CA-810 Relay not clicking

Stubla

New Member
Hi all!

First, thanks for all the great information available on this site. I'm a complete novice to this vintage amp malarkey and so I've scoured it to find an answer to my woes - but to no avail.

I suppose first a little history. I picked this amp up and it sounded great! After about three months though, it would make a popping sound through the speakers and then play a lot quieter. (There is another post that sounded similar to this issue but nothing there I tried worked).

1. So, recommendation 1 always appears to be clean all the pots, so I did that. In fact I also did it when I first got the unit. That had no effect.

2: A fairly complete recap. There are a couple of bipolar caps that I haven't change yet. This was the start of my current woes. Initially, I just changed the large filter caps and switched it on. The relay at this point started to click intermittently - i.e. every few times I turned it on. I bit the bullet and recapped pretty much everything else on the main board and tone control board. This also didn't help - in fact the relay stopped clicking completely.

3. I turned my attention to the relay circuit protection. I have replaced TR601 to TR606 with those suggested by Avionic here:
TR601 2SC1918
---2SC1918----sub KSC1815
http://www.mouser.com/ProductDetail...=sGAEpiMZZMshyDBzk1/Wi8oN7VHZ91Ok9NiSl87vuMg=
TR602 2SA844----sub KSA1015
http://www.mouser.com/ProductDetail...=sGAEpiMZZMshyDBzk1/Wi8oN7VHZ91OkEdHsVWhAnIo=

TR604 and TR601 are not differential pairs like 6 & 5 and 3 & 2, so I changed TR 604 for a KSC1815 the same as TR601 is.

It was at this point I screwed something up and TR606 shorted - the relay started clicking again every time I switched on the amp - but without a few seconds wait and with suitably large pop to the speakers (DC I assume). I swapped out TR606 for a replacement and the relay no longer clicks.

4. I swapped out TR806 and TR805 with replacement transistors.

Some Measurements:

TR01
E: 14.4 mv
C:1.17 vdc - which I suspect is cause of the problem. (or a symptom at least!)
B: 0 mv

TR02
E: 14.4 mv
C:25.2 vdc
B: 0 mv

TR06:
E: 35.8 vdc
C: 12.4 mv
B: 40.6 vdc

D01: is only 60 mv not 24 volts as I read somewhere it should be. I checked the diode and it is operational.

TR425 48.9 vdc
TR426 48.9 vdc
TR427 -48.9 vdc
TR428 -48.9 vdc

TR806 and TR805 are not giving off a stable 36 and -36 vdc.
806 (I think)
E:-39
C:-25 and
B:-40

805
E: 25
C: 39
B: 25

Bias is at 19mv for each channel.

Mid point is 0.00 for L & E and R & E.

A small victory: I managed to 'patch' the lamps and get them working again. I'm not sure if the board the lamps are on being cracked is adding to the problems stated here. There is a resister there that gets very hot indeed.

I admit my own poor soldering may well be the cause, although I've gone over it and re-soldered where I've thought there may be a cold solder. Also forgive me if I've missed off a negative from the above measurements.

Any help much appreciated!

(As an aside, I did get an Akai 2600 up and running with info from this site, so my recapping skills can't be too bad!)

Stuart
 
So, recommendation 1 always appears to be clean all the pots
Recommendation 1. a. Always fix issues before you proceed with a full blown recap.;)

This would have also been the best point to start a thread as well.:D
 
so I changed TR 604 for a KSC1815 the same as TR601 is.
Bad idea...If the OEM transistor was a 2SC1775 , according to the schematic anyway.
2SC1775 is a 90 volt transistor and you swapped in a 60 volt transistor. A much better choice would have been and KSC1845 <------ 120v transistor. ;)

I suspect TR604 ( KSC1815) could be history......
 
Avionic, thanks for the speedy reply!

Recommendation 1. a. Always fix issues before you proceed with a full blown recap.;)

This would have also been the best point to start a thread as well.:D

Now ya tell me ;) - I'm like a lost hiker who doesn't want to ask for directions until he sees a storm coming. :D

Measure the voltage at the base of TR601...
So the base is 0mv I think.

