U5000 shorting 2SC3688 but not 2SC3686 HOTs after flyback install (SOLVED) and wavy image.

[sabrewulf69]

I recently decided to challenge myself with repairing the roughest chassis I had laying around the shop, and finally got it operational, I felt it was best to start a new thread for this question, you can find the original post on this here...

U5000 Adjusting H-hold and Width puts chassis into HV shutdown.

I have a U5000 chassis that has had a very bad time aside from recapping it had a dead or faulty... Q704 HOT Q101 MOSFET U101 PWM IC R104 R106 R117 R107 R100 R105 And as mentioned an missing L103 that someone replaced with a piece of stranded wire and a ferrite bead. After replacing...

forums.arcade-museum.com

Anyway, after getting it operational I took a break until today when I tried to do some fine tuning and adjustment that's when I ran into an odd phenomenon, the top right quarter of the monitor started to completly cut in and out as the monitor warmed up (after about 10 minutes of operation). The rest of the monitor appears to be mostly unaffected by this. When I rebuilt the monitor I accidently replaced the original blown HOT with a used weaker 2SC3686 instead of the stronger 2SC3688, I had the 2SC3686 in the bag with the rest of my 2SC3688s and didn't realize until I started investigating this new issue. I'm not sure if a failing HOT can cause this issue or not, but I decided to replace the used 2SC3686 with a new 2SC3688 to see what would happen and it shorted immediately, which is odd since the 3686 is supposed to be weaker than the 3688. I replaced the flyback when I rebuilt this monitor due to the wire and anode cap having been terribly chewed on by rats. I've read that some new flybacks can blow some 2SC3688s should I try a FJL6920?

 

[JukeboxJon]

I recently decided to challenge myself with repairing the roughest chassis I had laying around the shop, and finally got it operational, I felt it was best to start a new thread for this question, you can find the original post on this here...

U5000 Adjusting H-hold and Width puts chassis into HV shutdown.

I have a U5000 chassis that has had a very bad time aside from recapping it had a dead or faulty... Q704 HOT Q101 MOSFET U101 PWM IC R104 R106 R117 R107 R100 R105 And as mentioned an missing L103 that someone replaced with a piece of stranded wire and a ferrite bead. After replacing...

forums.arcade-museum.com

Anyway, after getting it operational I took a break until today when I tried to do some fine tuning and adjustment that's when I ran into an odd phenomenon, the top right quarter of the monitor started to completly cut in and out as the monitor warmed up (after about 10 minutes of operation). The rest of the monitor appears to be mostly unaffected by this. When I rebuilt the monitor I accidently replaced the original blown HOT with a used weaker 2SC3686 instead of the stronger 2SC3688, I had the 2SC3686 in the bag with the rest of my 2SC3688s and didn't realize until I started investigating this new issue. I'm not sure if a failing HOT can cause this issue or not, but I decided to replace the used 2SC3686 with a new 2SC3688 to see what would happen and it shorted immediately, which is odd since the 3686 is supposed to be weaker than the 3688. I replaced the flyback when I rebuilt this monitor due to the wire and anode cap having been terribly chewed on by rats. I've read that some new flybacks can blow some 2SC3688s should I try a FJL6920?

You have this backwards. The 68 is much more reliable and the 88 is junk unless it the original with the chassis. Its been speculated almost every 88 reproduced was counterfeit or just dosent work im not sure why but this is just the facts. @zenomorp the amateur chassis god has stated in videos he can never get an 88 to work after the orginal has blown, puts a FJL in and no problems. Yes put in the FJL.

 

[JukeboxJon]

I recently decided to challenge myself with repairing the roughest chassis I had laying around the shop, and finally got it operational, I felt it was best to start a new thread for this question, you can find the original post on this here...

U5000 Adjusting H-hold and Width puts chassis into HV shutdown.

I have a U5000 chassis that has had a very bad time aside from recapping it had a dead or faulty... Q704 HOT Q101 MOSFET U101 PWM IC R104 R106 R117 R107 R100 R105 And as mentioned an missing L103 that someone replaced with a piece of stranded wire and a ferrite bead. After replacing...

forums.arcade-museum.com

Anyway, after getting it operational I took a break until today when I tried to do some fine tuning and adjustment that's when I ran into an odd phenomenon, the top right quarter of the monitor started to completly cut in and out as the monitor warmed up (after about 10 minutes of operation). The rest of the monitor appears to be mostly unaffected by this. When I rebuilt the monitor I accidently replaced the original blown HOT with a used weaker 2SC3686 instead of the stronger 2SC3688, I had the 2SC3686 in the bag with the rest of my 2SC3688s and didn't realize until I started investigating this new issue. I'm not sure if a failing HOT can cause this issue or not, but I decided to replace the used 2SC3686 with a new 2SC3688 to see what would happen and it shorted immediately, which is odd since the 3686 is supposed to be weaker than the 3688. I replaced the flyback when I rebuilt this monitor due to the wire and anode cap having been terribly chewed on by rats. I've read that some new flybacks can blow some 2SC3688s should I try a FJL6920?

