Rca cu121w

[MIPS]

I spotted it sitting in an alleyway.





For those who are into microcomputers you may notice it bears a striking resemblance to Tandy's monitor for the TRS-80 model I. That's because it's the same set but with the tuner and speaker removed.
I happen to own one of these systems and this is awesome because the expnsion cabinet has indents designed for the feet on this set and the ventilation grilles line up.



Tandy swaps out that vertical standing board inside with their custom board full of magic. There are no documents on what this board actually does that I can find so I'm forced to use an RF modulator instead of any kind of direct connection.

Anyways, the cord had been cut but when replaced I powered it up and man she wasn't happy.



It's hypnotic. The image oscillates and the speaker gives off an angry buzz. This will be a fun one.

[Jon A.]

Looks a lot like a '77 RCA I had briefly. That one seemed to work but it gave off a funny smell when powered on.

[zeno]

Odds are either an open filter can or cold joint in horz out.

73 Zeno

[Zenith26kc20]

Main electrolytic always opened up in these and the small color sets. Other than the electrolytic and solder connections we never had problems with that set.

[Electronic M]

Sort of looks like a mini Avanti/RCA 2000...

[zenith2134]

That multi section capacitor should be a breeze to change out with individual caps. I have seen a lot of bad multi-cans in tv sets and audio gear..Sprague, Mallory, etc .
It's almost as if the combining action of the capacitors reduces their reliability. But that can't be the case. It sure reduces cost to the manufacturer, which of course is the main reason they've done it. (In addition to space saving).
I'd consider leaving it that way and using it as a display piece for a weirdo tv collection(such as the one I have here) since they're garden-variety Taiwanese sets anyway. Just to see how long it would hang on in this electronic condition.

[NoPegs]

I'm sure you can add a baseband signal input to it without much effort. Just follow the signal path out from the tuner and probe for a point that has the standard two-porch signal around 1v p-p.

[MIPS]

Someone mentioned that EEV (ugh, that guy...) tore down a TRS-80 and in the video he briefly went through his video monitor. Finally, a close-up of the board.



The plot thickens...

[snelson903]

i like thoughs 70's tv's they have a look all there own.

[Fairlane500skyliner]

Originally Posted by snelson903

i like thoughs 70's tv's they have a look all there own.

1970s portables certainly have a very unique style - especially mid-70s portables, or at least it's that way over here.

Chris

[radiotvnut]

I have one of those that had a weak CRT and I replaced it with one from a junker TV. Those filter capacitors were a big problem on those little sets, as well as the '80's CTC107 through CTC120 color TV's. I always replaced them with individual capacitors.

[wa2ise]

I remember finding out that this board used an optocoupler (6N135 IIRC) to pass the video signal from the computer to the monitor circuits, as the monitor was a hot chassis design. It could do normal video.