[Yaesu] Rehabilitating An FT-901DM

Tue, 6 May 2003 09:44:07 -0700

Hi Greg -
I resuscitated a FT-902DM earlier this year, and although I didn't have your
problem with the WIDTH control, I did have your ATT problem with just about
everything else. What worked was simple "housecleaning," that is, No-ox on
all the switches, cleaning the edge connector fingers with alcohol and a
Pink Pearl eraser, and giving the relay contacts a stroke or two with some
fine emory paper. As far as the WIDTH problem, well, these Yaesus were not
known for great audio in the first place, so it may be fine. Hope this
helps.
Fred Wittman - KG6NYK
----- Original Message -----
From: "Greg Queen" <[email protected]>
To: <[email protected]>
Sent: Monday, May 05, 2003 9:44 AM
Subject: [Yaesu] Rehabilitating An FT-901DM
> I have an FT-901DM which has been sitting idle for 20+ years. I have just
> re-licensed (awaiting my call sign) and I am in the process of firing up
the
> rig. After dusting and a general check, I powered up the rig and it
> basically came to life. It looks like none of the electrolytic capacitors
> dried out. In testing the receiver I have encountered a problem and an
odd
> situation (which probably indicates a second problem) and was hoping
people
> on the list might have some suggestions.
>> The confirmed problem is with the ATT (attenuator) switch. The switch has
a
> "good" mechanical feel but it is intermittent. If I hold it just right
> (especially if I apply lateral pressure, that is pressure perpendicular to
> the pushbutton shaft) or if I work the switch a number of times, I appear
to
> get good reception. When it is not working I either have an "open"
circuit
> in the antenna feed to the receiver or I have the 20db attenuator. I can
> not tell which (no real test equipment) but from the schematic, I am
> guessing that I have an open circuit. Has anyone experience problems with
> the FT-901DM's push button switches? If so, is there any magic I need to
> know about? If I have to replace the switch, does anyone know of a source
> for the switches (Yaesu no longer stocks parts for the rig)?
>> The second issue I have is with the "width" control. As I understand it,
> this control moves one of the IF frequencies around causing the IF
bandwidth
> to narrow. The manual indicates that with the width control in the center
> (detent) position you would have normal bandwidth. Rotating the control
> either left or right would narrow the bandwidth on either the high or low
> frequency side. At present, I have to run with the control fully
clockwise
> to effect reasonable reception. Is this normal? If not, does anyone have
> any ideas of what may be causing the abnormal behavior?
>> Thanks in advance for your efforts.
>> Greg Queen
> [email protected]
>>> Moderator: Ray Brown, KB�STN
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