Voltage check issues with my Crack

quenya · 3828

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Offline quenya

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on: May 18, 2013, 05:24:42 PM
I'm having some serious voltage issues with my newly assembled Crack.

I got through the resistance check without any problems. Inserted the tubes and fuse. When I turn in the power, only the 12UA7-tube lights up (faint glow from two small points on the base + two barely visibly glowing rods). The 6080WA remains dark (however, I don't have any idea what it SHOULD look like while turned on, so I might be missing something here). I get the following voltage values with both tubes inserted:

1 - 203 (90)
2 - 203 (170)
3 - 0 (0)
4 - 203 (170)
5 - 85 (90)
6 - 0 (0)
7 - 0 (100)
8 - 0 (0)
9 - 0 (100)
10 - 0 (0)
11 - 0 (0)
12 - 0 (0)
13 - 203 (170)
14 - 0 (0)
15 - 212 (185)
20 - 0 (0)
21 - 220 (206)

A1 - 85 (90)
A2 - 0 (0)
A3 - 1.56 (1.5)
A4 - 0 (0)
A5 - 0 (0)
A6 - 203 (90)
A7 - 0 (0)
A8 - 1.62 (1.5)
A9 - 0 (0)

B1 - 203 (90)
B2 - 203 (170)
B3 - 0 (100)
B4 - 85 (90)
B5 - 203 (170)
B6 - 0 (100)
B7 - 0 (0)
B8 - 0 (0)

Is it possible I actually screwed this up this bad? Or is there any other explanation to my completely messed up values? It might be of importance that I'm using the 240V PT3, since I'm living in Europe.

I'm gonna get some sleep before rechecking the manual to see if I followed the instructions correctly. In the mean time, I'd be very grateful for any help on this issue. :)

Edit: I don't know if it is of importance in my scenario, but I also checked the AC voltages at the power transformer.

T1-T2: 230 V
T4-T5: 6.0 V
T6-T7: 164 V
T9-T10: 163 V
« Last Edit: May 19, 2013, 12:20:05 AM by quenya »



Offline quenya

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Reply #1 on: May 19, 2013, 01:29:56 AM
I rechecked the manual to see if I made any errors. As far as I can tell, everything appears to be in order. Could this be a cold solder or nicked wire? Could my 6080WA be broken? If it is of any help, here is a picture of my Crack: http://i.imgur.com/B5n5ohy.jpg



Offline Laudanum

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Reply #2 on: May 19, 2013, 02:32:17 AM
Your 0ctal tube socket (the big one) is not properly oriented.  That means the wiring is wrong on that socket which also impacts what's wired from (and to) that socket.  Get the socket wired correctly and the other wiring is also corrected correspondingly. 
Judging from the photo, the 9 pin socket looks oriented correctly.    You can either remove the large tube socket, orient it correctly and rewire.  Or leave it where it is,  note and / or re-number the terminals accoring to how the tube is currently oriented and re-wire.   Since you have to rewire anyway, I would desolder all the wires from that socket, rotate the socket and then reconnect the wires.  That will avoid confusion later on should you need to troubleshoot.   

Here is the key (pun intended) ...  If you notice, the large socket is keyed ... it has a notch, and octal tubes have a "key" / tab, to make sure they are properly oriented in the socket.   That keyway should be facing straight down, pointing toward the front of the amp (toward the small tube socket).  You have it oriented to the side.   

Compare your photo to the photo in the manual, focusing on that large socket and the keyway/notch that I refer to.  Smack yourself on the head, take a deep breath and warm up the iron  ;)
Realtively easy fix assuming everything else is correct.   And yes,  everyone here has probably done something similiar.   I probably have more often than most.
« Last Edit: May 19, 2013, 02:38:10 AM by Laudanum »

Desmond G.


Offline quenya

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Reply #3 on: May 19, 2013, 03:31:51 AM
Thank you so much for the suggestion! I would never have noticed my mistake. :P

I'll get back to you as soon as I'm done rewiring. Just out of curiosity, would this fix the haywire voltages (assuming everything else is in order)?



Offline Laudanum

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Reply #4 on: May 19, 2013, 03:40:41 AM
Yes, the voltages would be certianly be out of spec with that socket incorrectly wired.

Desmond G.


Offline quenya

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Reply #5 on: May 19, 2013, 05:14:50 AM
Alright, I just got back from rewiring and resoldering. It's certainly not pretty, but I got the job done. ;) Everything looks a lot better now, but I still have a few voltages that bother me.

