Yamaha CR-820 - guidance and possible help needed
- Thread starter JorgenSWE
- Start date
Look at your power transformer.. On the secondary side you should have ..
two orange wires -- Measure the AC voltage across the two orange wires ---- should see approx. 34.5 vac.
two red wires ----- Measure the AC voltage across the two red wires ---- should se approx. 31.8 vac.
two orange wires -- Measure the AC voltage across the two orange wires ---- should see approx. 34.5 vac.
two red wires ----- Measure the AC voltage across the two red wires ---- should se approx. 31.8 vac.
Hi!
So I measure with the diods and FR out of the circuit and I have full continuity between all four poles on the output transistor cases ( collectors).
Yes.. Pull F801 and F802 as well.
Hi!
I have now measured at the two different locations, and between the red, red and orange, orange and unfortunately the transformer does not put out anything. I get zero AC volt on the secondary side. I also checked that I had 230V on the primary, measuring at the power cord connection point.
So this means I have a fried transformer. Wonder what may have caused it ton fail. Age?
Where to get hold of a new used one? Ebay?
Yes, I beleive so, set to 230V at the moment. A black round "thingy", that you can select voltage from.
I guess the only available in the US are only set for 110V, so a step down transformer would solve the problem, should I find a new one.
I have also posted a request on a Swedish vintage HIFI group on Facebook. I might get lucky!!
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Make sure your power switch is working ..Unplug the CR-820 .. Measure the resistance across the AC power plug with the switch in the on position.( Approx 8 Ω ) Then in the off position. ( infinite resistance )
Hi!
So, I made some measurements. There is now a resistance of about 8 ohms over the regulator. It was after I had exercised the voltage regulator that things started to happen. Measuring the voltage over the two secondary transformer outputs gives some hope. Between the orange I have AC 34.6V, but between the red I have a higher reading of 67.4V.
The power led and also the FM indicator lamp lights up.
I don't know where this leaves us, but I hope it is not all bad news.
On tuesday I leave on an out of the country trip (going to Romania) during one week. Not sure how much time I have to work on the unit, but please do leave a reply and I will see what opportunities I will have. Else it will have to wait until after I get back home.
Again, thank you for your time and expertice. Much appriciated.
Hi!
I am back from my trip to Romania and would like to proceed with the restoration. What would be the next step, based on my previous post?
Seems that the voltage regulator was the culpit. Have not checked the fuse inside the transformer, but there is indeed an purple wire going in to the transformer. The rectifier bride is still out of the circuit as also the 22 ohm fuse resistor.
What could cause the elevated voltage on one of the secondary transformer outputs.
Should I solder back the rectifier bridge? With what should I replace the 22 ohm resistor?
Look forward to your reply.
I am back from my trip to Romania and would like to proceed with the restoration. What would be the next step, based on my previous post?
Seems that the voltage regulator was the culpit. Have not checked the fuse inside the transformer, but there is indeed an purple wire going in to the transformer. The rectifier bride is still out of the circuit as also the 22 ohm fuse resistor.
What could cause the elevated voltage on one of the secondary transformer outputs.
Should I solder back the rectifier bridge? With what should I replace the 22 ohm resistor?
Look forward to your reply.
The fuse is OK.....
Check them with your multimeter before re-installing.
Hi!
I checked them when I pulled them out, but will check again. What about the fuse resistor? Seemed a bit out of spec (appr 8 ohms) when I last measured it, taken out of circuit.
Any flameproof 1/4 watt resistor should do I would think.
Avionic will confirm but I think it should be ok.
Nashou
Hi!
My stock pile did not come up with the needed resistor of 22 ohms, so I have placed an order (along with some others stuff). I will report back once it has been mounted together with the other compontents taken out of circuit. I will re-measure the rectifier bridge,as noted by avionic before soldering them back into the circuit.
What about the hightened voltage on one of the transformer out puts. Will that be rectified once all the components are back in the ciruit? Last meausred at 67.4V
Can the voltage regulator be deoxied to not cause this problem again?
My stock pile did not come up with the needed resistor of 22 ohms, so I have placed an order (along with some others stuff). I will report back once it has been mounted together with the other compontents taken out of circuit. I will re-measure the rectifier bridge,as noted by avionic before soldering them back into the circuit.
What about the hightened voltage on one of the transformer out puts. Will that be rectified once all the components are back in the ciruit? Last meausred at 67.4V
Can the voltage regulator be deoxied to not cause this problem again?
Sorry my mistake.. From red to red should have been close to 63.6 vac.. You measured it unloaded at 67.4vac So it is where it should be..
No.. Just make sure you have good solder connections when you re-install it.