Yamaha CA-1010 vs CR-1000 overheating

sssboa

Super Member
Hi

I have both vintage amps
CA-1010 (from 1977 2x110W) has been bought recapped
CR-1000 (from 1974 2x70W) all original (it's a receiver)
I also have modern R-N500 receiver (2x70W)

I noticed that CA-1010 produces a lot of heat to a degree that could double as a heater and I mean in Normal mode not ClassA.
CR-1000 stays barely lukewarm even after hours just like the modern R-N500.
I measured their wattage intake on mains using a plug meter and I discovered that the cool CR-1000 and R-N500 take in almost perfectly the same 30W at the volumes I use. The hot CA-1010 takes 130W in Normal mode and 230 in ClassA. So it's like 4 times more in normal mode than CR-1000.
My question: Is CA-1010 (when in Normal mode) in a different energy class than CR-1000 or maybe something should be adjusted to prevent overheating and energy overconsumption?

I heard that the late 70s receivers like CR-1020 are overheating (they often can be seen with blackened grid) but never heard it about the amps in Normal mode.
Thx
Andy
 
CA-1010 (from 1977 2x110W) has been bought recapped

I'd be checking the idle current (bias) adjustment. Not the DC offset. The bias. To see if it is still dialed in to spec.If its set to high it will heat up the heatsinks. If thats where the heat is coming from.
 
I'd be checking the idle current (bias) adjustment. Not the DC offset. The bias. To see if it is still dialed in to spec.If its set to high it will heat up the heatsinks. If thats where the heat is coming from.

Thanks for this. It's what I was thinking about, maybe more vaguely as I don't know much about servicing electronics but would also like to hear from someone that maybe had both amps or knows about the energy class of both, if it's normal that CA-1010 heats up so much more than CR-1000 and takes so much more energy.
 
sound differences

Also if someone was interested the CR-1000 sounds warmer with stronger heavier bass than CA-1010 that has more airy sound to it but also enough bass. Despite CR-1000 being all original components it has excellent control over bass, it's punchy with no slack. Also both give similar volume.
 
the CA-1010 will be warm in Class B and hot in Class A (as in, hot enough you wouldn't want to set most plastic objects on the metal cover on top for fear of melting them). but depending on your personal experience with amps, hot and warm may not mean the same thing to you as they would to me.

in any case, as Avionic has stated, it's probably best to find someone to measure the bias in both modes if you can't, as that will tell the true story.
 
the CA-1010 will be warm in Class B and hot in Class A (as in, hot enough you wouldn't want to set most plastic objects on the metal cover on top for fear of melting them). but depending on your personal experience with amps, hot and warm may not mean the same thing to you as they would to me.
I never use the mode A but it's hard for me to imagine it may be hotter, in normal mode you could burn your hand if you put it on the grid and you have that smell in the room like a heater is on or an iron. I checked in service manual on page 20 there's about adjusting several things but they don't use the word bias and also it sounds complicated, will have to employ someone to do it.
 
I never use the mode A but it's hard for me to imagine it may be hotter, in normal mode you could burn your hand if you put it on the grid and you have that smell in the room like a heater is on or an iron. I checked in service manual on page 20 there's about adjusting several things but they don't use the word bias and also it sounds complicated, will have to employ someone to do it.

May have and issue with the class A switching relay being stuck in class A

but they don't use the word bias

Adjusting Idle current is the same thing as bias current.In the service manual -Page 21 para. 3 Idling current adjustment. All you need is a multimeter.

http://www.hifiengine.com/manual_library/yamaha/ca-1010.shtml
 
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Adjusting Idle current is the same thing as bias current.In the service manual -Page 21 para. 3 Idling current adjustment. All you need is a multimeter.

What can I connect as 8ohm 100W dummy load to speaker terminal, my 8ohm 100W speakers?
 
What can I connect as 8ohm 100W dummy load to speaker terminal, my 8ohm 100W speakers?

No speakers or load needed for the adjustment as Nakdoc has stated. Just flip the decoupler switch. Take measurements at the test points stated in the manual. First with the mode switch in normal position . Then place the mode switch in the class A position. and make adjustments along the way as required.
 
No speakers or load needed for the adjustment as Nakdoc has stated. Just flip the decoupler switch. Take measurements at the test points stated in the manual. First with the mode switch in normal position . Then place the mode switch in the class A position. and make adjustments along the way as required.

They mention the dummy load/resistance of 8ohm min100W in the service manual in the text and in the picture that's why I'm saying.
 
Hi
So I set the bias but it does not keep those settings, at least they change the same on both channels. Initially it was 45mV and 145mV. After I change it to the prescribed 25mV in B mode on both it goes to say 45mv, I set it again to 25mV, it goes to 21mV after another switching off and on. Also setting in class A to the prescribed 280mV changes the setting in class B.
On the bright side heating and power consumption dropped, wattage intake from 130W to 67W (with 31mV)
 

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Cr-1000

Hi

Could you please enlighten me on how to use the voltage regulators in CR-1000, the white round ones as in the pics attached?
OK, I know :)
 

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