K4600, no neck glow

mitchschaft

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Alright, I'm still on my quest to get my first machine up and running.

I have the monitor hooked up, the crt powers on and you can feel static on the screen. But the screen isn't black, it's white with no lines. The neck is not glowing.

I get 127v exactly for B+, pins 9 and 10 on the neckboard I get 5v, 475v to pin 7.

I followed the flow chart and I see 2ohms to R422, but I can't find where J402 is to reflow it. If you guys have any pics or anything that would be cool.

I have a capkit sittin' next to me from Bob Roberts. I wasn't sure if that would help or make it worse so I heald off.
Besides all that, do you have any suggestions?
 

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i think you have neck glow, check again with the lights out. i dont think you can have raster without neck glow.
 
Oh, ok. Well, if I do, I atleast learned a lot about how to troubleshit this problem.

I wasn't sure how bright it was supposed to be I guess. I'll check after dinner with all the lights out.
 
Well, the screen is blank, not white. I think I said the wrong thing. It does sound like it fires on and the screen feels static-y.
There's still no neck glow that I can see, even in the complete dark.
 
Schematic for a K4600-series is here: http://technical-department.servegame.com/monitor_schematic_diagrams/wg_k4600.jpg

Even if you only understand 1% of it, start looking it over.

J402 is on the neck board. It should be right next to R411, and quite near R422. There are only two headers on the neck board: J401 (5-wires) and J402 (3 wires).

If you have a static-y CRT, then it sounds like you have high-voltage (a good thing). However, without power to the heater (which causes neck glow), you'll get no image. There really isn't much at all to the heater circuit: the flyback has a secondary winding for 6.3V, wires go to J402, goes thru R422, then right to the CRT socket.

Oh, and I don't think I'd worry about the cap kit just yet.
 
Well, I took out R422, measured it (1.4ohm?), put it back in. Reflowed the J402 connector and nothing changed.

The only thing after the J402 connector is pin 9 on the tube. Which reads 5v so I'm not sure where to go since that's all the flowchart points at. Maybe it's a busted tube :(.

I've got an o-scope if that will help.
 
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Last thing I thought to check was continuity from pins 9 and 10. Both on the tube itself without the neckboard on and with the neckboard on. I have continuity, which would be expected since they read 5v on both ends when it's turned on.

I think I'm doing something or reading something wrong. This should be glowing. I think I get 160v on one of the connector ends with the plug out for J402. I get 5v from the 1st and 3rd pin with the connector plugged in, but halfway out so I can get my meter to the connector pin.

Can you tell I'm new?
 
I've noticed that 4600's for some reason don't always glow as bright as others.

But as to your no picture issue - have you replaced the screen pot on the interface daughtercard? Oh, and do the cap kit. Reflow all the solder on the pins for the daughtercards (both on the chassis and on the cards). Then see what you get...
 
Thank you! I'll get to work on that after these pancakes. I haven't swapped out any pots or caps. I guess I might have to track down a new pot since the bob robert's kit only that the one particular pot. Which pot are you talking about exactly? The one with the long, black handle?
 
Thank you! I'll get to work on that after these pancakes. I haven't swapped out any pots or caps. I guess I might have to track down a new pot since the bob robert's kit only that the one particular pot. Which pot are you talking about exactly? The one with the long, black handle?

No, the blue one with 4 legs that goes on the left daughtercard. Mount it on the back side to make it easier to adjust when in the game...
 
Alright, speant all day doing the cap kit and reflowing every single point on all the boards. It was fun, but I still get the same result. Powers up with static on the front of the tube, no neck glow at all even in complete darkness and the screen is just blank. Check out some pics. A couple of the voltage readings went up a point or 2. B+ is now 129 instead of 127.

If it means anything, when I went to make this post, I left the monitor on for about 30 minutes or so. Went back out to look at the neck and the monitor was shut off. Only way I could get it to turn back on was to unplug it and plug it back in.
 

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Poor Mappy wants to play :(.

Just got this board in and expected it to play blind. But I get nothing. Either the board is toast (sold as tested, working) or something is wrong with my harness/power supply. I wonder if its related.
 

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Looks like your neckboard has been cracked and then repaired. If I were you, I'd go over every single trace looking for another that isn't...
 
Here's a closeup of it. Maybe I should track down a new neckboard. It doesn't look cracked that I can see. Maybe it was scraped down that right side badly.
 

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You can see where the crack is (traced in red) and it looks like some scratches on another trace (circled). Check continuity to be sure...

DSC_0222Large.jpg
 
Something seriously weird is going on. I added more solder to those cut marks on the right. Now I get neck glow, but when I measure pin 10 I get 0 volts, but 4 from pin 9.

So this is what neck glow looks like! I guess I need to get pin 10 to light up. I get an ohm reading of 3.5 between pins 9 and 10 if that means anything.
 

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To measure heater voltage, you should put a probe on each of the 2 H pins on the neck board. The reason you measured 5 at both pins before was because of the bad trace that you then repaired. You were actually getting 0V across the heater as no current could flow due to the broken trace. If the monitor crackles at turn on and then shuts right off, it could be in HV shutdown, which jives with the symptoms you described.

Watch the Randy Fromm monitor videos on youtube... they are long, but a worthwhile endevor :)

cheers
/Tim
 
SUCCESSSS!!

I measured volts between pin 9 and 10 instead of from ground to each pin and get 4 volts.

But the good news is, I get RASTER! The screen is nice and white now. Well, it's actually tinted green, but it's lit up. I gotta take off for a bit and I'll check back later to play with it.
 
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