You need to make sure though first that youve checked r760 765 q703 (i think i cant remember the transistor next to them) etc are all in line though or you are going to keep going to back to shutdown and or blowing HOTs

 

[sabrewulf69]

You have this backwards. The 68 is much more reliable and the 88 is junk unless it the original with the chassis. Its been speculated almost every 88 reproduced was counterfeit or just dosent work im not sure why but this is just the facts. @zenomorp the amateur chassis god has stated in videos he can never get an 88 to work after the orginal has blown, puts a FJL in and no problems. Yes put in the FJL.

Oh wow I didn't know that, thanks! I've watched most of his videos but I must have missed or forgotten that lol.

 

[JukeboxJon]

Oh wow I didn't know that, thanks! I've watched most of his videos but I must have missed or forgotten that lol.

Well the 68 has been obsolete for a long time, the 88 was suppose to be the better replacement in theory but it appears most were counterfeit or just didnt work right.

 

[sabrewulf69]

You need to make sure though first that youve checked r760 765 q703 (i think i cant remember the transistor next to them) etc are all in line though or you are going to keep going to back to shutdown and or blowing HOTs

Q703 did test good, but that doesn't mean it couldn't be failing under load so I'll pick up a few spares. I believe I checked the resistors but I'll look again.

 

[JukeboxJon]

Q703 did test good, but that doesn't mean it couldn't be failing under load so I'll pick up a few spares. I believe I checked the resistors but I'll look again.

Its possible however unlikely but if you work on a lot of monitors i always keep some extras too. The 88s were just crap, most likely the problem if youve checked everything else, especially on the u5000 ive always thought that dual and tri-sync crts are rough on the HOTs

 

[chilibear13]

You have this backwards. The 68 is much more reliable and the 88 is junk unless it the original with the chassis. Its been speculated almost every 88 reproduced was counterfeit or just dosent work im not sure why but this is just the facts. @zenomorp the amateur chassis god has stated in videos he can never get an 88 to work after the orginal has blown, puts a FJL in and no problems. Yes put in the FJL.

I have never been able to get a new, bought from a vendor, 88 to work. I bought something like 20 of them from a beloved vendor. At first, I thought it was my mistake diagnosing the problem. After going through something like 10 of them and almost giving up, I put in a 86 from a working chassis. Fired right up. Put a new 88 in the working chassis, shorted right away. Several emails to the vendor about his bad HOTs, but no response until I told him I'm sending them all back and he can keep the money.

@JukeboxJon Thanks for pointing this out.

 

[JukeboxJon]

I have never been able to get a new, bought from a vendor, 88 to work. I bought something like 20 of them from a beloved vendor. At first, I thought it was my mistake diagnosing the problem. After going through something like 10 of them and almost giving up, I put in a 86 from a working chassis. Fired right up. Put a new 88 in the working chassis, shorted right away. Several emails to the vendor about his bad HOTs, but no response until I told him I'm sending them all back and he can keep the money.

@JukeboxJon Thanks for pointing this out.

Yep exactly, i kept saying 68 but yalll know what I meant 86

 

[sabrewulf69]

UPDATE:

After getting several FJL6920s and installing one the monitor now is functional again however the problem with the black spot coming in and out in the top right corner still persisted.
So my next thought was I wanted to rule out a faulty new flyback so I dug the old one back out and soldered an anode from a dead K7000 flyback on to it and still the issue persisted. Now however the black spots weren't getting as big as before and it no longer seemed like run time was making it any better or worst, it just seemed to happen at random. At this point I turned off the TPG and turned up the screen knob to get a solid color and even with no image the corner was still flickering. After this I decided to check again for any cold solder joints I may have missed before, especially in the HV section and redid all of the headers pins and cleaned the contacts, but this as well seemed to have no effect. After that I decided to see what the issue looked like if I changed it over to 25khz, initially it continued to do the same as before but then suddenly the entire screen started violently flickering instead of just the top right corner doing so randomly, and then it suddenly stoped and settled on this image...

I thought maybe something was going on with the IC on the neckboard (u500) but I found that after turning up the (screen) brightness and adjusting the remote board and colors the image was just fine.

And it continues to be just fine as of the writing of this post. I had adjusted all of the pots on the flyback (both old and new), remote board and neckboard, but never once did I notice any symptoms of a dirty pot, so I dont believe it was that, but once the image freaked out and did as I just mentioned the black flickering had completely stopped. Now the only noticeable issue is the picture has a case of the wiggles. At this point I shut it off for 25 minutes and turned it back on and watched it for another half hour aside from the wiggles and the obvious poor convergence, it appears to be running smoothly. Throughout this whole ordeal I kept checking in on the B+ and it was always in acceptable parameters never less than 116.8 or more than 117.4.

This u5000 has been a endurance test, but despite all of the challenges it has and is presenting it has at least never not been interesting and educational for an amateur like myself.

 

[mecha]

I'm proud of your accomplishments. the U5000 as I've said for awhile now is not the most user friendly monitor to work on.

