Please give me advice about an ARC VT 200 amp

@irish_tim

First tube amp! Wow, did you pick doozy for your first tube power amp.

It should arrive with the tubes removed. You will need to install the tubes. You can’t just install the small 6922 tubes where ever want. Hopefully the guy you bought the amp from marked, identified, each of the 6922 for the tube socket they are biased for. Match the number on the tube to the appropriate tube socket number. Tube socket numbers are on the circuit board near the sockets.
DO NOT JUST STICK THE 6922 TUBES BLINDLY IN THE AMP. You will seriously damage the tubes, and or the circuit boards, and or resistors in the amp.

Hopefully the guy marked, identified, the 6550 power tubes as well. They also require biasing and are matched pairs or matched quads. Not sure on the VT200, can’t remember. Even if they are identified for the correct tube socket, they should be checked for proper bias. Power tubes are somewhat easy. That is for someone that has done it before. Lethal voltages inside.

If the guy did not mark, identify, the 6922 tubes when he pulled them you are screwed! You will have to either send the amp to ARC, or find someone locally that works on ARC VT series power amps.

How to bias an ARC VT200.
http://www.audioresearch.com/ContentsFiles/VT200_BiasAdjust.pdf

ARC VT200 schematic wiring diagram, download.
https://elektrotanya.com/audio-research_vt200_amplifier.pdf/download.html

http://www.arcdb.ws/VT200/VT200.html

Jim

Did any of you guys look at the AC circuitry for the power supply of the VT200?
If has a soft start circuit that incorporates a triac (switch) that is in series with two parallel 10 ohm 20 watt resistors (5 ohms 40 watts) that feeds the Hot lead of the power transformer. For this circuit a 4 amp dual element, slow blow, fuse is used.
https://elektrotanya.com/audio-research_vt200_amplifier.pdf/download.html

The triac gate is powered by AC through a 100 ohm resistor. Main AC line fuse is a dual element, slow blow, 10 amp fuse.

Two relays RY1 and RY2 contacts are used in the AC power circuitry. A n/c contact on RY2 controls the triac gate and a n/o contact on RY1 controls full power to the hot lead of the power transformer.

Both RY1 and RY2 are controlled by the power transformer secondary windings DC power supplies.

The AC On/Off power switch is a DPST switch. In the ON position one set of contacts supplies power to the n/c contact of RY2 that feeds power to the gate of the triac. The other set of contacts, on the power switch, completes the circuit for the coil of RY1.
.
I’m not sure the series light bulb thing will work on this amp.
.

I will say I have used the series light bulb trick on simple across the line circuits in the past. It does a great job of reducing voltage and limiting current.

FWIW I have an old Marartz 5.1 multichannel amp I no longer use that I tried the series bulb thing on earlier today. It would not work on the amp. I used a 75 watt light bulb and when I energized the series bulb/amp circuit a relay in the amp started chattering causing the lamp to blink off and on. I could not get the amp to switch from standby to power on. Just a guess the relay was used somewhere in a protection circuit.

>>

@irish_tim ,

Have you received the Amp yet? How about an update.

.