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Re: Laney problem

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4/22/2004 1:07 AM

Re: Laney problem

ok--im a complete idiot--i was measuring with no tubes i the sockets--SO.....the voltages look fine--the amp sounds awesome,but it will still pop the 1A ht fuse--i stuck a 4A in there and its working and not blowing that.I swapped out all the tubes.Nothings burnt,no smoke,voltages look good,bias is good,etc...

what would cause the 1a to pop ,but not a 4amp ?
its got to be in the heater supply??

4/22/2004 12:13 PM
Dai Hirokawa	maybe it'd be a good idea to learn a bit more about how an amp works before messing with them. What if you mess up a friend's amp or something, you know? If you're going to go ahead with it anyway, then you might try checking out R.G. Keen's tube amp troubleshooting pages and maybe also hammer.org(?)'s scan of the Jack Darr book which has a section on troubleshooting.

4/22/2004 6:02 PM
km	im not even going to comment on that one--- can anyone shoot me some constructive ideas here??

4/22/2004 7:08 PM
Dan Z	I don't think Dai was being a smart-ass or busting your chops. If the amp was designed to use a 1A fuse and it keeps blowing fuses, going to a 4 amp fuse is not a solution. Dai's suggestion to follow RG Keen's troubleshooting guide is a good one. Find out what is drawing so much current before you put the tubes back in. Dan Z

4/22/2004 6:28 PM
Shea	I would shut it down, drain the filters, and start measuring the DC resistance between various points on the B+ rail and ground with the tubes pulled. You'll probably have to disconnect the filters or else you'll get weird readings that drift around. If I'm reading that schematic right, all the points on the B+ rail should read open. Shea

4/22/2004 8:45 PM

I'm just saying that maybe a bit of theory and understanding a bit better how an amp works might help you troubleshoot better. Increasing the fuse value when it keeps blowing just doesn't seem to be the soundest of troubleshooting approaches. Plus, you didn't know what a de-coupling cap was and didn't have one in the homebrew schematic of yours in the first stage. Again, I'm not saying you should quit or give up, but what am I supposed to think given my knowledge? Sorry if I'm coming off as harsh but I'm just trying to give you good advice. I'm no amp genius myself but I do think that trying to understand how an amp works is helpful.

4/22/2004 9:17 PM

THANKS SHEA--I WILL TRY THAT

and Dai,i know a bigger fuse isnt the answer !

As far as my homebrew,I didnt have the de-coupling cap in the first stage because im basing this preamp off a Marshall 800 that i modded (sounded awesome and still does..)and it had the same 50/50 caps in the same stages i have.

Like i always say,im still learning everyday and i thank everyone here for their help!!By the way,thanks for bringing up the "knowledge of the decoupling cap" in public.You really didnt need to do that.Ive always heard these referred to as "filter caps".wow--sorry!!----I guess i'll add that your ground wiring idea was much worse than what i had in the first place.

I come on here to learn ,not to be mocked by anyone.99% of the time i can get informative,direct,and helpfull ideas and answers.

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