Motorola Quasar Vertical Issue

[mcmlxv]

Just took delivery of a Motorola Quasar TS-915 with a chassis date of 11/68. The set is in excellent original condition and is operational. The set initially presented with a vertical issue: the vertical height expands to full screen then shrinks top and bottom by an inch or so. Within a few days, the set lost vertical hold, and the bottom third of the screen showed an upside down, folded image.

I replaced the video drive and vertical amp panels with NOS units, cleaned the mounting pins, and cleaned and reseated the convergence panel. The picture now fills the full screen and the vertical hold has returned. However, the picture suffers from intermittent vertical judder and the image is rolling occasionally.

Any ideas?

[zenithfan1]

Maybe there are some leaky caps on the NOS modules. Remember, those are "new" parts that are as old as the "old" ones. Sometimes it works better to totally recap those modules before installation.

[mcmlxv]

Good advice. I was hoping I'd get lucky with the NOS parts. I'm not really familiar working with transistors. Are they a known failure point on these modules?

[zenithfan1]

Most of the time, the transistors are ok but caps go bad just sitting there, used or not. Shouldn't be more than a couple bucks to recap a board that size. I'll bet the vertical stabilizes after that. Good luck with it, those are cool sets that are getting kinda scarce these days.

[drh4683]

This is without a doubt a faulty capacitor situation as I can speak from experience in working on Motorola sets. You will notice that the capacitors used throughout those modules are a translucent gold color, typically with the name "ERO" on them (which was a German manufacturer). Motorola was one of the very first companies to start using foreign parts in domestically produced consumer products starting back in the early 60's. Intermittent faults with Motorola TV's such as the TS-915 chassis and others from the late 60's-early 70's are attributed to those capacitors which typically have terrible dielectric leakage. Those caps were basically junk when they were new. Rather ironic that the Germans put out something of inferior quality as they are usually known for engineering overkill.
A word of advice; use good quality replacements! I have always used Sprague "Orange Drops" for tube sets, but for the Motorola's and other low voltage solid state applications, I particularly like the DME series from Cornell Dubilier because of their high quality and smaller size (comparable to the originals) so that they neatly fit on the PC board without "over crowding" if you will. I have used these many times on Motorola sets with great results. I strongly advise that you replace ALL of those gold "ERO" caps on all of the modules. Those leaky caps are loading down other important components that you don't want to have fail... They will cause all sorts of intermittent problems, from washed out video, weak color, to the deflection problems such that you've already experienced. If Motorola used a better cap on their solid state sets, I think it would have greatly improved their reputation.

Since we're on the topic of a TS-915 recap, its also very important that you replace the 3 or 4 electrolytics on the convergence board. Those caps are clustered near the compactron socket that is used to connect the convergence yoke. I've had those lytics fail on me before, as in a direct short out! It took out the vertical oscillator transistor which also happens to be on the convergence panel in those sets. Any combo lytics in cans such as the main filters are going to be fine. Just replace those ones on the convergence board and you'll be all set.

I attached a link (below) to the datasheet from Mouser electronics for the DME caps. They are available from 100-1000VDC, just order the type per the original cap. Also note, most if not all the original ERO caps are going to have their values listed in nanofarads (nF) which is typical of the European caps. Nanofarads are 1 billionth of a farad. Since most caps sold today are marked in microfarads (uF), which is 1 millionth of a farad, you will need to convert the "nF" value to "uF" simply by diving the nF value by 1000. It seems to come up often, so I figure I'd mention it.

Once you take care of the re-cap, a TS-915 will have an excellent picture. They are great sets once properly brought up to par.

http://www.cde.com/catalogs/DME.pdf

[mcmlxv]

OK. FINALLY completed the suggested recap with the CDE DMEs, and sure enough, the vertical is stable. Recapped the convergence board as well. Thank you Doug! Your advice was spot on. The picture has been good for the last couple of weeks.

New problems have appeared now. The picture pulls diagonally and shakes all over the place. I guess one would refer to this as horizontal judder? I turned the set on yesterday to capture and post a screen shot, but the set won't produce a raster now. There is power. Audio is present, and the CRT neck is glowing.

I removed all the boards and cleaned the connectors and mounting pins with Deoxit. I also have inspected the works for any loose connections and suspect wiring. Still no raster.

I'm unsure of my next step. I have tackled radios and simple B&W TVs with success, but never anything SS, and certainly nothing like the Quasar.

I am committed to returning this set to correct operating condition, as I feel it's very much worth the effort and the learning experience.

[rca2000]

The tubes weren't too good in the TS-195 were they?? Not compared to a good CRT anyway. Especially if they used the "wonderful "23EGP22. The 25AP22 was only marginally better.

[rca2000]

DO you have HV?? This is one thing to check for first. I believe this set powers the tube filaments through the power transformer--NOT the flyback. SO, even though the fils. are lit--HV could be absent. IIRC, this set has an 80 volt B+ line for the horiz. output ckt and flyback, ran through a regulator somewhere , not on the power supply.

If HV is ok--what does the cathodes of the tube look like?? Are they being biased off?? If there is over 175 or so on them, not varying with the brightness or contrast control--the tube is in cutoff. Often if you crank up the screens in this situation you can get a dim raster.

If in cutoff--make sure the video module is not dying. It likely has those same shitty german caps, and they may be giving up.


If not in cutoff--is the screen voltage ok?? Should be variable, somewhere up to 600 volts or so for each gun. Comes from the horiz. ckt, not sure where, likely from the H-output itself through a resistor or two.

DOn't overlook the FOCUS voltage, either. On a lot of CRT's from the "day" if you lose focus voltage--you get no raster. LIkely derived from a bleeder off of the main HV.

CHeck these things--likely you will get a clue to the problem.

[mcmlxv]

OK. No HV.

Just before the loss of raster when the picture was going crazy, I noticed a low hum coming from the area of the power supply. I removed the back of the set and placed my hand on both the power transformer and the filter cans: they were all roasting hot. I couldn't keep my hand on the transformer for more than a few seconds. What could be going on?

All the transistors on the horizontal board test fine. While testing them, I noticed a few of the those gold ERO caps on the board, and 3 more ERO caps housed in white and blue plastic rectangular housings. Would failure of some or all of these caps cause loss of HV on their own? They'll get replaced soon.

I'm leaning towards a problem with the filter caps, but I'm unsure how to rule out that issue.

Thank you in advance for any advice.