Advice Admiral 12X12 20Z1 low contrast w/ lines

[rca21d645]

Originally Posted by Yamamaya42

I have the same CRT in my FADA, but it's hooked in differently, the cathode on mine is grounded, and video fed into G1.

The voltage readings for each pin on yours is listed on the SAMS, also you need to be sure you have a good video to the cathode, not sure what it will be for yours, but mine was about 39v PtP, my guess yours should be about the same, but inverted, since its going to the cathode, as opposed G1 on mine.

You also need to find a way to check that you have good HV, if it is low, it may be causing you problems, and/or a misaligned / weak ion trap.

But however, if all checks nominal, you most likely have a very tired / dead CRT, and must find another, and most likely end up paying way too much to some fool on Ebay, like.

https://www.ebay.com/itm/Vintage-Syl...-/174589841825

Is the 12LP4A a common tube, would it be possible to find someone willing to sell one on here?

[Yamamaya42]

Originally Posted by rca21d645

Is the 12LP4A a common tube, would it be possible to find someone willing to sell one on here?

All you can do is ask in the classified area, and hope, and you do not have to limit yourself to a 12LP4A exactly, if you find a 12LP4, ( same CRT, but without the gray face ) you could use that, or some other compatible one, for example a 12KP4 will work, just leave off the ion trap, I'm sure there are others that can work as well.

Also, when I was bringing up my FADA, I did not want to risk hurting my 12LP4, so I used a 8YP4 Test CRT that I got from ETM, not exactly the right one to use, but it worked for me with some minor mods!

you can see it all here :p
http://videokarma.org/showthread.php?t=272325

[rca21d645]

Originally Posted by Yamamaya42

All you can do is ask in the classified area, and hope, and you do not have to limit yourself to a 12LP4A exactly, if you find a 12LP4, ( same CRT, but without the gray face ) you could use that, or some other compatible one, for example a 12KP4 will work, just leave off the ion trap, I'm sure there are others that can work as well.

Also, when I was bringing up my FADA, I did not want to risk hurting my 12LP4, so I used a 8YP4 Test CRT that I got from ETM, not exactly the right one to use, but it worked for me with some minor mods!

you can see it all here :p
http://videokarma.org/showthread.php?t=272325

Thanks for the advice, I'll try the classifieds.

[rca21d645]

Here's what it looks like with the retrace supression modification. The lines aren't really visible so long as the brightness is turned all the way down, however if I turn the brightness up at all they appear. I also noticed that the longer I leave the set on, the more visible the lines become. I'm guessing this might be an issue with the high voltage?

[rca21d645]

I checked the horizontal output tube and the HV tube and both measured bad on emissions. I was able to swap the 6BG6 with another that tested ok, but I don't currently have another 1X2 tube to swap for the HV. I also changed a resistor on the HV which measured as 446k in the spot where a 1 meg resistor should be, so I put in a 1.1 meg resistor that I had on hand. The picture looks significantly better but now the audio is worse, with a fairly loud hum drowning out the audio, much more than it did originally. Video of it working here: https://drive.google.com/file/d/1rF1...ew?usp=sharing Photos are with the brightness turned all the way down.