Yamaha CA-1010 switch-on

sssboa

Super Member
Is it normal that CA-1010 switches on always in ClassA and then stays so if has been set to classA mode or changes after a second or so to Normal (AB) mode if the mode switch is in position Normal? I noticed it doing voltage adjustments.
 
Noticed what exactly?

classA is set to 280mV and Normal to 25mV
I have multimeter clamped to the pins
I switch on in Normal mode, voltage goes up to 280mV and then creeps down to 25mV
I switch on in ClassA and it stays at 280mV of course

I set classA to 20mV and Normal to 30mV
I switch on in Normal mode, voltage hangs around 20mV first and then creeps up to 30mV
I switch on in classA and it goes straight to 20mV and stays there.

I mean it looks like the amp always starts-up in classA and then switches to Normal or stays in classA depending on the position of the mode switch.
Also after adjustment the voltage increases roughly 5mV per day on left channel and 10mV on the right that is not good, after 2 days I have 35mV and 50mV instead of 2x25mV in Normal mode that depresses me. In class A I had 310 and 330 instead of 2x280mV. When I opened it first time it was 45mV on L and 145mV (one hundred forty five!!!) on R in Normal mode after adjustment half a year earlier.
 
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Have you did anything else to this amplifier besides adjust the bias ?


What your experiencing does not sound right. I've worked on quite a few of these CA models.
 
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When you switch from "normal" to" Class A" do you notice the topside relay "set" instantly? Then "reset" instantly when switching back to "Normal"mode ?
 
How long does it take to drop from 280mv to 25mv? A few seconds or a minute maybe. I can see that senerio as the supply caps are charging up to the "normal mode" higher operating voltage.
As far as the creeping up over time..:scratch2: Maybe time for trimmers to be replaced.
 
Ok I don't know much about electronics. I wrote from memory, now will examine accurately.
I set again class A to 280mV Normal to 25mV.
Switch on the amp in Normal mode. On multimeter I have 24mV the first instant, then jumps straight to around 250mV and creeping up quite fast for about 3 seconds. Before it gets to 270mV I hear the click and jumps down to 42mV and falling fast to 30mV then creeps down slowly to 25mV.
The problem is that after a few hours I will have 30mV in Normal and 300mV in A. This happens after I switch off and on a few times.
If I never switch off whole day the settings will hold.
 
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I set the current s in my Yamaha CR-1000 that is on original caps and trimmers and it keeps the setting quite well. After a year the settings did not move much if at all.
And this CA-1010 gives me such headache.
 
The relays can and will become pitted from the current cycling on/off A&B operation. Switching A/B when the unit is operating will hasten this. If the contacts were just a little pitted it might be a cause.

If I were into the relay board they would be replaced at that time if any age to them.

Barney
 
I would not worry myself with the start up bias. But the drifting bias over time isn't right.
Most Yamaha service manuals tell you to let the amplifier warm up for 10 minutes or so before adjusting bias(idle current).
 
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You could replace the relay. The mode relay and protect relay are the same part number and should be available at Mouser or Digikey.

http://www.mouser.com/ProductDetail...GAEpiMZZMtGt%2bn33CgIP7/QWMhKj5BFxDAtLtDTBVU=

ok, thanks, so saying this in my language I replace the seethrough box with the one you gave me the link to?
btw the relay was recently refitted by a tech guy cause it was the reason for some crackling in the right channel and it really cured that. The amp overheated before the repair already. I don't know if it is still original factory relay, I will examine it.

This is what the tech guy wrote me:
I traced the fault to the protection relay contacts. I could bring the fault on and off at will by moving the relay. I took it off the board to inspect and the contacts did not show any significant wear although they were tarnished. I cleaned them and refitted it. There are a number of transistors on the same board that run hot and the soldered joints to these have suffered so I have remade these for good measure. Once reassembled all was well.
 
ok, thanks, so saying this in my language I replace the seethrough box with the one you gave me the link to?
btw the relay was recently refitted by a tech guy cause it was the reason for some crackling in the right channel and it really cured that. The amp overheated before the repair already. I don't know if it is still original factory relay, I will examine it.

This is what the tech guy wrote me:
I traced the fault to the protection relay contacts. I could bring the fault on and off at will by moving the relay. I took it off the board to inspect and the contacts did not show any significant wear although they were tarnished. I cleaned them and refitted it. There are a number of transistors on the same board that run hot and the soldered joints to these have suffered so I have remade these for good measure. Once reassembled all was well.

Wrong relay. He is refering to the protection relay. We are refering to the mode select relay.

The mode selection relay is visible from the topside of the amp front left. The protect relay is only visible from the bottom side of the amp.
 
I just looked at the relay. It says matsushita on it. I guess it has been already replaced to a new panasonic. Or is the original Panasonic too? Anyway thx for advice, I learned a lot.
 
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I set the the bias to aroud 20mV in classA and 25mV in Normal and it seems to be more stable. Class A is a joke anyway.
 
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