Yamaha CR-2020 power up, no click, no sound

thesuau

Active Member
Why no click sound from relay after power up, therefore no sound?
Once it is clicked (not always) after power up and everything performs beautifully.
However 99% of the time it doesn't click and no sound. What should I look into and fix?
 
I would check the bias and offset first thing. There is a sticky about this. Your values may be too close to the tripping point, hence the flaky behavior.
 
There's a sticky topic at the top of this forum that explains measuring dc offset. Basically, you measure for dc voltage at the speaker outputs with the speaker switch set to the A speakers, input set to an unused input, volume at zero. let the receiver warm up for a few minutes, then measure. You should see a voltage like 0.02 vdc.
Bias setting is more involved, and will require access to a service manual.
Let us know what you get!
 
The 2020 has no DC offset adjustment, however adjusting the Idle current generally brings down the offset. On each power amp circuit board there is a terminal pin (TP0) ate the very front that has nothing connected to it. Next to TP0 is either a brown or yellow wire on the next pin. Set input to an open circuit (Phono 2 is good) and volume to 0. DC volmeter across TP0 and yellow wire and adjust the variable resistor at the far end of the board to get a reading of 10 millivolts. Do the same on the other board between TP0 and the brown wire. See if that helps.
 
The 2020 has no DC offset adjustment, however adjusting the Idle current generally brings down the offset. On each power amp circuit board there is a terminal pin (TP0) ate the very front that has nothing connected to it. Next to TP0 is either a brown or yellow wire on the next pin. Set input to an open circuit (Phono 2 is good) and volume to 0. DC volmeter across TP0 and yellow wire and adjust the variable resistor at the far end of the board to get a reading of 10 millivolts. Do the same on the other board between TP0 and the brown wire. See if that helps.

merrylandar, thanks so much for the guidance.
I removed the wood case and see relay on the left front PCB and the black output cooling fins (2) in the center section. Would you point where the "power amp circuit boards" are? Are the two PCBs sit between the cooling fins? If yes, please ignor the photo request below.
There is no Phono 2 input selection, just Phono. Set to Phono OK? Speak at A or None? Volume at 0?
Do you mean to measure VDC between TP0 and the yellow wire on one PCB; between TP0 and the brown wire on other PCB?
Anywhere I can find a photo to identify the location of these parts will be wonderful. I can do this task but just need locations so I won't mess up other things.
Thanks
 
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The schematic for the CR-2020 from the owner's manual is unreadable in the Yamaha database.

We definitely need a better scan.

Is there somebody here with the original manual, a scanner and a few minutes of spare times, who could scan this schematic in 400 or 600dpi for us all ?

It would be very very appreciated.

Thanks!
 
merrylandar, thanks so much for the guidance.
I removed the wood case and see relay on the left front PCB and the black output cooling fins (2) in the center section. Would you point where the "power amp circuit boards" are? Are the two PCBs sit between the cooling fins? If yes, please ignor the photo request below.
There is no Phono 2 input selection, just Phono. Set to Phono OK? Speak at A or None? Volume at 0?
Do you mean to measure VDC between TP0 and the yellow wire on one PCB; between TP0 and the brown wire on other PCB?
Anywhere I can find a photo to identify the location of these parts will be wonderful. I can do this task but just need locations so I won't mess up other things.
Thanks

Those are the power amp boards, Phono 2 usually has shorting plugs and is selected by the small knob above the bigger selector knobs. So yes, those are the places to measure.
 
There's a sticky topic at the top of this forum that explains measuring dc offset. Basically, you measure for dc voltage at the speaker outputs with the speaker switch set to the A speakers, input set to an unused input, volume at zero. let the receiver warm up for a few minutes, then measure. You should see a voltage like 0.02 vdc.
Bias setting is more involved, and will require access to a service manual.
Let us know what you get!

