How to tell if chassis has already been recapped?

ccie38296

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I just purchased a game from another KLOV member. The monitor on the game (a K4906) was not displaying a good image — it was showing significant and rapid "in/out" waviness with both the game board being sold and another board the seller had on hand. His opinion was that it needed a cap kit and filter cap, possibly a voltage regulator. In short, he said that this board had not been serviced while in his possession (I don't know how long that was) and he recommended sending it out. We struck a deal on the game given the monitor condition, so now I have it.

After getting it home, I inspected the chassis a little more closely. I notice a few things:
1. The neck board wire that goes to the strap around the tube/aquadag has previously been cut and wire-nutted back together
2. The flyback says "Made in China" and has a model number sticker MSH1FAP08 on it, the same model sold by APAR for this chassis
3. The caps all "look" fairly new (visually consistent, non-bulging) and are all Nichicon 105c caps, including the filter cap which also matches (visually and in rating) the one APAR sells for this chassis. Visually they match the caps in other kits I have on hand from APAR.
4. The chassis isn't sparking clean, but it's also not "40 years of grime" dirty. I have not yet removed the chassis from the frame to inspect solder or anything yet.

So it *looks* to me like maybe it has been recapped and had the filter cap and fly replaced already.

I haven't had a chance to hook the monitor up to my TPG yet or do any other diagnostics. At this point, I'm just curious if the consensus would be that it probably has already been recapped, or if the above clues don't really mean anything. Or is there any other good way to tell for sure, short of removing and testing each cap? The Made In China fly and the Nichicon 105c caps "seem" like a dead giveaway to me but I'm still pretty new to this stuff…

Thanks!
 
I don't really understand why people are changing filter caps. also most people think servicing a monitor is literally just replacing caps and flyback and just neglect everything else.

my ugly not very aesthetic K4900 servicing video:
 
4900's didn't come from the factory with Nichicon caps
I wasn't able to discern the OP lol

the original caps are mostly grey and have some kind of green sealant on the top. they're significantly larger than the replacements.
 
OK thank you for the responses. Looks like someone did some replacement on this chassis at some point. I'll keep investigating.
 
You can also look at the date codes on the capacitors if you could read them. A company I worked for changed out all capacitors on these cable TV boxes if they were more than three years old.

I've heard that most reputable repair guys will replace them if there's any question about them because you're paying for that, and their service. If I can tell they are newer than 3 years old and everything works fine, I'll ask the customer if they still want a cap kit done or no (which hasn't happened to me yet, they've all been originals, very old, or weird Amazon ones). If they are over 3 years old, or they are the Amazon caps with no date code, I'll replace them and I will do an automatic cap kit anyways.

Nichicon caps have an easy date code to read starting with the year than the month. In the attachment below, the date code is the 26th week of 2014 (Julyish 2024).

4BB4OD2box.jpg

-Pat
 
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I recapped a G07 recently and replaced all cap, regardless of 1/3 of them being previously replaced. Not all were 105 and I had no history or age, so it made sense. Now I know everything is current and solid.

As others have said, look at the cap dates, if they're present.

Scott C.
 
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You can tell if a component has been replaced from the solder job.

When these boards were manufactured at the factory, they were wave-soldered, meaning the parts are populated on the boards, then the boards are passed over a pool of hot tin, which solders everything in one shot.

When parts are replaced, you can see that the solder has been disrupted. Even if it's a clean job, it still won't look like the original wave soldering.

Also, what mecha said. If the chassis is working, there's no need to replace the filter caps. I also don't replace the flybacks either, if the monitor is working.
 
You can tell if a component has been replaced from the solder job.

When these boards were manufactured at the factory, they were wave-soldered, meaning the parts are populated on the boards, then the boards are passed over a pool of hot tin, which solders everything in one shot.

When parts are replaced, you can see that the solder has been disrupted. Even if it's a clean job, it still won't look like the original wave soldering.

Also, what mecha said. If the chassis is working, there's no need to replace the filter caps. I also don't replace the flybacks either, if the monitor is working.
yeah it's a pretty exceptional scenario when you kill a K4900 flyback lol

if you catch the video you'll see I remove flybacks because you don't want to accidentally bust the anode stem. makes the board way easier to handle too.

those little paper clip jumpers where you slide the deflection board into that plastic clip are must solder items. I believe I demonstrated one handed and awkwardly the proper way to put the board back in..
 
