[ICOM] 756PRO - let some smoke out

[Adam Farson]

Hi Kelly,

The board in the compartment behind the antenna sockets is the CTRL (ATU
controller) board. It looks as if the receiver input LPF (L27/L28) has blown
up. Can you send me a photo of the damaged board, so that I can take a
closer look? If you wish, I can send you excerpts of the service manual.

One possibility is that the SB200 developed an internal tube short-circuit
or a parasitic, and threw a blast of RF energy or HV back into the exciter.
A lightning surge could be another scenario.

I would suggest that you call the Icom Canada service centre (604-952-7266),
describe the damage to the service people and make arrangements to ship the
756Pro to them. The repair may be quite costly, as parts availability may be
an issue. Your insurance carrier will cover lightning damage, but probably
not damage due to an electrical malfunction.

Please keep me posted. Sorry you had such a setback.

Cheers for now, 73,
Adam VA7OJ/AB4OJ


-----Original Message-----
From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net] On
Behalf Of Kelly Taylor
Sent: 03 January 2007 17:24
To: ICOM Reflector
Subject: [ICOM] 756PRO - let some smoke out

Hi Adam,

Help!

What's the board immediately behind the antenna connectors? I hooked my PRO
up today after a hiatus that included a trip to VE4VV for WW and could not
get any power out. I returned to my TS850 and everything was fine, which
seemed to point to something inside the PRO. (The PRO's receive audio also
sounds thin and noisy.)

Sure enough, between the silver rectangular box in front of the 'PURPLE' 
coax connector are the charred remains of something... Whatever it had been,
part of it is in a semi-liquid state on various parts of that board. It is
about two inches forward of the ground bolt.

VV indicated that he had trouble getting the PRO to hear when he hooked it
to an SB200 (through a buffer device on the key line). He said it was fine
with the SB200 off, but deaf when the SB200 was on.

That I was able to hook the 850 back up without blowing it up seems to
indicate it wasn't something here that blew the PRO up.

Your thoughts? Am I looking at an expensive repair? Perhaps an insurance
claim in the making...

Thanks and 73,

Kelly
ve4xt



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