don't worry.....I never even think of a scope when fixing amps.
ie unless I want to measure crossover point.

I will have sometime off today later since it's holidays. so it would be nice if u can get the pics up.

 

Cut the wire shown at RED.

Measure the voltage at the BLUE point with respect to GND.

Do not replace any components yet.

(I've seen your Tektronix 564 scope. I will post instructions for desired setup.)

 

Consider yourself very lucky. That is a nice scope you just got yourself!

Post a picture of DISPLAY controls.

Set the DISPLAY to Normal (non-storage) (I cannot make out the writing on the front panel).

Set TYPE 3B4 TIME BASE
TIME BASE = 10uS.
TRIGGER MODE = AUTO
SLOPE +
COUPLING AC
SOURCE INT

Set TYPE 3A1 DUAL-TRACE AMPLIFIER

Set CH1 to GND, 5 VOLTS/DIV
Set CH2 to GND, 5 VOLTS/DIV
Set MODE to CHOP

Adjust CH1 POSITION so that CH1 trace is at 4 grid line from the bottom.
Adjust CH2 POSITION so that CH2 trace is at 1 grid line from the bottom.

Set CH1 to DC
Set CH2 to DC

 

Can we get a better photo of the components here and behind the caps?
A view from above would be better.

Changed my mind. There is nothing behind the caps and it would be difficult to connect to the jumpers behind the transformer.

 

Connect scope CH1 and CH2 to these points.

Delete: (You may be able to reach these points (the wire jumpers) from the top side of the board.)

Or you can solder two wires on the bottom side and feed to the CH1 and CH2 inputs on the scope. Don't forget the GND connection.

Adjust the controls of the scope to show the two waveforms and post picture.
Indicate VOLTS/DIV and TIME/DIV settings if these are changed.

 

Cut the wire shown at RED.

Measure the voltage at the BLUE point with respect to GND.

Do not replace any components yet.

(I've seen your Tektronix 564 scope. I will post instructions for desired setup.)

i cut the wire. on the left side is 12.7v the right side by the blue is 1mV.

i hosted the pics on a free site here:


http://www.mediafire.com/file/43bab7d783buk48/Amp%20Pics.zip

 

i cut the wire. on the left side is 12.7v the right side by the blue is 1mV.

Something is not right here.
Leave that wire cut for now.

Are you absolutely certain that Left side is +12.7V? Watch your polarity.
My expectation was 0V on left side, 18V on right side.

Measure the voltage on the wire just above the one you cut.

What is the voltage from your power source? Is it a car battery?

Were you able to connect the scope and get those CH1 and CH2 waveforms on post #65?

Edit: I can only assume that the OP made a mistake and the reading on the LEFT side of the jumper was -12.7V.

 

Before you connect the scope....

What are you using for a 12V power supply?

See this first

 

I see chips is still at it....I'll wait for now.

 

I see chips is still at it....I'll wait for now.

This is my baby now, now that OP has a scope!

(unless you can spot something that is obvious)

 

I haven't yet studied the case yet.
And I do not like to barge in, cause it is not polite.

When you are done, let me know. Giving up does not belittle you in my eyes.
I am always happy to teach what I know to you guys. And I want to learn what I dunno from you.

Chips....please do not use scope...you do not need it really. trust me on this.

 

Chips....please do not use scope...you do not need it really. trust me on this.

Sorry, you have your style and I have mine.
The voltage readings OP is reporting do not make sense.
OP is reporting 12.7V on the load while the source is 0V. Makes no sense. Like he has something backwards.

If I have a scope I can find the fault 100 times faster.

OP still has not reported back. I need to know if the DC-DC Converter is switching.

 

You want scope because you have always worked with it.

I do not use because I did not get one when I needed it. Hence, I have learned not to use it under the circumstances.

 

You want scope because you have always worked with it.

I do not use because I did not get one when I needed it. Hence, I have learned not to use it under the circumstances.

True. I learn to make do.

If I had no scope I would make do with what I have.

If I were stranded on an island in the middle of the Indian Ocean I'd be drinking coconut water instead of Tequila.

 

We all have our styles. An ESR meter is way better for finding bad caps vs. looking at each side on a scope, IMO. Since cap plague is still killing everything, I've gotten a lot of nice dinners and a bit of cash here and there with only a Fluke 87V and the Blue ESR meter. I use those more than any other tool, I think. Next is PicKit, LCR meter, Signal generator and scope.

Somebody else's way of going about things can be entirely different. For this case, after power and caps, I often look for the B-E & C-E voltage on the transistors in the area of question, check inductors, they have an odd way of breaking off right at the board (esp when in subwoofer area), etc. Over half the transistors I've found fail in an amp fail in a way that is hard to miss. Oh, then there's the smell of burning resistors...

Here we only have what we can see and have somebody measure, and things still always get fixed, which amazes me.

 

If I were stranded on an island in the middle of the Indian Ocean I'd be drinking coconut water instead of Tequila.

Seriously....How am I doing ?

 

Seriously....How am I doing ?

You're doing fine!

 

ok, heres some more pics. im getting -49 on the top wire, -12 on the left and .1mV on the right. im using a variable 20v 20 amp power supply. were you guys able to download my pics from mediafire?

 

few more...

 

So my assumption was correct. It is -12V and not +12V.
Can you move on to the test on post #65?

Have you already pulled C908 and C925 and tested for shorts?