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Aleph J illustrated build guide
Aleph J illustrated build guide
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Old 4th June 2021, 05:16 AM   #6681
Kingsportal is offline Kingsportal  United States
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Quote:
Originally Posted by Kingsportal View Post
Dang getting ready for work.
Will post later tonight
Here are a few shots of the board that never worked.
20210604_011339.jpg20210604_011348.jpg20210604_011411.jpg20210604_011416.jpg
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Old 4th June 2021, 11:16 AM   #6682
Chris In Milwaukee is offline Chris In Milwaukee  United States
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Aleph J illustrated build guide
I see a burned/damaged component beside C1 (the big red cap). Did that occur as a function of the failure? or while removing Q1A/B? Or is that a jumper? It's been a while since i looked at my own.

Any chance you have some denatured or isopropyl alcohol and a toothbrush? If you could scrub the flux residue off the backside of the board it will help us see if there are any connection problems.
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Old 4th June 2021, 11:50 AM   #6683
poseidonsvoice is offline poseidonsvoice  United States
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Aleph J illustrated build guide
Chris,

It looks to be the insulation of the jumper was melted off in attempts to resoldering and/or removing the J74 JFETS which are part of the input stage (differential long tailed pair).

Just on a cursory look, I see several cold soldered joints. A board devoid of flux and debris would make it easier to discern where the problems lie. Chris’ advice is good.

Best,
Anand.
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Last edited by poseidonsvoice; 4th June 2021 at 12:06 PM.
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Old 4th June 2021, 12:09 PM   #6684
Dennis Hui is offline Dennis Hui  Canada
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Aleph J illustrated build guide
KP, I also agree with Chris and Anand's suggestion that the board be cleaned to allow for a better visual inspection.

I assume this is the board with the funny R7 voltage measurement.
Since you've managed to measure good Idss values with your jfets, it's
quite possible some cleaning and carefully resoldering will get this channel
working.
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Old 4th June 2021, 02:50 PM   #6685
Kingsportal is offline Kingsportal  United States
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Here are a few more with things cleaned up.
Toothbrush and alcohol.20210604_104631.jpg20210604_104641.jpg20210604_104651.jpg20210604_104702.jpg20210604_104532.jpg20210604_104538.jpg20210604_104548.jpg20210604_104605.jpg
I have new jfets for Q1A and Q1B coming this weekend.
Do you reccomend replacing the previous batch even though they measured ok?
Just to start fresh.

Last edited by Kingsportal; 4th June 2021 at 02:59 PM.
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Old 4th June 2021, 06:20 PM   #6686
peppennino is offline peppennino  Italy
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Aleph J illustrated build guide
Quote:
Originally Posted by peppennino View Post
Let's play!

Attachment 954650

PSX_20210604_191824.jpg

So, BOM, PCB layout and schematic: I'm ready!
First of all, degreasing with Isopropyl:

PSX_20210604_191845.jpg

PSX_20210604_191904.jpg

PSX_20210604_191927.jpg

And begin soldering the small components. I use normal 60/40 "Super solder wire", 0,7mm:

PSX_20210604_192008.jpg

PSX_20210604_192037.jpg

PSX_20210604_192058.jpg

PSX_20210604_192120.jpg
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Last edited by peppennino; 4th June 2021 at 06:33 PM. Reason: typo
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Old 4th June 2021, 06:24 PM   #6687
peppennino is offline peppennino  Italy
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Aleph J illustrated build guide
I measure each resistor before installing it:

PSX_20210604_192143.jpg

PSX_20210604_192156.jpg

PSX_20210604_192212.jpg

PSX_20210604_192241.jpg

Tomorrow I'll continue with semiconductors, big res and caps...
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Last edited by peppennino; 4th June 2021 at 06:34 PM.
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Old 4th June 2021, 06:31 PM   #6688
poseidonsvoice is offline poseidonsvoice  United States
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Very nice work Peppennino!

I wish I had ZM's Aleph J boards too. I doubt he has any more left!

Best,
Anand.
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Old 4th June 2021, 06:34 PM   #6689
Zen Mod is offline Zen Mod  Serbia
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Aleph J illustrated build guide
these are provisional Store boards

peppennino is sorta beta tester, one of several
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Old 4th June 2021, 06:42 PM   #6690
Dennis Hui is offline Dennis Hui  Canada
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That'll be a nice addition to the diyaudio store.
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