Does that perhaps use solid state switches to turn on the main power? I have
seen them (in a different amp) get leaky which produced a low control voltage
when they were supposed to be off, something like that on a digitally
controlled amp could produce flakey displays or maybe give enough voltage to
run the fan.
David Robbins K1TTT
e-mail: mailto:k1ttt@arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: telnet://k1ttt.net:7373
-----Original Message-----
From: Amps <amps-bounces@contesting.com> On Behalf Of gudguyham--- via Amps
Sent: Monday, October 10, 2022 09:52
To: w5cul@sbcglobal.net; 'Eric Dobrowansky' <k2cb@comcast.net>;
amps@contesting.com
Subject: Re: [Amps] Alpha 87A - strange power related issue
Eric, most likely you have a problem on the primary start up board. This is
where the step start is and all the primary wiring gets routed. Often times
the sticky tape gets conductive over time and it shorts out the blower traces
and blows them open. It’s possible there’s a problem with the step start
relay. It’s most likely a problem in this area. Don’t discount a problem with
those push on/off switches on the front panel of course. But do remove that
primary board and investigate it. It removes very easily. Here’s a step by
step procedure. 1. Pull the transformer plug from the board.2. Remove all
transformer wires from boards 3. Pull out transformer.4. Remove two screws near
the two fuses that hold start assembly.5. Remove one nut holding one bracket on
opposite side of variable cap middle divider. The board comes right out along
with the AC cord, remove plug if you have to.
Once you get that board out there’s your relay on there etc. you’ll see that
sticky tape that hold down the electrolytic cap. It’s best to remove that tape
because it will create problems if it hasn’t already. Just let the cap
support itself that’s fine. If you email me personally I can send you some
photos. Lou
Sent from the all new AOL app for iOS
On Sunday, October 9, 2022, 8:42 PM, w5cul@sbcglobal.net <w5cul@sbcglobal.net>
wrote:
Eric,
There is an 87A Email Group. You can find them here:
Alpha87A@groups.io
You will have to sign up for an "groups.io" account and after that you should
be able to query for the Alpha 87A group and request access.
https://groups.io/
Hope this helps.
Thank you,
Mike
W5CUL
-----Original Message-----
From: Amps <amps-bounces@contesting.com> On Behalf Of Eric Dobrowansky
Sent: Sunday, October 9, 2022 7:26 PM
To: amps@contesting.com
Subject: [Amps] Alpha 87A - strange power related issue
It's been a long time, and I'm not sure if there is a dedicated Alpha 87A
related mail list in existence any longer, so I will go ahead and ask here.
I have an 87A that started exhibiting a strange problem.
When the amp is plugged in, the blower automatically starts, and various band
and segment LEDs illuminate, but the amp does not start up. The LEDs which
illuminate vary each time the amp is plugged in.
If I try to push the POWER OFF switch, the amp will turn off the blower and
LEDs, but as soon as I release the switch, it returns to the state where the
LEDs and blower are on.
If I push the POWER ON switch, the amp starts up normally. The amp works fine
once it completes the warm-up period.
If I then press the POWER OFF button to turn the amp off from when it is fully
running, it shuts down properly. IE - all the LEDs turn off, and the blower
stops.
However, if I leave it plugged in, out of nowhere sometime later the above
symptom repeats, and I have to pull the AC plug to get it to shut down
completely.
Any recommendations as to where to start troubleshooting? Maybe a cap going
bad somewhere is pulling down a particular control circuit?
Eric
K2CB
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