How to tell if chassis has already been recapped?

[LinguistiX]

Everyone's posting valid points, and even with my ESR meter endorsement, I too would never replace "just" a few bad caps if I've already gone thru the trouble of pulling a chassis and having it on my bench. I'm all or nothing at that point.
My suggestion for the meter was merely so that he's not guessing and taking a shot in the dark in a situation where the chassis' history is undetermined. SOLELY using production dates to decide if a cap is "good" is like the tire analogy above, but in reverse. If a tire has a production date that was only 6 months ago, but visually has a hematoma-like bulge in the sidewall, I'm not driving THAT either
Production dates are merely a clue (a very good one, but an incomplete one nonetheless).
The ESR meter COMBINED with production dates would be the difference between "I think" versus "I know" they're good.

 

[mecha]

Be careful with the ESR meter. Great for troubleshooting a specific issue and getting something back up an running. The main problem is, the part may be good today, but if it's 40yrs old, the chance of it failing tomorrow is much higher than a new high quality part.

Here's my analogy: ESR = Tire Pressure Gauge. A tire pressure gauge can tell you the tire is holding air, but can't tell you how old and dry-rotted the rubber is. Most tire places will not service any tire where the date code is 10yrs old or more. Even if an original tire on a 1969 Corvette was holding air, I wouldn't put my daughter in the car and drive across the country.

If you pull the chassis out: clean it, replace the electrolytics, clean the connections, etc.. Step up and get the quality parts too.

~Brad

it's funny, the analogy I use for cap replacement is a set of tires on a car. you replace all 4 of them at the same time, right? lol

like @KaBoom1701 has suggested, it was a different time some 30+ years ago. when people were dumping quarters in games, if the top money making game went down, that's money lost. couple that with an expensive fix through a shop or distributor, that makes the net loss greater. I know old timers that will swear the only part you need to replace on a K7000 is C57 (which is the B+ filter cap and the most common part to fail on those). if you leave all the other ones original and let time and wear do their thing, you'll probably have a myriad of geometry issues. a guy I know brought monitors to me to fix last week, one of the tubes needed rejuvenation. so I did that before the surgery, it had vertical linearity issues, and they wouldn't adjust out. after doing my signature K7000 service the monitor looked immaculate.

my jedi master told me in the very beginning that 80% of video game failures is monitors. through my efforts the last 16 years I'm certain I knocked that statistic down to something like .000153%. those K7000s took me 3 hours to do and barring flyback or voltage regulator failures they're probably going to work for a long time. (like the hundreds of K7000s I've gone through)

 

[ccie38296]

OK I made some headway today. First, hooked the monitor up to my TPG, thinking maybe it was just having trouble syncing with the game board. After some adjusting of pots, I got the image to "mostly" settle down and not look too bad, although it is too wide (need to get a tool to adjust the width coil) and it had a slow wave of "bowing" crawling up the image, taking 10-12 seconds to get from the bottom of the image to the top. You can see it in the images below.



The image was tilted as well — twisted the yoke a bit to fix that and I think there's some minor convergence problems but the main issue is the "wave" passing through the image.

Then I hooked it back up to the game just to see what would happen now that the monitor was better adjusted. Once I tweaked V.HOLD to get it to stop rolling, the image was sort of stable, but had a very rapid (maybe 10 times per second?) in/out wobble most noticeable along the edges. Wide, bright horizontal bands move from the bottom of the image to the top at the same very rapid rate along with the wobbling sides. Here is a video showing what I'm attempting to describe:

I also grabbed some pictures of the chassis. Once I got all the dust off it was obvious it had been cleaned when the caps and flyback were done, apparently a couple years ago. No clue if any of the other preventative maintenance stuff described in the videos posted to this thread have been done, I haven't removed the chassis from the frame to inspect solder yet.







Any suggestions on where to focus, considering that the chassis has been recapped in the last 3-4 years, would be a huge help. Are these kinds of issues likely to be helped by doing some of the reflow on the jumpers and headers? Anything else that would be a good starting point to test or plan to replace?

The help so far is much appreciated!

