Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Kaypro-II : display video to repair

Hi at all,
I bought an old computer with the wishing to make it alive. Its name is
Kaypro-II and it has 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?
I seem to hear at the power on of the CRT an high-frequency hiss and i
tryed to see if come out a shoke from the flayback transformer but nothing
come out.
Other useful info:
1) on the PCB
SN 23989586 K10MRDO
Toshiba 23879862 TLC-134-T-V-O
There is a chip NEC PC1031H2
Flyback transformer with those info: TFB1026 2L24DS
2) on the back of the CRT
CRT Monitor LR30477 E39164 E2728531 2A13 3D Hu

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/Kayvideo/Foto2768.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2771.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2772.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2773.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2774.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2775.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2776.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2777.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2778.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2780.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2781.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2782.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2783.jpg
and
http://www.flickr.com/photos/6777273...7627837488485/ .

Thanks in advance for any support.
Enrico

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Default Kaypro-II : display video to repair

On Tue, 1 Nov 2011 16:14:19 +0100, Enrico lazzerini
put finger to keyboard and composed:

Hi at all,
I bought an old computer with the wishing to make it alive. Its name is
Kaypro-II and it has 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?
I seem to hear at the power on of the CRT an high-frequency hiss and i
tryed to see if come out a shoke from the flayback transformer but nothing
come out.


Other useful info:


1) on the PCB
SN 23989586 K10MRDO
Toshiba 23879862 TLC-134-T-V-O
There is a chip NEC PC1031H2
Flyback transformer with those info: TFB1026 2L24DS


2) on the back of the CRT
CRT Monitor LR30477 E39164 E2728531 2A13 3D Hu

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/Kayvideo/Foto2768.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2771.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2772.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2773.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2774.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2775.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2776.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2777.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2778.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2780.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2781.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2782.jpg
http://elazzerini.interfree.it/Kayvideo/Foto2783.jpg
and
http://www.flickr.com/photos/6777273...7627837488485/ .

Thanks in advance for any support.
Enrico


With respect, your circuit should not be too difficult to troubleshoot
without a circuit diagram.

From your description, it appears that you are hearing the EHT at
startup. You also appear to have a functioning CRT heater.

I would carefully measure the voltages at G1 (brightness), G2 (CRT
bias), and G3 (focus). See if these voltages vary as you adjust the
Focus and Sub-Bright controls.

Also measure the voltages at the diodes and fusible resistors
connected to the flyback transformer secondary outputs. Perhaps one of
these resistors is open. Also check the resistances of any high-ohm
resistors on the CRT neck PCB and elsewhere on the main PCB.

If you have an oscilloscope, then you could confirm that there is EHT
on the CRT by aiming your scope probe at the face of the CRT. You
should see a radiated flyback pulse.

The uPC1031H2 is a vertical amp IC.

According to the following document, the uPC1031H2 is equivalent to
CD1031, KA2130, LA1385, TA7242, or ECG1245:
http://www.datasheetarchive.com/inde...SL00155947.pdf

Datasheet for KA2130:
http://f1chf.free.fr/PDF/KA2130.PDF

Datasheet for CD1031CS:
http://www.datasheetarchive.com/dl/D...DSA-187948.pdf

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.
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Default Kaypro-II : display video to repair

On Tue, 1 Nov 2011 16:14:19 +0100, Enrico lazzerini
wrote:

Hi at all,
I bought an old computer with the wishing to make it alive. Its name is
Kaypro-II


Schematic of the logic board in the Kaypro-II:
http://www.z80.eu/downloads/Kaypro_II_schematics.pdf
The 3rd sheet shows the video outputs going to the display. Put an
oscilloscope on the vert sync, horiz sync, and video lines and see if
there's any output. If no output, then the problem is probably NOT
the display.

More Kaypro schematics and manuals:
http://www.bitsavers.org/pdf/kaypro/1484-D_KayproTechnicalManual_Dec84.pdf
No monitor schematic. It does mention the Toshiba display on Pg 7-2.

--
Jeff Liebermann
150 Felker St #D
http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
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