Yamaha CA-1000 III (CA-1010) Relay Both relay's not turning on

[wildmermaid7]

This points to the right channel amplifier. Need to check the output transistor base voltages. Should all be around . 58 vdc. ( 580mv )

How to check that ?

 

[wildmermaid7]

Get the power amp module out and check the transistors ?

 

[mbz]

You will need to remove the right channel (assembly on right side when looking from front) power amp and heat sink
ie, unsolder the 4 smaller wires (blue, orange,,,) and unplug the 5-6 connectors at the middle of each board
(take some pix before hand). Unscrew the 2(?) bolts. Remove, then connect up jumpers from the disconnected wires to
the board terminals...

more to follow...

 

[mbz]

You will need to measure DC voltage at several locations, connect black meter probe to chassis or any black
speaker post. Try measuring at the following points marked in red

R330 (4.7ohms)
R331 (4.7ohms)
R338 (4.7ohms)
R339 (4.7ohms)
D306 anode
D307 cathode

All fusible resistors should be checked, try in circuit first, marked in blue
FR301 (220ohms)
FR302 (220ohms)
FR303 (390ohms)
FR304 (68ohms)
FR305 (39ohms)
FR306 (47ohms)
FR307 (100ohms)

Check for any heat stressed resistors, typically having a discoloured middle body

 

[wildmermaid7]

You will need to measure DC voltage at several locations, connect black meter probe to chassis or any black
speaker post. Try measuring at the following points marked in red

R330 (4.7ohms)
R331 (4.7ohms)
R338 (4.7ohms)
R339 (4.7ohms)
D306 anode
D307 cathode

All fusible resistors should be checked, try in circuit first, marked in blue
FR301 (220ohms)
FR302 (220ohms)
FR303 (390ohms)
FR304 (68ohms)
FR305 (39ohms)
FR306 (47ohms)
FR307 (100ohms)

Check for any heat stressed resistors, typically having a discoloured middle body

View attachment 3051307

Thanks MBZ i have removed it before for Cap upgradation so wouldnt be a problem. I will check the voltages and report it back. I will also reinstal TR403 AND 404 as they are fine and fault seems to be some where else.

 

[wildmermaid7]

Guys,
Not sure what happened but as soon as i installed the TR403 and TR404 Both Relays are working now. Isnt it strange ! I have to test the voltages again on RI and RO as well as the left Channel.

 

[wildmermaid7]

Guess what after some time when I turned it off and turned it on the relay wouldn't click again.I let it stayed on for few mins and the relay came on again.

 

[wildmermaid7]

I think all my transistors are dying.

 

[avionic]

TR403 and TR404

Replace them with new pieces. Worth a shot.. Just because the test good statically. Doesn't mean they will work properly under circuit load.

https://www.mouser.com/ProductDetail/512-KSC2383YTA

 

[Sparkplug]

Check your transistor soldering pads for continuity with the traces they’re connected to. Remove transistors, remove any remaining solder and inspect the pads … re-solder the transistors in.

 

[Soundscape]

Congrats on a tough recap. Let's assume ya did it right. Have you cleaned the control switches? I'd clean the speaker selector switch & clean the headphone jack before any further surgery. Sometimes ya get lucky.

 

[wildmermaid7]

Replace them with new pieces. Worth a shot.. Just because the test good statically. Doesn't mean they will work properly under circuit load.

https://www.mouser.com/ProductDetail/512-KSC2383YTA

I agree.I don't have a curve tracer otherwise would have checked them.But will replace all I guess to be future safe.These are all 40 year old transistors so performance would degrade overtime.

 

[wildmermaid7]

Check your transistor soldering pads for continuity with the traces they’re connected to. Remove transistors, remove any remaining solder and inspect the pads … re-solder the transistors in.

Checked them. They are fine.

 

[wildmermaid7]

Congrats on a tough recap. Let's assume ya did it right. Have you cleaned the control switches? I'd clean the speaker selector switch & clean the headphone jack before any further surgery. Sometimes ya get lucky.

Thanks.I did it alright otherwise wouldn't be hearing any good music .This issue suddenly occured after two weeks of recapping.I have changed all the caps , relays minus the transistors so I guess thats the next step.As for the pots I give it a clean with contact cleaner but not the speaker one so good call I will do it.Thanks.

 

[wildmermaid7]

Some pics

 

[Soundscape]

Looks nice. Maybe clean the pre-out coupler switch in back too...and cycle it.

 

[wildmermaid7]

Hi Gents

Apologies for reviving this thread again. To give you an update, i decided to upgrade the transistors in the power board as well as both the AMP boards. Have replaced all the transistors (Not the output transistors ofcourse, they are still original) but the relays are not coming up again. I have checked the voltages from the power board to both the amp boards which seems to be ok.

Can you please advise if i have missed checking anything or how to move forward ? Your help is apperciated. Thanks.

 

[avionic]

Power up the unit.. Visually verify by looking at the " class A " relay while toggling the Normal/Class A switch and verify if it is working or not. Are your indicator lamps illuminated ?

Class A relay is topside on the Electrolytic Capacitor board.. Protect relay is on the bottom side power supply board. If neither relays are working then trouble shoot the +B3 power supply. +B3 power supply is the common denominator of the two relays.

 

[wildmermaid7]

Thanks @avionic I have done as you asked but Class A relay is also not engaging. When i turn on the amp, VU meters needles do move. Also checked DC voltage on speaker terminals and they are in Milivolts so no problems there. I have tested the amp through a bulb tester for any shorts but all is well there too. I am at a puzzle as all the transistors i replaced are subsititutes of what ever is suggested on this forum.Thought maybe coupler switch might be dirty so opened it and yes it was dirty, cleaned it and its still the same.
I am at a puzzle.

 

[avionic]

.Thought maybe coupler switch

Has nothing to do with relay operation.