 

[mecha]

OK I made some headway today. First, hooked the monitor up to my TPG, thinking maybe it was just having trouble syncing with the game board. After some adjusting of pots, I got the image to "mostly" settle down and not look too bad, although it is too wide (need to get a tool to adjust the width coil) and it had a slow wave of "bowing" crawling up the image, taking 10-12 seconds to get from the bottom of the image to the top. You can see it in the images below. View attachment 769109

View attachment 769111

The image was tilted as well — twisted the yoke a bit to fix that and I think there's some minor convergence problems but the main issue is the "wave" passing through the image.

Then I hooked it back up to the game just to see what would happen now that the monitor was better adjusted. Once I tweaked V.HOLD to get it to stop rolling, the image was sort of stable, but had a very rapid (maybe 10 times per second?) in/out wobble most noticeable along the edges. Wide, bright horizontal bands move from the bottom of the image to the top at the same very rapid rate along with the wobbling sides. Here is a video showing what I'm attempting to describe:

I also grabbed some pictures of the chassis. Once I got all the dust off it was obvious it had been cleaned when the caps and flyback were done, apparently a couple years ago. No clue if any of the other preventative maintenance stuff described in the videos posted to this thread have been done, I haven't removed the chassis from the frame to inspect solder yet.

View attachment 769115

View attachment 769116

View attachment 769117

Any suggestions on where to focus, considering that the chassis has been recapped in the last 3-4 years, would be a huge help. Are these kinds of issues likely to be helped by doing some of the reflow on the jumpers and headers? Anything else that would be a good starting point to test or plan to replace?

The help so far is much appreciated!

watch my video. it targets everything you need to know about.

 

[KaBoom1701]

I never trust anyone's cap job.

Except @tron guy and a few other well know monitor repairs dudes in klov I trust no one.

 

[ccie38296]

watch my video. it targets everything you need to know about.

Thank you. I skipped around a bit on it previously but I will watch end to end and go from there. I appreciate it.

 

[mecha]

Thank you. I skipped around a bit on it previously but I will watch end to end and go from there. I appreciate it.

I need that camera apparatus @zenomorp uses

 

[DuffCon]

Agree with what @KaBoom1701 said. To respond to the original question, some things that I look for:

1) cap sizes; modern caps run smaller for the same values
2) telltale clues like larger caps usually have a blob of adhesive to secure them. Replaced ones will be missing the adhesive, but there might be a blob nearby.
3) (obvious) in addition to date codes, a variety of manufacturers will tell you that some have been replaced while others remain

That being said I also fully recap everything I work on so that I know the caps are solid. It pains me to toss a Nichicon, but not when the date code shows me it's 20+ years old!

Also agree with @mecha said about people shotgunning caps and fly backs. I've worked on quite a few k7000s at this point and I've yet to encounter a legit failed flyback. There's a ton of information here and in "mikes amateur monitor repair" on YouTube. Literally k7000 university. @zenomorp has done the world an incredible service documenting this chassis. Spend some time on his channel and you'll know everything you need.

 

[security0001]

OK I made some headway today. First, hooked the monitor up to my TPG, thinking maybe it was just having trouble syncing with the game board. After some adjusting of pots, I got the image to "mostly" settle down and not look too bad, although it is too wide (need to get a tool to adjust the width coil) and it had a slow wave of "bowing" crawling up the image, taking 10-12 seconds to get from the bottom of the image to the top. You can see it in the images below. View attachment 769109

View attachment 769111

The image was tilted as well — twisted the yoke a bit to fix that and I think there's some minor convergence problems but the main issue is the "wave" passing through the image.

Then I hooked it back up to the game just to see what would happen now that the monitor was better adjusted. Once I tweaked V.HOLD to get it to stop rolling, the image was sort of stable, but had a very rapid (maybe 10 times per second?) in/out wobble most noticeable along the edges. Wide, bright horizontal bands move from the bottom of the image to the top at the same very rapid rate along with the wobbling sides. Here is a video showing what I'm attempting to describe:

I also grabbed some pictures of the chassis. Once I got all the dust off it was obvious it had been cleaned when the caps and flyback were done, apparently a couple years ago. No clue if any of the other preventative maintenance stuff described in the videos posted to this thread have been done, I haven't removed the chassis from the frame to inspect solder yet.

