Yamaha CA-800 Restoration Project

kretinus

kretinus

squanto was a fool
A few days ago, I acquired a very nice Yamaha CA-800 amp from a friend, with what should be a minor ps/cap issue, in fact it sounds wonderful as is, just a low threshold static. Anyway, as you can see from the pics, cosmetically it's very nice, the case will need refinished, I'm actually thinking of re-veneering it with the Yamaha logo inlayed in a contrasting veneer on top just for giggles.

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Anyway, I have been in contact with an AK subscriber/Yamaha tech who will be taking care of the ps/cap issue, is there anything else I should be having him do while he's in it. I want to end up with a reliable working amp that I can make the center piece of a vintage system and I think this one's worth putting the money into.
 
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If you are using an AK tech my guess is they will do everything needed to make it last when they are in there. I'd have this discussion with the tech. There is only one tech here that I know of who is "Yamaha only" and if we are talking about the same one he fixed my cursed CA-1000 up very nicely.
 
Amp is now safely in the hands of Avionic.

Unfortunately took a few minutes to listen to his system, went home and everything that was once shiny and pleasing to the ears is now seeming somewhat dull and harsh.
 
Man you got too much cool stuff!

Pat my Kenwoods on the head for me, Paypal will eventually get it sorted out :thmbsp:
 
Here is something he can do, replace the two micro switches in the Mode switch. This picture shows what happens when you switch from Class AB to Class A with the power on - not pretty. Fortunately they are Omron switches part no V-10-1A4.

Sometimes if they are not too far gone you can open them up clean them and put them back. This one had been subjected to so much current that the snap spring had lost all tension. Result was that one channel was trying to run in Class A and the other in Class AB. Instead of using both 40 volt windings of the power transformer on the rectifier it got 40 V one side of center and 25V on the other.
 
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Rob at the ready!

The CA-800 is essentially identical to the TOTL CA-1000. Next to a Yamaha B-2 amp (and A-1 not far behind), I think that the CA-1000 is one of the nicest sounding Yamaha amps, ever. I can only imagine that the CA-800 will not disappoint once it's all tuned-up.

Also, a suggestion: make sure that the pre-out, main-in coupler switch (along with the phono cartridge resistance switch) have had a good dose of DeoxIT and a hearty exercise. These little switches are also a chronic weak point of sound quality/reliability.

Unless avionic has worked on one previously (likely!), he'll have fun removing the metal shield behind the front panel to get at servicing the filter and muting switches :D
 
I went to Mouser to order two new switches - %$#@^ what is the matter with Mouser, and DigiKey they make ordering online enough to try the patience of a saint. Insted of an order they got a nastygram. I heve written code on and off since 1963 and I never ever wrote crap like that. Take a number from their latest paper catalog, input it and their computers go Duh. If the farking paper catalog is useless why do they bother sending them to me.
 
Well, the good news is I got it into the hands of someone who knows what they're doing before the urge to start learning diagnostics on the fly. The bad news is, a flame has been kindled for things Yamaha, and in the heat of passion purchased a dead Yama CR-820 Reciever for $75.00 that is nice cosmetically, but described as powering on with lights etc, just no sound. But hey, that incuded shipping.

At least from the pics, it appears to be about as clean as my CA-800, the case is in much better shape, and it has all the lights on that Isee on working models, appears to have a station in tune etc.

Obviously my first hope is a I gambled on a blown fuse, but we'll see. As far as I can tell the two models are equal in size (someone correct me if I'm wrong) I have a barrister case they would both look nice sitting on side by side.

Oh, and the friend I got it from specifically warned me to never, never, ever touch the mode switch while powered on:thmbsp:
 
Well for starters.The constant pops in both channels is a cooked transistor on the power supply board--caps don't look to swell either. The 100Ω resistor next to the overheated transistor looks toasty also.
Fortunately they are Omron switches part no V-10-1A4.
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Point noted ! Darn normal/class A switching with power applied.:nono:
 

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avionic said:
Well for starters.The constant pops in both channels is a cooked transistor on the power supply board--caps don't look to swell either. The 100Ω resistor next to the overheated transistor looks toasty also.
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:yikes: Give it to me straight doc, does it have a chance without breaking the bank?

avionic said:
Darn normal/class A switching with power applied.:nono:
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Is that what caused that? because it was definitely not me that did it if it was.
 
Is that what caused that? because it was definitely not me that did it if it was.
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No that didn't cause the power supply issue. The "Mode switch" is a known weakness in the amps design especially I one does not heed the warnings and change modes frequently with power applied.Chances are that the caps in your power supply caused the transistor to draw more current than it was rated for..Probably would be a good idea to replace those micro switches with new units--there only a couple dollars apiece.
Unless avionic has worked on one previously (likely!), he'll have fun removing the metal shield behind the front panel to get at servicing the filter and muting switches
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Yep its buried.But no where's near as buried as some of the avionics systems I've repaired in the past.:D
 
avionic said:
...Chances are that the caps in your power supply caused the transistor to draw more current than it was rated for. Probably would be a good idea to replace those micro switches with new units--there only a couple dollars apiece. Yep its buried.But know where's near as buried as some of the avionics systems I've repaired in the past.:D
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Save the caps you replace, I'm going to punish them for what they have done:D

You have PM.
 
Dave, while you are working with the power board measure the fusistors (look like resistors but they are blue bodied) and see if any are out of spec. I will replace those &^%$# things in preference to caps.
 
Rob
About R706 on PS board its a 100 Ω but not sure of the wattage 1/2W ,1W,2W..?

Dave
 
merrylander said:
Dave, while you are working with the power board measure the fusistors (look like resistors but they are blue bodied) and see if any are out of spec. I will replace those &^%$# things in preference to caps.
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This was the same advice you gave me and both ended up being out of spec. Replaced them with 1% metal oxide and we are in business.

I would still like to know where to get replacement relay - havent found one yet.
 
Avionic, if your reply was about the relays I think we are on different pages. I meant the speaker relay, sorry.
 
Sorry my bad..You were talking relays I was thinking Omron they make relays and switches..I Order them by the dozens at my daytime job.:D
 
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