Help with 12" monochrome CRT circuit TDA1175/TDA1180

[Paolo Cravero]

Hello.

A friend gave me a 12" monochrome CRT with its circuits that was taken off an injection molding machine (most likely from the control console Sandretto Selec 90). As I haven't been able to find documentation I started reversing the circuit to understand the meaning of the 10 pins on the card edge connector.

There is the PSU, the HV generator and two ICs TDA1175P (vertical deflection) and TDA1180P (horizontal processor). I write here in hope someone was into these circuits and can help me understand what I need to get it working.

Checks completed so far: fuses don't blow, CRT filament glows, there's a 14 kHz whine (I cheated using an audio spectrum App), 12Vdc is present. Nothing on screen.

The closest documentation I could find is this service manual http://oz1db.dk/hp/omnivision_man_lp06xx_rev0_0611.pdf, however I'm missing something.

The 10-pin connector has 3x GND, 1x 12Vdc (output), the 3 contacts for (what I think is) the remote brightness control, 1x not connected. I am left with one contact going to a 2N2222 which should be "video input" and another going to the TDA1180P horizontal processor. Where is the VSYNC input? Not needed?

I've assembled an Arduino with the TVout library and got no reaction from the CRT both with just the [video signal] and [video signal + TVout sync output to the contact going to the TDA1180P]. The only difference between the two input configurations is that when I add the sync signal I hear a very low frequency buzz coming out of the screen circuits. I haven't been lucky enough to find a schematic diagram with both these ICs and just one sync input, and I've finished my guesses.

I wonder if someone in this great community has experience with this circuit configuration and can suggest what kind of signals it is expecting. Also, should it show something with no input signal, or at least some noise? I know the dangers of EHT and I would try all low-voltage checks first.

Thank you,

Paolo

[gregebert]

There was a standard 10-pin interface on video monitors back in the 1980's, so you probably have that. I know the video, vert-sync, and horiz sync were on the connector. Check pin 7; I recall that was for power and usually had a fuse on the PCB board. You should be able to find a pinout on the web.

[gregebert]

I found this online (service manual for Ball Brothers video monitor). At the end of the document is a schematic, and you can see the pinout numbers (for the 10-pin card-edge connector) called-out on the schematic. For example, pins 1 and 10 are GND, 2,3, and 4 are for the external brightness control.

I used to test/repair terminals, printers, and small-business computers as a summer job, and encountered several video monitors from different manufacturers with this same pinout.

http://www.bitsavers.org/pdf/ballBrothers/5-017-1017B_Ball_TTL_Series_Service_Manual_Oct76.pdf

[Paolo Cravero]

Hello.

On Sat, Apr 22, 2023 at 5:58 PM gregebert wrote:

I found this online (service manual for Ball Brothers video monitor). At the end of the document is a schematic, and you can see the pinout numbers (for the 10-pin card-edge connector) called-out on the schematic. For example, pins 1 and 10 are GND, 2,3, and 4 are for the external brightness control.

This reference, together with the Omni Vision PDF I had found, confirm what the previous owner told me: the pinout in the card connector is non-standard (mixed-up). Regardless, I've identified where signals are supposed to go. It's just that I am missing one of the sync lines. The device has certainly been in use since there are signs of phosphor burn.

Meanwhile I have found a better source of composite video, that is [video]cameras from 2000's, which my current TV displays properly and I'll feed it to the monitor circuits as soon as I can get it from the storage room to the lab desk. Then I will see if that is enough or I need a sync separator with LM1881.

Will post updates,

Paolo