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