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23rd December 2012, 09:50 PM
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#1 |
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diyAudio Member
Join Date: Feb 2002
Location: Canada
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SIT Startup Problems - What did I miss?
I built the original circuit exactly as pictured here:
 I need help here figuring our what I missed when wiring my SIT. Observations: All four lamps light up what appears to be correctly and they increase or decrease in brightness when I adjust P1 on either channel. I also have an ammeter in line with the main power circuit so I can see current increase and decrease when P1 is adjusted. Problem: When drawing 2 amps bias I have 25vdc on the speakers terminals. If I increase the bias to 2.6 amps I get 8VDC on the speaker terminals. Thoughts anyone? Regards, Dan 
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23rd December 2012, 10:37 PM
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#3 |
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The one and only
Join Date: Mar 2001
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Bad cap, reversed cap or mis-wiring.
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23rd December 2012, 10:57 PM
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#4 |
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diyAudio Member
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
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besides bad cap , there is missing bleeder resistor on speaker side
that's the price when Pa is in a hurry to please everyone it can be a problem when connecting speaker to still excited cap 
__________________
my Papa is smarter than your Nelson ! tnx to  clean  thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb
Last edited by Zen Mod; 23rd December 2012 at 10:59 PM. |
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23rd December 2012, 11:14 PM
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#5 |
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diyAudio Member
Join Date: Feb 2002
Location: Canada
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Slipped in a spare 47000uF/25v electrolytic and got the same results. My current vote goes to some sort of miswiring. Bias circuits and main PS supply circuits seem to be behaving 'normally' so I'm inclined to look elsewhere. Since both channels are consistent I think it's safe to assume I made the identical mistake in both channels. Hmmmmm........
 Regards, Dan 
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23rd December 2012, 11:15 PM
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#6 |
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The one and only
Join Date: Mar 2001
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Was that my schematic?
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23rd December 2012, 11:37 PM
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#7 | |
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diyAudio Member
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
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Quote:
'twas your blessing 
__________________
my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb
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23rd December 2012, 11:39 PM
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#8 | |
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diyAudio Member
Join Date: Jan 2003
Location: ancient Batsch , behind Iron Curtain
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Quote:
not just those from Playboy , when you were a teen , but also ones posted on forum , as additional info 
__________________
my Papa is smarter than your Nelson ! tnx to clean thread ; Cook Book ; PSM LS Cook Book ; Baby Diyaudio FORUM ; Mighty ZM's Bloggg;I'm dumb
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23rd December 2012, 11:42 PM
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#9 | |
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diyAudio Member
Join Date: Feb 2002
Location: Canada
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Quote:
Built the identical circuit as displayed in the first post. Thinking.............  Regards, Dan
Last edited by dantwomey; 23rd December 2012 at 11:45 PM. |
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