New build [resolved]

Chris45set · 1680

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Offline Chris45set

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on: April 24, 2020, 04:05:05 AM
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
« Last Edit: May 09, 2020, 12:48:51 PM by Paul Birkeland »


Offline Chris45set

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Reply #1 on: April 24, 2020, 07:22:55 AM
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


Offline Paul Birkeland

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Reply #2 on: April 24, 2020, 07:29:42 AM
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. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Chris45set

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Reply #3 on: April 24, 2020, 07:36:07 AM
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


Offline Chris45set

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Reply #4 on: April 25, 2020, 03:38:19 PM
It's alive.
sounds absolutely amazing.
Listening to Ahmad Jamal's "The Awakening" and Oliver Nelson's "Stolen Moments".
Never heard either one sound so good.
Perfect match with HD650.
Thank You again to all who make this product and this Forum possible.
Chris


Deke609

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Reply #5 on: April 26, 2020, 05:21:42 AM
That's a nice looking amp! Is that copper hammertone on the chassis and end bell?

cheers, Derek


Offline Chris45set

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Reply #6 on: April 26, 2020, 06:51:19 AM
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.


Offline mudvin

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Reply #7 on: April 26, 2020, 09:14:43 AM
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.



Offline oguinn

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Reply #8 on: April 26, 2020, 12:58:41 PM
On the other hand black hardware was a negligible cost and was very easy

Jameson O'Guinn

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Main System: Schiit Bifrost MB, Rega Planar 6 with Exact cartridge, Eros 2, BeePre, Kaiju/Stereomour II, Jagers, Mainline

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Offline Chris45set

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Reply #9 on: May 03, 2020, 11:00:03 AM
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


Offline Paul Birkeland

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Reply #10 on: May 03, 2020, 11:04:20 AM
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.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Chris45set

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Reply #11 on: May 03, 2020, 11:38:20 AM
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


Offline Paul Birkeland

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Reply #12 on: May 03, 2020, 12:18:22 PM
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.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Chris45set

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Reply #13 on: May 09, 2020, 12:45:03 PM
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


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