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In Reply to: RE: Dynaco SCA-35 replacement boards problem... posted by gkargreen on May 06, 2017 at 18:55:36
Since the ebay seller probably ripped-off Dave's board design anyway, maybe you can use Dave's installation guide as a...wait for it...guide. I'm not suggesting to follow it exactly, 'cause I don't know if the boards you bought are exactly the same. But since what you bought didn't come with instructions, that's where I'd start, looking for any differences between Dave's instructions and the boards you have during the hook-up.
Thanks, shovel, that is kind of the way I am thinking of going, even though the boards are not quite the same as Dave's design...
You never said which ebay seller you bought your boards from, but in doing a search, I found the ebay seller linked below. Is that where you got yours?
If so, you're right, they do differ from Gellespie's circuit. I only count 9 resistors on the ebay board (same as a stock SCA-35), while Dave's board contains 10 (eleven, if you count the 10K which goes between V-8 pin #2 and eyelet #8, which he adds underneath). Also, I only see the stock Dynaco circuit 12pF cap, no additional (C1) 18pF, as on Dave's board.
If it were me and I had already purchased the stuffed ebay boards, I'd try and shoehorn in the 18pF @500V C1 cap and R38 100k 0.5W resistor missing from the Chinese (i.e. otherwise stock) circuit, as well as using the 10K 0.5W Dave recommends.
Also note that Dave has increased the value of C18, which was 0.1uF @ 250V on the stock board to 1uF @ 250V in his circuit.
Good luck with your project.
Thanks, shovel, that is exactly the boards I bought, I am guessing they are based on another design, not Dave's!
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