Yamaha CR-2020 Stuck in Protection Mode

[Nashou66]

Both of these red circled caps were replaced with 10/63’s on both boards.

One of those is 25uf , unless the schematic is wrong.

 

[avionic]

unless the schematic is wrong.

That is not the schematic.. That is a parts locator diagram. Schematic says 10µf@25vdc... C601

 

[SharkBait07]

Close to D607.. tan/brown resistor on the lower left side edge..

The fusible resistor tested at 72 ohms. I did find a slightly lifted pad on the brown capacitor to the left of the B- fuse. Luckily there next component was really close so I was able to use a small piece of solid copper wire. After putting it back together, the behavior is slightly different. The left side audio is back only when the yellow wired amp board B+ fuse is removed. Removing the B+ fuse brings the unit out of protection.

Is the schematic correct in saying the brown wired output board is the ride side and the yellow wired board the left?

 

[avionic]

+B is still shorted to TR611 base...

 

[avionic]

With the 2020 unplugged.. Measure the resistance between TR611 base lead and the +B fuse... With the fuse installed in circuit.


Should be at least 4.2 K Ω

 

[SharkBait07]

With the 2020 unplugged.. Measure the resistance between TR611 base lead and the +B fuse... With the fuse installed in circuit.


Should be at least 4.2 K Ω

Measured 0.741 K the first time and 1.14k the last few times.

Earlier today reflowed some joints and cleaned the back of the board with Flux-off and an exacto.

 

[avionic]

Should be at least 4.2 K Ω

Measuring through TR611..

Measured 0.741 K the first time and 1.14k the last few times.

Due to the B-C junction of TR611 and your test lead polarity.. If C616 is leaky or checks like a fixed resistor it could be bad. <---- needs to be removed from circuit as does TR611..and checked out of circuit.

C616 is a 47pf@500v probably a ceramic disk.

 

[SharkBait07]

Measuring through TR611..

Due to the B-C junction of TR611 and your test lead polarity.. If C616 is leaky or checks like a fixed resistor it could be bad. <---- needs to be removed from circuit as does TR611..and checked out of circuit.

C616 is a 47pf@500v probably a ceramic disk.

In order to rule out TR611 I swapped TR611 and TR612 for new MJE15032G/03G’s I had as extras. I had originally tested TR611(2sc1624) on the bench but took the extra step to make sure.

My Fluke 83 or DT830B DMM was not reading continuity across C616. I also swapped C616 between amp boards to rule it out and ordered a DROK transistor/capacitor tester.

Happy Saturday!