Yamaha CA-710 no tension in VU-meters bulbs

Gurufrendix

New Member
Hi all.

I tried to change the VU-meters bulbs of my CA-710 but with no success. I thought, first, that I have chosen the wrong bulbs (12V 100mA) but when I tested the wires (red and white) with a multimeter I realized that there was no tension.

Is there any fuse for these bulbs that I must change? If so, where is it?

Has anyone come across a problem like this?

Thank you in advance.
 
Welcome to AK..Look on the main board for a R575 it should be a 2 watt metal oxide resistor --15Ω it may be "open"..Or may have a cold solder connection.The bulbs are suppose to be 14.5v @ 80ma.If you can hear a relay click the fuse is good.If not ,there is and "open " fuse.
 
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Thank you avionic.

Yes, I hear the relay and the amp functioning good. I'll look for the R575 2 watt metal oxide resistor --15Ω and report back.
 
http://sportsbil.com/yamaha/ca-610ii-sm.pdf

CA-610II should be the same as euro CA-710.
R575 should be right behind the front phone jack , right next to a fuse.
Check the AC voltage at both ends of the resistor referenced to chassis ground.Should be around 27vac.
 
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Thank you for the pdf doc. In case the resistor is off the amp should be presenting other mulfunction symthoms, shouldn't it?

I'll try to test the resistor this weekend.

I have also thought to take those 14.5V somewhere else. Is it possible?
 
cap issue

My lit up front end of my Yamaha uses a circuit from the main power board. It is supposed to be DC with diodes and all. Check yours for blown diodes or possibly a cap leaking .
The circuit I have actually uses a cap to filter the DC for a few measly 14V bulbs.
My cap was leaky. Replaced and bulbs magically lit up.
Sort of over designed for some reason.

Paul
 
In case the resistor is off the amp should be presenting other mulfunction symthoms, shouldn't it
No..Its in series with the two series wired lamps. Strictly dedicated to the lamps AC circuit.That being said.If the resistor is open or either one of the lamps are open.No current will flow to either of the lamps.
 
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I have also thought to take those 14.5V somewhere else. Is it possible?
The lamps are wired in series..So it requires at least 27-28 volts.In this case its about 27 volts.


Just fix the problem. Just how tough can it possibly be. 2 lamps,4 lengths of wire,1 resistor, 6 or 8 solder connections..
 
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Well, finally it's done. The resistor R575 was open. Not easy to find it and solder it but the bulbs now shine.

I also put two 3V LEDs, instead of the incandescent bulbs, soldering a resistor to each one.

Thank you avionic for all your help and support. Had it not been for the schematic I wouldn't find the R575 in years.
 
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