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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Fri Jan 28, 2011 5:48 pm Post subject: Be careful when using general RTV componds in HV circuits |
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While at a training seminar this week, I found this out, and it could be one of the main reasons that HV power supplies were failing.
For instance, the Barco Quads that were so commonly known to fail, the failure was due to the RTV or sealing solution that they used in the manufacturing process. They later changed that solution. Not sure when though.
I've had very similar problems with RTV, and that's why I've been saying to only use the GE version of it. Which was the only version of it that I did not find to be a problem.
A good RTV should not require an overnight curing before it can handle the voltage that's being used. And that may be because it should not have any water or moisture content being pure RTV.
Test has obviously proved that nothing seemed to have been failing internal in a QUAD itself after these failures. Or no component was found to be defective and the cause of the failure.
Not sure if this can be versed in a QUAD itself be removing and replacing the solution, but for sure, it has been determined to be the cause of the failures.
So be careful, because all RTV's are not the same or suitable for High voltage applications.
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WTS
Joined: 08 Mar 2006
Posts: 1276
Location: Calgary
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| Posted: Fri Jan 28, 2011 6:57 pm Post subject: |
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Mike,
--Test has obviously proved that nothing seemed to have been failing internal in a QUAD itself after these failures. Or no component was found to be defective and the cause of the failure.
Really, how many quads have you rebuilt lately? Every failed quad I rebuilt had failed components in them and I saw no reason to blame the RTV on the failures.
Walter
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Thanks
Walter
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mp20748
Joined: 12 Sep 2006
Posts: 5689
Location: Maryland
TV/Projector: 9500LC Ultra / Super 02 and 03 VIM
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| Posted: Fri Jan 28, 2011 7:42 pm Post subject: |
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| WTS wrote: |
Really, how many quads have you rebuilt lately? Every failed quad I rebuilt had failed components in them and I saw no reason to blame the RTV on the failures.
Walter |
Now this is really interesting. Didn't your QUAD fail in your Zenith 1200, and you were looking for a replacement?
https://www.curtpalme.com/forum_archived/viewtopic.php@t=23417.html
BTW, I have not attempted to repair any Quads, nor have I ever had to replace one. Even in the many 909's I've been repairing the past 8 years. So I myself am not claiming anything here, only what I have got first hand from Barco directly. And decided to share it here.
So nothing I'm saying here is my idea, theory or anything that I've tried myself. This failure as I've posted it here is a documented fact, as mentioned directly to me and some others from an Barco engineer.
He was clear, that there were NO reported component failures after their investigation into the problem, they only used a different RTV. And he knew of no other reported QUAD failures since that change.
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crteaman
Joined: 27 Nov 2007
Posts: 53
Location: UK
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| Posted: Fri Jan 28, 2011 10:46 pm Post subject: |
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Barco did indeed change the RTV...but simply because it was cracking//opening up ...not good...it's the failed components inside which er..cause the failure ...but RTV (potting compound) with splits is not ideal...
I must aslo say...I only use the Mil Spec RTV...been a long time now...but it may well have been GE...damned expensive (very) but never wanted to take a chance ..so played safe...and paid the money for it....it was in an orange and white tube...
Last edited by crteaman on Fri Jan 28, 2011 11:01 pm; edited 1 time in total
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WTS
Joined: 08 Mar 2006
Posts: 1276
Location: Calgary
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| Posted: Fri Jan 28, 2011 10:56 pm Post subject: |
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Hi Mike,
Yes my quad failed and it was a cap that failed not the RTV. I've repaired about 6 quads and all the problems were component failures and not from cracked RTV. Although you could tell the difference between the RTV compounds from the old to the new, none of them were cracked.
Granted that is a small number to be basing any kind of conclusions, it's just what I've experienced thus far.
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Thanks
Walter
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