1 - 77 (90)
2 - 164 (170)
3 - 0 (0)
4 - 164 (170)
5 - 76 (90)
6 - 0 (0)
7 - 99 (100)
8 - 0 (0)
9 - 101 (100)
10 - 0 (0)
11 - 0 (0)
12 - 0 (0)
13 - 164 (170)
14 - 0 (0)
15 - 185 (185)
20 - 0 (0)
21 - 204 (206)

A1 - 76 (90)
A2 - 0 (0)
A3 - 1.56 (1.5)
A4 - 0 (0)
A5 - 0 (0)
A6 - 77 (90)
A7 - 0 (0)
A8 - 1.54 (1.5)
A9 - 0 (0)

B1 - 77 (90)
B2 - 165 (170)
B3 - 100 (100)
B4 - 76 (90)
B5 - 165 (170)
B6 - 101 (100)
B7 - 0 (0)
B8 - 0 (0)

T1-T2: 230 (230)
T4-T5: 5.6 V (6.3)
T6-T7: 158 V (150)
T9-T10: 158 V (150)

Are these numbers alright? If not, is there anything a can do about them? Thanks for helping me, by the way. I really appreciate it! :)



Online Paul Birkeland

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Reply #6 on: May 19, 2013, 07:00:58 AM
The voltages in the 70's just indicated a stronger than normal tube, you're all set to listen.

-PB

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Laudanum

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Reply #7 on: May 19, 2013, 07:04:01 AM
A little low on those few but 15% or less variance is fine and it's right there.  I wouldnt worry about those too much, they may change as the tubes get some burn in.   The heater voltage is the only one that would concern me a little and I wouldnt freak out about it ... that's the 5.6V on T4, T5.  That may also regulate with some tube burn in.  If you had a couple spare tubes you would probably see that the voltages would be different.   I'll let the more tech savvy chime in on that 5.6 volts but it should be safe to listen to so how does it sound? 

Edit.  And there is CB, one of those tech savvy gents I mentioned who beat me to the punch  ;)

Glad I could help.  Enjoy

Desmond G.


Offline quenya

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Reply #8 on: May 19, 2013, 09:35:42 AM
Can't really say anything about how it fares soundwise yet. I'm still waiting for my ODAC to arrive. :) I'll get back to you on that!

Paul, I'm glad to hear those lower-than-usual voltages are perfectly fine. What are your thoughts on the heater voltage? Is that also due to the stronger than normal tube?

I'm really excited to try this kit out as soon as my DAC arrives, thank you both for your help. :)



Online Paul Birkeland

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Reply #9 on: May 19, 2013, 10:46:29 AM
The heater voltage may just be a bit of meter error.  Seeing that the tubes are operating as they are lets us know that this voltage isn't an issue. 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline quenya

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Reply #10 on: May 22, 2013, 11:54:39 AM
I just wanted to write back and give you guys an update. I recieved my ODAC yesterday and plugged in along with my Crack and newly bought HD 650's. I have to admit that at first I was quite skeptical. It took me some time before I got used to the sound of it (I thought it kind of sounded a bit harsh), but now I can't stop listening to it. I'm listening to music I've listened to for over 10 years, and I'm discovering things I've never heard before. This is beyond amazing. It may have been a premium price all in all, but it's definitely worth it! :D

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FxDVsptP.jpg%3F1&hash=6db7ce56fdd0f1217259b5ccb2b0c3b10811179d)
« Last Edit: May 22, 2013, 12:06:08 PM by quenya »



Offline mikkosjun

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Reply #11 on: May 22, 2013, 11:30:49 PM
Hello!

Your voltage list after finding wiring problem is just like mine. You are also getting 230 mains as I am. I'm metering just 5,3 VAC in T4-T5. Could you comment you clear is the glow in 12AU7? My heaters show only two dim orange spots on the top. 6080WC center is glowing clearly.

After adding Speedball  voltages in 1/5/A1/A6/B1/B4 (90V -> 75V with Speedball) and in B5/B2/2/4 (170V) are within +/- 1 volt. And with the Speedball I can say amp is dead quiet.

But music with my HD800 sounds great, I can't say would +1,0 volt higher heater voltage have effect. May be I test it in summer with outboard DC powersupply. I don't have suitable supply yet because of the current rating of heaters. 

Mikko



Offline Laudanum

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Reply #12 on: May 23, 2013, 03:01:08 AM
Some of the 12AU7's glow more than others.   I believe that some new production 12AU7's (ie EH and Sovtek)  have spiral filaments and emit very little glow at all.   I dont think your filament voltage is having much impact on the amount of glow.

Desmond G.