C-50 issues.

[csmith]

Just snagged this but haven't received it yet. Guy said it has this issue:

"preamp passes signal but the controls phono aux tuner controls freeze up when the preamp warms up"

Any Yamaha techs in here that have an idea?

 

[pdm4606]

My C-50 and its problems...

I would tear down the entire case and examine the circuit boards for loose solder connections. There are several hundred solder connections. I fought bad connections for years. My latest search found many bad solder connections and some questionable ones. In all I re-soldered approx 30 connections and the unit has sounded the best I ever heard.
I replaced all larger caps. some time ago and that was an issue also.

There is an issue setting inside adjustments that takes some time but should be checked. A good service manual is a must. Some settings look to be "bias" type and important for proper distortion control.

All in all if setup properly the pre sounds very good.

Paul

 

[pdm4606]

Really funny postings...

The C-50 will go for years without postings then all sorts of folks will have fresh postings such as now.
I posted a few weeks ago and there is another posting started recently also about the C-50 in addition to yours. I would suggest a full search for more info.
Many postings seem to be focused on a very narrow issue, solder joint poor connections.

Paul

 

[avionic]

Relay and solenoid issues as well.

 

[csmith]

Thanks guys!

 

[avionic]

controls freeze up

What do you mean by freezes up ? Fails to function anymore and where ever it was selected before the "freeze up" it stays ?
If so, solenoid switch or controler for the switch.

 

[avionic]

When it freezes up. Check your B+ and B- voltages at the power supply. Might be missing the 29vdc to energize the solenoid/relays.

 

[avionic]

Check the solder connections on the pass transistors (they usually are fastened to small heatsinks. TR440 and 443.
Also look for glue damage around C479 and 480 (1000µf/50v caps).