One for the books

[Sheeshawawa]

Okay see if anyone can figure this one out. ARC VT100 MKII. From the moment I brought it home it has been possessed. After warming up (approximately 1 hour) the right channel begins to crackle. This continues in intensity until it becomes unlistenable. I send it back to the dealer, it returns seemingly fine only to start up again after a month or two. Back to the dealer, back to me back to the same problem. This time I take it to an eccentric (aren't they all) electrician who finds that the ground fault resistor has blown. He fixes it and it holds together for almost a year. The problem comes back so I take off the side panel and sure enough the resistor has blown again. This time I send it to an ARC dealer, informing him of the problem. It comes back and has been working - sort of. Now the noise appears within the first hour to two hours of use and fades after this time. The resistor is still fine (at least not blown) but.... The sound is like an unprotected balanced output but much quieter. If the devil is registered to this forum I would very much appreciate him telling me why he is messing with my amp in such a manner. Thank you

 

[hifi_nut]

This is a very good and expensive piece of equipment you´re talking about, here.

Have you considered writing directly to ARC? They have a reputation to live up to.

 

[mwr885]

This is a very good and expensive piece of equipment you´re talking about, here.

Have you considered writing directly to ARC? They have a reputation to live up to.

I agree an email informing the company may get a replacement in order to keep your business.

 

[dogscanskate]

Call Len at ARC, I'm sure he can help. If it were mine, I'd have them have a look at it.

 

[dogscanskate]

If you are not the original owner, many things can happen to an amp. The VT-100mkII is a fully balanced amp, and all tubes have to be critically balanced (per section, meaning a 6922 must have both triodes matched in current draw and transconductance) to achieve its full potential. If tubes have been changed in this amp and the amp was not re-biased correctly, anything can happen. I own the VT-50, it's smaller brother and trust me, biasing these amps is critical.

 

[thunderroad]

Okay see if anyone can figure this one out. ARC VT100 MKII. From the moment I brought it home it has been possessed. After warming up (approximately 1 hour) the right channel begins to crackle. This continues in intensity until it becomes unlistenable. I send it back to the dealer, it returns seemingly fine only to start up again after a month or two. Back to the dealer, back to me back to the same problem. This time I take it to an eccentric (aren't they all) electrician who finds that the ground fault resistor has blown. He fixes it and it holds together for almost a year. The problem comes back so I take off the side panel and sure enough the resistor has blown again. This time I send it to an ARC dealer, informing him of the problem. It comes back and has been working - sort of. Now the noise appears within the first hour to two hours of use and fades after this time. The resistor is still fine (at least not blown) but.... The sound is like an unprotected balanced output but much quieter. If the devil is registered to this forum I would very much appreciate him telling me why he is messing with my amp in such a manner. Thank you

I think this is definitely ARC's problem to solve, but having said that, it sounds like you've got a high voltage fault to ground. Maybe the high voltage supply isolation is faulty or breaking down. If the GF resistor is blowing (burning open?), it is passing some major current to ground which definitely isn't right. I'm thinking that the crackling you are hearing is a high voltage flashover of the GF resistor. If the resistor is flashing over, each flashover will track the resistor a minute amount and eventually it'll breakdown. If you want to get into troubleshooting, try measuring the voltage across the GF resistor to get some numbers and then talk to the ARC factory, but be very, very careful because I think you are dealing with a high voltage source. Hope this helps!

 

[Sheeshawawa]

Wow thanks for the responses guys. I have talked to Len at ARC and I've talked to his protege Ernie. Ernie actually was the last one to "fix" the amp. Neither one can seem to find any inherent problem with the thing. I have a feeling though that these guys may be just bench testing the amp. You know all parameters are fine ergo the amp is fine. I'm getting tired of lugging the 100 pounds of equipment down my stairs and then second mortgaging my house to pay for the shipping charges. Also I'm getting the feeling that these people think I'm nuts! I've rewired my house so that the amp is on a separate outlet, I've upgraded the preamp from the SP 9 to the SP 17, new interconnects. I even went so far as to buy new speakers (okay so those were somewhat unnecessary but don't tell the wife hehehehe) by the way Harbeths and they're SWEEEEET. Ah but I digress..oh ya so last night I run the amp for like 5 hours and not a peep - just perfect sound. I'm playing the turntable all night and not the CD but some nights I've had the opposite happen too. Perhaps I will get the voltmeter out and just end it all!