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24.49.29.38
Just wanted to share my experience that I recently had with a pair of stuffed Dynaco ST-35 boards from Ebay.
The PC board quality is excellent. But the capacitors that come with the boards are not good.
This particular PC board came with WIMA signal caps and some small picofarad cream colored caps that look to have their DNA from Tantalum caps than real Silver Mica.
After many hours of attempting to rid the amp of a raspy distortion in the midrange, I started to swap out the small cream colored caps for real Silver Mica's and the distortion was somewhat reduced.
Finally I replaced the red WIMA caps and the amplifier is now working well.
Granted I saved about $30, but lost time and parts from my stock.
Heads-up on these boards.......
Follow Ups:
I thought those square red WIMA coupling caps were a step above some of the low cost ones. Maybe yours were faulty? I've seen them in some expensive production amps too. Maybe fake parts!Randy
Edits: 05/27/12
I had the same thought. Wimas aren't trendy or spendy, and I've always liked their up-front presentation. His might very well be counterfeit.
Wima are good caps. True quality general use electrical components. Not like the overpriced audiophile junk either.
Maybe the WIMAs were counterfeit. Were these boards intended for use in jet fighters?
--------------------------
Buy Chinese. Bury freedom.
I have to agree that its a strong possibility that the WIMA's are fake.
In the past, I have had equipment that used WIMAS and sounded very good.
The Dynaco PAS-4 was one of them.
Once I pulled the WIMAS and those small "mystery" cream colored Pico-farad caps, the ST-35 amplifier opened up and now sounds awesome.
No distortion.
I am not sure if the small cream colored Pico-farad caps are Tantalum as I have never seem them before.
Pulling these caps made a difference as well but not as much as the WIMA'S.
Especially the one that across the input resistors; C2.
I replaced C7 with a 500V silver mica (has 22pf on hand, not 27pf).
Also pulled out C6 altogether as this was also contributing to the distorted sound. Running the amp without this until a get an Silver Mica 500V 18pf replacement.
Coming from China the PC boards are very well made, except for the Capacitors I have to admit..
The Metal film resistors look high quality and haven't given any grief.
But I can't say the same about the capacitors on the board.
The PC boards have held up very well to my troubleshooting (removing and resoldering parts).
This board also offers differently spaced cap solder pads for C4, C5 and C3 that are spaced for "Real" WIMA caps :) or larger axial capacitors.
I am using Kimber's for C4 and C5, a regular Polyester "Brown-Orange" cap for C3.
My plan to ask the seller if they are willing to sell the Bare Boards, no parts. The board material is solid and the PC traces are pretty thick, they don't lift with the soldering gun heat.
This is the link to the boards I purchased....
http://www.ebay.com/itm/pair-Dynaco-ST35-ST-35-Amp-Fully-BOARD-PC13-free-delive-/290524674281?pt=LH_DefaultDomain_0&hash=
Here are some pics of the parts I removed.
Sherman if you want another set of bare boards wouldn't the new boards from Kevin at dynakitparts be worth the few $ more as they are the highest of quality and even now faithfully look exactly the same in color and material as the vintage ones.
I will let you know when I get the price on the empty boards.
Great question, it's about the price.
Another guy selling nice boards and a new PS board with the EFB mod is Audioregenesis in Canada.
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