There is mention about a warranty of the AB-Q-ST70-ST120 Board. This is great news to me!
Pavil is quoted:
pavlikkkk wrote:Added on 6/16/20 > Autobias boards ..
I cannot recommend anymore the autobias boards sold by 3rd party vendors for the VTA ST-70, VTA ST-120 and VTA M-125 amps. These boards are made by Audioamp.eu in the Czech Republic and are now distributed by a USA seller in Arizona. These boards do work properly when installed but the problem has been long term durability of the board itself. I have had now
sixseven customers who have installed the boards, got them working properly and then had the autobias board fail on them after a few months to about 2 years.
Yes, as you write correctly, these AB-Q-ST70-ST120 boards work properly when connected. We have already sold more than three hundred of them.
With the recommended connection of fuses with varistors and respecting only one, maximum two cathode current settings, there are no problems with the boards.
Most often, however, the user often spins with the trimmer on the board. The trimmer is not a potentiometer. Repeated adjustment destroys the resistance layer in the trimmer. The reference setting then loses stability and the cathode current then fluctuates. The trimmer must then be replaced by a fixed resistor.
If the board is equipped with protection by fuses and varistors, there is no risk of damage to the board even after a tube accident.
In total, we have sold in the last eight years about a thousand plates of autobias in various designs.
We use only branded components for their production.
After experience with their reliability, we provide an UNLIMITED WARRANTY for our modules. We perform repairs free of charge even if you do the customer damages the module himself.
These terms and conditions are also respected by our representative reseller in America.
These are our experiences.[/size][/quote]
We've been in contact before.
Actually, it was me who after talking to Don Sachs about how my ST-120 amp was messed up with the AB-Q-ST120 board, he told me about the fuse & varistor protection method, I forwarded that info over to Roy Mottram that he offered fuses for free to anyone who had purchased the AB-Q board from him. That’s old news.
I have an AB-Q-ST120 board that when working with Roy, he told me that it and my Tubes4hifi VTA preamp board in my ST120 were both presumably dead.
At that time, there were no real clear directions on how to connect them, I purchased new pre-built VTA Driver & AB-Q-ST70-ST120 boards from Roy that have been working perfectly ever since.
Looking at my email archive with Roy, the error was all mine, I had wired up the bias backwards, I owned the error & ordered all new boards.
All is good now... except for that I have a dead VTA Driver board & a dead AB-Q-ST120 board you are now telling us now that latter has a lifetime warranty.
Anyway, water under the bridge.... But it brings me to the question, how do I send back an AB-Q-ST120 board for warranty service?
Some day I may want to use it in another amp. I do like the AB-Q-ST70-ST120 Board, since I installed it correctly, with the fuse & varistor protection method, I'm a happy customer.
Hopefully I can send this back to Holger the 'Arizona' representative of the AB-Q-ST70-ST120 Board for warranty service. I can send more details from my email archive to the warranty representative.