Over the weekend I attended a vintage computer workshop held at the System Source computer museum in Hunt Valley, MD (I highly recommend visiting, they have a very impressive collection on display!), and during the course of the workshop I ended up bringing home this cute little set to fix for the museum. It is apparently a teleconferencing device able to send video over the telephone line as well as via composite. They own two units, and this one did not turn on or display any signs of life.
The set was apparently plugged in with a 13.8V AC adapter, when the original adapter is a center negative DC supply, so I decided to first take a look at the power supply. That turned out to be easier said than done, as the entire power supply is enclosed in soldered-together shields also acting as a big ground plane. After about an hour I was finally able to free the power supply only to discover there was nothing wrong with it aside from a marginally testing electrolytic. The search continued..
I eventually found a diode in the horizontal circuit that tested completely shorted, but after desoldering, it seemed to test fine. I backtracked the circuit a bit and found the culprit: a .047uF film cap! The set works fine now, as can be seen in the photos.
Does anyone have information on these weird things? I couldn't find any manuals, schematics or anything on them aside from random eBay listings. I'd love to know more about them as they seem quite interesting but obscure little sets that IMO deserve more attention.
