I have this DAT tape unit that is rarely used when I tried it yesterday it
ran fine but the display was entirely dark. Tape runs and I get audio out.
Opened it up and saw nothing obvious. Hoping somebody has seen this and can
advise where to start
Thanks in advance
Bob

On Sat, 3 Sep 2005 08:05:43 -0400, "BoborAnn"
put finger to keyboard and composed:

I have this DAT tape unit that is rarely used when I tried it yesterday it
ran fine but the display was entirely dark. Tape runs and I get audio out.
Opened it up and saw nothing obvious. Hoping somebody has seen this and can
advise where to start
Thanks in advance
Bob

I'm not familiar with your device, but many displays use a cheap
readily available incandescent lamp as a backlight.


-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

Unfortunately its not that simple this is one of those with a blue display
that can be partially turned off (air only the level meters remain on) which
would rule out a lamp
Bob


"Franc Zabkar" wrote in message
...
On Sat, 3 Sep 2005 08:05:43 -0400, "BoborAnn"
put finger to keyboard and composed:

I have this DAT tape unit that is rarely used when I tried it yesterday it
ran fine but the display was entirely dark. Tape runs and I get audio out.
Opened it up and saw nothing obvious. Hoping somebody has seen this and
can
advise where to start
Thanks in advance
Bob

I'm not familiar with your device, but many displays use a cheap
readily available incandescent lamp as a backlight.


-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

"BoborAnn" wrote in message
...
I have this DAT tape unit that is rarely used when I tried it yesterday it
ran fine but the display was entirely dark. Tape runs and I get audio out.
Opened it up and saw nothing obvious. Hoping somebody has seen this and
can advise where to start
Thanks in advance
Bob


I think that this unit uses a VFD. You can easily identify one of these.
It's flat, glass, has an evacuation pip, a single row of pins along the top
edge, all equally spaced, except for the last two at the left and right
ends, which have an extra space. Thes 4 pins are the device heater
connections - each is a parallel pair so the heater is connected between the
left two end pins, and the right two. There should be about 2 to 4 volts AC
across these pins, and measuring from ground to either pin pair should give
you about -30v DC, as the heater is floated on a negative 30v supply to keep
it at about the same potential as the segment drives.

It's very common for the -30v supply to fail, usually due to dried out
electrolytic caps. Also, with some models using this type of display, there
is a small picofuse, or safety resistor in series with the heater feed.
These often fail for no apparent reason.

Arfa