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C70: Fuse Blew

Gary D Olson

Gary D Olson

Skilled Tightwad
I connected my C70 to the MAIN IN on the rear of my Luxman R-117 and powered everything, up but the C70 wouldn't power on. Long story short, it had blown a fuse. I've owned this many years and it had performed flawless up to this moment. The fuse in question is the internal 250V 1A fuse closest to the PS.

I'm not a tech but can solder and use a multimeter. Would anyone with a tech background be kind enough to offer some advise? Replace the fuse and cross my fingers? Send it out for repair? Attempt to repair it myself? Or start saving up to send it to Tom Ishimoto for restoration?

And for bonus points...

Which would you prefer to power your system:
A) Yamaha M70
B) Luxman R-117 bypassing its pre


As always, much obliged.



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Hello Gary

First rule : a fuse don't burn without serious reason
second one : is it dark black or just open in the midle (you can see the filament in this case) ?
If it is black don't even try to replace it because you will have the same result ! there is a big short somewhere and the fuse did his job ! protect your preamplifier
if it is just open in the midle you can replace it without any risk
 
clinic-audio said:
Hello Gary

First rule : a fuse don't burn without serious reason
second one : is it dark black or just open in the midle (you can see the filament in this case) ?
If it is black don't even try to replace it because you will have the same result ! there is a big short somewhere and the fuse did his job ! protect your preamplifier
if it is just open in the midle you can replace it without any risk
Click to expand...

Dark black. Of course. About the size of a small blow fly.
 
Couldn't it just needs a fuse with more meat on its bones? kidding. Okay, will put up with the Luxman's pre until the C70 can be fixed. That'll be a while. I do appreciate the advise.
 
DSC04399.JPG

That long black rectifier has 4 solder pins. Once removed it needs to tested like 4 individual diodes.
 
1B4B41
page1.png
 
Never done this before so please forgive. With positive probe on "-" pin:
contacting next pin with negative probe: .543v
and the next pin: .002v
and the 4th pin: .543 v
 
Looking at the beveled end - pins down 1,2,3,4
1 -2 forward and reverse
2-3 forward and reverse
3-4 forward and reverse
4-1 forward and reverse
 
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