[Amps] Alpha 87A Fault 20 Problems and General Questions

Dave Haring dcharing at gmail.com
Mon Feb 11 07:39:20 EST 2019


Sounds like it's almost certainly oxidized connectors... thanks for all the
help, and also pointing out the Yahoo reflector. We have some "snake oil",
and will work over the contacts this morning.

regards,

Dave N3AC

On Sat, Feb 9, 2019 at 3:24 PM Dave Haring <dcharing at gmail.com> wrote:

> When powering up, we get a Fault 20. After clearing with Stby/Operate, it
> recurs from from time to time and switches the amp to Standby.
>
> The unit has date code 9408, s/n 0614. Software is version UPX-X 108-G.
>
> An internet search did not reveal that units with a Fault 20 normally
> experienced high filament current, but pointed to possible high-resistance
> contacts at connectors or aging monitoring circuitry and components such as
> C27, and C28 as likely suspects.
>
> Manual selection of bands and sub-bands worked properly when the amp was
> not faulted. Changes were also successfuflly done using a terminal program.
>
> When connected with a terminal program (https://putty.org/), we tried the
> commands listed in the 2005 manual... but a few were returned as Syntax
> Errors (perhaps the manual was more current than the software in the amp?),
> and possibly needed additional parameters which were not documented.
>
> These are the commands from the list which did not work or function as
> expected, and no explanation or example was found in the manual:
>
> DM# (“use with factory help”)
> ENT
>
> The HELP command listed many commands; the following were were ones not
> listed in the manual:
>
> ADS
> ANTENNA
> GPIO
> AD
> KEY
>
> Here are the questions:
> 1. What’s recommended for our next steps to resolve this Fault 20 issue?
> Start with Deoxit on the contacts in the Filament Sense line as suggested
> by N8RR and respondents, and then follow up with possible capacitor
> replacement if the problem continues?
>
> 2. Are the AlphaMax chips and associated software still available
> somewhere for owner installation?
>
> 3. Are there more complete instructions available anywhere on the command
> set, and any needed parameters to use them? Including the DM# command, and
> how to use it? Why might some of them not work - no AlphaMax, or something
> else?
>
> 4. Though hopefully not needed in the future, how is the Hard Fault lock
> cleared? I can’t find anything online.
>
> 5. We’re uneasy using schematics that are probably a lot more recent than
> this amplifier. Are older schematics available? I expect there are
> differences...
>
> thanks in advance,
>
> Dave N3AC
>
>


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