Re: [IC-7000] PTT Switch Failure


N1GBE
 

I also had the intermittent PTT issue about 3 or 4 years ago. As someone said
before, the switch is not sealed. I was able to clean the contacts with DeoxIT
from Radio Shack & it's been fine ever since...

Ralph, N1GBE






________________________________
From: Steve W3AHL <w3ahl@att.net>
To: ic7000@yahoogroups.com
Sent: Tue, October 26, 2010 1:18:46 PM
Subject: Re: [IC-7000] PTT Switch Failure


I took the defective switch apart and inspected it under a microscope to see why
it failed. The switch has a snap action metal membrane that is slightly dome
shaped. There are three contacts inside -- one lead connects to the top &
bottom contacts which the circumference of the dome rests on. The other lead
goes to the center contact which the center of the dome touches when the button
is pushed. There are raised bumps on all three, which are intended to provide
the point of contact and some wiping action between the surfaces.

There is clear evidence of wiping on the center contact and the dome. However,
the bumps on the top & bottom contacts are set in too much and don't seem to
touch the dome and there is no evidence of wiping action. The edges of the dome
that line up with the contacts are heavily tarnished or discolored for some
reason. This could result from elevated temperatures during soldering being
transferred to the dome. The contacts were bright and clean. The leads are
sealed adequately where they enter the body and there was no evidence of flux
flowing along them inside the case.

Alps specifies that for manual soldering the temperature should not exceed 350C
(662F) for 3 seconds. This is probably why we see so many cold solder joint
problems on the PTT switch.

If you retouch the through-hole solder joints or replace the PTT switch in the
mic, I would pay heed to this. My iron is 700 F and I probably exceeded 3
seconds when I reflowed the joint because the solder wouldn't wick up the
plated-through hole to form a good fillet on the top side. Or the
discoloration could have happened when I removed the switch with a solder
sucker.

Also, the switch is not sealed, so you should not clean flux residue with flux
remover or alcohol unless you are very careful. The factory's flux was still on
the board, as was mine. Just use a known "no clean" flux solder.

Steve, W3AHL

--- In ic7000@yahoogroups.com, "Ivan Silva" <ivan@...> wrote:

After 5 years using everyday one of mine get same problem...
Ivan - PY1YB
www.py1yb.com
----- Original Message -----
From: Jim Townsend
To: ic7000@yahoogroups.com
Cc: Steve W3AHL
Sent: Tuesday, October 26, 2010 12:34 PM
Subject: Re: [IC-7000] PTT Switch Failure



On 10/26/2010 09:11 AM, Steve W3AHL wrote:
> My mobile 7K refused to transmit a couple of days ago. It had worked fine
the night before. I swapped mic's and it worked. Reflowing the solder joints on
the PTT switch and RJ-45 connector again didn't help.
>
> I pulled the switch out and confirmed in would only occasionally make
contact no matter how it was pushed.
>
> Mouser normally carries an Alps switch that I have used previously, but
they were out of stock until 11/22/10. So I ordered a couple from IcomBellevue
for $2.79 each. Mouser sells them for $0.30.
>
> The switches are rated for 200,000 cycles by Alps. I don't think I've come
close to that in 4 years, especially since I use a headset mic or boom mic and
foot switch much of the time.

Hmmm... My mic PTT switch has been getting flaky lately.

It occasionally fails to make contact. It clicks, but nothing happens.
Just last week I thought I was talking to someone, then realized that
the radio wasn't transmitting. It doesn't happen often, but it sure
is annoying when it does.

Looks like I might be ordering a new switch too.

73 de Jim VE4CY





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