The picture on a TV set used to be the combined product of multiple analog systems, and since TVs had no internal diagnostics, the only way to know things were adjusted properly was to see for yourself. While many people were more or less satisfied if their TV picture was reasonably recognizable and clear, meaningful diagnostic work or calibration required specialized tools. [Thomas Scherrer] provides a close look at one such tool, the Philips PM 5519 GX Color TV Pattern Generator from 1981.
The Philips PM 5519 was a serious piece of professional equipment for its time, and [Thomas] walks through how the unit works and even opens it up for a peek inside, before hooking it up to both an oscilloscope and a TV in order to demonstrate the different functions.
Tools like this were important because they could provide known-good test patterns that were useful not just for troubleshooting and repair, but also for tasks like fine-tuning TV settings, or verifying the quality of broadcast signals. Because TVs were complex analog systems, these different test patterns would help troubleshoot and isolate problems by revealing what a TV did (and didn’t) have trouble reproducing.
As mentioned, televisions at the time had no self-diagnostics nor any means of producing test patterns of their own, so a way to produce known-good reference patterns was deeply important.
TV stations used to broadcast test patterns after the day’s programming was at an end, and some dedicated folks have even reproduced the hardware that generated these patterns from scratch.
I remember if memory serves signetic (or was that Philips) chips that embodied TV test generators.
Philips bought Signetics in 1974 but brand name change was 1992
Yes, the generator has a connector market RF so the TV with an antenna picks up the signal disconnected.
A tool like this was a lifesaver for more than just circuit board diagnostics…
I once replaced a picture tube of a large color television and that was an art that took the entire day. Every adjustment possible, especially magnets, yokes, degaussing, etc and each one had a direct effect on the other…
Back in the ’70s and ’80s while I was going to college my day job was as a consumer electronics technician. Mostly TV/VCR. A good pattern generator was mandatory when replacing a CRT, or after repairing the convergance circuitry on an old delta gun CRT. Some of those old convergance boards ran very hot, destroying the substrate and the adjustment pots.
I remember old TVs with, like, 20 trimmers to adjust convergence. It seemed totally insane doing the adjustments (I never did..)
That reminds me, if you have a bunch of those portable analog TVs, you may be interested to know someone is making NTSC/PAL transmitters like the old Video Sender available at the usual outlets. They have even been trickling onto Amazon in the past year. Best get yours before they are cracked down upon!
Can you say more about it?
Looks like it’s for the British market. Got a U in colour and the voltage is not set for North America. Phillips was bigger in Europe.
I remember it well. Also we used different types from Nordmende and Grundig also instead of the Philips you showed. From that era I still have a working D61 oscilloscope from Textronics :-)
That name mention doest do justice to autors YT channel. I randomly clicked to see what else hes got and WOW its a huge stream of vintage gear teardowns, only after this I read full channel name : ‘Thomas Scherrer OZ2CPU Teardown’ :-)