Yamaha CR-1000 couple issues

C

cjkpkg

Member
I am looking into a couple issues a friend is having with his CR-1000.

!. The bulbs need replacing - 10V is the reading
2. He is experiencing that the amp goes into limp mode after a while and a terrible static from one channel
3. I read about -90DC on the left channel and 6DC on the right channel - I am a little concerned on the left...not sure which transistor might be out of whack...

I plan to deoxit everything for him and replace the bulbs. Someone here sells them no?

I searched for about 20 mins and got a lot of threads and came up empty...I know I've seen it here though...
 
Awesome! yes they are MV readings...

Thanks!

And now I have a reason to finally re-lamp my 810 too. Just contacted dgwojo.
 
OK I observed the amp going into limp mode with some robust listening. I had the meter on the channel with the high DC reading - I have not adjusted yet. Out came some loud crackle/static and the DMM read briefly about 1100MV and the amp went into limp mode.

After a few seconds it turned right back on.

Would the 100MV that I observe across the terminals cause this issue? OR would something else trigger the 1100MV reading? The voltage at all 4 large power transistors reads about 50V.

Otherwise the amp sounds great in both channels.
 
Could be several things.First that comes to mind is a cracked solder connection or a transistor breaking down in the front-end of that amplifier.
 
I will perform the adjustments tonight. I got about an hour of uninterrupted listening the other day at low volume. Once I cranked it up it went into limp mode after about a minute...
 
avionic said:
Could be several things.First that comes to mind is a cracked solder connection or a transistor breaking down in the front-end of that amplifier.
Click to expand...

And I would not limit "front-end" to just the pre-drive for the main amp. I thought I had a problem with an amp going into protect mode at higher volumes that just turned out to be noise (probably a little AC ripple) riding on the source signal channel. There could be something in the preamp section going on. Does it do the same on ALL input sources?
 
I have observed it go into protection on the FM tuner and one of the AUX inputs.

I guess it is some detective work to figure out how the DC is getting into the output.

I am thinking the culprit is somewhere here...
Protection circuit
Picture1-1.jpg

Main Amp circuit
Picture2.jpg
 
I have adjusted both channels to within spec and the boards appear to be in good shape. I still get occasional crackling into limp mode.

I have now ordered the electrolytics for the amp boards.

The crackling did appear to be in both channels and irregardless of mode. I think next are the transistors if this does not solve it.

I got my bulbs from DGWOJO and got 3 out of 4 done last night. Last is the Radio dial lamp. Its a steel base lamp - might have to get creative with the shrink tubing here...
 
Using the pre-out/main in jacks you can determine if the problem is in the pre amplifier or the power amplifier.Of course this will require another power amp or a pre-amp.
 
Yes...I had it hooked up to my CA-810 for about 4-5 hours using the CR-1000 as a preamp and all was well. Also, I have found acceptable subs for the 2SA566 and the 2SC680 for reasonable prices so I ordered 2 of each. I will wait on the larger TO-3 transistors and work in phases...

First the electrolytics - since I believe the problem to be on the main amp boards
Then the smaller TO-66 transistors
Then find some NOS TO-3's or the On-Semi's
Lastly start looking into the PSU...I get acceptable, stable power so I suspect the PSU to be in agreeable shape.
 
I re-capped the amp boards tonight, cleaned the front panel and switch covers. I then re-adjusted the voltages. Gave it a robust listen tonight and not a hint of static/crackle/hiss or otherwise.

I should add that the electrolytics - 3 in each amp board - all STUNK and upon closer inspection had what was a sticky goo under them. I can only imagine how long ago they finally gave up and oozed their innards over the pcbs.

After some cleanup and reinstall everything seems to be A-OK. I think I will hold onto the TO-66 chips for now but I will probably install the MJ's that I ordered from Mouser when they arrive tomorrow.

Not bad...$3 worth of caps, $17 worth of transistors, $4 worth of bulbs and some elbow grease the old Yammy is back in action.

Thank you AK!
 
There was definitely some sticky glue there but also some dark brown "charred" gunk that I had to scrape away. The larger 220 and 47uF caps had a very potent burnt smell to them.
 
In the face of overheating the Yamaha glue does char, however unlike some other's glues I have never seen it corrode wires.
 
It was definitely like some type of light brown "booger" glue - I'm assuming these were the original caps. A little scraping and a quick alcohol wipe and the boards looked great.

I hit the wooden case with some Murphys last night and finished cleaning all the knobs and switches...I almost don't want to give it back!

I found myself scouring ebay this morning for an old CR-XXXX. I do not currently have a radio tuner in the LR.
 
OK...making progress

I conferred with the owner and he was agreeable to spending some more $$$ on the yamaha. I started to ivestigate the PSU board and this was one of the power caps...
CIMG0217-1.jpg


the bulging top is obviously not a good sign...I have temporarily installed some 50V 10,000UF caps and placed an order with mouser for about 40 more electrolytics to replace all of them...not bad only like $35 for everything.

I also took the liberty to upgrade the large PSU caps to 18,000uF 63V. A little extra capacitance cant hurt right?
 
cjkpkg said:
OK...making progress

I conferred with the owner and he was agreeable to spending some more $$$ on the yamaha. I started to ivestigate the PSU board and this was one of the power caps...
CIMG0217-1.jpg


the bulging top is obviously not a good sign...I have temporarily installed some 50V 10,000UF caps and placed an order with mouser for about 40 more electrolytics to replace all of them...not bad only like $35 for everything.

I also took the liberty to upgrade the large PSU caps to 18,000uF 63V. A little extra capacitance cant hurt right?
Click to expand...

Though they are without a doubt old, it's quite common to see those caps with plastic covers bulging. The cap itself is likely fine (subjectively) unless it's swelled and pressed tight against the plastic covering.
 
Update:

I have finally replaced ALL electrolytics, bulbs, and the output transistors on this CR1000.

I gave it a couple hours of hard listening tonight and it performed flawlessly. Thanks AK for the suggestions on this project. I think the owner will be very happy.
 
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