Sorry but that should be "impossible". Measuring the resistance between wire C and other wires on the power amp board. Perhaps MM incorrectly set to volts???
Click to expand...

Yeah thats weird . Maybe one but not all !!!

Nashou
 
First of all, there's no rush to get back to me. Do it at your leisure.

Left (working)Channel C to -50, +50, -B, +B, are all open.
From here on in, I'm going to first take any measurement from the Left (working) channel.
Then compare it to the Right (non working) channel.

Not sure what you want me to look for on: C-VR603(zero ohms)-R617(470)-R620(33)-TR605c-e-R619(68)

Remember,
Do it at your leisure.
 
jandajr said:
Wire C and -50V wire = 1.798K ohms
Click to expand...

mbz said:
Path is possibly
C-VR603(zero ohms)-R617(470)-R620(33)-TR605c-e-R619(68)
Click to expand...
Wire C and -50V are "connected" via components with resistance 1.8K or abouts. Above is possible connection path however TR605ec should give OL.

With one probe fixed on the -50 wire can you test/measure resistance at various points along this path, ie, one side of R617, then the other then TR605e. Wanting to see the 1.8k decrease. If you see open then it's the wrong path. Maybe wire C,R621, D601 or TR609...
move in the direction where the 1.8k decreases. Possible paths to trace, red most likely
upload_2022-2-11_19-52-13.png
 
Does "RED LINE" make sense. The measurements are very close to the measurements on the left channel.
I will complete the three others upon your examination.

C and -50V = 1.792 K
RED LINE: B (1.792K), thru R617(1.409K), thru R620(1.372K), thru TR605(69.7) at E, thru R619(0.2)


BLUE LINE: C ( ), thru TR606( ) at E, thru R20( ), thru TR605( ) at E, thru R619( )



GREEN LINE: C ( ), thru R621( ), thru D601( ), thru TR607( ) at E, thru TR608( ) at C, thru D602( )

thru R622( ), thru TR605( ) at E, thru R619( )



VIOLET LINE: C ( ), thru R621( ), thru TR609( ) at E, thru D607( ), thru R625( ), thru R626( ),

thru TR610( ) at B, thru R622( ), thru TR605( ) at E, thru R619( )
 
I turned the amp to take a couple of voltage measurements.
Turned it off after a minute.
10 minutes later Left Channel C to -50 13.45 K Right Channel C to -50 13.41 K

So that makes the Red Line readings posted above completely useless!
I'm ready to give up.
 
Replace TR605 (KSC2690A) from a reliable source. Possibly going intermittent giving these inconsistent measurement results.
 
Mouser/Fairchild on the KSC2690AYS

Can I do the same (ohms) testing, if I pull all the leads from the main board and remove the board from the chassis?
Trying to do the test is killing the ABCS leads. They keep breaking from turning and twisting the board. This would allow me to also double check all the components and PCB.
 
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