Wells K7191 Horizontal/ Vertical Rolling

john2654

Well-known member

Donor 3 years: 2011, 2020, 2024
Joined
Mar 30, 2010
Messages
6,426
Reaction score
1,272
Location
Rhinelander, Wisconsin
I recently bought a Well Gardner 25K7191 Chassis from a fellow KLOV member. It works fine except the image constantly rolls from top to bottom. Tried to mess with the remote board and the V-Hold Knob (VR105 500K) is very touchy. After many tiny tweaks, I can get it to freeze but it rarely lands in the correct spot. Usually the top is on bottom and vise versa. Tried a different remote board of a similar K7000 chassis and it does the same thing, so I don't think a pot replacement would help. When I finally get it in the correct spot, if I turn the machine off and on, it either is scrolling again or it is not, but the top is on bottom thing. Would a cap kit help? Getting ready to give up on this Mortal Kombat 4.
THANKS!
 
Make sure the sync is only connected to the negative horizontal sync pin...
 
if you have an ESR meter

then you'd know which capacitor is bad
and
you'd know the capacitor you've installed is good

:)

Let me tell you why that isn't the best answer:

If a 20-yr-old monitor has a cap failing, it's true that you could replace that one cap and have it work - until the next old cap fails in a week or a month. That causes a lot more work. The K7000 chassis only has 17 caps, the cap kit costs $5 from Bob Roberts, and doesn't take that long to put in. Plus, if you only replace one cap, put the chassis back in, and still have other problems, you don't know whether or not you need more caps. If you put in all new caps and still have a problem, you most likely have other issues than caps.

And I rarely find bad new caps anymore when doing cap kits (unless they're put in backwards), and you don't need to buy an ESR meter unless you do a lot of monitor repair...
 
Let me tell you why that isn't the best answer:

If a 20-yr-old monitor has a cap failing, it's true that you could replace that one cap and have it work - until the next old cap fails in a week or a month. That causes a lot more work. The K7000 chassis only has 17 caps, the cap kit costs $5 from Bob Roberts, and doesn't take that long to put in. Plus, if you only replace one cap, put the chassis back in, and still have other problems, you don't know whether or not you need more caps. If you put in all new caps and still have a problem, you most likely have other issues than caps.

And I rarely find bad new caps anymore when doing cap kits (unless they're put in backwards), and you don't need to buy an ESR meter unless you do a lot of monitor repair...

i love my ESR meter. it has paid for itself and i can prove it cause i havent pulled all my hair out yet !
recently i just found a bad batch of 100uf 25v i had bought and almost installed one. what a headache that would have been had i not had my lovely ESR friend to test either way
 
UGHHHHHH!!!! I am having the worst luck ever with this thing. Hooking the sync wire up to negative H sync worked perfect. Don't know why it was defaulted in the other location, but 1st pic shows my rig (black wire = neg H sync). Pic 2 is when it was working. When I was going to remount the remote board it slipped and touched the frame of the chassis and POP! Blew out two traces on the remote board and the main 3 Amp fuse. Used a different remote board and replaced the fuse and all I get is a red line if I crank the BLK LEVEL & CONTRAST all the way up (3rd pic). What did I blow now?
 

Attachments

  • DSC01238.jpg
    DSC01238.jpg
    94.2 KB · Views: 26
  • DSC01241.jpg
    DSC01241.jpg
    94.1 KB · Views: 22
  • DSC01244.jpg
    DSC01244.jpg
    91.5 KB · Views: 23
  • DSC01245.JPG
    DSC01245.JPG
    92.7 KB · Views: 27
What did I blow now?

Looks like IC3 is bad now. Check to make sure you get the exact replacement, as the wrong one will give foldover issues.. It's probably a LA7833, and costs $4 from Bob Roberts...
 
Looks like IC3 is bad now. Check to make sure you get the exact replacement, as the wrong one will give foldover issues.. It's probably a LA7833, and costs $4 from Bob Roberts...

Replaced IC3 (LA7833) and did a complete cap kit and the red line across is still there. Any other ideas on what I fried?
 
Yeah, it'll be something in that vertical section. Look @ some schematics and anything that the circuit through the vertical yoke runs through is suspect. Check your resistors and things, and fix that old remote board, you may be using one tha'ts not compatible or in worse shape than yours is. If if was strong enough to fry that trace like that, though, which was solid metal..... think what it did to all the other shit in the vertical section!
 
Was messing around with the chassis and the flyback knobs and now all I have is a horizontal straight white line in the middle. Don't know if that makes a difference.
 
recheck resistors
do a continuity check on traces from one point to another
check diodes

something is bad and you have to find it

look real close. just because you have continuity from one point to another doesnt mean it will work under load. a crack in a trace can cause this

keep going, dont give up yet
 
I would re-inspect anything that you soldered or reflowed and make sure you did not make an extra contact with solder from one trace to another that it was not supposed to be touching.

Steve
 
Back
Top Bottom