New Crack Build Voltage Problem [resolved]
- Thread starter jminassin
- Start date
OK, the resistor isn't getting too hot. It will actually be about twice as hot when the amp is working.
Could I see some tighter shots of the 6-10 terminal strip?
You have the correct resistance at 7 which should allow the 6080 to draw current on that side, but it isn't. Can you carefully measure the voltage at B1?
Could I see some tighter shots of the 6-10 terminal strip?
You have the correct resistance at 7 which should allow the 6080 to draw current on that side, but it isn't. Can you carefully measure the voltage at B1?
The voltage at B1 is 98.1 V DC. When I first turned on the amp the voltage was as high as 250 V and then it came down.
One side of the 6080 tube lights up.
I’ll take some tight pictures and send them via my computer as the forum’s system doesn’t recognize photos from my iPad as .jpg files.
Thanks,
John
One side of the 6080 tube lights up.
I’ll take some tight pictures and send them via my computer as the forum’s system doesn’t recognize photos from my iPad as .jpg files.
Thanks,
John
If only one side of the 6080 is glowing, I would seek out a different 6080.
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
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
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
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
That's a working set of voltages.
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
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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