Yamaha CR 620 Mystery

Jpowell1

Active Member
I have a mystery regarding a CR 620
When I turn it on the relay clicks and the power light comes on
the receiver is on tuner input no matter where the input knob is turned, the am/fm button does work
The meters for signal move and the stereo light even comes on with a strong enough signal but no dial or meter lights work and no sound comes out of the speakers Nothing not hiss just silent
Upon closer inspection nothing looks amiss inside, the selector switch moves forward and back
I am stumped
Help

and if your response is that I should do a search save it for another thread
I did and nothing
 
When I turn it on the relay clicks and the power light comes on
the receiver is on tuner input no matter where the input knob is turned, the am/fm button does work

Are you sure that what you hear is the click of the relay, or the mecanical click of the power switch? The speaker relay should switch (click) 5 or 6 seconds after the power switch is engaged.

The tuner is active all the time, whatever the position of the source selector. It is normal in this receiver because there is a record selector switch, that allows you to record from the tuner as you are listening to a vinyl record, for example.
 
I just looked at it again and noticed that there is not a relay click
but shouldnt the lights come on without the relay
Unless..... they are all burned out
BTW I get no voltage at the connectors for the meter lights
But what you are saying is a relay issue could manifest itself this way?
 
I did
fuses are fine
However no current at the fuses

Current..You mean voltage.The transformer is fused internally. Looks like one fuse for the Primary AC side and 2 fuses on the DC power supply.
No lights,no voltage for the lights and no protect relay "click"-----Common factor--- low voltage regulated power supply..
 
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Are those replaceable or does the whole transformer need to be replaced?

They are not in the transformer, they are in the power supply section of the circuit board. At least I'm pretty sure that's what he's talking about. Fusistors, likely candidates for CR series problems.


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CR620 Mystery

hello Jpowel1

1) As you can see on my attached file (CR620 power supply section) the light are not fused so if they don't light on, that's because they are open (bad) :no:
2) can you explain how you make "mesurement" on fuses ? are you mesure in // the fuse with your voltmeter ? because if the fuse is good you will find 0V !
3) it seems to me that your bulbs are bad and one channel out because the relay do not work :scratch2:
4) can you take your voltmeter and check what voltage you have on the emitter of each power transistor . If you find any DC volt the channel of this power transistor is damaged ! The relay will not be activated and no sound at the output ! :music:
 
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hello Jpowel1

1) As you can see on my attached file (CR620 power supply section) the light are not fused so if they don't light on, that's because they are open (bad) :no:
2) can you explain how you make "mesurement" on fuses ? are you mesure in // the fuse with your voltmeter ? because if the fuse is good you will find 0V !
3) it seems to me that your bulbs are bad and one channel out because the relay do not work :scratch2:
4) can you take your voltmeter and check what voltage you have on the emitter of each power transistor . If you find any DC volt the channel of this power transistor is damaged ! The relay will not be activated and no sound at the output ! :music:

I do believe the bulbs are bad
I measured the voltage across the fuse holder with no fuse present
Both channels are out
I will check for DC at the power transistor
 
Just find the DC adjustment procedure - if it's not adjustable, then check the outputs themselves - you'll have to pull them off the receiver to test. They're on the left side... under the heatsink covers.

Use the datasheet for them to determine base/emitter/collector, and diode test on your meter. If this is completely greek to you, google "transistor testing"

But I suspect that it's the fusistors - exactly which ones they are on the 620 I am not able to say just now. Do you have the schematic?? Look in the power supply section...
 
I have a schematic in the orig owners manual but the print is tiny but even under magnification I cant see the fusistors
What is the symbol for them?
 
I have a schematic in the orig owners manual but the print is tiny but even under magnification I cant see the fusistors
What is the symbol for them?

yeah... that is a problem. the link above is a good one... save, print... etc.
I'll take a look in mine at home and see if I can point you in the right direction... but someone else might have more experience and not need to guess as I will likely end up doing...:rolleyes:
 
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I measured the voltage across the fuse holder with no fuse present
Both channels are out
Can't measure voltage that way.
Ground the neg test probe to the metal chassis ground.The with the pos probe you can measure for voltage on either side of the fuse holder. One side should have voltage and the other won't , unless a good fuse is installed.
 
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