Yamaha CA-610ii Power light Only

[Audi2014]

Good evening everyone,
Picked up a Yamaha CA-610ii for a project. Pulled off the cover and looked around the unit and found both fuses in tact.
Looked closely at the 2 (50 volt) 470uf caps in the picture and they looked like the unit has been in a damp area. Only thing I get
when turning on the unit is the red power light. The unit smells musty. I will download the service manual. Any tips would be helpful.
Thanks

 

[avionic]

Good evening everyone,
Picked up a Yamaha CA-610ii for a project. Pulled off the cover and looked around the unit and found both fuses in tact.
Looked closely at the 2 (50 volt) 470uf caps in the picture and they looked like the unit has been in a damp area. Only thing I get
when turning on the unit is the red power light. The unit smells musty. I will download the service manual. Any tips would be helpful.
Thanks

Start t-shooting the DC power supply.

 

[Audi2014]

Start t-shooting the DC power supply.

Good evening Avonic
That’s where I was going to start. Checking to see what voltages I am getting from the power supply per the schematic.

 

[Audi2014]

Good morning,
With meter and schematic in hand I went to test the voltages at the power supply area.Voltages were exactly what the schematic posted. I then tested one leg of the 250volt fuse and the relay kicked in and as soon as that happened the square white resistor on the left in the picture started glowing red and I shut everything down. I am guessing I am going to have to build a dim bulb tester to proceed my troubleshooting without damaging any components.

 

[mbz]

the square white resistor on the left in the picture started glowing red

R523 Left channel

Yes, DBT
Also test FR491(220) and test the emitter resistors,R523, R521 still in spec 0.47ohms.
Diode test left channel outputs TR501,3, c-e short?
Disconnect speakers, don't want to burn them

 

[Audi2014]

R523 Left channel

Yes, DBT
Also test FR491(220) and test the emitter resistors,R523, R521 still in spec 0.47ohms.
Diode test left channel outputs TR501,3, c-e short?
Disconnect speakers, don't want to burn them

Will do..thanks!

 

[avionic]

Like your avatar.

 

[Audi2014]

R523 Left channel

Yes, DBT
Also test FR491(220) and test the emitter resistors,R523, R521 still in spec 0.47ohms.
Diode test left channel outputs TR501,3, c-e short?
Disconnect speakers, don't want to burn them

R523 Left channel

Yes, DBT
Also test FR491(220) and test the emitter resistors,R523, R521 still in spec 0.47ohms.
Diode test left channel outputs TR501,3, c-e short?
Disconnect speakers, don't want to burn them

Good afternoon,
I finally have gotten some time to look at the Yamaha. I checked the 2 resistors R521,R523 and they are still good.Transistor Tr502.. reads 42 volts dc on both the emitter and collector. TR 501 is reading 6volts dc on the emitter and 26vdc on the collector. Haven’t checked resistor FR 421 just yet.

 

[Audi2014]

Good afternoon,
This is what I have found so far. I picked up a pair of output transistors for the left channel due to one tested as a short. When both are installed no relay click.
When I remove TR501and power up unit, the relay clicks . I am guessing that a component that is in its path has gone bad.

 

[mbz]

Results a little confusing

Transistor Tr502.. reads 42 volts dc on both the emitter and collector.

TR502 is on the right channel, suggests either it has failed short c-e or fault with driver TR498

When I remove TR501and power up unit, the relay clicks .

TR501 is for the left channel, removal will mask a problem from it or its driver TR497.

Suggest build a dim bulb tester to reduce damage to new parts.

I'd be tempted to pull both L&R output transistors and replace with diodes (1N4148, 1N400x, whatever you have handy), connect the diodes between output base and emitter solder tabs, for PNP outputs connect diode cathode to base, for NPN connect diode anode to base. The diodes replicate the b-e junction of the transistor. DBT power up and verify dc offset is ok

 

[MFRD]

Proceeding methodically and documenting the results in the thread might be helpful if you want targeted help.

Pulling TR501 through 504 out of circuit and testing them might be a good way to start. No desoldering required.