Thank you for your guidance.
The measurements as follow: the left spker 20 mili VDC; the right spker 40 mili VDC.
When I double check the measurements, they shift wildly, why?

What are these indicating?
Thanks
 
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The 2020 has no DC offset adjustment, however adjusting the Idle current generally brings down the offset. On each power amp circuit board there is a terminal pin (TP0) ate the very front that has nothing connected to it. Next to TP0 is either a brown or yellow wire on the next pin. Set input to an open circuit (Phono 2 is good) and volume to 0. DC volmeter across TP0 and yellow wire and adjust the variable resistor at the far end of the board to get a reading of 10 millivolts. Do the same on the other board between TP0 and the brown wire. See if that helps.

The left side:
Prior to adjustment 7.5 mili VDC, after adjustment 10 mili VDC.

The right side:
Prior to adjustment 6.7 mili VDC, after adjustment 10.2 mili VDC.

After adjustment for longer time the voltage increases another 0.3~0.5 mili VDC.

Turn off and turn on receiver, the relay still does not click and no sound.

Thnaks, next?
 
With the power on what readings do you get between the chassis and either the yellow or brown wires noted above?
 
With the power on what readings do you get between the chassis and either the yellow or brown wires noted above?

Thank you for your kindness to follow up. Before that was yesterday's measurement.

Today Cold start re-measure
Relative to TP0, LHS 4.5 mVDC; RHS 4.8 mVDC.
5 minutes later LHS 9.2 mVDC; RHS 9.4 mVDC.
Longer time later, stay in LHS 9.6 mVDC; RHS 9.6 mVDC.

Relative to chassis, LHS 5 mVDC; RHS 6.8 mVDC.
5 minutes later LHS 6.6 mVDC; RHS 7.2 mVDC.
Longer time later, stay in LHS 6.2 mVDC; RHS 7.2 mVDC.
 
OK, that pretty well says the outputs are good, so that leaves the protection circuit itself. Clustered near the relay are the group of transistors that test the output and if they detect no high DC the two 22mfd/25V caps are supposed to charge up and turn on the final transistor (that's the one closest to the relay). It may have gone weak and no longer has the cojones to drive the relay.

I do believe the AK database has the SM for the CR-1020. The parts on the relay board are virtually identical between the 1020 and the 2020, heck they use the same circuit boards and same chassis, major differences are in the power supplies and power amps. The schematic for the 1020 should give you voltage readings that you should be seeing on the relay board.
 
merrylander,
Thank you again for following up.
Yes, left to the relay, there are two transistors (labeled D234, D235) attached to tall aluminum wall for cooling. There is a closest trans (labeled b544) just in front of the relay. Is this the closest one?
To do the voltage reading check using SM, do I need to remove the lift the protection board or just do as it is? Would you be giving more details as I haven't done this before?

Thanks
 
First get the 1020 SM and see if it has all the voltages shown on the schematic. AFAIK the one in the database was a copy from that Mauritius outfit in the UK and they are never especially good, vintageaudiomanuals AFAIK is the only professional supplier out there.

No need to remove the board but you do need a sharp nosed test prod and a steady hand. All measurement are between ground (chassis) and the transistor leads. The B544 is the relay driver, the two on the heatsinks (should both be D234) are the 25 volt regulators.
 
merrylander,
At here I did a search; I only see Sansui database and Marantz database. Just didn't see Yamaha's.
In HiFiEngine.com, the CR-2020 diagram is un-readable. CR-1020 circuit diagram doesn't show Voltage. May be I missed
By the way, I recheck the two on the heatsinks, and they trually labeled D234 and D235. I guess they are the same stuff, but ID differently.
 
OK, I thought the larger schematic I have for the CR-2020 was from Mike Thomasen and I could not share that as that's how Mike makes his living. As it turned out it was TIF file from some other source. The TIF is monsterous so I converted it to JPEG at some 30megs.

As soon as sigurd emails me I will send it to him to put in the database.
 
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