View Full Version : Zenith 25LC20QS back up and running


TUD1
04-26-2018, 06:16 PM
Finally got this chassis back and installed in the cabinet with the 1963 Zenith picture tube from that old metal cabinet set. Beautiful colors, but not very bright due to the old school phosphors in the tube. Correct me if I'm wrong, but isn't the green phosphor the sulfide? Or rare earth? I forget. But anyway, just thought I'd post this thing and show it working. Putting it back together involved quite a few four letter words, but luckily I had help so it made it much easier to work with in this teeny-tiny house.

Popester
04-26-2018, 10:07 PM
It's just great to see anything that vintage working still today. I would think the picture would be somewhat brighter than that though.

mrjukebox160
04-26-2018, 10:22 PM
When you set this up were you able to get lines on all 3 colors in service mode? If you have the diagram I would check the voltages and waveforms at the CRT socket. Looks pretty dim for a good CRT even if it's an early one.

TUD1
04-26-2018, 11:41 PM
The camera makes it look slightly dimmer than it is in real life, and on top of that, the CRT has woken up a little since I last used it. I set it up per the factory manual. I keep the brightness and contrast pretty low on this set. Puts less stress on the already high hour chassis.

zeno
04-27-2018, 05:03 PM
I dont see any green but that may be the scenes. IMHO old sets
always lacked in red but B&G were good. The rest of the pix looks
very good. Follow Zenos old rule " make it as perfect a B&W set
as you can BEFORE turning up the color".

If grey scale is VG+ go to the demodulator stage. I once had one
of these Zenith round sets, maybe not the same chassis. Outdoor
scenes showed wonderful green trees. Also had an early Admiral &
it was the same. Keeping brite & cont down along with very little
room lighting is the norm. Even new they could never light up a room.
It wasnt til Chromacolor that things really got better.........

73 Zeno:smoke:
LFOD !

TUD1
04-27-2018, 07:35 PM
I always make sure my sets have good greyscale before I put then into service.

radiodocs
04-30-2018, 03:36 PM
What kind of picture tube is that, Dave? An FJP22 or something earlier?

John