PA 32 of DX10 faulty after power failure

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T123
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Joined: Tue Jun 26, 2018 3:40 pm

PA 32 of DX10 faulty after power failure

Post by T123 » Wed Jul 25, 2018 8:56 pm

Please why PA 32 of DX10 fault after power failure? After the mains recovered then one of the MOSFET of PA 32 was burnt. How is this happen? Is it enough just to replace the faulty PA or is there other things need to be corrected in order for this problem not to happen again? Please advise.

TPT
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Re: PA 32 of DX10 faulty after power failure

Post by TPT » Thu Jul 26, 2018 6:41 am

With any piece of equipment with some age on it, I would suspect filter capacitors. Especially if the power is off for a long period of time.
The caps are OK so long as they are powered up--though ripple would be increasing, but allowed to discharge then stressed when the power comes back on--the ripple increases, causing other components to fail. Same for smaller electrolytics, especially on the failed module.

RodeoJack
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Re: PA 32 of DX10 faulty after power failure

Post by RodeoJack » Thu Jul 26, 2018 9:51 am

There are no filter cans in the DX-series PA card. The fact that "PA32" failed in yours doesn't necessarily mean much. Any one of them can fail at some point, and the cards are all interchangeable... so long as you have a complete set (good or not) installed when you turn the transmitter on.

Most of the trouble I've had with the PAs seem to revolve around incoming events from the power company... or perhaps lightning. In any case, there's not always an obvious reason for a failure, especially when the rest of the cards continue to run fine.

I carry a few spare PA cards with me when I travel around to these rigs. If one has blown a side, I just exchange it and bring the bad one back to my shop for repair... which makes it good as new.

The MOSFETs are not expensive and are fairly easily replaced, for most anyone with decent soldering skills.

The fuse, powering the side that's blown, will always blow with a failed MOSFET. Be prepared to replace it... and get the same type that came out... no hardware store substitutes.

A fuse CAN go out without anything else being wrong with the card. If you check the MOSFETs and they appear to be fine, it can be just a fuse that's lived its life. Sometimes, replacing it is all that's required.

The best part about the DX- transmitters is that they can run with several blown PAs. One or two red lights is no reason to panic... though remember that you can't run the transmitter with a card being taken out of it. If you can find/buy a spare card, you can save potential down time.

TPT does have a point about the filters the transmitter does have. Gates Air has a service bulletin on the DX, SX and Gates series' of transmitters, covering the periodic need to replace the large electrolytics (and one small one). If your transmitter hasn't seen new caps in over 7 to 10 years, you should consider replacing them. The transmitter will do some strange things as these cans start to fail. At worst, it will eventually refuse to start.

You can research your own sources or buy a replacement kit from Gates Air. Depending on your engineering talents and available people, you can knock out a complete set in anywhere from 2 to 4 hours or so... and use the opportunity to clean out the interior while you're at it.

If you haven't already noticed, the DX-10 is a very reliable and sturdy transmitter. Not much seems to bother it, though worn-out filter caps and excessive heat and dirt are among the things it doesn't like.
Last edited by RodeoJack on Thu Jul 26, 2018 10:30 am, edited 2 times in total.

T123
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Joined: Tue Jun 26, 2018 3:40 pm

Re: PA 32 of DX10 faulty after power failure

Post by T123 » Thu Jul 26, 2018 2:44 pm

Thank you RodeoJack and TPT for a very useful and necessary advice.

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