Dove right in! Help with RCA 21-D-8628

[Kevin Kuehn]

Originally Posted by BandDirector

I have swapped the tubes a few times, will do it again later this evening to double check. I have made a list of the resistors and their capacities/wattages/variance level and will draw my own schematic that is more blown up than the one in my service manual. I did not purchase any of the needed resistors, instead I bought all the wrong values! But I'll keep them. PW500 is the vert/height board

This blow-up may be easier to read on my end!

Do you have any way to verify DC voltages on the pins of the vertical oscillator and vertical output tubes against what's shown on your schematic? Those would be measured with the set operational, so it may be a problem to reach those connections without a socket extender. Personally I would not risk measuring on the plate(pin 9) of the vertical output. If we knew those voltages it could provide us a clue as to where the problem is.

Originally Posted by Kevin Kuehn

Do you have any way to verify DC voltages on the pins of the vertical oscillator and vertical output tubes against what's shown on your schematic? Those would be measured with the set operational, so it may be a problem to reach those connections without a socket extender. Personally I would not risk measuring on the plate(pin 9) of the vertical output. If we knew those voltages it could provide us a clue as to where the problem is.

There is an electronics store that looks right out of the 60s in the next town, he may have tube extenders. I found an original tv cord, interlock style, out there; plus a wall of tubes. He probably has them.

A gent earlier suggested the new electrolytics may be problematic the way I installed them. I may move them and replace the resistors next to them.

[Electronic M]

Originally Posted by BandDirector

I have swapped the tubes a few times, will do it again later this evening to double check. I have made a list of the resistors and their capacities/wattages/variance level and will draw my own schematic that is more blown up than the one in my service manual. I did not purchase any of the needed resistors, instead I bought all the wrong values! But I'll keep them. PW500 is the vert/height board

This blow-up may be easier to read on my end!

You see the dashed line that represents the PCB on that schematic. You want to check every resistor right of the plate of the sync sep inside the box formed by the dashed line plus the hold pot and it's resistor.

If you don't have a socket extender another method is to use long alligator clip leads to bring hard to reach test points out from under the chassis.

Originally Posted by Electronic M

You see the dashed line that represents the PCB on that schematic. You want to check every resistor right of the plate of the sync sep inside the box formed by the dashed line plus the hold pot and it's resistor.

If you don't have a socket extender another method is to use long alligator clip leads to bring hard to reach test points out from under the chassis.

Will do, I made a list of resistors I need so I'll send that to my electeonics guy to see if he has them in stock.

Replaced 3 resistors this evening, now I can't stop and clear a smaller image, nor a larger image; me thinks the resistors are now the problem.

I'm finding more failed/undervalued resistors; I wonder if this happened over time, or because I tested too early. Probably ovet time.

[Notimetolooz]

You do realize that depending on the circuit connections that other components could effect resistance measurements. Unless you check the schematic and check for additional connections that may effect the measurement, it is better to disconnect one side of the resistor. Some people take the position that if you solder one side you may as well un-solder the other and replace it anyway.

[Electronic M]

Originally Posted by Notimetolooz

You do realize that depending on the circuit connections that other components could effect resistance measurements. Unless you check the schematic and check for additional connections that may effect the measurement, it is better to disconnect one side of the resistor. Some people take the position that if you solder one side you may as well un-solder the other and replace it anyway.

You only need to clip a lead if the resistance tests low (and you are suspicious of it) if it tests at nominal value to the upper tolerance limit the resistor is probably just fine... examining the circuit for parallel resistors or inductors is advisable with this approach.

I tried clipping to measure, found normal ranges. Still have the dame image issue; however, I cannot return a clear, non-flickering image like previous.

[old_tv_nut]

I think it's time to triple check wiring and soldering, especially of electrolytics. (Any electrolytic wired wrong may be damaged and may need to be replaced.)

BUT, first I would suggest walking away from it for at least three days, forgetting about it, and then taking a look with fresh eyes. I think everyone has experienced looking at a problem repeatedly without seeing something obvious when you are frustrated, and that could be the case here.

Maltese Falcon

[Notimetolooz]

There is a component on schematic of the vertical sweep circuit area that you posted that is labeled PW500-A. It is probably a "couplate" (there are other names for the type), a collection of capacitors and resistors on a small ceramic plate. Couplates have many leads. They are difficult to test completely. Pretty difficult to find replacements for them but from the SAMS info they can be built from scratch.

Originally Posted by Notimetolooz

There is a component on schematic of the vertical sweep circuit area that you posted that is labeled PW500-A. It is probably a "couplate" (there are other names for the type), a collection of capacitors and resistors on a small ceramic plate. Couplates have many leads. They are difficult to test completely. Pretty difficult to find replacements for them but from the SAMS info they can be built from scratch.

I have a second chassis for this tv (chassis A), it is the original with a dead main transformer. The chassis currently in use (chassis B) was recently found and purchased from TheRadiolaGuy.

I can pull boards from it if needed (chassis A), I checked the little board today (chassis B) and found correct components, soldered a few spots on it and on the PW500. Still stuck with a flickering split image (chassis B).

I may take a break from the working chassis (B), and disassemble the other boards on the dead chassis (A). I am VERY lucky to have a duplicate of everything; including the Height/Vertical Linearity pots (it is one unit), it may be failed on the working chassis (B).

The resistors inside the double Height/Vert resistor unit/pot may be bad.

I keep forgetting the horizonalt/vertical deflection yoke, could that be the culprit? I am going to slow down and study the schematic and redraw my own version so I can comprehend, or see what I may miss.