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HELP!!

 
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Jeff Barnett
This ain't no Disco


Joined: 12 Jan 2007
Posts: 55
Location: SoCal
PostPosted: Mon Mar 08, 2010 8:58 pm    Post subject: HELP!! Reply with quote
(Hi Norm & Moss...)
I have a home-built version of the 18 watt lite & am having a problem with weak volume & unwanted distortion.I believe its a power tube bias problem, but all the voltages seem to be OK (albeit,a little higher than most examples...).One clue is, when the standby switch is shut off, volume rises quickly to where it should be , before it dissipates..Normally I can iron out these problems, but this one has me stumped.I've changed the tubes & tried another output transformer.Any Ideas???
Thanks in advance for your help.
Jeff
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rocco
Site Admin


Joined: 27 May 2006
Posts: 1252
PostPosted: Tue Mar 09, 2010 3:06 pm    Post subject: Reply with quote
sounds like maybe you are dumping your B+ to ground, and it's coming up when you flip to standby.
Check your 220K bleeder resistor, and all your power supply connections, including grounds.

let me know...
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Jeff Barnett
This ain't no Disco


Joined: 12 Jan 2007
Posts: 55
Location: SoCal
PostPosted: Tue Mar 09, 2010 11:17 pm    Post subject: Re-HELP! Reply with quote
Found the culprit...After hours of brain wracking & parts swapping , found that something I omitted purposely was causing the voltage drop...I left out the #1 input jack...Doesn't make any sense to me, but apparently having the cathode tied to both pins 3 & 8 necessitates having a grid input...(???)Anyways, got it fixed & it sounds great.I also added parallel input switch while I was at it.
Thanks for your input, I really appreciate it.
Jeff
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