Avante On/Off issue

[TinCanAlley]

Originally Posted by Adam

Mine wouldn't turn on -- this is the thread about it: https://www.videokarma.org/showthread.php?t=276998

And here's some information I found about how this circuit works - from TAB books - Zenith Color TV Service Manual - volume 3.

I'm going to pull the tuner assembly again, but this time remove the remote control board so I can replace all electrolytics, test transistors and clean up the triac.

The pics you posted from those books seems to be a year or so newer as they talk about 4 volume positions over the old 3. Makes me wish I had that as 3 position volume always seems to leave it too low or too loud. It also noted something about staying in the powered down mode when plugged in. Mine is just the opposite. With the power issue, I cannot turn it on or off, but pulling the cord and plugging back in always has the set on. Other odd thing is once I plug it in and it's on, I do have to push the power switch as the screen is shimmying and the channel number is fluctuation in brightness a bit. Once I press the power switch, it stops and a second push brings it back, etc. So I'm hoping it's the caps on the remote board that are connected to the trigger circuits of volume and power.

[Electronic M]

When I get around to fixing the no-power issue on my 1980 remote CCII I may have to analyze that circuit and see if I can add a switch to make it default to on when line power is applied as it's plugged into a switched outlet that comes on when my basement signal rack gets power...The non-remote CCII it replaced was left switched on so if I saw it running I knew my signal rack was on (I could also choose what material was on screen by watching it).

[TinCanAlley]

Originally Posted by Electronic M

When I get around to fixing the no-power issue on my 1980 remote CCII I may have to analyze that circuit and see if I can add a switch to make it default to on when line power is applied as it's plugged into a switched outlet that comes on when my basement signal rack gets power...The non-remote CCII it replaced was left switched on so if I saw it running I knew my signal rack was on (I could also choose what material was on screen by watching it).

When the power switch or remote power isn't working, it is always on when plugged in. I know when it is working again as when I plug it in, it is off and I need the remote to turn it on. Of course after this, the remote no longer turns it off and in manual the power switch doesn't turn it off, so I unplug it. Since it is intermittent, I'm hoping it's failed capacitors. My guess is the triac will either work, or it won't. Not sure about the optocoupler. I figure that since it's from the early 70s, it's not an LED inside.

[TinCanAlley]

I've finished recapping the remote control board. The smaller trigger caps had high ESR and were around 25% above value. One was 75% below (2.2uf read .52). I also decided to recap the audio board since I had everything to do it.

I cleaned up the triac and found they they used 2 mica insulators (mistake at factory?) and a ton of thermal paste. Guess they didn't believe in using it sparingly. The way the stuff hardened, and the amount, I'm sure it was acting as more of an insulator than a transfer. I don't have any of the white thermal grease, but I do have a tube of CPU thermal paste. I'm sure it will be better than the stuff from 50 years ago. Also going to use a ceramic insulator instead or mica.

[TinCanAlley]

Well it's done and reassembled. It turns on and off as it should. Also, recapping the audio board helped with a background static you could hear when volume was low.

I'm attaching a few pics of the cleaned up and reattached triac (I cleaned off that little blob on the side), the two capacitors causing all the trouble in the trigger circuit, the capacitor that was 75% of it's value that seems to be a decoupler in the volume circuit of the remote board and in the same pic you can see the optocoupler.

As a side benefit, now when I use the volume control on the remote it changes level with no crackle/static type noise like before. It's quiet and smooth in level change.

So far I'm quite happy with fixing these issues. This along with the jailbars being gone, it only leaves me with one last issue. I need to figure out how to get the setup function fixed so I can properly set the G2s. Otherwise I'll just keep it as set by a B&W image and always wonder if it's set optimum.

Thanks for all help and advice. Without everyone here, this might not have gone as well as it did.