 

[JukeboxJon]

Mmm did you plug in the degause wires? It almost looks like a degausing issue making the screen dark on the corners… do you have a degause coil or wand or move the monitor physically in a different position and see if it changes…i cant think of anything else that would cause that. I would of doubted the flyback the 7400 series flybacks are very reliable a lot of people say bulletproof.

 

[sabrewulf69]

I'm proud of your accomplishments. the U5000 as I've said for awhile now is not the most user friendly monitor to work on.

Thanks, I appreciate that! I had always heard that as well, this is my second U5000 but the first that needed any major repair. I have several projects to work on but I picked this specifically for a good challenge, for that at least I definitely chose correctly lol.

 

[sabrewulf69]

Mmm did you plug in the degause wires? It almost looks like a degausing issue making the screen dark on the corners… do you have a degause coil or wand or move the monitor physically in a different position and see if it changes…i cant think of anything else that would cause that. I would of doubted the flyback the 7400 series flybacks are very reliable a lot of people say bulletproof.

Yeah degause was plugged in every time. I do have a degause wand but I hadn't been able to get it to replicate the problem reliably enough to test. I even took a screwdriver and tapped all around the chassis with the handle to try and set it off on command but never could get it to do so. If it starts doing it again I'll try. I do need to put it back on 15khz and see what its doing there now, it wasn't shimmering until I put it 25khz. I also need to go over the service bulletin sheet to make sure I didn't miss any upgrades.

 

[JukeboxJon]

Yeah degause was plugged in every time. I do have a degause wand but I hadn't been able to get it to replicate the problem reliably enough to test. I even took a screwdriver and tapped all around the chassis with the handle to try and set it off on command but never could get it to do so. If it starts doing it again I'll try. I do need to put it back on 15khz and see what its doing there now, it wasn't shimmering until I put it 25khz. I also need to go over the service bulletin sheet to make sure I didn't miss any upgrades.

Ahhh it started with 25khz, i had one before that u501 chip on the neck caused the shimmering and then it completely took it out, worked fine on standard but when i fired it up in medium it did that. Id be suspicious of u501 on the neck as well if it comes back after ruling out any bad solder joints etc, reflow of connectors

 

[sabrewulf69]

Ahhh it started with 25khz, i had one before that u501 chip on the neck caused the shimmering and then it completely took it out, worked fine on standard but when i fired it up in medium it did that. Id be suspicious of u501 on the neck as well if it comes back after ruling out any bad solder joints etc, reflow of connectors

Yeah, when it went dark like the screen in the second image the neck IC was the first thing I thought of. To be honest I've been using using this monitor as an excuse to stock up on spare parts lol. Every time I've ordered something for this I've been getting 5 - 20 extras for spares (depending on price) im trying to get a good collection going, so I'll get some of those too lol.

 

[JukeboxJon]

Yeah, when it went dark like the screen in the second image the neck IC was the first thing I thought of. To be honest I've been using using this monitor as an excuse to stock up on spare parts lol. Every time I've ordered something for this I've been getting 5 - 20 extras for spares (depending on price) im trying to get a good collection going lol.

Lol yeah i have a list waiting for APAR and on thst list is u501s the neckboard i have with the bad u501 is on my bench. I stole the neckboard off a 7500 to fix that u5000 chassis. I do the same. Probably never use them all but i like knowing I have them. Then one day when im gone someone will be like what was he doing with all this shit lmao

 

[sabrewulf69]

Lol yeah i have a list waiting for APAR and on thst list is u501s the neckboard i have with the bad u501 is on my bench. I stole the neckboard off a 7500 to fix that u5000 chassis. I do the same. Probably never use them all but i like knowing I have them. Then one day when im gone someone will be like what was he doing with all this shit lmao

Haha yeah, my new problem is trying to get them all organized, right now I just have large box full of APAR boxes and dozens and dozens of DIGIKEY/Mouser bags lol. I have some folding parts bin boxes to put them in but I haven't finished building my storage room to put them in yet.

 

[JukeboxJon]

Haha yeah, my new problem is trying to get them all organized, right now I just have large box full of APAR boxes and dozens and dozens of DIGIKEY/Mouser bags lol. I have some folding parts bin boxes to put them in but I haven't finished building my storage room to put them in yet.

Same. I have like 4-5 small boxes 1 with WG cap kits, 1 with Makvision pentranic neotec etc cap kits, 1 with resistors from APAR, mouser and digi key, 1 with random caps I use a lot for mobos and other things and chassis from Digikey/mouser, and 1 bigger one that has every thing else transistors, ICs, HOTs, Pots, etc.

Somebody is going to be like he was def working on a flux capacitor machine.

 

[JukeboxJon]

Haha yeah, my new problem is trying to get them all organized, right now I just have large box full of APAR boxes and dozens and dozens of DIGIKEY/Mouser bags lol. I have some folding parts bin boxes to put them in but I haven't finished building my storage room to put them in yet.

Also just had a thought an obvious one I forget sometimes that can cause weird shit, make sure the TPG battery is good lol it can cause shimmering and weird stuff if the battery is low.