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In Reply to: RE: Why wouldn't they last posted by unclestu on June 26, 2015 at 12:35:51
Thanks for the comments and history on the VT150.
Overall the amps looked great. They actually arrived in the evening so things were dark. The next day I gave them a closer examination and my heart just sank. The corrosion on all the PCB traces was just incredible. My initial reaction was just set them at the curb and take your lose! There is no way these are ever going to work again given the level of damage to the PCB traces.
I also knew there was a way to get them working again but the solution will be drastic. Remove the boards and all the components. Carefully remove the corrosion on every trace, paste flux the board, reflow with solder, clean. About (8) cycles of this. Now the traces look perfect again time to re-populate the boards. I bought new components, sockets from the factory.
While they are apart thoroughly clean the chassis, replace all the corroded hardware, replace the main B+ caps, etc., reinstall the boards, dress all the wiring harnesses. Quite the job probably 80 hours in the pair.
I had never seen damage quite like this. Just the small amount of dust, etc., that had collected on the boards mixed with the Hawaiian environment, salt-water, etc., caused everything to corrode.
One hell of a project but I learned a lot.
Follow Ups:
Just imagine I see that on a everyday basis and on far newer devices. Even those using conformal coatings suffer from bleeding in at the solder pads which insidiously creep and corrode.
With certain brands I suffer even more issues than others. AR is one such brand, The Old Golden Tube stuff used a circuit board laid out utilizing a lot of computer techniques. They crapped out left and igh and my intial order of 6 units had only a 100% failure rate. Still have three units stashed awayy: transformers are good but boards with their ground planes and such are horrible.
Another issue I notice is that B- traces running adjacent to B+ or even ground traces cause an electrolytic issue for some reason. Its a constant battle over here. In fact on the first generation Rhue amps I took a glance at the innards and pointed out to the designer the problem and the ( the cure). Next year at CES he approached me and thanked me because the exact issue came up on certain models sold in certain areas.
And talk about batteries in remotes !!!!
I now highly recommend use of Cortex products and periodic cleaning. This is especially true if you have indoor pets like cats or dogs.....
Cortex once had Don Moses (of Wadia fame) as a resaercher and sales manager. calling the off shoot (O2 blocker), you could reach him personally, so I had the opportunity to speak to him one on one. His point in working with Cortec was that the increasingly tiny traces needed preservation in order to insure good sound. My experiences of core mirrored his comments.
Once an 02 dealer, I had a surprising customer: the USMC . A corporal called me up requesting audiophile contact cleaners because their computer mother boards had to be wiped down and cleaned every morning they were in use. In the field, the Colonel was furious, because you can't fight a war that way. They ordered some cleaner and when I explained about the 02 blocker, they called back and ordered 100 of the one inch foam squares. Colonel was so happy he came back and ordered 500 of them but I explained that this product was originally developed for the military so they had to have it somewhere in their supply system. 500 was overkill, but the Colonel did not want to ever have clean mother boards edge cards ever.
as always YMMV and FWIW
My apologies about those amps, BTW. The transformers were good, though. And you did exactly what I had to do so often:clean the traces paint them over with liquid flux and solder them over. Very tedious and painstaking. On some new components with a histor of such failures I solder over when new as the thicker layer of tin in the solder seems to resist corrosion better.
People wonder why I go through 3 to 4 ounds of solder in less than a year.....
No problem with the amps. As the old saying goes you get what you pay for!! I figured they would need some attention but I never imagined they would require that level of work.
Like many things in life if I had known up front what I know now I would have passed. But I always wanted a pair of these amps. In the end everything worked out fine.
Do you have a link for the Cortex?
Here you go; the vci stands for vapor corrosion inhibitor. In the beginning, they used oil of cloves (they still do but found a way to deodorize the chemical) so components used to smell like a Christmas ham...
They make a large variety of products including heavy duty industrial apps. Look up the VCI products when you go on their website.
They will inhibit but not completely stop corrosion. I often will tear small pieces of the foam and stick it in RCA ends and such wear open copper ends are involved. They do seem to work ( I have about a decade of experience with them so far).
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