BE AM-1A power issue.

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Nathaniel Steele
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BE AM-1A power issue.

Post by Nathaniel Steele »

So My AM-1a went off the air. When I get to the building, all the LED's on the two racks are blinking rapidly, at the same time, so it looks like something is failing in the power supply cutting on and off rapidly (Since all the LED's light up briefly on power on). I shut the front panel breaker off, let it sit a while and flipped it back on....nothing. flip it off and i think I hear a relay. try a couple more times, no power no lights but I still think I hear a relay on power off. any thoughts? It's pretty cold down there today and I was lacking any significant tools, so I decided to see what I can dig up and go back after lunch. was hoping I was just going to have to go in a press the reset button.....Not today!

Pretty sure I'm looking at a PS fault so I'll probably yank the box out of the rack and bring back to the office where its warmer and I have a test bench setup.....
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RGORJANCE
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Re: BE AM-1A power issue.

Post by RGORJANCE »

Inside the controller chassis, kinda buried on the right rear side is a small power supply. I think it croaked. If you have an old Starguide Sat rcvr laying around, it uses the exact same power supply. It will not be real physically easy to replace as it is tight in there, but it is plug-in. You will have to remove the cards to get at it.
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Nathaniel Steele
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Re: BE AM-1A power issue.

Post by Nathaniel Steele »

I think there are a couple starguides stored in the same building! no idea about the condition of the PS in them, they were here before me....

Any chance of replacing that PS without removing from the rack? I'f not I'm definitely bringing it back to my warm office.....


Thanks!

This exactly why I post a question before spending a ton of time working on something....I'd probably be troubleshooting that little PS right now...

Is it linear or SMPS? Linear=Easy repair, and for ME SMPS usually = long time troubleshooting and eventually giving up and finding a replacement, unless it's just caps, I usually have a hard time with SMPS....
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RGORJANCE
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Re: BE AM-1A power issue.

Post by RGORJANCE »

Yes, you can certainly do it without removing it from the rack, but it ain't gonna be fun. As they say....grin and bear it. I might suggest speaking in tongues while doing the replacement, it will help relieve the stress.
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Nathaniel Steele
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Re: BE AM-1A power issue.

Post by Nathaniel Steele »

Whats the best way in? I've never had one of these open....
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RGORJANCE
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Re: BE AM-1A power issue.

Post by RGORJANCE »

Open the controller card door, remove cards, go after p/s. That is all I can come up with. As I recall, access on right side of card cage by p/s was pretty tight. We might have used mirrors and voodoo to get at it. I seem to recall that we needed to access (from rear of rack) the left hand side of the rig by the controller for something related to removal, but it was a couple years ago and I kinda have fuzzy images of that.
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kkiddkkidd
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Re: BE AM-1A power issue.

Post by kkiddkkidd »

_Sometimes_ if you flip the front panel breaker on and off a few times, stopping long enough to see if the lights stay on, the power supply will work for another short while...

That power supply is pretty easy to change unless the control cage is mounted in the bottom of the rack. You don't have to remove anything from the rack.

The power supply is mounted in the back right hand corner inside the control card cage. I can probably change one in about 10 minutes.

Pull the cards (note their slot position) and use a screw driver to remove the PS cover screws and then a nut driver to remove the standoff nuts (1/4 or 5/16 IIRC). Pull the connectors, put the replacement PS in (pay attention to pin alignment), put the standoff nuts back on and throw the cover in the trash.

I think that the cover is a contributing factor to PS failures.

Stick in a new 9v battery while you are down there...

Good luck,
--
Kevin C. Kidd CSRE/AMD
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Nathaniel Steele
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Re: BE AM-1A power issue.

Post by Nathaniel Steele »

kkiddkkidd wrote: Thu Dec 17, 2020 6:46 pm _Sometimes_ if you flip the front panel breaker on and off a few times, stopping long enough to see if the lights stay on, the power supply will work for another short while...


I think that the cover is a contributing factor to PS failures.

Stick in a new 9v battery while you are down there...

Good luck,
I saw you posted that in another thread here, I'm going to run down and try that in a little while...

I'll agree the cover doesn't seem all that necesary......

Will take a fresh 9v with me, will i lose my presets when I pull the battery?

Replacement supply should be here monday, order from mouser yesterday, this is what I ordered: NFS40-7610J , $48.69 plus shipping.

Hope it is correct.

Thanks
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Shane
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Re: BE AM-1A power issue.

Post by Shane »

will i lose my presets when I pull the battery?
i think not if you change it with the AC on. You lose settings if the power goes out and the battery is already dead. There’s no lethal voltages up there by the battery so that can be changed while on air. Of course the PS change out requires breakers off, but you already knew that. Just change the battery before you shut er down for the PS work!
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grich
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Re: BE AM-1A power issue.

Post by grich »

The first time I worked on an AM-1A, the battery had been ignored and it had exploded! That was fun.
Nathaniel Steele
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Re: BE AM-1A power issue.

Post by Nathaniel Steele »

The supply I ordered was drop in replacement and I had it back on the air in 10 minutes.

The supply I pulled out was a power-one MAP40-3003. From What I can the the starguide receiver supplies should work as well, and are rated at 60W output instead of 40W, unfortunately the 2 starguides I had both had dead PSU's. I'm going to attempt to repair at least on of the PSU's out of the three I know have (transmitter one and 2 starguides).

Oh and I left the cover off at Kevin's suggestion. It doesn't seem like it would restrict airflow that much, but it also didn't seem super necessary to me, other than as an anchor point for the cables running around the supply. the hardest part of the job was not losing the lockwashers. If someone is reading this in the future and you go out to do this job you will need a small nipper to cut some cable ties (If they havent been cut before, a phillips screwdriver, and a 1/4" nutdriver. The philips screws hol on the cover, Via 1/4Hex standoffs, which will need to be removed to pull the supply. there are lockwashers between the standoffs and the supply PCB, and if not careful they could drop through holes in the frame of the exciter, and possibly into the PA or somewhere else you'll have a hard time retrieving them from.

Only other thing is I should have taken my 3M antistatic service Vacuum with me, a few light cobwebs inside. I blew off the cards before reinstalling, good enough for the next 10 years I suppose.....
PeteG
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Re: BE AM-1A power issue.

Post by PeteG »

Heat is the enemy of all these compact OEM supplies (yes it happens to GatesAir products as well). In this case the unit is mounted above the heat exhaust grill of components below, so I agree with Kevin that pulling cover seems a good idea, though I have not done so with any of my BEs.
I have a pen-looking device that is a screw starter on one end and powerful little magnet at the other. I keep it handy for jobs like this. It grabs lockwashers, etc very nicely.
What I do before I start is to cut a piece of stiff paper, like file-folder material, to fit onto the floor of the compartment. That will grab any errant hardware.
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RGORJANCE
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Re: BE AM-1A power issue.

Post by RGORJANCE »

RE: magnetic thingy........

Well, there is another trick and it is bees wax. I took an old PLSTIC 35mm film cannister and scooped the toilet plumbing wax seal stuff into it. Works great when magnet sometimes won't. Noncorossive.

Fossil.
PS-Glad to hear you got rig fixed with thE new P/S.
Nathaniel Steele
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Re: BE AM-1A power issue.

Post by Nathaniel Steele »

The first Chief I worked under gave me a chunk of cosmoline (Spelling?) for the same use. I still have it...somewhere....

I do have 1RU of space between my PA and Exciter cabs.

Yes paper/cardboard over the holes would work too.
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