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Post subject: Re: hotrod deluxe loss of power
Posted: Mon Jul 25, 2011 12:39 am
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5V wah ! The PI has a gain of 10, AB stage a gain of 10 that's pretty descent.
Then the path from the "Power In" is working well. Let's investigate in the preamp section.
8)
Can you post captures of your oscilloscope ?

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Post subject: Re: hotrod deluxe loss of power
Posted: Mon Jul 25, 2011 6:03 am
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okay so i figured it all out.
so i was getting a bit annoyed at how $@!&*% all my measurements were and how the gain satges were all out so i decided to start from scratch.
i did what shimmilou suggested and brought up the bias to 90mv, then i replaced all the 12ax7 s including the pi...........................and voila! clean as a wistle. tons of power and really chimey.
so i think the combination of those things caused all that mayhem.
i would like to thanks all you guys who helped me out and pushed the train along. choo choo!!
thanks


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Post subject: Re: hotrod deluxe loss of power
Posted: Mon Jul 25, 2011 6:45 am
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Sounds like you're ready to rawk again!

8)

Arjay

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Post subject: Re: hotrod deluxe loss of power
Posted: Mon Jul 25, 2011 8:56 am
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Good news, great 8) 8) 8)

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Post subject: Re: hotrod deluxe loss of power
Posted: Tue Jan 17, 2012 2:09 pm
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I have a strange issue.... at idle my HRDX hums...buzzes...just started this.... I have had problems with the Cap c-31 SOLDER JOINT LOOSE...I have fixed that. I see crud...like brown stuff scratches off of the Caps a the lead that enters the caps at C-31, C-33, C-35 and C-36.

If I take a VOM and go Ground (Chassis) to the lead on the Caps I get this:
C-31 781 v
C-33 779v
C-35 706 v
C-36 610 v

With the tubes OUT...the voltage is over 1000v at each cap!

So I have ordered new Caps...are the Caps Bad?


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Post subject: Re: hotrod deluxe loss of power
Posted: Tue Jan 17, 2012 2:23 pm
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If you are measuring with the DVM using VDC settings and getting these voltages-- it definitely sounds like the caps are bad. Esp the first cap (C31). What you are reading is the inverted sine wave peaks off the diode bridge which is usually around twice as high as the FILTERED voltage (when the caps are working correctly).

Like measuring the Vpeak of this graph. Whereas the filter DC voltage would be at the line about midway.

Image


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