You can also look at the date codes on the capacitors if you could read them. A company I worked for changed out all capacitors on these cable TV boxes if they were more than three years old.

I've heard that most reputable repair guys will replace them if there's any question about them because you're paying for that, and their service. If I can tell they are newer than 3 years old and everything works fine, I'll ask the customer if they still want a cap kit done or no (which hasn't happened to me yet, they've all been originals, very old, or weird Amazon ones). If they are over 3 years old, or they are the Amazon caps with no date code, I'll replace them and I will do an automatic cap kit anyways.

Nichicon caps have an easy date code to read starting with the year than the month. In the attachment below, the date code is the 26th week of 2014 (Julyish 2024).

View attachment 768847

-Pat
Thank you! I was not aware of date codes on the caps. I will check them out. The board has definitely had the caps (including the filter cap and flyback) replaced. After watching the videos linked in this thread I can see the filter cap on the chassis is much smaller than the originals (and also a Nichicon). The flyback was clearly replaced too with the one APAR sells. The guy I bought the game from didn't seem to know the history of the chassis, so no idea when this was all done. Hopefully the date codes will tell me something.

After some air dusting, I also found the chassis board is much cleaner than I originally thought. Very clean. I haven't pulled it from the frame yet to look at the soldering or those jumpers.

Thanks for all the info and tips! I have a couple of other 19" monitors that I had been planning to use to replace a couple of LCDs in other machines (a Pentranic 1119/CH288 and a Kortek KT-2001). I'm going to test those with this cab as well and if one of them looks good I'll probably just install it on Smash TV and then investigate this K4600 as time permits.
 
OK, date codes from the caps on the chassis are all from mid-2020. I'm guessing an owner previous to the one I just bought it from must have done that and probably the fly back at the same time.

With the caps only being about 4 years old, I will work under the assumption that they are probably OK at least for now and focus on the other reconditioning steps in the videos from zenomorp and mecha. Hoping to at least get the TPG on it tomorrow so I can confirm it isn't just something wacky with the PCBs the seller was using to test.
 
there's seriously nothing wrong with those caps. anyone suggesting such is probably only interested in selling you more caps that will achieve the same end result.
 
In addition to the date code, you can also invest in an ESR meter and then actually KNOW whether the caps are good or bad. Quality meters can even test them in circuit. Best $130 I ever spent!
 
there's seriously nothing wrong with those caps. anyone suggesting such is probably only interested in selling you more caps that will achieve the same end result.
The seller wasn't trying to sell me caps or services. I think more likely he didn't know what was wrong with it and/or didn't realize it had been done already and suggested it as a default action.

Either way, it's mine to figure out now, so I appreciate the tips and pointers. This is my first 4600 and I'm definitely a beginner with monitor work so the comments have been really helpful.
 
There are two schools of thought in replacing caps in this forum.....

One is to just replace what is only broken or out of spec. This would apply to commercial environments where time and money are a consideration. Having the experience and correct tools like ESR meters to test bad caps is a must.

Another is the camp I'm in. In a home environment I believe while the monitor and chassis are out rebuilt it. I don't have time to keep pulling these 300 lbs cabs out to replace caps or flybacks as they go bad. When I take the time to pull the monitor I do a full rebuild so I know it's good to go for another 40 years.

Now with that said there are several factors at play. If your solder skills are not up to par replacing parts that are not needed can open you up to addition troubleshooting issues. Using sub par replacement parts can make things worse as well. And knowing what parts to replace and which original ones to leave alone is a valuable skill in this hobby. G07 flybacks... Most need replaced. 20EZ flyback... Original's are best left alone unless they are truly bad. I'm also a big fan of cleaning the tube and chassis. Can't stand working in dirty chassis when doing a recap.

And I always cringe when I power up a chassis and I'm done doing a cap kit chassis rebuild.... The first power up is the scariest. Lol
 

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OK, date codes from the caps on the chassis are all from mid-2020. I'm guessing an owner previous to the one I just bought it from must have done that and probably the fly back at the same time.

With the caps only being about 4 years old, I will work under the assumption that they are probably OK at least for now and focus on the other reconditioning steps in the videos from zenomorp and mecha. Hoping to at least get the TPG on it tomorrow so I can confirm it isn't just something wacky with the PCBs the seller was using to test.
For my personal monitors, if the monitor looked okay (straight picture, no jailbars etc) I wouldn't recap it.
 
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
 
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