I was recently contacted by the owner of a local studio who had two high end mic preamps (Universal Audio 4110, and Millennia HV-3D), both of which had developed noisy channels. In both cases the channel in question was producing a constant low level crackling sound, making it unusable. Unfortunately I found both manufacturers to be less than helpful in supporting the repair.
I took the units away and started investigating. Universal Audio 4110 and Millennia HV-3D are both expensive, high end boxes, and they represent a big investment for most people.
I was unable to find service manuals online, so I contacted both companies, asking for copies. After a few days, Universal Audio informed me that the unit is no longer manufactured or supported, and that they do not release service information for it. They suggested sending the unit to a repairer in the US. I think that I never heard from Millennia at all.
I am happy to say that I was able to deduce enough information about both units to repair them successfully (and much more quickly and economically than by sending them half way around the world). The UA box was suffering from a poor solder joint; the Millenia needed the input devices replacing.
The repair was not made easier by the fact that Millennia had ground the top of the integrated circuits, removing the IC marking to prevent identification. However there are only so many low noise audio IC’s in existence, and it wasn’t that hard to work it out. I was able to deduce the part type and obtain a replacement. (The body of the IC in fact appeared to be slightly cracked as a result of the grinding, which may have contributed to its failure.) Measuring noise and other figures with my Audio Precision showed that the repaired channel was performing as well as the others in the unit.
To do the repair I had to spend some hours figuring out the circuit of the part of the unit that was faulty. I keep these schematics on file in case I ever have to fix this type of box again.
In both cases I would have been willing to purchase the service information at a reasonable price, and even to sign a non-dislosure agreement. I really do not understand the attitude of manufacturers that refuse to support discontinued product – product that the owners paid top dollar for originally. Insisting that it be sent half way around the world when is not realistic. I think that loyal customers deserve better.
(Postscript : luckily, there are heroes as well as zeroes in the world of pro-audio customer service! Yes ART, I mean you!)