VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Forum dedicated to discussion on EF Johnson Radio products such as the VP8000, VP6000, VP5000, VM7000, VM6000, radios. Support for Armada software platform.

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elyps
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Joined: Tue Apr 07, 2009 11:21 pm

VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Post by elyps »

Anyone else have same problem (?) and if so any idea if the following is more likely a faulty engineering design or a bad component run: I've had good results with many VHF 5100 portables (mostly legacy models) over time but have been stumped by three VHF radios all *rev.4* with faulty RX stemming from what appears to be (3) faulty high current SMDs (all 27uh) in RX circuit near TX/RX split. Problem was identified as being caused by heavy ambient VHF RF nearby at time of failures. I've tried with zero success to locate the components, as EFJ will only sell said new components (27uh inductor, 1.2A, case style 0805) to EFJ-authorized service centers; EFJ says solution is to buy another radio or buy a replacement RF board. Last avenue before giving up so far was searching Mouser, Digikey, and the like with no such components being available without buying a reel and waiting a few months. If anyone has access to sell said components either generic or EFJ Part number 542-5010-019, I'd love to buy quantity 12 or 15.
125
Posts: 19
Joined: Wed Apr 08, 2009 2:46 pm

Re: VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Post by 125 »

You might want to check out globalsources.com (SMD Inductor) or Hammond Mfg.
mam1081
Posts: 6
Joined: Thu Feb 09, 2006 10:44 am

Re: VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Post by mam1081 »

Ever have any luck? I have a Rev 4.x.x with a RX sensativity issue also. I attempted to swap the RF board with a Rev 1.x.x and the radio errored out on test. So, the low RX radio is just a TX radio!
-Mark
rftech
Posts: 5
Joined: Mon Nov 23, 2009 3:56 am

Re: VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Post by rftech »

Any luck with this?

I also have a deaf vhf RX... Not sure of the rev of the board but any direction on where to look on it when I open it again would be appreciated.

Mike.
VE7KED
rftech
Posts: 5
Joined: Mon Nov 23, 2009 3:56 am

Re: VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Post by rftech »

Any luck with this?

I also have a deaf vhf RX... Not sure of the rev of the board but any direction on where to look on it when I open it again would be appreciated.

Mike.
VE7KED
rftech
Posts: 5
Joined: Mon Nov 23, 2009 3:56 am

Re: VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Post by rftech »

Well I popped the radio back open with the hope that this info might help identify what I have.

The board says it is VHF and on the top of the board etched is the manufacturer - CALAMP (c 2004)

Under above where it says REV it says 5A811

the bottom of the board has a sticker with barcodes:

P6A811
S34004812

Does this help someone identify the board? The RX is deaf but TX appears to function as expected.

Mike.
willbartlett
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Location: Boston, MA

Re: VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Post by willbartlett »

Hi all.

I too have the same issue here with a vhf rev 4. I've isolated my issue to what I believe to be an LNA, refdes u39, associated with D4. I'll ping a few folks to see if I can get a copy of the schematic or at least part numbers. It's hot to the touch, not normal under most circumstances for small signal stuff. If it's the same issue with others radios, I'll offer to help with repairs. I do SMT stuff all day long, so no fear on the size of components.

Will
flat4turbo
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Joined: Wed Dec 26, 2007 3:06 am

Re: VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Post by flat4turbo »

It may be a good idea to post the serial/series number for the radios having this issue. Maybe we can figure out if it came from a specific plant or lot.

Post ALL BUT THE LAST FIVE DIGITS as some manufacturing info is encoded there.

f4t
willbartlett
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Location: Boston, MA

Re: VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Post by willbartlett »

5110F2305T-xxxx

Don't have a new enough service manual to decode this. using the old template, I assume this was made in the 23rd week of 2005. Does the T=Texas?

Will
willbartlett
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Re: VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Post by willbartlett »

Alright, I ordered the appropriate parts today, actually enough for 10 radios. I'll report on results later this week or next when they get here. If it's a success, I'll offer to do repairs if anybody needs help. Will work for beer :lol: .......

Will
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Intrinsically Safe
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Re: VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Post by Intrinsically Safe »

willbartlett wrote:5110F2305T-xxxx

Don't have a new enough service manual to decode this. using the old template, I assume this was made in the 23rd week of 2005. Does the T=Texas?

Will
Just to help out a little here:
The T means it was made at their MTI Contract Mfr.
The C means it was made at their CTI Contact Mfr. (the better of the two IMO)
Sean Penn: Last year I went to Iraq. Before Team America showed up, it was a happy place. They had flowery meadows and rainbow skies, and rivers made of chocolate, where the children danced and laughed and played with gumdrop smiles.
willbartlett
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Re: VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Post by willbartlett »

Evening All. So, I can certainly confirm that this device U39, Avago model MGA-71543 is the cause of the unhappiness with my radio. I was concerned about D4, which as if happens , is a fet capable of handling 3A of current.. I'm not worried about it.

I'm going to look at sensitivity, but a quicklook shows it back in the realm of -115db for usable quieting, or approximately .35uV if you're calibrated that way. needed -55dbm to get that before, or 400uv

Once I get real numbers I'll post results. Looks like we might have a fix for these radios.

Also, Most of the inductors in the front end should be rated at 1A or better, so they're unlikely to be at fault. I need to look into the clamping diode fix for these so the repair won't get undone.

Will


Update.

Checked the thing out and it's at spec.

So, I you aren't comfortable repairing your own radios, I can do surface mount work, do It all day for my real job. If anybody is interested in a repair, Email me off list and we can discuss how to get some of these back to life.

Will
mancow
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Joined: Tue Jan 22, 2002 8:00 pm

Re: VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Post by mancow »

Excellent. I had one of these fry out like that just out of the blue. I was driving along noticing there was no traffic and the RX sensitivity was crap. I was lucky enough to have a friend with connections help me out through his shop or it would have cost a small fortune.
ve7ked
Posts: 3
Joined: Sun Mar 28, 2010 5:25 pm

Re: VHF 5100 rev.4 radios with bad RX boards/faulty SMDs...

Post by ve7ked »

Hey,

I obtained the part as you described and I now have a fully functional reciever. Thanks so much. I have had this radio sitting in a box for nearly two years. I sure am glad I never parted with it. The wait had definately paid off. Nice 5 dollar fix :)

Cheers,

Mike.
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