Maggie roundie combo

[mikeh]

I may have the HV cover for your set. I parted out a magnavox console a while back. Your chassis looks like my parts unit. You can have the HV cover.
PM your address and I will send it to you.

Mike

[DaveWM]

PM sent

[DaveWM]

Got the horz AFC diodes in, I think I will spend some time tomorrow cleaning the crud off the PCB's really dirty. Gives me something to do while waiting for the caps. I seem to get a lot of sets with defective horz AFC diodes, whats the deal there? most of the other diodes always seem fine.

[Findm-Keepm]

The early dual AFC diodes were selenium, but we always replaced them with 1N914's or 1N4148's from Radio Shack - they used to have them 50 to a pack for 1.99. Just use two diodes in whatever combination you are replacing, common cathode, common anode, or series. NTE177 is the analog to the 1N914's AND 1N4148's if you choose to go that route.

ECG113's ECg114's and ECG115's were the replacements back in the day. ECG updated the ECG113 to the ECG113A, a silicon replacement , when GE and International Rectifier no longer supplied the selenium ones.

I guess the epoxy packages weren't moisture-proof, or the selenium degraded somehow over time. Either way, an unstable Horizontal Hold would merit replacement if the old black epoxy package was in the set. Admiral and Sylvania Color sets always seemed to have weak hold, even with new diodes...

Cheers,

[DaveWM]

hmm I used some 1n4004's I had handy, I thought I had used those before, CTC17 and I were discussing this off line the other day, he had some concerns about the switching speed, but I though I had used them in the past.

[ctc17]

I have been using those TO220 package dual diodes you find in modern switching mode power supplies. Mostly because I have extras. They work great.

Every tube caddy I have run into has a few of these in it. They must have been a common fail even back in the day. They are only rated at 1ma so the new high current diodes should last.

[ctc17]

I just looked at the specs on the 1n400x series and those are really for 60hz. Im sure they will work but some fast recovery shottkys would be better.

[DaveWM]

ok I have some 1N4148's that I will use.

[DaveWM]

got the new degausser guts in (CL-90 and VDR). Replaced 3 color amp coupling caps .01 one was very lossy (would barely open the eye) the other two were not so bad, open about 80%, I figured I would do'em all.

There are 3 100k resistors that couple the plate from the color amp to the CRT, two of them look a bit toasty, and have decreased in value to 80k the ohter is 110k, so I will replace all 3 as well.

I still need to check the HOT coupling cap. After that I may hook it back up and see how its doing (hope I have not messed anything up).

I did see where the focus lead from the focus rectifier tube had broken, prob due to the way it bounces around with out the cage to hold it all steady. easy fix but just a reminder to look over work well (I found it while I was degreasing all the wiring harnesses).

[DaveWM]

the .01 horz coupling cap was about 10-15% away from fully opening (fuzzy like those other .01 I just did). These are brown dipped caps. the one that tested very bad had turned a bit dark almost black on the very top. It sat next to one of the large color amp tubes, and I suspect got a lot of heat, perhaps that is what does them in. Still no leakage at all.

I went ahead and checked a couple sections of two of the other cans, both tested fine for both value and leakage, maybe just a bit slower to open in the leakage than a new cap, but they did fully open. I am leaning towards not doing any but for the doubler which was not orig, and I dont know if it was even for the correct rated value or voltage, I would have to peel off the masking tape to see. I did pick up some 1.5" heat shrink today, will use that since I cant seem to locate a proper can cover. will of course have to make a cardboard disk for the top.

Done for the nite will try it out tomorrow to see how badly I have goofed it up.

[wa2ise]

Originally Posted by ctc17

I have been using those TO220 package dual diodes you find in modern switching mode power supplies. Mostly because I have extras. They work great.

Those switching power supplies run at or higher frequencies than TV set horizontal circuits (15734HZ). So those diodes would be an excellent choice.

[DaveWM]

back in, no HV, HOT starts to red plate. Hmm horz osc filament not on. move tube around and it comes back, HV comes back, wiggle it again, HV goes out. So it looks like the filament connection to the 6FQ7 is intermittant (prob what side lined it in the 1st place). I tried a different tube just to be sure it was not the tube itself, same deal. So I will pull the chassis and do a close up exam, my guess is a ground stake (if there is one that just feeds this tube) or maybe a loose contact pin socket. What ever it is I dont think it will be too much. Plus I have some NOS sockets that I would be willing to just replace it, esp on such an important tube. I have had tube socket failure before on this type, last time was the vert osc of a predicta. the bridge between the tube PCB pin and the actual socket can fracture, very hard to see, and the only real way to catch it is with a socket test adapter, since touching the pin sockets with a test lead will often close the cap and make it look good. I prob just got lucky the 1st time after checking the tube, and the install happened to be good (when the set was working after the inital check out). I do recal the HV was not there when I got it and I did a wiggle of the tube and it came back. Its just a bit too sensitive as is.

[DaveWM]

good vert/horz sync, good color, just some intermittant snow so prob a dirty tuner, but looking good. I will take a close look at the 6FQ7 socket next time I have it on the bench.

[DaveWM]

reflowed the 4/5 pins on that socket they looked a little cold. I also reflowed the ground stakes. Working ok, but will wait until tonight for darkness and see if I can wiggle it OFF now. I used my pick to also tighten up the sockets.

while I have good light out in the garage I plan to pull the tuner case off (I found one that fit) and clean the tuner contacts. the pots have been cleaned and lubed but for the pots on the back, I am going to leave them be for now since I dont think they get much use anyway.

Still have to find a place to mount the cathode fuse for fusing and checking the HOT.

[ctc17]

Then once you got it all fixed up you can stand it up on end in the garage and forget all about it. Just like me.... The fixation is the escape into the diagnostic realm and the sense of accomplishment when the thing actually works. Its hard to get that when you work in a cubicle or make sandwiches for an existing.

Its to bad we cant do this for a living. The timing is a few years off, thats ok though. I would much rather get cancer from a cell phone than a stupid ass pipe.