New Crack Build Voltage Problem [resolved]

jminassi · 3983

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Offline jminassi

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Reply #45 on: December 25, 2020, 08:31:32 AM
Ok, I'll have to buy a couple of new ones.

I tired posting pictures, but the system keeps giving me an error http500 or something.  I'll try later.


Offline jminassi

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Reply #46 on: December 25, 2020, 08:33:10 AM
Pictures


Offline jminassi

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Reply #47 on: December 25, 2020, 08:34:35 AM
Picture


Offline jminassi

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Reply #48 on: December 25, 2020, 12:11:55 PM
Another photo


Offline jminassi

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Reply #49 on: December 25, 2020, 12:12:59 PM
Last photo


Offline jminassi

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Reply #50 on: December 26, 2020, 06:45:25 PM
Paul,

I am ordering a couple of different brand 6080 tube and a couple of different brand 12AU7 tubes from Tube Depot (Digikey).

I repeated the resistance checks and it all checks out.  Because the flash/puff I experienced came from the side with the rectifier diodes, I have removed all four of them from the circuit.  They all measure between .501 and .504 Volts.  Is this the value that you would expect?  If so, I’ll put them back in the circuit..  If not, let me know and I’ll order new ones.

Thanks,

John


Offline jminassi

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Reply #51 on: January 29, 2021, 05:34:55 PM
No, I didn't give up and stop the build.  It took this long to get a new 6080 tube (NOS RCA 6080).  I also bought a new 12AU7 (EH).  I also decided to replace the four rectifier diodes with Vishay diodes UF4007.

At this point my resistance checks are all good.

My voltages look good to me.  Here they are:

Terminal

1.  81 VDC
2. 177.8
3.    0.5mVDC
4. 172.7
5.  80.4
6     0.4mVDC
7. 106.0
8.    0.6mVDC
9. 106.3
10.  0.4mVDC

Please confirm I am good to go to plug a pair of headphones into this thing.

Many thanks,

John Minassian


Offline Paul Birkeland

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Reply #52 on: January 30, 2021, 04:51:41 AM
That's a working set of voltages.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline jminassi

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Reply #53 on: January 30, 2021, 12:40:22 PM
Success!  Holy moly, this thing sounds awesome!  I just plugged my Ah! Njoe Tjoeb CD player into and played Trower's Bridge of Sighs.  Complete silence between tracks even with the volume up at eleven o'clock.  It's driving those Drop/Sennheiser 6xx's like it owns them.  I can't wait to get one of my DACs into the mix or my phono stage.  Next step is the constant current source upgrade.  I am going to start the build, but I will listen to the Crack in its present form for weeks before installing one of the new boards.

A special shout out to PB for your patience with me (I will get better), and to Deke for the help.

Let me know if there is something I need to do to close this thread.

Many thanks,

John


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