crack bad tube/voltage?

Costes · 2721

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Offline Costes

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on: February 04, 2015, 05:32:29 PM
Hi,
After a good resistance check of the standard crack, i passed to the voltage check.
There i got some values that where seriously out of range:
T7=0 (should be 100)
T9=150 (100)
T13=193 (170)
T15= 205 (185)
B2= 185 (170)
B3= 0 (100)
B5= 170 (187)
B6= 150 (100)

What could be the cause of these values? Maybe a broken 6080 tube? All other values where within range.
Thank you in advance!

Edit: both heat filaments light up on my maybe broken 6080 tube
« Last Edit: February 04, 2015, 05:38:04 PM by Costes »


Offline Paul Birkeland

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Reply #1 on: February 04, 2015, 05:47:59 PM
Is your octal socket properly oriented?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Costes

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Reply #2 on: February 04, 2015, 05:54:41 PM
Yes, it is.


Offline Paul Birkeland

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Reply #3 on: February 04, 2015, 05:56:43 PM
If it's not too much trouble, could you post a pic of your octal socket wiring?

-PB

Paul "PB" Birkeland

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Offline Costes

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Reply #4 on: February 04, 2015, 06:15:15 PM
(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fs8.postimg.org%2Fm6vcoryap%2F1925277_10153657249568484_352389790130911394_n.jpg&hash=0c84c64e34246c3d628673eb93eddf3a40446f05)

http://s8.postimg.org/w46dhu5wl/1925277_10153657249568484_352389790130911394_n.jpg


Offline Paul Birkeland

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Reply #5 on: February 04, 2015, 06:37:42 PM
Did you happen to do the shorting mod? 

I would be somewhat suspect that one of the black wires that makes up the ground buss isn't all the way soldered, but you have one half of the 6080 that's overconducting, and the other half isn't conducting at all.  The 0V on T7 would be something I would expect if the 3K resistor feeding T7 wasn't installed properly, or if the shorting mod had been added to the circuit, and there was a miswire (output wire to the headphone jack going from T6 instead of T7).

The 150V on T9 is an odd one, what are your voltages at T1 and T5? 

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Costes

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Reply #6 on: February 04, 2015, 06:59:53 PM
It was a speedball upgrade that worked (but i did some work on the crack, and it failed)... what i think happend is that the TIP50 touched the heat sink... so that is indeed where there might have been a short circuit.
I went back to stock now... the small circuit boards of the speedball seemed still operational (leds still working etc), but i went back and replaced them by the 22K resistors as well. On the big board the leds where out after the fail.

T1 and T5 where on the high side, 93V, but within limits?


Offline Paul Birkeland

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Reply #7 on: February 04, 2015, 07:07:27 PM
Yeah, if the TIP50 touches the heatsink, you'll get 0V. 


Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Costes

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Reply #8 on: February 04, 2015, 07:12:08 PM
The speedball upgrade is removed completely and i put the 3K resistors back, as well as the 22K resistors, but i still get the weird voltages... that's why i'm a little worried...
could it be that the 6080 broke because of that and gives me these weird voltages?
Thanks for the help so far btw!

The voltages i give in the beginnen of the post are the voltages i measured today after the removal of the speedball, so the stock crack still gives me 0v.
« Last Edit: February 04, 2015, 07:13:41 PM by Costes »


Offline Paul Birkeland

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Reply #9 on: February 04, 2015, 07:27:09 PM
If you run a Speedballed Crack without the insulators on the TIP50, and you run it long enough, you can really put some stresses on the 6080 and the power transformer.  Basically, that half of the 6080 will draw as much current as it can, and the limiting factors end up being how much current the power transformer can supply and/or how much current the tube's cathode can source.

If you have proper voltages at terminals 1 and 5, but not at 7 and 9, but you had the amplifier working before, trying another 6080 may not be a bad idea.


Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline Costes

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Reply #10 on: February 05, 2015, 08:09:47 AM
Ok, I will try that!
I will keep you updated! Thank you!


Offline Costes

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Reply #11 on: February 09, 2015, 08:59:02 PM
Hi, i got some new tubes today, and it appeared that with my earlier mistake, the original 6080 tube sufferd damage.
Now everything is up and running again by replacing the tube.

I wanted to include some pictures of my finished crack + speedball:

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FJfDAEOX.jpg&hash=0a25d13b5c641a814153cd6013d202f459a811ad)

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi.imgur.com%2FGq8cGKM.jpg&hash=59ff19155efebfe23896a3b9b9cac9a3856cc7c5)

Added a VU meter, TIP50 temperature sensor with cooling fan, changed output caps.

(https://forum.bottlehead.com/proxy.php?request=http%3A%2F%2Fi.imgur.com%2F33WKoPE.jpg&hash=7a3cbd126aa03a8f7ce5182d666721afab994fb1)

Just one more question... do i need too make changes to use a 5998 tube?

Grtz and thank you very much for the help!!


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