Schematic of Audio Research VT 100

Alex helge · 26th April 2004, 09:13 PM

Dear members

here the Schematic of VT 100
http://www.drtube.com/audioamp.htm#AR

and the Bias adjustment of VT 100

http://mycollins.net/audio/artube1.html

Best regards Alex

PTSOUNDLAB · 15th June 2004, 07:09 AM

Hello,

this link is dead http://mycollins.net/audio/artube1.html have you more informations ?

Do you know the OUTPUT TRANSFORMER specifications ?

Thanks

Pascal.

toprepairman · 31st August 2011, 06:56 AM

Hi Alex.
Don't suppose you have the VT100 power supply section schematic?
Regards
Henry

toprepairman · 31st August 2011, 08:06 AM

Hi again, found it now so no need, thanks.

alex mm · 31st August 2011, 10:57 AM

...... maybe will help this link ARCDB - VT100

Alex.

toprepairman · 31st August 2011, 11:30 AM

Great link, thanks Alex.
This amp has a problem in the 320v regulator.
Started with a big bang and puff of smoke.
The 4A power fuse blew, and the 10R 0V to ground resistor blew.
Now it runs but puts 420 onto the 320V rail.

smoking-amp · 02:38 PM

Looking at the pictures of the MKIII versus the MKII, the MKIII has got significantly smaller OTs and a smaller power xfmr. It's lost half the input/driver tubes and no heatsinks are visible for the CCS's anymore. Cost cutting with a much higher price?

toprepairman · 31st August 2011, 06:48 PM

It could be a problem of perspective, the pictures are from different distances, I suspect the transformers are the same.
Back to the fault. In this amp (a Mk 2) the resistor R50 has been replaced by a 3 legged fuse (a transistor of unknown type- numbers removed and replaced by paint colour code) and a couple of resistors. The fuse went short so forcing the 320 rail up to 420!
So an imperceptable performance 'improvement' compromised the reliability and could have caused some serious damage, when will they ever learn......

kevinkr · 1st September 2011, 12:16 AM

It's one of the reasons I stopped working on ARC amps - lots of complexity and owners who modded the amp or put poor quality KT88s in the amplifier resulting in a lot of collateral damage.. Not easy to get the parts out of their very thick PCBs either..

26th April 2004, 09:13 PM	#1
Alex helge diyAudio Member Join Date: Oct 2002 Location: Germany	Schematic of Audio Research VT 100 Dear members here the Schematic of VT 100 http://www.drtube.com/audioamp.htm#AR and the Bias adjustment of VT 100 http://mycollins.net/audio/artube1.html Best regards Alex

31st August 2011, 02:35 PM	#7
smoking-amp diyAudio Member Join Date: Dec 2001 Location: Hickory, NC	Looking at the pictures of the MKIII versus the MKII, the MKIII has got significantly smaller OTs and a smaller power xfmr. It's lost half the input/driver tubes and no heatsinks are visible for the CCS's anymore. Cost cutting with a much higher price? __________________ Ohms Law V = I R Last edited by smoking-amp; 31st August 2011 at 02:38 PM.

1st September 2011, 12:16 AM	#9
kevinkr diyAudio Moderator Join Date: Sep 2004 Location: Boston, Massachusetts Blog Entries: 6	It's one of the reasons I stopped working on ARC amps - lots of complexity and owners who modded the amp or put poor quality KT88s in the amplifier resulting in a lot of collateral damage.. Not easy to get the parts out of their very thick PCBs either.. __________________ www.kta-hifi.net

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15th June 2004, 07:09 AM	#2
PTSOUNDLAB diyAudio Member Join Date: Dec 2001 Location: FRANCE / TOULOUSE	Hello, this link is dead http://mycollins.net/audio/artube1.html have you more informations ? Do you know the OUTPUT TRANSFORMER specifications ? Thanks Pascal.

31st August 2011, 06:56 AM	#3
toprepairman diyAudio Member Join Date: Nov 2010	Hi Alex. Don't suppose you have the VT100 power supply section schematic? Regards Henry

31st August 2011, 08:06 AM	#4
toprepairman diyAudio Member Join Date: Nov 2010	Hi again, found it now so no need, thanks.

31st August 2011, 10:57 AM	#5
alex mm diyAudio Member Join Date: Mar 2006 Location: ROMANIA ,	...... maybe will help this link ARCDB - VT100 Alex.

31st August 2011, 11:30 AM	#6
toprepairman diyAudio Member Join Date: Nov 2010	Great link, thanks Alex. This amp has a problem in the 320v regulator. Started with a big bang and puff of smoke. The 4A power fuse blew, and the 10R 0V to ground resistor blew. Now it runs but puts 420 onto the 320V rail.

31st August 2011, 06:48 PM	#8
toprepairman diyAudio Member Join Date: Nov 2010	It could be a problem of perspective, the pictures are from different distances, I suspect the transformers are the same. Back to the fault. In this amp (a Mk 2) the resistor R50 has been replaced by a 3 legged fuse (a transistor of unknown type- numbers removed and replaced by paint colour code) and a couple of resistors. The fuse went short so forcing the 320 rail up to 420! So an imperceptable performance 'improvement' compromised the reliability and could have caused some serious damage, when will they ever learn......

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