Picture problem in Crosley 9-408
 

I’ve had this set now for about three years. I replaced all the FP twist lock electrolytic capacitors as well as all the paper and wax capacitors a few years ago and the set has been working well. A few days ago I turned it on and the left side of the picture has a dark grey vertical bar that cuts off the picture. Also the rest of the picture looks washed out with poor contrast and little brightness as if it’s a weak CRT. I substituted a strong 10BP4 and got the same results. Also tried another 6BG6G with the same results. It’s all quite baffling because the set worked fine the day before. The chassis in this set is an RCA 630TS. I don’t own an oscilloscope and only have a digital multimeter. Any idea what is going on here and is there anything I can do to fix this problem?
Thanks for any suggestions!
Paul D.

Left side problem could be a faulty damper (5V4G ) and / or a problem with the huge multi tap resistor in the HV cage, for horizontal linearity setting, they love to go bad!

Agreed. My money is on the resistor.

Thanks guys! That resistor looks okay and measures 5K6 ohms but I’ll try replacing it anyway. I’ll order another 5V4G as well. Can a 5AR4 be substituted here? I think I have one.

Don't replace it if it tests OK. It's an oddball value and high wattage.
Yes, a 5AR4 will work

Thanks Bob! Glad you mentioned that. The only thing I could find was an Ohmite 50 watt 6K adjustable wire wound chassis mount deal but they are expensive! $27.00 plus shipping!!!

My problem here has gradually gotten worse. The large resistor in the high voltage cage isn’t the problem. It tested right on the money. Now I have a raster but no picture at all. I decided to check my voltages in the bleeder box and discovered that I have virtually no negative voltages. All the resistors here measure within specs. I have less than 1 volt on the green wire to the focus coil where there should be 100 volts. Only a few millivolts where there should be -18 volts and -2 volts. No smoke from any of the aluminum electrolytics but I suppose something might have failed here despite having all of them being replaced three or four years ago. It’s all very puzzling and I’m not sure where to start. This set has an RCA 8TS30 chassis. Any suggestions are greatly appreciated! Thanks!

Maybe you should recheck all the twist locks you replaced three years ago? All the twist locks in my 630TS remained good and did not need replacing.

Start going through the tube socket resistance checks using the chart in the Sams Photofact. I'd start with the 5U4 rectifiers.

Thanks Penthode! That was my first thought so I unsoldered the positive lead of C220 section C (Riders service manual) which is an 80uf / 150 volt unit that has its positive soldered to ground.
I assume that this is the section that provides the B negative bias supply and the negative 100 volt rail. I measured 81.7uf. With my digital multimeter. This may not prove that the capacitor is good. I will have to remove the entire can and open it and inspect the individual parts which were Nichicon pencil shaped radials. I had one fail in the past, the end was bulging out but it didn’t vent and let out smoke.

Thanks Bob! I measured resistance on pins 2&8 of the 5U4G’s and got 6K ohms. The chart in Sam’s says 5K5. Pins 4&6 measured 490, with the chart showing 460 ohms. I guess that’s in the ballpark no?

Yes, that's close enough. The negative voltage is developed across the focus coil and several power resistors. It doesn't seem possible that you could have a visible raster and only a few millivolts negative unless something has shorted to ground.

Measure the resistance between the negative leads on the power supply caps (C1, C2, C3) and ground (chassis).
https://live.staticflickr.com/65535/...3d08d806_o.png

I was thinking the same thing. :scratch2:

The horizontal Discharge cath is tied directly to -100v, and the output cath via 100 ohm resistor, with it that far off, can it still work?
Or is ALL voltages skewed making the ground ref wonky?

Bit of a question. :o

When you started this thread, you said it was a RCA 630TS chassis, then later it was a RCA 8TS30. :scratch2:

It seems the two are virtually identical, but then, which do you have, and what IS the difference between the two? :D

None as far as I know. Same Sams covers both.

The 8TS30 also uses a 630 chassis...the 630TS, it's console version (630TCS?), and the 8TS30 were the only sets RCA sold that used the genuine 630 chassis....Later 630 esq RCAs exist and some people call them 630 confusingly.

Okay I did that and all tested zero ohms with the exception of C6 in the Sams folder which measured 6K ohms.i also checked voltages on the two sections which are 250uf/10 volts and 1000uf/ 6 volts and am seeing 345 volts here!

How do I post some pictures? I haven’t seen any information on how to do this.

Attach files, link below?

Could perhaps that 56pf cap in the yoke on the horizontal core be a source of this problem?
If it were open/shorted, throwing the entire horizontal section out of tune, and thus, upsetting the balance of the power supply?

I disconnected one end of that mica capacitor and measured 70pf so I replaced it. No change. Having a closer look at the FP electrolytics which I pried open and re stuffed with Nichicon radials. Ugh! Will never do that again! Ordered some adapt-cap circuit boards that Bob Anderson uses and decided to re-do them all. Finding bits of solder blobs here and there so could be a short somewhere. Also lots of brittle and cracked cloth covered wire to replace. Looks like I’m in for a lengthy project!

