25K7195 ONly a line visable

dieseldogpi

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Picked up a WG 25K7195, powered it up and this is what I got. I plan on doing a cap kit, but there is probably something more the problem here right? I see movement within the line, but the adjusting pots accomplish nothing
 

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Is this one with the remote board? Is it attached? are any of the pots broken?
 
Yes, the remote board and other pot locations are pictured below. How can I tell if the pots are broken (besides physical damage)? Could it be anything else?
 

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The vertical IC's have been known to go out on these. (IC3 if I recall)
Do a cap kit too while your at it if it looks original.
Solder joints probably need going over as well.

And clean it. :)
 
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wow ive only ever seen one other monitor with that kind of remote board.


first off make sure the yoke connectors are seated and not burnt up. Check thr yoke connector pins for bad solder...

follow the traces away from the yoke pins and see if you see any bad/cracked/burnt traces and or solder. the large resitors in the r101 area run hot. Regardless of how r101 traces look undsolder it, check the traces, and resolder, If the trace is black under the solder then scrape it clean then resolder, If its burnt too badly then youll need to rebuild the trace with some leftover cap lead, old desoldering braid, or wire. wiggle all large resistors etc while looking at the solder side to help locate any cracked traces etc


usually if the ics go bad you can see it, however yes it could be one of those too... id check this obious stuff first


lets hope you have better luck with this then i have had in vegas this week.... its dasmn near bled me dry heh
 
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Sounds like a plan. what is the best way to clean it? Just electronic spray cleaner?
Also, just looking at it I noticed at the end of the tube that goes into the neck board, it seems it might have broken a bit. The first two pics, although badly lit, are of the area that seems broken. The last pic is of my K5500, it shows there is a little plastic housing at the tip. Looking into the neck board, I can see the piece of broken plastic. Is this going to cause a problem? Thanks again guys.

really sorry about the bad pics, can't seem to get a better shot. But it is definitely broken, I just pulled the broken piece out of the neck board. Little worried this dooms the monitor.
 

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Clean with a clean 1" bristle paint brush and either a vacuum cleaner or can of air to get all that dust and dirt off.
 
Nah..... as long as the glass isn't broke you're good.
Just be sure to line the pins up properly with the neckboard before pushing it back on.

Very common for them to become brittle and fall apart on those.
 
Any one of the vertical trimpots on the main board of the 7195 could have a crack in it that could cause "no vertical deflection" symptom. If capacitor C51 is bad that would do it too.

Most likely though is the vertical output IC bolted to that heat sink is bad. Replace like numbered part with like numbered part.
 
Look at the numbers on the chip presently installed in your board. Wells used 4 different vertical output IC's and you must replace with the number that's in it now.
 
OK, a little update on this. I replaced the IC in IC3. I ordered the one that is listed in the manual, UPC1378. Got it, took out the old one, soldered in the new one. Still same problem. BUT...I think it was the wrong IC. The old one was numbered 7831 (I think), and was wider. The new one, although the same number of leads, is not wide enough to be screwed to the heat sink. Again, all I'm getting is a line across the screen. As before, there is movement within the line, and adjusting pots (ie. brightness) does have an effect on it, so somethings working. Could it still be the IC? I haven't done a cap kit yet, I plan on it tonight when I get home from work, but I have a feeling that the caps are not the problem. Any input would be greatly appreciated, I'm too green at this too really have a grasp on whats going on. Thanks guys.
 
Could it still be the IC? I haven't done a cap kit yet, I plan on it tonight when I get home from work, but I have a feeling that the caps are not the problem.

Any one of the vertical trimpots on the main board of the 7195 could have a crack in it that could cause "no vertical deflection" symptom. If capacitor C51 is bad that would do it too.

Most likely though is the vertical output IC bolted to that heat sink is bad. Replace like numbered part with like numbered part.
You should try replacing C51 or just to a cap kit altogether. It will probably be the best $10 spent.

Some of the newer IC's are a bit smaller than the older ones. You would need to drill a hole in the heat sink so you can bolt down the smaller IC. As long as the part number is the same it should be the right replacement part.
 
You should try replacing C51 or just to a cap kit altogether. It will probably be the best $10 spent.

Some of the newer IC's are a bit smaller than the older ones. You would need to drill a hole in the heat sink so you can bolt down the smaller IC. As long as the part number is the same it should be the right replacement part.

Yeah, I will do a cap kit tonight, I have it already. I just wanted to replace the IC, then check the monitor again, so if it stopped working completely I would know it was the IC. Now as far as it being the same number IC, the original IC was not the same number that was listed in the manual. The manual calls for a UPC1378, which is what I got, the one that I took out (which I couldn't see until it was completely out) was a different number, 7831 (I think).

And about drilling holes in the heat sink, how the hell do you get that sucker out? Maybe my soldering iron wasn't hot enough, but I could not melt the solder points on the heat sink itself. Thanks again for the help, I love this crap.

Oh and C51?? Thats not listed as an electrolytic cap. manual says "Tan .68 10% 35v" whatever that means
 
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OK, a little update on this. I replaced the IC in IC3. I ordered the one that is listed in the manual, UPC1378. Got it, took out the old one, soldered in the new one. Still same problem. BUT...I think it was the wrong IC. The old one was numbered 7831 (I think), and was wider. The new one, although the same number of leads, is not wide enough to be screwed to the heat sink. Again, all I'm getting is a line across the screen. As before, there is movement within the line, and adjusting pots (ie. brightness) does have an effect on it, so somethings working. Could it still be the IC? I haven't done a cap kit yet, I plan on it tonight when I get home from work, but I have a feeling that the caps are not the problem. Any input would be greatly appreciated, I'm too green at this too really have a grasp on whats going on. Thanks guys.

You got the wrong IC. You should have ordered the number of the one that was in it already. Sounds like it was an LA7831 (which is for 25" monitors). Randy Fromm even wrote an article about this very thing in the early 90's. People were replacing the IC's with the wrong ones. Get an LA7831 for your monitor.

1. Recap monitor

2. Install correct vertical output IC. Be sure to put white silicone heat sink grease on the back of the new IC. Otherwise it will overheat in a few minutes and die.

3. Reassemble monitor and test it out. Make sure you're running it from an isolation transformer.

And remember, this is a 25" version of a k7000 monitor. You use the k7000 manual in conjunction _with_ the schematic here at this site:

http://jstookey.com/arcade/WG_25k7191/
 
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I'm gonna run home during lunch to check the old IC. I could be wrong on the 7831, because I looked up the LA7831 on MCM and it was a 10 pin. This is a 7pin IC. I will post when I get back in from lunch. Thanks.
 
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