Crack Shuts down after about 3-4 min.

ualcap · 2280

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Offline ualcap

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on: April 28, 2013, 01:04:57 PM
 After a phone call to Bottle head HQ Doc and I decided that I should rewire a few things on my crack because of some strange high voltage reading.
 Finished rewiring and the high voltage on terminal 1and A1&B1(150v) now 75V(book calls for 90V). A1,A5,B1,B4 volts read 75V. Ohm check within tolerance.
 Connected source and headphones and everything worked great sound was perfect. I shut the amp down and changer the input tube fired it back up and enjoyed for about 5 min. then the amp shut down. I checked the fuse and it was find. Amp was off for about 10 min., long enough to cool down some. I turned the amp back on and this time it  stayed on for a couple of min.and shut down a second time. A recheck of Volts and ohm check same as above until amp warms up then it shuts down.
What up guys?



 


Offline Paul Birkeland

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Reply #1 on: April 28, 2013, 03:21:16 PM
Put the other tube back in and see if that helps.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline ualcap

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Reply #2 on: April 29, 2013, 05:12:07 AM
Paul,
I replaced the tube with the original same results. Sorry I forgot to include that last night.
I turned the amp back on this morning and worked great with same voltage as last time. Made it through one 3:00mim song and it shut down again.


Offline Doc B.

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Reply #3 on: April 29, 2013, 05:19:19 AM
This is a real long shot - the rectifiers can behave like that if they are seeing too much voltage. Double check the numbers on them to be sure they are all UF4007s.

It's also possible you simply have a bad connection somewhere that is opening as the components warm up.

Dan "Doc B." Schmalle
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Bottlehead Corp.

Offline ualcap

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Reply #4 on: April 29, 2013, 05:50:47 AM
Doc,
The UF 4007 rectifiers are the originals. I restarted the amp after last posting and this time it ran for about 10min. How hot are the 3K wire wound resistors be getting? They are very hot. Volt check this morning same a last.


Offline ualcap

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Reply #5 on: April 29, 2013, 06:11:22 AM
Typo: how hot should the 3K wirewound resistors be getting.


Offline Paul Birkeland

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Reply #6 on: April 29, 2013, 07:24:58 AM
The 3K wirewounds should run nice and toasty.

What you will want to do is run the amp until it shuts down, then look around for voltage issues. 

It's pretty easy to just eyeball the 9 pin socket, if the LED's are lit up, you should be OK.


Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline ualcap

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Reply #7 on: April 29, 2013, 09:53:26 AM
Thanks Paul,
It's working

Danny


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