[Yaesu] Repaired a Yaesu FTR-5410 440 repeater

[Phil]

A couple weeks or so ago a gentleman brought a Yaesu FTR-5410 440 
repeater by for repair.  He had taken it to several different folks and 
they couldn't do anything with it.  The ham who maintains our own club 
repeaters suggested he bring it to me.  It had receive and would switch 
to Transmit when it received a signal, but no RF power output.

The owner was convinced (as were the others who'd worked on it) that the 
problem was in the DC switch-over board (switches between the internal 
13.8V PS and external battery backup. A fairly simple switching circuit 
with a single relay and some additional circuitry to charge the external 
batteries when on AC.  They thought this because the PCB board had a 
couple burnt traces that had been repaired via jumper wires some time in 
the past.  He asked if I could make him a new relay board (repeaters are 
much more expensive than the usual 440 transceiver).

I quickly determined that the repaired board was OK as everything had 
the required 13.8VDC, whether on external battery or internal PS. If the 
board was bad the repeater would have been completely dead!

After further troubleshooting I deduced that the "output brick" (like a 
large IC) was the most likely culprit (ya can't test it like you can a 
transistor) as it had no RF output but I COULD hear the transmitted ID 
on an HT in close proximity to the transmitter module.

A web search for the obsolete part showed that it is made of 
"unobtainium" as it's not been available for many years. Apparently it 
had a high failure rate and Yaesu and every other supplier of RF devices 
I could find was sold out of them.

At that point I told the owner it was beyond my ability to repair as the 
only option was to redesign the transmitter module to use a different 
output brick (something suggested by the folks at RF-Parts).

Well, yesterday I got a call from the owner and he'd located the part 
after putting a 'want' on eBay (didn't know you could do that).  It came 
to him from Canada, and today he brought the repeater over again.  A 
couple hours later I have the part installed (it was quite a chore) and 
testing shows that it's putting out 15 Watts. The output brick is rated 
at 13W so that's close enough to anticipated spec.  Especially as my 
inexpensive ($60) VHF/UHF power meter is most likely not "Lab Standard".

Over the next couple days I'll clean up some of the internal wiring, 
some tech in the past was quite a slob in his workmanship.  Then I'll 
burn it in for a couple days by cycling it with my HT and tell the owner 
to come and get it.


-- 
73 From "The Beaconeer's Lair"
Specializing in DXing NDBs (Longwave Beacons)
Phil, KO6BB
http://www.qsl.net/ko6bb/

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