[1000mp] Display

[Mike Gilmer, N2MG]

If the problem is what I had, it's on the inverter board that provides 
some rather high voltage - a few kV?  - to the display.  The 
inverter board is not manufactured by Yaesu, so there's no schematic 
for it in the manuals and they do not repair it (at least based on my 
phone call to them a few months back) and so have no components for 
it.  They will sell you an entire board (I don't recall the price).

The inverter is behind the front panel.  You need to remove at least 
the top cover (and I believe the bottom as well) in order to get access 
to the screws that hold the front panel on the main chassis. (No need 
to take the front panel itself apart - just disconnect it physically 
from the MP's main chassis.)  You *can* get it to kind of hinge down on 
two screws though not enough, if I recall, to get full access to the 
inverter.

The inverter is a board about 25mm x 75mm (under a metal shield) 
mounted on the far right as you are looking at the MP from the front.  
It's not on the front panel assembly, but on the front surface of the 
main chassis.  If I recall correctly, a couple of screws hold the cover 
on - remove these and then you can get to the screws that hold the 
board to the chassis.

There's not much to the board - just a few components.  There are two 
fuses - a leaded over-current type (looks like a resistor) in series 
with a thermal fuse (mine looked like a square-package capacitor - 
about 5mm x 5mm x 2mm thick with radial leads).  The thermal fuse 
proper is mounted between and thermally coupled to two transistor (or 
FET) devices.  My fuse was open circuited - I simply bypassed it and 
the display started working.  I am still looking (albeit less 
enthusiastically) for a suitable replacement.  It says 2A 102�C.

In addition, apparently lots of folks have seen this happen (and I have 
as well):
You turn the radio on, and the display takes an inordinate amount of 
time to come up (many seconds) but it does light up.  Next time you 
power it up, it may come up much faster.  No solution has been 
offered for this problem as far as I can tell.

Hope this helps. (Next time I open the MP, I'll try to think straight 
and shoot some digital photos.)

Mike N2MG



ND8L wrote:

> The display on my 1995 vintage 'MP went dark tonight.  The rig
> still seems to function (I can computer control it)...and the front 
> panel indicator lights are working.  I tried resetting the CPU...no 
> luck.
> 
> Anybody have an idea?
> 
> Thanks!