Kaypro-II : display video to repair

- E
- Enrico lazzerini
  
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posted
12 years ago

Tue, Nov 1, 2011 3:14 PM

Hi at all, I bought an old computer with the wishing to make it alive. Itÿs 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 µPC1031H2 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:

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and

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.

Thanks in advance for any support. Enrico

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- F
- Franc Zabkar
  
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posted
12 years ago

Sun, Nov 6, 2011 3:08 AM

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

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:

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Datasheet for KA2130:

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Datasheet for CD1031CS:

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- Franc Zabkar

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- J
- Jeff Liebermann
  
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posted
12 years ago

Sun, Nov 6, 2011 3:56 AM

Schematic of the logic board in the Kaypro-II:

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:

No monitor schematic. It does mention the Toshiba display on Pg 7-2.

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