Help diagnosing Motorola Quasar/WU821FS

I got the screw out, and voila! Here's some pics w/ the drawer out.

Now I still need to figureout how to get those tacks out so I can remove the entire back panel.

[Steve D.]

Originally Posted by RVonse

I haven't seen your video because all I have is dial-up. But if the line crawls it is could be a capacitor in the vertical section. In particular, look at the cathode circuits in both the vert output and oscillator.

If there is no crawl but just bad height and linearity it could be a bad tube or off value resistor in the vertical circuit.

Also, pay attention to any other clues such as a slow crawl that warps the picture which would then indicate bad power supply filtering.

I have archaic webtv dial up and can't believe I was able to download the video images. Good diagnostic tool. This set looks very fixable. It can't be stressed enough...High Voltage is DANGEROUS!

-Steve D.

Most definately I understand the precautions. I would never work on this myself, as I don't have enough experience working with such high voltages. My guitar tech, Chris Siegmund, builds tube guitar amplifiers and would be my first candidate to work on these. I thought it'd be wise to get a general concensus from a group that are familiar with this avenue before taking it over to him. You guys have been great!

[maxm]

If you do need to service the vertical section, it is located inside the drawer on one of the circut boards. It is the one on the bottom, with the two tubes in it. The small orange plastic cylinders on the board are electrolytic capacitors, and if the vertical problem can't be cured by fiddling with the controls, these are probably what has gone bad. They are very ease to replace, as the small board can be removed from the drawer, by very carefully pushing from behind it (if you can get to it from behind, be careful, as those long silver cans on the other side can store high voltage even after the set is off and unplugged), you should start to feel it pop out. This is another cause of problems on these sets, as the pins on the boards (called modules) might not make good connection to the rest of the set, and can cause problems, though they are usually more major than this, such as no vertical deflection at all (only a thin horizontal line in the center of the screen), or no color.

[blue_lateral]

I still need to figureout how to get those tacks out so I can remove the entire back panel.

Tacks? I don't know what you mean. There is probably another screw or two in the back, but it's mostly held on with metal clips. You just squeeze them and they pop through the rectangular holes.

John

There are tacks holding the plastic panel to the back piece...so I thought these were the reason why the back panel wouldnt come off, but sure enough it was the same hex screw I took out to bring the drawer out.

[holmesuser01]

Find the 6CW5 tube. It's a tall 9-pin. That is the board with the vertical circuits on it. Chances are good that the big caps in the power supply have issues, too.

Is the horizontal and damper tube installed on a small separate chassis? Dont mess with these tubes, as it looks like you have good width on the images you provided.

I see a few trim pots that adjust vertical characteristics...Is it possible that I would just need to adjust some of these to fix some of the issues? Or is a cap and/or tube replacement definate?

[kc8adu]

iirc thats the ja board.
replace all the orange ero electrolytics
they are much more likely to be the problem than the 6cw5.
that set is a easy fix.

Originally Posted by holmesuser01

Look for the FA board. If not mistaken, this has the 6CW5 vertical output tube on it, and the horizontal oscillator tube. 6CW5's can cause lots of issues.

I have not seen one of these sets in at least 20 years.

If not mistaken, you need to remove that 1/4" hex screw near the power connector before you pull the drawer out the front of the set. I can see it in your pics.

[Chad Hauris]

Adjustments are just to compensate for small changes in picture size due to tube aging...this case looks more severe and I agree that the problem here is likely bad caps.

K, so I located these caps...They are the radial electrolytic type, correct?

There were 2 on the same board as the tubes, and one more on a board above...

2 on the tube board read:

8/50 A36 20
50/50 A29 20

The one on the board above read:

40/50 E2 A 30

I'm assume the 50 is voltage? Is the prefix uF? If so, I'm familiar with 10uF and 47uF but have never seen 8 or 50, or 40 for that matter...

Thanks

[holmesuser01]

Originally Posted by kc8adu

iirc thats the ja board.
replace all the orange ero electrolytics
they are much more likely to be the problem than the 6cw5.
that set is a easy fix.

Thanks, You're right. Recalling things can be fun, especially when you haven't look at a Quasar TV in about 15 years.

There's a simplified schematic on top of the drawer that signifies each section (this being the FA section). It doesn't say much about each part (other than tube names, and adjustment areas)....more of a map than a true schematic.

Although, by looking at this I noticed that the 3rd cap in question is not a part of the FA section that we are dealing with.

I've attached 2 pics of the 2 caps, labelled accordingly.

[maxm]

Yes, those are the two caps that are probably giving you trouble, the 50uF cap can be replaced with a 47uF, as they are almost the same, the industry switched over to the slightly different values for a reason that has slipped my mind. You should also be able to replace the 8uF with a 10. If you replace these two little caps, you should have a nice fully working set on your hands.

I headed down to Radioshack and they had some radial electrolytic caps for 47uF and 10uF, but both were at 35v rather than 50v...Would these suffice, or should I stick with the 50v?

P.S. If anyone can get the Sams document for this (#1159-2) that would be wonderful. This way I can be sure that I need a 47uF not a 4.7uF, etc.

Thanks a million