24 Oct
2011
24 Oct
'11
4:08 p.m.
The computer-Kaypro II had a 9" green phosphor monochrome monitor composed
of a LR30477 E39164 TOSHIBA CRT and a printed circuit steering Toshiba
TLC-134-TV-0. I tried to supply it with 12Vdc and I noticed that the
cathode of the CRT is lit, while the screen does not turns on and no shows
light even using the knob back adjustment for the light intensity.
Wishing to do TV repair technician I need the wiring diagram of the circuit
electric drive Toshiba TLC-134-T-V-0. Is there someone who has it?
Here some pictures:
http://elazzerini.interfree.it/Kaypro-II/Foto2026.html
http://elazzerini.interfree.it/Kaypro-II/Foto2018.html
<http://elazzerini.interfree.it/Kaypro-II/Foto2019.html>
http://elazzerini.interfree.it/Kaypro-II/Foto2019.html
http://www.flickr.com/photos/67772736 at N07/sets/72157627837488485/
.
Unfortunately I did not notice on the board (component side) or under the
card (solder side) no sign of burning. I seem to hear at the power on of
the CRT an high-frequency hiss. Having found the power supply of the
Kaypro-II not working and not knowing whether it is the motherboard, I was
first trying to see if the CRT works. As a signal source I am using the
monochrome output of a PC 8088 XT video card because the kaypro-II accepts
distinct signals: video, Hsync and Vsync. It could be not true that the
polarities of these signals are useful as a signal generator to test the
video section of Kaypro-II.
I would go back ot using the Kaypro 2 motherboard as the signal source
(since we know that configuration can work).but check to see if it's
producing suitable signals. Use a 'scope to look at the VSync, HSync and
video signals between the motherboard and the monitor section and see if
they look sensible.
Assuming they do. I would then measure the CRT pin voltages. Most small
monitors use a 7 pin (modified B7G based) CRT with a pinout like this :
1 : Control Grid (Could be +ve or -ve with repect to ground, but a few
10's of votls at most)
2 : Cathode (expect about +80V here)
3) Heater. One of these pins wll most likely be groudned, the other will
4) have about 12V on it
5) Control grid (same as pin 1)
6) First anode (accelerator). + A few hundred V
7) THrid anode (focus). + A few hundred V again.
If you have an EHT meter, check the votlage on the final anode, expect
about 12kV there.
Often you find all the high votlages are missing, which suggests a
problem wit hthe horizontal output stage/flyback transformer
-tony