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Toshiba PF & PD-1843 no picture / video (it's becoming a trend!)

kazuo

kazuo

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I came into possession of a PF that was sold to me as working (with video proof); long story short, when I got it the chassis had suffered physical damage (but the tube itself seems to be intact). After purchasing several secondhand PF-1843 chassis and testing, I was unsuccessful in getting any image on the screen. I could hear the monitor/chassis humming and clicking, but I couldn't get any picture, and no OSD. I couldn't tell for sure, but the neck glow also seemed to be very, very dim. At this point, I was (and still am) a little out of my element since I am far from an expert on monitors & chassis, so I sent the two boards off to PNL to have them looked at.

A week goes by, I get a call from PNL: one of the boards works perfectly fine. The second one had an issue, and they've fixed it. 8|

Now I'm struggling to understand what to do next. I couldn't get an picture with EITHER of those chassis, including the one that is confirmed working, so... what do I do now? I tried checking resistance across the H/V windings on the yoke, and got very low resistance on both (I'll double check the numbers and update the thread), but no OL or short reading.

Does anyone have any ideas on where I should go from here?

Thanks very much!
 
My New Net City with PD1843 chassis and Tosh tube has the following specs.

Lh: 0.30 mH
Lv: 14.8 mH
Rh: 0.9 ohm
Rv 8.2 ohm
 
HMM, thanks @BuddyC! That seems somewhat in line with what I got:
R,B (I assume this is probably Rh) - 0.5-0.8 ohms (it would fluctuate slightly, but usually around 0.8 ohms)
G,Y (I assume this is probably Rv) - 8.0-8.5 ohms (also fluctuated, but usually settled somewhere in that range)

I got these measurements where the wires connect to the yoke, not at the connectors since my probes wouldn't fit into the connectors.

Curiously, where did you measure Lh and Lv? Sorry if that's a dumb question, kind of my first rodeo. ;)

Thank you!
 
Looks like your yoke is in good shape.
Lh and Lv is inductance measurement (in millihenry - mH)
Some multimeters have this option, but I bought a cheap tool from ebay that measures inductance and capacitance + more snacks.
Good tool to have since I have done a couple of yokeswaps and inductance needs to be pretty spot on when trying out different chassis on different yokes for good results.

You measure inductance the same way as you measure resistance, but with a inductance meter.
I recommend you test that tube with a rejuvinator so you can rule out the tube itself.

I have the B&K 467 and it’s a fantastic tool for troubleshooting tubes. 🤘🏻
 
Ps. Did you try to turn up the screen pot on the flyback? Maybe it was just turned way to low? Fingers crossed it’s a easy fix.
 
 
BuddyC said:
Ps. Did you try to turn up the screen pot on the flyback? Maybe it was just turned way to low? Fingers crossed it’s a easy fix.
Click to expand...

Not yet! I'm getting the chassis boards back tomorrow and will give it a try. Fingers crossed!

I unfortunately do not have access to a rejuvenator, and don't know anyone local to me who has one. Well, I can think of one guy, but he doesn't like taking his tools out in the field (understandable).

Thanks again for your help.
 
kazuo said:
Well, I can think of one guy, but he doesn't like taking his tools out in the field (understandable).
Click to expand...

Most rejunevators literally come in briefcases. They're meant to be taken in the field!
 
I'm aware! But these things are getting expensive and harder to find... so I kinda get why he doesn't wanna bring it out. I'm sure a non-zero factor is that it's a seller's market (CRT repair that is), so he's happy to make you do the legwork. ;)
 
UPDATE! It works! Kind of.

So I plugged in a TX1 (and a TX2) to test, since I don't have a cab nearby and using a SuperGun would be a massive hassle... and I'm getting some weirdness with the image.
  • TX1: OSD is perfectly visible, screen is extremely dim. I am guessing this might be related to the settings corruption bug that Dewman has documented a fix for. Will try this later.
    • I used the VGA port on the TX1 and plugged the chassis end into the 3.0V header (I assume that's correct since it should be 15K RGB?)
  • TX2: This is the more concerning one - the picture is SUPER out of focus, and the entire screen looks like someone ran a Earth magnet across it. The OSD is barely legible. Degaussing didn't help. 720p DVI out works perfectly fine on a HD display.
    • I set the dipswitch on the TX2's I/O header for 31K/VGA and plugged a DVI->VGA cable into the TX2, with the VGA side plugging into the chassis end on the 0.7V header (guessing this is correct since it is 31K VGA?)
Not super concerned at this point, since I suspect these issues can be resolved (or else it's more user error with me plugging stuff into the wrong ports, haha), so curious what you all think.

Also, does anyone know what that 3 position switch next to the flyback is for?

Thanks all!
 
Noted, thank you! Didn't seem to make much of a difference unfortunately. :( It now basically looks the same way the TX2 did.

Here's some pics, kind of hard to reproduce because CRTs and my phone camera is terrible, but I tried my best. The best way I can describe it is the red and blue guns (?) seem to be "blooming" at the corners. I tried messing with the settings (including a reset), but didn't seem to help too much... couldn't find a sweet spot where the colors looked even halfway decent, and the focus is totally messed up. I'm going to try messing with the focus on the flyback next while I wait to see if anyone has ideas on the color issues.

-6QqPK-Q.jpeg
 
Is that just not in really bad need of being degaussed?
 
rewrite said:
Is that just not in really bad need of being degaussed?
Click to expand...
Could also be a purity issue its not totally far fetched that the tubes purity rings or the yoke moved slightly at some point and its enough to throw it off.
Would start with the easy stuff like demag/degauss

And absolutely worse case is that maybe the shadow mask or something on or around the tube is some how magnetized.

Can help to post a photo of a pure white raster or a solid color too but not everyone has the ability to do that easily
 
The built-in degauss is definitely working but not fixing the problem. I've waited for that timer to run down so I could mash degauss more times than I care to admit. :( Maybe I just need a wand?

On the solid white screens like the Naomi logo, SEGA logo, etc., it's really hard to reproduce the problem. It's somewhat visible but it's way more obvious when there's multiple colors on screen. I can try to get something like a CPS2 hooked up that will show color bars etc. but I'm a little space constrained at the moment and limited as far as what I can plug into this display.

Pics from the side, before I started messing with the color settings:
OyLR3v8l.png

V7ziYMWl.png


Front pics, after messing with colors for a bit. The weirdness with the colors being blown out was less visible from the sides at this point, but still obvious:
W0fiTPWl.png

d1qm4Rol.png


I do have an extended remote, so I am able to access the advanced settings if needed.

Thanks all!
 
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honestly that COULD be a purity issue, if you can get a more powerful demag wand try that too ofc.
If its a purity issue its not going to be remote related you have to adjust one of the rings on the neck of the tube resposnible for purity OR have to readjust the yoke (which you shouldnt have to move the yoke but can cause purity issues if its out of alignment some how)

If the aperture/shadow mask grill is damaged internally you can get issues like this too because the beams cant be split and land on the phosphor properly.
If you bump the tube does the behavior change?
 
GeekMan1222 said:
Could also be a purity issue its not totally far fetched that the tubes purity rings or the yoke moved slightly at some point and its enough to throw it off.
Click to expand...
I guess this begs the question: is the yoke glued down and the purity rings locked in place @kazuo ? If they are, I don't expect they'd have shifted during shipping.

Which would leave it was either this bad before shipping, or it's likely something like the aperture/shadow mask and she's landfill bound.
 
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It should be, but the truth is I don't know for sure. I'm a little out of my element, so please forgive my lack of experience on this. Happy to start rattling things around back there if someone can give me some basic pointers on what I should be looking for.
 
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