Hi, can someone guide me to troubleshoot this circuit.
I have 15RTN shorted with +15V.
That is B72 and B69 are shorted together.
I am not sure why but its causing all the rest of the circuits not to work.
Can someone guide me through this?
Thanks

 

Here are some possible approaches:

1) Get a current tracer
2) Get an IR imaging camera
3) Get a can of freeze mist
4) Start cutting away at the 15V power rails on the PCB.

 

Here are some possible approaches:

1) Get a current tracer
2) Get an IR imaging camera
3) Get a can of freeze mist
4) Start cutting away at the 15V power rails on the PCB.

I don't know if we have a current tracer. I have never used one
I don't know if we have an IR imaging camera.

I can find a can of freeze mist. What do I do with it? What should I see or look for?
what is start cutting away at the 15V power rails on the PCB?
Thanks for your help!

 

Hello,

Check C5 and C6.

Bertus

 

Could this problem be at the board level and not because of a component damaged?

 

Hello,

Check C5 and C6.

Bertus

I will check that out! thanks!

 

Could this problem be at the board level and not because of a component damaged?

What do you mean by board level?
To me, board level and component damage is referring to the same thing.

 

I don't know if we have a current tracer. I have never used one
I don't know if we have an IR imaging camera.

I can find a can of freeze mist. What do I do with it? What should I see or look for?
what is start cutting away at the 15V power rails on the PCB?
Thanks for your help!

If you apply +15VDC and it is shorted to GND, all the high current is going somewhere back to the power supply.
The idea is to trace where the current goes and usually the shorted component is going to have elevated temperature. You are trying to find which component on the circuit board is getting the hottest.

If you cannot locate the fault visually, you have to do a binary search.
You divide the circuitry in half and cut the power supply trace leading to one-half of the circuitry.

 

Hello,

Check C5 and C6.

Bertus

I lifted a lead from each CAP and do a resistance test and its not shorted.
The CAPs seems okay.

 

I must be one of the few people on the planet that owns an HP546A Pulser and HP547A Current Tracer. (They come as a kit with other parts.)
If you can find a pair for sale, it is worth their weight in gold for this type of trouble shooting.

 

Hello,

Lift a leg of R1 and see if the +15 Volts stays healthy.

Bertus

 

If you apply +15VDC and it is shorted to GND, all the high current is going somewhere back to the power supply.
The idea is to trace where the current goes and usually the shorted component is going to have elevated temperature. You are trying to find which component on the circuit board is getting the hottest.

If you cannot locate the fault visually, you have to do a binary search.
You divide the circuitry in half and cut the power supply trace leading to one-half of the circuitry.

I like that idea. But I only have a can of freeze mist. So how do I use it?
What do you mean do a binary search? I am not too sure how to divide the circuitry in half since I don't know which half to begin with. I have an IR temperature meter. Maybe I can use that to find components that are the hottest?

 

What do you mean by board level?
To me, board level and component damage is referring to the same thing.

As in could the board paths or wires is broken in the multilayers.

 

I must be one of the few people on the planet that owns an HP546A Pulser and HP547A Current Tracer. (They come as a kit with other parts.)
If you can find a pair for sale, it is worth their weight in gold for this type of trouble shooting.

View attachment 132194

View attachment 132195

I will youtube this and purchase one for troubleshooting purposes. thanks!

 

I have an IR thermometer! will that work?

 

http://www.ebay.com/itm/HP-546A-Log...521510?hash=item5b3c597ca6:g:-m8AAOSwPH9Zgeb5

$20 for the pair! Grab it before it's too late.

 

The R4 area is hotter than the rest of the components on the board

 

Hello,

R4 is in the - 15Volts line, wich is working.
What is the temperature of R1, compared to the other components?

Bertus

 

Hello,

R4 is in the - 15Volts line, wich is working.
What is the temperature of R1, compared to the other components?

Bertus

 

Hello,

Is the +15 Volts lost on pin 1 and 2 of JP2?
If so, there is no + 15 Volts coming in.

Bertus