Bad idea...If the OEM transistor was a 2SC1775 , according to the schematic anyway.
2SC1775 is a 90 volt transistor and you swapped in a 60 volt transistor. A much better choice would have been and KSC1845 <------ 120v transistor. ;)

I suspect TR604 ( KSC1815) could be history......

Thanks - I added that description just in case it was an issue. I will swap it out and see if it helps. I'll also review the schematic to see if I can see where it states the voltage, because that will be helpful in the future!
 
When I did mine I found some cracked solder joints at the biggish red resistors that are wrapped in a flameproof sleeve...
And that caused the relay clicking in and out when the contact was lost.
 
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my thread is here, might be useful

index.php
 
So the base is 0mv I think.
Thats what it is suppose to be... This voltage is the voltage off of the output of the amplifiers.
As long as it remains zero it indicates that the protect circuit or the power source for the protect
is suspect.
 
Bad idea...If the OEM transistor was a 2SC1775 , according to the schematic anyway.
2SC1775 is a 90 volt transistor and you swapped in a 60 volt transistor. A much better choice would have been and KSC1845 <------ 120v transistor. ;)

I suspect TR604 ( KSC1815) could be history..

I've ordered the part you suggested, looking at the schematic (now I see how the transistors are listed) I can see that TR604 and 5 use the same model. I swapped back in the original transistors I had taken out just in case that made a difference, but it didn't seem to - I'll wait until the new transistors arrive and try again.
 
I have replaced both TR604 and TR605.

TR601 reads:
E: 14.4 mv
C:1.224 vdc
B: 0 mv

What's next for the patient? :)
 
So, I thought I'd add a little more info after doing some more readings:
1. The collectors of TR601, TR603 and the base of TR604 all read 1.224vdc. Looking at the schematic, they all look like they're connected, so where does this value come from originally?
2. TR605 (that I just replaced) is showing 3.2vdc on the base and a whopping 40.6vdc on the collector - neither of which is to spec - I note there's a resistor between the base of TR606 and collector of TR605, could it be at fault?
 
Coming back to this as I've some time (finally) and hoping some people are able to help. I checked R470 and R469 and both were reading 1.6v, which is high enough I assume to stop the relay clicking. I also remember when I originally re-capped, the relay was sporadically working as I swapped the first few caps next to the large filter caps, and then stopped working completely once I swapped out the filter caps themselves.
 
Its been 3 years ago.... How about a quick run down of what is working and what is not working.. Basically lets start from scratch...
 
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Sure and thanks for the help. The same issue still persists, in that I get power, but the relay won't click.

History:
1. 3 years ago, I mostly recapped the Yamaha. There was an issue with a popping sound, which I (hoped in my naivety?) a recap may fix. I was periodically checking as I went that the unit would still work. After the first few caps I replaced, around the large filter caps, the relay periodically stopped clicking. After I replaced the filter caps, the relay stopped clicking completely.
2. I then turned to the internet for answers, discovered this forum. That's when I started to look at the relay circuit and replaced TR601 to TR606. After that didn't work, I asked the question above, then followed the advice, but alas still no joy. Then life got complex and the Yammy was stored...
3. Fast forward three years, (and after watching a YouTube restoration) - I replaced the factory output transistors with MJ15003 and MJ15004 pairs. This didn't fix the relay issue, but the original popping issue which would cause the meters to spike after a few seconds to a minute, hasn't happened since the output transistors were replaced (just looking at the meters for reference as there's no sound). Although that may just be because something else is broken.
4. Today, I decided to look at the DC to the speakers and I got a reading of 1.2v. from both R470 and R469. I thought perhaps it's a clue to what the underlying issue could be and bumped this thread.

I have to admit I've not tested any of the transistors I replaced 3 years ago to see if they're still OK. I have checked, to the best of my ability, that all caps are seated properly and there is no obviously cracked solder anywhere, or any blown components.
 
What voltage are you seeing on TR601 or TR602 base lead ?
 
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Need to know the collector voltage of TR425 and TR428 .. As well as TR426 and TR427..Precisely..down to the millivolts.
 
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