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HELP! - Need a Repair Recommendation for my Raysonic Amp

After 5 years of flawless service, my Raysonic SP-66 tube integrated wouldn’t power up yesterday evening. The fuse at the electrical input was blown, but it still didn’t power up even after I replaced the fuse with one that tests good. I took the bottom plate off, looked around inside, and didn’t see anything obviously wrong. The 2 internal fuses tested good.

It ocurred to me that the power button was probably in the ON position when I went to start listening. This suggests that either I accidentally left it on the last time I listened, or one of my grand-children turned it on, and it over-heated. I also noticed a paint blister on one of the transformer covers suggesting that it over-heated.

My suspicion is the power transformer, but I don’t how to confirm it, or replace it if it is in fact the problem.

Raysonic is long gone and they had a reputation for being secretive with product details, so I doubt that anyone will have schematics or parts values.

The amp has been a pleasure and it is a perfect match for my CD128 CD player which has also performed flawlessly.

Therefore, I would very much like to get the amp repaired, as long as it isn’t cost-prohibitive, but I don’t know who to turn to, much less trust, to do the work.

I would hope that a well-qualified tube amp technician would be able to fix this even if they are not specifically familiar with Raysonic. I just don’t know who that is.

So, I would appreciate suggestions/recommendations of someone who may be able to help me out.

Thanks in advance.

Brady




bbroussard
atmasphere's avatar
atmasphere
11,615 posts
 
It seems unlikely that the power transformer has failed- a rectifier is far more likely. .


Power transformers have to be dipped in something very much like varnish to help them have low mechanical noise. Then they are baked- so you can get bubbles. This is not to say that the transformer hasn't failed; to test it all the secondary circuits have to be opened so that there is no load on the transformer whatsoever. If it continues to blow fuses then you know its bad.

oldhvymec
5,101 posts
 

The blister on the transformer cover, is something to be concerned about. The "why" more than anything..That's hot!!

Pulling the top on the transformer and doing a "look see", if you can. If it's burnt, it's burnt.. The ol sniff test goes a long way, too, does it smell burnt?
   
Did you pull the valves and see if it will stop blowing fuses.  If it turns on, look to the valves. Is there a chance one blew and that caused a fuse to blow.  Happened to me more than once.
I've lost valves that caused a resistor or two to fail, and the other way around, lost resistors that blew a valves..

If it won't power up, MAKE SURE the fuse is good, (could have blown) pull all the valves and check again, if not, look for a second fuse inside. Then make sure the on/off button didn't go bad.

One visual, the transformer. The on/off, a DMM. Unless you lost a valve it's shop time.. You don't need a schematic, but it can sure help in some cases. Probably no schematics because it was scribbled on a paper bag.. Their not that complicated of a circuit.. No matter who made the amp..The reason there is no information is because there never was, very common in the valve preamp/amp world..

Regard


bbroussard OP
188 posts
 
Thanks for all of your input so far.

I agree that simply leaving the amp on shouldn't cause damage.

As I said, I know just enough to be dangerous.  

I live in Lafayette, LA and the closest thing we have to an audio shop these days is Magnolia inside Best Buy.

What would a rectifier look like?

I haven't tested the tubes yet.

I put a fresh fuse in and it doesn't blow when I push the power button on.  Nothing at all happens.  Pulled fuse and checked again.  Still good.

Shipping this thing back and forth is going to cost a small fortune, so I am trying to avoid that.  

Any suggestions for a tech in Houston or New Orleans?  I will traveling to both of those cities once restrictions are lifted and I could hand-carry to avoid shipping cost and risk.

Thanks again.
atmasphere's avatar
atmasphere
11,615 posts
 
I put a fresh fuse in and it doesn't blow when I push the power button on. Nothing at all happens. Pulled fuse and checked again. Still good.
Was it plugged in properly (did it light up)? If it lit up but nothing happened, in my estimation the power transformer is off the hook.


If you don't know what the rectifier looks like, then its also a good idea to *not* go looking for it!



newbee
4,751 posts
 
I have experienced your problem with several other amp's and each time, as suggested by oldhvymec, I lost a resistor in the bias circuit, replaced it and all was fine. FWIW there are quite a few manufacturers that use a 'sacrificial' resistor as opposed to a fuse. PITA IMHO, especially for some one who can't do his own repair work. 
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