Many thanks for the tip, most appreciate it... however I opened the
shield cover as suggested - the black foam was there but looked pristine,
but I removed it anyway. No signs of any arcing at all. Powered it up and
it faults out as before. Drat. I'll leave it out and put something else
in there, so good PM for the future - if I get it to emit RF again!
That fault explanation doesn't address the TUNE bar graph not moving.
I did swap the tubes out, no difference - as I suspected.
Ignore my comment about the fan at startup - I was thinking of the $@%^&*
ICOM PW-1 that's also in my sick bay....
73 Don
VE6JY
On Fri, Dec 9, 2016 at 5:53 AM, K2CB <k2cb@comcast.net> wrote:
> Do a search of the 87A Yahoo group regarding the large L1 choke coil on
> the RF output wattmeter / pin diode / bypass relay module near the rear
> antenna jack. Don't quote me on the exact part designation, as I am not at
> my desk top at the moment, but it is the large green one on that board.
>
> Remove the four screws and shield cover. You will see a large green wire
> wound choke coil. Alpha placed a piece of black foam between the coil and
> circuit board as an insulator.
>
> This material is breaking down over time, and causing the coil to arc over
> to the ground plane of the circuit board. It will get worse over time, and
> the fault 17 will occur with less and less rf output power as time goes on.
>
> Remove the choke from the board, remove all the old foam pad, clean off
> any carbon on the circuit board from the arcing , and install a replacement
> piece of insulation material. I used some thin black plastic. Then
> reinstall the choke coil.
>
> If you must remove the entire circuit board, be especially careful with
> the pin diode mounting and associated insulators. They are somewhat
> fragile.
>
>
> If you like, I can send you some pictures I took of the last 87A I
> repaired with the same problem. The photos are on my desktop. I can send
> them tomorrow when I get back to my office.
>
> FYI - Credit is due to Brad from Alpha (or whatever their name is this
> year!) for originally suggesting this as a possible Fault 17 cause.
>
> Eric
> K2CB
>
>
>
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