My Yamaha CA-1000 mk2 acting funny: help!

What do you mean? Open value?Are you measuring millivolts,ohms etc?
Which channel has a class A adjustment issue? Did class B adjust Ok in that same channel? If so. You have a problem with the either
A.micro switches (2 each)
B.Mode slide switch itself.



You have a problem in the switching for Speakers A..Bad switch,dirty switch,cold solder or broken connection. See schematic...

I am measuring in millivolts and the number showing on the DMM is 1 and wont respond to adjustments in VR 603. Class B adjusted ok in both channels. Its the Right Channel that wont adjust in Class A.
 
Pre/Main Coupler Switch was the Culprit!!

Am happy to report that after using lots of contact cleaner on the coupler switch located at the back of the Yammie, the left channel came back on. Also, was able to adjust the idling on both channels.

However I was unable to perform the adjustment on the Function Circuit Board as I could not identify it on my unit. Anyone have a close up pic of this board and TP1/TP2, and VR401 & VR402? Are there any other adjustments that need to be performed on this unit? I wasn't sure that the SM I downloaded from hifiengine & elektrotanya which had 8 pages in all were complete.

Thanks for all your help guys!!
 
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If you can follow/read the schematic..
TP 1 is located between the emitter resistors of TR411 and TR413
TP 2 is located between the emitter resistors of TR412 and TR414
Both are on the function board.
 
Where is the function board located? Is it accessible from the top or the bottom of the amp? Where is it near?

Does my DMM's + test lead go into TP 1 and the negative goes to E?
Likewise + test lead goes to TP 2 and negative to E? Sorry the service manual does not explicitly state where they should go.

Avionic - thanks for guiding a newbie like me!
 
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YES!! Thanks a bunch Pete!

Function board is on the top side center of the unit.
Clue: the input select switch is mounted to the function board.
 
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maybe this is missing in your manual

That schematic and procedure is from the CA-1000 manual for function board NA06335

Be aware that the CA-1000 II function board NA06772 may be a little different.

The procedure is the same in both models..Test point locations might be the same.

Note: transistors are reference identified totally different between the two boards..
 
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Maybe I missed it, but you still didn't answer AVIONICS question. You said it worked WITHOUT the fuses and then put some fuses in the fuse holders. But, aren't you wondering why you even need fuses if it works without? This is extremely important. Fuses protect and disable power if there are issues. Since yours doesn't need them to operate, why put any in at all. Of course if something goes wrong you are going to see a light show like very few have seen! You should really find out WHY you can run it without fuses before continuing. According to the schematic those 5A fuses are protecting the power transistors and you should have had no sound if they weren't there. Personally, I would find out why they weren't needed (as AVIONICS has been saying in a couple of his comments) and undo whatever was done. I have an ADCOM 545 that only needed new fuses on one channel to work again (I guess the old ones did their job) probably because it was asked to drive too much current. Power transistors are just fine: fuses were allowed to do what they do best: protect. Ok, tirade over. Just sayin' If you already fixed this, my bad!
 
Reviving an old thread

Just hooked up my Yammie after more than a year out of rotation. Here's what I noticed. If the switch is set to Class A,(I use 2 small fans to keep it cool) both channels play fine. However, if it is set to Normal, the left channel is very faint and distorted.
Any ideas, why this is happening?
 
Guys,

Honestly, I would not answer any more questions until the OP clears up the missing fuses issue. It's a hazard and dangerous to keep letting him troll you for answers when he hasn't offered up any explanation and keeps avoiding the issue.

IMHO, it's downright rude to come back after all this time asking for help when you've been told to be safe and have the reason for the missing fuses investigated and corrected. Installing fuses did NOTHING to correct that issue.
 
Avionic was more than generous with help and the OP has skirted the fuse issue consistently.

Take it to a pro and leave it at that.
 
I thought i had addressed this issue. I guess most of you guys missed my earlier post.

I don't know if it is your ignorance,arrogance, or if you're just trolling, but several posters have told you that it is not normal for the fuses to be missing and the amp still functioning and that you should take it into a tech or someone who knows what they're doing to get fixed and functioning SAFELY!!!!! :sigh:
 
I thought i had addressed this issue. I guess most of you guys missed my earlier post.

If the amp was working without the fuses in, it means somebody bypassed the fuses. Simply putting new fuses in does not correct the pre-existing problem. If you keep running this amp you are likely to blow it up and/or set your house on fire.
 
I'd go there as a last resort. Just wondering if you have a hunch as to what parts may have failed?

I predict a CA-1000 showing up with $500 damage.

Does it work without the fuses in the original post?



FWIW, there is some info that says the micro switches for class A/B fail.
I have found that issue.

The power supplies in that vintage Yamaha seem to get stressed.

Look for any fusistors and replace them.
 
As much as I don't understand the technical jargon, I continue to follow these "broken to repaired" threads to see how they turn out. I am particularly interested in this one; kind of like someone about to witness a plane crash.

If his amp does blow up do you think he'll post about it? As Dave posted :lurk:
 
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