Chris45set
New member
Started the S.E.X. Build. Haven’t had this much fun in years. Base will be dark walnut. Not enough posts to attach pic yet. Perhaps later. Thanks to all who provide the kits and invaluable advice.
Chris
Chris
New build [resolved]
- Thread starter Chris45set
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Chris45set
New member
I do have one question. Both the chokes and OTs had some sort of thick epoxy like coating. I removed from the chokes before painting (thank you dremel sanding drum). I left the OTs as is. Will this interfere with the grounding plane connections on the OTs?
Thanks for any advice.
Chris
Thanks for any advice.
Chris
That's varnish that's applied to the transformers in a vacuum chamber. You can remove it from the shiny steel parts, but I would leave it on the dark steel laminations (these aren't really visible on the plate chokes). I would not remove any from the output transformers since you can't see them.
Chris45set
New member
Good to know. I only removed from the frame bell ends and mounting tabs on chokes as that was all that was visible and painted. Glad I don’t have to remove the OTs and sand them.
Thank you for the quick reply.
Chris
Thank you for the quick reply.
Chris
Chris45set
New member
D
Deke609
Guest
That's a nice looking amp! Is that copper hammertone on the chassis and end bell?
cheers, Derek
cheers, Derek
Chris45set
New member
Yes. Copper hammer tone. Used Doc’s advice. Two coats and wide even strokes. Wanted to paint screw heads black until I counted them. Thanks for the compliment on the looks.
To paint Screw heads, push them into some cardboard (protects the threads as well as holding them) then spray paint. I have had good results with epoxy black.
Some people will say you cant do it and need to buy black hardware, however, good paint, careful installation (and you are only doing it once) it seems to work fine.
Some people will say you cant do it and need to buy black hardware, however, good paint, careful installation (and you are only doing it once) it seems to work fine.
Chris45set
New member
I had everything working well and went to install the C4S and I screwed up.
I connected the White OA wire to terminal 1u (ground) instead of 2U and fired the amp up.
The tubes glowed, no LEDs, voltage at OA 0.0 at OB -1.5 VDC
I shut down, found the problem and corrected the wiring fault.
Now on power up I get tube glow, no LEDs lit (either side), voltage at OA is 74.4 DC voltage at OB still -1.5.
I tried running resistance checks through the 5731 and found no shorts on OB side.
Same with the 2907 on the OB side.
Can you please help me find what I fried?
I am am idiot, I should know better than this . . . .
Thanks for any assistance.
Chris
I connected the White OA wire to terminal 1u (ground) instead of 2U and fired the amp up.
The tubes glowed, no LEDs, voltage at OA 0.0 at OB -1.5 VDC
I shut down, found the problem and corrected the wiring fault.
Now on power up I get tube glow, no LEDs lit (either side), voltage at OA is 74.4 DC voltage at OB still -1.5.
I tried running resistance checks through the 5731 and found no shorts on OB side.
Same with the 2907 on the OB side.
Can you please help me find what I fried?
I am am idiot, I should know better than this . . . .
Thanks for any assistance.
Chris
Replace the transistors and LEDs on that side of the board. When you have them out, measure the resistances of the resistors to be 100% certain that they are OK.
Chris45set
New member
I removed all semiconductors from OB side, resistors measure OK.
Putting together an order for Mouser now, will order 4 LEDS and two of each transistor.
do you think the LEDs on the side which measures OK are also cooked since they also do not light?
I will order enough replacements, just wondering how much I should replace once they arrive.
Or am I better off to take the shotgun approach and replace all transistors and LEDs?
Thank You again for your help and support.
Chris
Putting together an order for Mouser now, will order 4 LEDS and two of each transistor.
do you think the LEDs on the side which measures OK are also cooked since they also do not light?
I will order enough replacements, just wondering how much I should replace once they arrive.
Or am I better off to take the shotgun approach and replace all transistors and LEDs?
Thank You again for your help and support.
Chris
It sounds like one half of the board still works, and it's not unreasonable to imagine that only the miswired side would experience all those failures.
If you can't light the LEDs with your meter on the diode check setting on that side, I would definitely replace them. My guess is that you can light the LEDs on the good side and that those transistors still measure OK. The 75V you have at OA also tends to confirm this.
If you can't light the LEDs with your meter on the diode check setting on that side, I would definitely replace them. My guess is that you can light the LEDs on the good side and that those transistors still measure OK. The 75V you have at OA also tends to confirm this.
Chris45set
New member
Parts arrived and were installed today.
Replaced all four LEDs and both transistors on the bad side.
All four LEDs lit and the amp is playing sweet music again.
The C4S makes a big difference. Better bottom end and much tighter presentation.
The band members are definitely all in the same groove.
Thank You again for your help.
Chris
Replaced all four LEDs and both transistors on the bad side.
All four LEDs lit and the amp is playing sweet music again.
The C4S makes a big difference. Better bottom end and much tighter presentation.
The band members are definitely all in the same groove.
Thank You again for your help.
Chris
