Heathkit GR-2000 Sold State Color TV

[Electronic M]

Perhaps I have found another anime to watch...

[Lain94]

Preface:

I will admit that I did a major goof up awhile back when I was removing the boards for recapping. I had accidently while being in a hurry and not paying close attention accidently put one of the boards on the wrong way (right orientation but shifter to the right by one pin margin to where one pin was not connected and the others shift over by one). I realized this mistake when turning on the tv and not getting vertical deflection and smelled a horrid burning smell emanating from the tv. I quickly turned it off and fixed the mismatched board and all seemed to be well after that....for awhile. Unghh well I am not making that mistake ever again.

I used my CRT tester on this tv as well. No shorts in the CRT were found and WOW are the color guns strong. This tv was certainly not used much. Sadly, I ran into another issue with this tv recently when I tried to turn it on and adjust purity and convergence for it.

First off I am not longer getting vertical deflection just a horizontal line. But it gets worse, I turn the tv off quickly and after inspecting the tv I notice a burnt/shorted carbon comp resistor (I tested it to verify it was bad) The resistor was on the horizontal output board just above the high voltage cage which houses the flyback. So I replace the resistor with a high quality metal oxide resistor of appropriate wattage and value.

I turn the tv on again and this time I get nothing at all, no filament being lighted up even. Just the hum coming from what I think is the high voltage area. This leads me to believe the issue is regarding the voltage somehow being low or off due to a bad winding in the flyback or perhaps the Double or tripler went bad.

I don't have a high voltage probe yet to test the voltage output so verifying voltage output will have to wait. I did try resetting the circuit breaker switch which I am unsure of if it actually tripped. This did not fix the issue.

I am at a loss at this point as to what may have went wrong exactly.

[Lain94]

No further knowledge as to what caused the CRT to no longer light up. I am assuming yoke burnt up and TV is a goner. I should have just left it alone and gave it to someone.

[Lain94]

Well I found out at least part of the issue and should have suspect this sooner. It looks like the power supply board on this tv has a thermistor and posistor for controlling the automatic degaussing. The thermistor appears on visually but....the posistor will a picture is worth a thousand words.

The posistor was found dangling loosely between the two leads and fell off as I touched it. Somehow this failed but I do know thermistor tend to fail often on old tvs so I would assume the same is often true for posistor as they are related components.

https://imgur.com/a/PKW0Y8F

[Lain94]

I ordered and obtained the original heathkit manuals and books for the tv including the partlist. The partlist is of not much help though it appears what actually failed was the thermistor but other than a heathkit part number, the part list provides no ohm values whatsoever and the schematic I already have had not given any other info either. How do I find out what the ohm value was supposed to be for this thermistor? Any place to cross reference heathkit part numbers?

[Alex KL-1]

Originally Posted by Lain94

Preface:

I will admit that I did a major goof up awhile back when I was removing the boards for recapping. I had accidently while being in a hurry and not paying close attention accidently put one of the boards on the wrong way (right orientation but shifter to the right by one pin margin to where one pin was not connected and the others shift over by one). I realized this mistake when turning on the tv and not getting vertical deflection and smelled a horrid burning smell emanating from the tv. I quickly turned it off and fixed the mismatched board and all seemed to be well after that....for awhile. Unghh well I am not making that mistake ever again.

I used my CRT tester on this tv as well. No shorts in the CRT were found and WOW are the color guns strong. This tv was certainly not used much. Sadly, I ran into another issue with this tv recently when I tried to turn it on and adjust purity and convergence for it.

First off I am not longer getting vertical deflection just a horizontal line. But it gets worse, I turn the tv off quickly and after inspecting the tv I notice a burnt/shorted carbon comp resistor (I tested it to verify it was bad) The resistor was on the horizontal output board just above the high voltage cage which houses the flyback. So I replace the resistor with a high quality metal oxide resistor of appropriate wattage and value.

I turn the tv on again and this time I get nothing at all, no filament being lighted up even. Just the hum coming from what I think is the high voltage area. This leads me to believe the issue is regarding the voltage somehow being low or off due to a bad winding in the flyback or perhaps the Double or tripler went bad.

I don't have a high voltage probe yet to test the voltage output so verifying voltage output will have to wait. I did try resetting the circuit breaker switch which I am unsure of if it actually tripped. This did not fix the issue.

I am at a loss at this point as to what may have went wrong exactly.

I don't know this model, but some things I wonder if occurred:
I'm have the impresion that the inverted board can be shorted with the inversion since (is the vertical output one?), when you changed the burnt resistor, the TV cannot work anymore. I wonder if this board don't have making shutdown or blowing fuses on TV (or messing with driver/oscillators/controllers).
Certain TV models derive vertical power from flyback, also, to be in mind.

[Lain94]

There are several possibilities with the Heathkit tv...I just hope it is nothing major from when I put that one board on off by one pin, it was right side up though. Shorting was likely happening to some extent when that happened, hopefully no damage was done to the yoke. Once I get a New old stock thermistor on and recap all old electrolytics I will be able to rule at least bad capacitors and the thermistor out. Without the thermistor however, it is certain that this tv will not turn on until then sadly.