View attachment 769115

View attachment 769116

View attachment 769117

Any suggestions on where to focus, considering that the chassis has been recapped in the last 3-4 years, would be a huge help. Are these kinds of issues likely to be helped by doing some of the reflow on the jumpers and headers? Anything else that would be a good starting point to test or plan to replace?

The help so far is much appreciated!

those nichicon caps are the cheapest series they make in the 105c which are all VZ or VR which are 500-1000 hours caps or less not the series we use in our kits and some vendors that sell this junk also use some very old date codes mixed in with newer stuff so check all your date codes as you may have one or more all dried out.

 

[ccie38296]

those nichicon caps are the cheapest series they make in the 105c which are all VZ or VR which are 500-1000 hours caps or less not the series we use in our kits and some vendors that sell this junk also use some very old date codes mixed in with newer stuff so check all your date codes as you may have one or more all dried out.

Oh wow, I had no idea there were different series. Thank you!

 

[andrewb]

Invest in an Equivalent Series Resistance (ESR) meter.

It will allow you to test caps in-circuit, and know how good or bad they are.

In this case, also check to make sure all caps are correct. Correct capacitance and voltage ratings, in the correct locations, and correct polarities. Any one of these things could have been screwed up by the person who installed them. Then measure the ESR of all of them and see if any are grossly out of the expected value.

Also, for the schematics, you need a reference to know what's correct. Don't trust what's installed on the board. Don't trust the silkscreen alone for polarity (as some boards can have backwards silkscreen.) Check each cap against the schematics at least, though you should also not trust schematics blindly, as some schematics have errors. Also, schematics aren't just schematic drawings, there is also the parts list (also in the doc) which contains another set of values and information, and there can be errors between parts lists and schematic drawings. So it can be hard to know which is correct when you find differences, and you often need to look at multiples of original factory boards to figure it out. But it's something you need to always be vigilant of when working on any monitor, as discrepancies DO come up.

Usually you have to go through a process, if you want to be really thorough. Compare an original (ideally working) board to the schematics and parts list, then compare to the board you have. Take notes on any differences. And note what revision PCB you have, as some models have multiple revisions, in which errors may or may have not been fixed. Take notes on everything you find, so if you do another of the same chassis and it's different, you have notes to compare back against.

This is why doing a cap kit is more than just soldering and desoldering a bunch of caps. You need to pay attention to all the details, including anything the last person may have done wrong, and know which revision you are working on, and if there are any special things to know about that revision (which you can do a deep search here for, and see if anyone else have has worked on this same chassis.)

 

[zenomorp]

OK I made some headway today. First, hooked the monitor up to my TPG, thinking maybe it was just having trouble syncing with the game board. After some adjusting of pots, I got the image to "mostly" settle down and not look too bad, although it is too wide (need to get a tool to adjust the width coil) and it had a slow wave of "bowing" crawling up the image, taking 10-12 seconds to get from the bottom of the image to the top. You can see it in the images below. View attachment 769109

View attachment 769111

The image was tilted as well — twisted the yoke a bit to fix that and I think there's some minor convergence problems but the main issue is the "wave" passing through the image.

Then I hooked it back up to the game just to see what would happen now that the monitor was better adjusted. Once I tweaked V.HOLD to get it to stop rolling, the image was sort of stable, but had a very rapid (maybe 10 times per second?) in/out wobble most noticeable along the edges. Wide, bright horizontal bands move from the bottom of the image to the top at the same very rapid rate along with the wobbling sides. Here is a video showing what I'm attempting to describe:

I also grabbed some pictures of the chassis. Once I got all the dust off it was obvious it had been cleaned when the caps and flyback were done, apparently a couple years ago. No clue if any of the other preventative maintenance stuff described in the videos posted to this thread have been done, I haven't removed the chassis from the frame to inspect solder yet.

View attachment 769115

View attachment 769116

View attachment 769117

Any suggestions on where to focus, considering that the chassis has been recapped in the last 3-4 years, would be a huge help. Are these kinds of issues likely to be helped by doing some of the reflow on the jumpers and headers? Anything else that would be a good starting point to test or plan to replace?

The help so far is much appreciated!

Are you using the correct yoke for a 5-pot 4900? Might have been mentioned already but I didn't see it.

 

[mecha]

Invest in an Equivalent Series Resistance (ESR) meter.

