View Full Version : 21FAP4 with a Predicta test, it works but...


madlabs
12-11-2016, 03:17 PM
HI All,

Well, I finally got around to hooking up the 21FAP4 to my Predicta Holiday, chassis G4242L. I got it a few months ago from the ETF and is supposed to be NOS. No sign of wear on the anode or pins, so I think it is. The only change I made was that I swapped G1 and G2, which are pins 2&3 of the connector that plugs into the chassis. It works but...

First, an embarassing admition: I connected the video output wire to connection point 19 instead of 20. Ooops! I had no brightness control. All the other controls worked. It was like that for a few minutes. Once corrected the brightness does function but...

The picture is dim and blurry. Constant retrace lines. Contrast and brightness do work but not much range and it doesn't get very bright. The yoke I am using is a little damaged but it worked a week ago just fine, at least in terms of brightness etc. Hard for me to test the pins on the CRT directly as it is face up on the bench. I decided to check the video output voltage as it is directly involved with the brightness circuit, but I can only check it on the board at point 20 and I see 300ish volts! Now, it is supposed to be measured after L14 and be 35V. I've never checked it before but this chassis was playing Honey West last night on a different CRT.

So, is it possible that the tube just needs some time to wake up? Or am I not meeting some electrical criteria? Or is this tube a bust?

WISCOJIM
12-11-2016, 04:57 PM
Any chance you'd combine all your threads on this same set? Nobody is going to want to spend all the time having to locate and read through all your previous threads to help you along the way. All these separate threads are just going to make it way too confusing to follow along and monitor your progress to give you good information as you continue this restoration.

.

madlabs
12-11-2016, 06:10 PM
Sorry if I am creating confusion. My thought was that I had seen the question of will this CRT work with this set in a couple of places and so was hoping that the next person wondering about it would be able to easily find it with a specific thread title. I'm happy to move it, I'll try to figure out how that is done.

Kamakiri
12-12-2016, 11:52 AM
Post the links to the threads you want merged and I can take care of it :)

madlabs
12-13-2016, 10:43 AM
Thanks Kamakari. Can you just delete this thread? I can repost to the other thread if needed.