[ICOM] 756PRO - let some smoke out

[Don Moman VE6JY]

I think it's more likely R58  (2P-50-W1L301) that has melted, it's some
kind of protective device.  A friend has a similar issue with his PRO  -
R156 is burnt.  Hasn't done more than a visual inspection yet.  All in
the same area and fed from the RF-RX jack.  Maybe got RF back into the
RX antenna jack?? 

73 Don
VE6JY

-----Original Message-----
From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net]
On Behalf Of Adam Farson
Sent: January 4, 2007 1:44 AM
To: 'ICOM Reflector'
Subject: RE: [ICOM] 756PRO - let some smoke out


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



Scanned for viruses by Blue Coat
http://www.WinProxy.com/
----
Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net Icom
Users Net: Sundays, 1700Z, 14.316 MHz Icom FAQ: http://www.qsl.net/icom/