Interesting... I just purchased a VK-5i here on Audiogon, and I have the same problem. I had another problem in addition, so sent the unit to BAT to look at. I wonder if it's a common problem with all their older preamps.
The exact same thing happened to me with my VK-30SE. I changed the tubes but that didn't cure it. I e-mailed BAT and described the problem and Victor e-mailed me back saying the most likely cause is a six-pack module that developed an electrical leakage. He said most likely the two modules will be replaced and the cost is $600.00.
>>Smeyers: Would you mind contacting me after you get the diagnosis from BAT? It could save the preamp a trip if it ends up just being tubes.<<
Sure. I don't think it is a tube problem though, as I just got a brand new set from BAT. My primary problem is static and popping from one channel, which I thought a new set of tubes would fix since the tubes have never been changed. The unit is at BAT, and I should know something within the next few days or so.
The problem has been found. Here is an email exchange with Vladimir of BAT:
My message to BAT:
I wanted to mention one other problem that I remembered about the VK-5i I sent to you for repair (static/popping from one channel). Whenever I put the unit into Mute mode, I hear a somewhat loud pop coming from one channel, I believe from the same channel that is having the other problems.
You are right. All three problems (occasional static, low gain, and louder pop) in right channel are connected.
We found broken connection inside oil capacitors module (black box) in right channel. This broken connection was going on and off in which case you heard static.
While connection was lost the right channel output was just half of that of left channel. The same problem was causing louder pop when you muted the
output. The broken connection was inside "black box" with two decoupling oil capacitors. We replaced the box with new one. Hopefully, it'll be fine from now on.
I need a couple more days to confirm.
Yes, $600.00 to replace the two modules. The quote came directly from Victor Khomenko of BAT. Read the ff e-mail from him:
Most likely the output cap/caps developed electrical leakage and need to be replaced. Usually in such case both SIX-PAKs should be replaced.
2nd email below:
"The whole job cost $600. We replace the complete modules. You may keep the old modules, as those caps are great and can still be used in many projects. Out of 12 caps there chances are a couple are leaky, the rest might still be fine."
Keep in mind that this is his analysis of what might be the cause of the loud pop when muting. It might turn out to be something different/more when you ship the unit to BAT.
Well, here's my take. I taked to BAT and the suggested swapping the 6V6 tubes, as the pop is only in one channel. They said if this doesn't help, try taking the two 6922 tubes from one side and swapping them to the other side.
Well, I tried both suggestions to no avail. I'm supposed to call back to BAT tomorrow and get a RMA number from them to send the unit in.
Now, my unit doesn't have any oil caps in it, unless I'm mistaken, so maybe my cost will not be as bad?!
Now the real question, should I expect the seller to share the costs with me? He said that the unit was from a customer of his, and it wasn't exhibiting any problems; the customer just wanted an upgrade. I'm not sure I could file a claim with UPS... could I?
Thanks guys for your quick and helpful advise (as usual)
Hard enough to get a claim paid from UPS with visible obvious shipping damage. Not likely to get anything that route. High cost of 6 packs are due to each containing 6 large expensive capacitors. It is an expensive upgrade to most BAT units ($500, I think) and is standard some SE models. Definately not standard in 3i. If the upgrade is $500, adding in diagnosis charge brings you to $600 pretty quickly. BAT service is not cheap, but in my experience very fast and reliable (fixed is fixed).