RV2 AND RV3 are fuses. RV2 from one side to the other is measured at 1.1 ohms. RV3 is measured at 0.4 ohms. They are not the same part number so I think its okay.

There is something wrong in the +15V circuit.
Could it be that the CAPS (C20 OR C19) are busted?
how do I check?

 

Hello,

A poly fuse should recover when power is removed.
Remove the power for about a minute and try again.
When the output on the +15 Volts is down again, there is a short on the +15 Volts.
It can be that C19 is a tantalium capacitor, wich I have seen to create a short.

Bertus

 

I would desolder one end of each RV and check resistance across them that way. We can't see the rest of the circuit and there may be other devices in parallel causing the readings you have..

 

If the voltages in red are your measured values then it looks like there is a short circuit on the +15V which could be either of C19 or C20 but could also be in whatever the +15V feeds.

 

resistances across C20 and C19 are 0.2 ohm
I will try to replace both C20 and C19 and see if that fixes the problems.
Probably one at a time first.
RV2 is what I don't have available so I don't want to touch that.

 

Hello,

Take the capacitors of the board and measure the resistance again.
As I said, tantalium capacitors can create a short.

Bertus

 

I was told from my professor that if normally if the C19 is damaged. I will see the burnt on the CAP or smell it.
From looking. It looks okay.
He thinks I should look at other COMPONENTS THAT uses the +15V and go from there.
The fuse SMD050-2 is a resettable device which will reset when the voltage in the circuit is removed or in some cases will reset automatically when the overload condition is corrected.

 

I was told from my professor that if normally if the C19 is damaged. I will see the burnt on the CAP or smell it.
From looking. It looks okay.

Yes, but they can be short with no obvious signs too.