It will allow you to test caps in-circuit, and know how good or bad they are.

In this case, also check to make sure all caps are correct. Correct capacitance and voltage ratings, in the correct locations, and correct polarities. Any one of these things could have been screwed up by the person who installed them. Then measure the ESR of all of them and see if any are grossly out of the expected value.

Also, for the schematics, you need a reference to know what's correct. Don't trust what's installed on the board. Don't trust the silkscreen alone for polarity (as some boards can have backwards silkscreen.) Check each cap against the schematics at least, though you should also not trust schematics blindly, as some schematics have errors. Also, schematics aren't just schematic drawings, there is also the parts list (also in the doc) which contains another set of values and information, and there can be errors between parts lists and schematic drawings. So it can be hard to know which is correct when you find differences, and you often need to look at multiples of original factory boards to figure it out. But it's something you need to always be vigilant of when working on any monitor, as discrepancies DO come up.

Usually you have to go through a process, if you want to be really thorough. Compare an original (ideally working) board to the schematics and parts list, then compare to the board you have. Take notes on any differences. And note what revision PCB you have, as some models have multiple revisions, in which errors may or may have not been fixed. Take notes on everything you find, so if you do another of the same chassis and it's different, you have notes to compare back against.

This is why doing a cap kit is more than just soldering and desoldering a bunch of caps. You need to pay attention to all the details, including anything the last person may have done wrong, and know which revision you are working on, and if there are any special things to know about that revision (which you can do a deep search here for, and see if anyone else have has worked on this same chassis.)

yes. look for PNL or distributor stickers on the side. then you'll know you have a lot of fact checking to do. lol

 

[ccie38296]

Another update on this old thread. Everyone's previous comments were extremely helpful.

I finally dug more into this chassis and followed the Randy Fromm flowchart. In the end it turned out that IC501, the STR381 voltage regulator which clearly had been changed on this chassis prior to my acquiring it, was bad. I had about 150V on the B+ when I tested as described in the chart.



I ordered a fresh IC501 from AP&R and changed it out last night. Indeed, one of the 3 pins on the old one was shorted to the case, whereas the new one had no continuity between any of the 3 pins nor from the pins to the case.

I powered the chassis back up, and the image is perfectly stable. Need to adjust the color pots today and the image is really wide so I may just change the width cap rather than mess with the coil which seems frozen up, but the image itself is rock solid now.

Just updating for anyone that finds this thread in the future. Randy Fromm's flowcharts are gold!

 

[ccie38296]

Final update on this one!

I pulled the C365 width cap, and my ESR meter couldn't get a reading but it was marked 154J 400V. Looked this up and found it to be a 15 nF cap.



I found this thread which mentions this value (along with a removed horizontal centering jumper for Williams' Moon Patrol):

WG K4900 Moon Patrol

Anyone have a list of the mods for a WG 4900 to make Moon patrol full screen?

forums.arcade-museum.com

This chassis also did not have the jumper wire for horizontal centering. So I'm thinking this was either factory-installed in a Moon Patrol or had been modified for use with that game.

So I swapped in a 33 nF replacement for C365 from the kit I had bought from @security0001, and also made up and installed a new centering jumper.



After these adjustments, the monitor looks pretty solid.



Thanks for all the help on this one!! I'm calling this chassis repaired and working.

 

[zenomorp]

Final update on this one!

I pulled the C365 width cap, and my ESR meter couldn't get a reading but it was marked 154J 400V. Looked this up and found it to be a 15 nF cap.

View attachment 863780

I found this thread which mentions this value (along with a removed horizontal centering jumper for Williams' Moon Patrol):

WG K4900 Moon Patrol

Anyone have a list of the mods for a WG 4900 to make Moon patrol full screen?

forums.arcade-museum.com

This chassis also did not have the jumper wire for horizontal centering. So I'm thinking this was either factory-installed in a Moon Patrol or had been modified for use with that game.

So I swapped in a 33 nF replacement for C365 from the kit I had bought from @security0001, and also made up and installed a new centering jumper.

View attachment 863781

After these adjustments, the monitor looks pretty solid.

View attachment 863782View attachment 863783View attachment 863784

Thanks for all the help on this one!! I'm calling this chassis repaired and working.

Great!