Yamaha C-70 MM/MC amp repair help

[bberkom]

Well, I finished completely recapping the C-70, which went fine. Many of the caps were out of spec, especially in the power supply. I also replaced RY101 with a replacement relay from ebay. I still couldn’t get the right channel MM/MC phono board to adjust, and I still got no output in the right channel at the rec out jacks when using the phono input.

It made sense that something around the relay was causing the loss of signal, so I took a real good look at the circuit board until I saw this tiny crack.

I patched the crack by scraping the traces on both sides and bridging it with a leftover component lead clipping. It works now!

I’m listening now, and it sounds great. I won’t make any judgements about the sound quality after the recap, but I do really like this preamp.

 

[avionic]

It made sense that something around the relay was causing the loss of signal, so I took a real good look at the circuit board until I saw this tiny crack.

I patched the crack by scraping the traces on both sides and bridging it with a leftover component lead clipping. It works now!

I hate cracked pcb's..

 

[Robbie G]

RY101 may have a bad/fouled set of contacts. It is a small yellow/orange reed relay.HB2E-DC24V When I refurb the C-70's all eight of these get replaced with new pieces. They quite frequently have issues. They are $10-13 a pop.

The more I think about it....



I'd replace the relay first. Before the opamp.
That relay connects the phono REC out signal to the REC out jack.

Hi Dave, I just picked up a C-70 for repairs, I just desoldered all those orange relays to test them due to all the issues with them. I have looked for a datasheet to know the ohm reading to test the coils in the relays. Cannot find any, do you remember off hand what the initial ohm reading should be? Should I bother testing? , just replace them as they are a known issue while its apart. Also is this replacement you mentioned for $13.00 a piece replacement relays from mouser or digikey. thanks Rob

 

[avionic]

1KΩ
https://www.datasheetarchive.com/pd...5760aa2a9c4b116cece3b7&type=P&term=HB2E-24DCV

 

[avionic]

Also is this replacement you mentioned for $13.00 a piece replacement relays from mouser or digikey.

Not !!! Ebay They all come from the same supplier in Bangalore..

 

[Robbie G]

I’ll order some relays today. After reading so many C-70 threads, I should have known, but I never would have known which specific one to look at. Thanks again @avionic

just read your posts on the C-70 repair. I am in the same process, desoldered 8 of those relays, do you remember the part # for the replacement you got? was it this one on ebay ,
Hb2e-dc24v Matsushita Relay 24 Volt NAIS Aromat Compatible Aw622244?? if you can help thanks, Rob

 

[avionic]

Its usually the contacts that fail..

 

[Robbie G]

Not !!! Ebay

thanks Dave, should the relays be tested with 24 volt dc source to actually determining if they are actuating?

 

[avionic]

just read your posts on the C-70 repair. I am in the same process, desoldered 8 of those relays, do you remember the part # for the replacement you got? was it this one on ebay ,
Hb2e-dc24v Matsushita Relay 24 Volt NAIS Aromat Compatible Aw622244?? if you can help thanks, Rob

See post # 25

 

[avionic]

thanks Dave, should the relays be tested with 24 volt dc source to actually determining if they are actuating?

Yes.

 

[Robbie G]

awesome thanks Dave , just recapped this beauty.

Cheers Rob

 

[Robbie G]

no ebay! got it thanks