Sorry. That's why I rarely restuff cans anymore - can't see what's going on inside or make repairs.
Those brittle wires are a challenge and frustrating. Heating them gently with a heat gun on low or hair dryer usually makes them more flexible. At least until they cool down

My preferred method is to cut the top of the can off and after restuff slip a cardboard can insulator sleeve (remove and reuse the original if there is one) over to hide the missing top. Much more serviceable and original looking than a straight rebuild or the adapt a cap.... I'm probably never going to use an adapt a cap in my work because for cheaper I can solder a period correct looking terminal strips underneath to hook the new caps to and then only have the underside of the chassis (which, let's face it, nobody sees) look unoriginal. The adapt a caps make the bottom AND TOP of the chassis look unoriginal and to me the top of the chassis is the most important part to keep looking original as it will be seen periodically.

Thanks Tom C.! I don’t think I can use the adapt-a-caps on two of the cans. They have no phenolic insulators and are affixed to the chassis by the four twist lock tabs, one of which is soldered to the chassis. I would have to drill two holes to mount them, even then the chassis cut out is not round but a smaller square shape with corners rounded which could present problems.

.

Hi-

So I been trying to follow you guys on this one, I assume this tv is this schematic
https://www.earlytelevision.org/pdf/...s30_manual.pdf

I see you are not getting the -100V source... So my question is are you getting
the 135V source, or is it high? If its high then R186C has to be open, or the
ground lug is not making it to the chassis....?

If the 135V is ok, then I guess you could possibly have
an open R240?? anyway they deserve a sniff...

What is the +275V source reading?

If the 275V is missing, then you have to look at the path through R181, R211.
But then you say the tv has stuff on the screen..... so 275V is there....

Or am I just off in left field here....

.

.

Ok, so I been thinking about this goofy power supply part of the day, and I think that
if R186C was open, it would really mess up the chassis ground potential, and make
readings off for each source. Or C224B Is Shorted (Unlikely). So I think the best
way to figure out where the open resistor is, is to put the (-) volt meter probe
on the green wire of the focus coil and move the (+) probe along each of
the resistors towards the 275V source till you start reading high positive
voltages, then you will find the open resistor when you hit a big positive
jump..... So between R185A and R186A I think you should read about
+82V if the set is working... Just re-adjust your brain to think of the
-100V source as 0V with the (-) meter probe on it for reference.
I have not worked on this model before, But my thinking is that
with the point between R186C, & R240 making the ground
point, or 0V potential, then using that point as a reference
would make all readings off, if one of those resistors
is open....

And with your (-) probe on the red-yellow wire (Center Tap)
of the power transformer, know that your 275V Source
will read closer to 375V and be OK.


Just my thoughts on this one...

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Picture problems in Crosley 9-408
 

Well it’s been quite a while since I last posted here!
I finally got around to having another look at this set. In the meantime I bought new leads for my multimeter as I was having difficulty getting readings with the old ones. I think this was causing problems with the automatic range function on the meter because now I have B+ of 282V and +128V. Pretty close to what is specified here (275V. and 135V.). My B- is much better at -20V. and -1V. Should be -18v and -2v. The green wire to the focus coil reads -108v.
I also had a close look at the FP can capacitors and found nothing wrong here. I replaced four with the adapter-a-cap circuit boards and new components. The two twist locks soldered to the chassis seemed to be okay as well. C224 was re stuffed with new components even though the old ones looked good and measured with specs. C223 a three section can was left in place and not opened as I found nothing wrong with any of the other parts.
I now am able to get a picture but problems remain. The contrast is poor and washed out with inadequate vertical height. I can get the vertical to lock but the horizontal will not, it will roll to the right if I turn the control to the right and left if I turn the control to the left. It is not stable and eventually drifts. Also there is a bright white band running horizontally across the picture at the very top where the blanking bar should be.
I’ve replaced the mica capacitors and all out of spec resistors in the sync section. I don’t have an o-scope or any other test equipment. If anyone has any suggestions on how to proceed I would greatly appreciate it! Thanks in advance!

"contrast is poor and washed out" "inadequate vertical height" "the vertical to lock but the horizontal will not"

These are all clues to something, but what exactly is the hard part. It still may be a power issue, who knows.
This set pulls sync from the final video amp, at DC restoration, so if you have poor contrast (weak video), makes sense for there to be poor lock as well, but the lack of height is also a sign of a problem someplace.
Still much to look into. :(

It may be worth injecting composite video at various points between the detector and DC restoration diode (make sure to use a series cap around.1uF 600V to protect your video source). You may have to try s couple to get correct video polarity. If you get good sync injecting composite video of the correct polarity and better amplitude than the tuner/IF are making them the sync and osc system is fine and you need to trace the weak tuner/IF issue...if bad sync with good composite video then the sync separator or sweep osc is an issue.

Do you still need to know how to post images in the thread? You will need to create an account in Imageshack, a photo file uplink website. The easiest way forward is to access it on your phone through your phone's internet browser.
Follow the instructions on Imageshack to upload photos from your phone to the website. Once the photos are uploaded, I usually switch over to my laptop for the next part.

Open your images and click on the one you want to include in a VK post. You will be given an option to access links. Select your image size (not too big!) and copy the link.

Back to VK. In the posting window do the following: [img]...the copied link...[/img]
(no dots, just the link between the brackets). Don't forget the backslash. It won't work without it. Click on preview post to see the image as it will appear.