Another one! WG27k7501

[SiLeNtNiNjA1]

I got the chassis from a downsizing retailer non working. Cap kit will be in on monday. The chassis is now out of the cabinet, and on my bench. I was touching up and reflowing solder when i found the holes with a leg sticking out, and nothing there. I did the continuity and resistance checks before starting.

Heres what I dont get. I looked at both 7501 chassis that I have. They both have legs sticking out of the c519 hole, but no cap. But the BOM on the service sheet dosnt list anything for C519. Can anyone confirm on a working chassis if there is anything there?

Well back to the resoldering - one of the small 3 leg ic's seems to be lifting the trace under it right off the board.

I also have a 7401 I could steal the neckboard off of if I need to. Ill see what I get with the reflowing first though

Thanks!

 

[Ohmerone]

Caps

I thought it had a CK already
There were different version Neck boards
over the years,that mod is normal,c519 is not the problem..
These are old chassis they all need a cap kit
not all the caps are bad,so you could troubleshoot
the problem by starting with certain caps first to see which ones it is.
Normally I replace all caps and new flyback vertical ic and connections
the first round.Just for kicks swap the neck board first.

 

[SiLeNtNiNjA1]

Swapped the neck board, no change. So I followed the earlier suggestion, and checked the screen / focus and tried adjusting them. Ive been told before its bad to do it with the monitor on, so i shut it off, adjusted, then turned it back on. I found the screen had to be nearly maxed out for me to see anything at all. When the focus got turned down, I got alot of streaky lines across (see 2nd and 3rd photos).

First photo is just with the new neckboard.

Im starting to think the little bit of an image I kindve see behind this thing is burn on the tube, not an actual image.

Do you think I should just order a flyback for this to go along with the cap kit? Now 2 people have mentioned it so I suppose its worth doing!

Edit : ordered the flyback from chad @ arcadecup - hopefully it comes in quick since hes just across the lake and I can get it all in with the caps early next week!

 

[StreetzKing]

get this damn thing running already

 

[Ohmerone]

Swapped the neck board, no change. So I followed the earlier suggestion, and checked the screen / focus and tried adjusting them. Ive been told before its bad to do it with the monitor on, so i shut it off, adjusted, then turned it back on. I found the screen had to be nearly maxed out for me to see anything at all. When the focus got turned down, I got alot of streaky lines across (see 2nd and 3rd photos).

First photo is just with the new neckboard.

Im starting to think the little bit of an image I kindve see behind this thing is burn on the tube, not an actual image.

Do you think I should just order a flyback for this to go along with the cap kit? Now 2 people have mentioned it so I suppose its worth doing!

Wow, Man you work with the monitors, i thought you had done the earlier post
come on man get with it..
You got more issues do the caps and the 74 and 7500 all need atleast one flyback
some fail others just have focus issues.
You need to restore the chassis then test and minor adjustment's
don't forget the flys come with the master brightness on fly is turned down
need to adjust it too.

 

[SiLeNtNiNjA1]

get this damn thing running already

Im tryin!! Theres no debugger on the hardware compiler! Thats why im much better with software!! Being a programmer will do that to you! :\

We should make ocmponents with large neon signs that flash when they are bad. Problem here!! Look at me!! CHANGE ME!!!

 

[SiLeNtNiNjA1]

Wow, Man you work with the monitors, i thought you had done the earlier post
come on man get with it..
You got more issues do the caps and the 74 and 7500 all need atleast one flyback
some fail others just have focus issues.
You need to restore the chassis then test and minor adjustment's
don't forget the flys come with the master brightness on fly is turned down
need to adjust it too.

Im tryin my best to learn these things!! Flyback is ordered. Originally I just ordered all the caps. Someone mentioned the flyback, and I questioned if it was likely enough I should do it along with the caps and never got an answer, so I figured id do the caps first, then if it was still wonky, do the flyback. Since you brought up the flyback as well, and I know you know what your talkin about, I ordered it right away

But I suppose with this, the project is halted till I get parts on monday. Maybe Ill poke at the neotec nt500dx over the weekend?

I have so many at the moment as I made a lot buy awhile back and got 6 tubes and 10 chassis in the bundle. So far, not a single one has worked, and im trying to work on the nice ones I can use first, then take what I learn and see how it goes on the others that ill just pass along.

 

[SiLeNtNiNjA1]

OK, flyback is in. Cap kit is in. Replacement R811 resistor is in. I have not powered it up yet because of a discrepancy with 1 cap. C615 is labeled 3.3uf 16v from the list I pulled on here, however the BOM in the service manual states 33uf 16v. The one I pulled was 33uf 16v as well. Ill pick up a brand new one from radio shack tomm.

I also reflowed the 3 HOT ic's on the neckbard, and the connector on both sides, as well as the remote board connector pins.


I guess im getting better at this, only took 2 hrs to replace everything!

 

[SiLeNtNiNjA1]

Alright, replaced the last cap and fired it up. Image is alot brighter, but still no picture behind it. I am going to try changing the sync input to another section and adjust the h-hold a bit and see if that changes anything. Ill get pics up in a few as well.

 

[SiLeNtNiNjA1]

Adjusting the h-hold (WAAAAAAYYYY in the back) had an effect. I can now see an image, but I cant get it to stop rolling, larger on top, smaller on the bottom. I also have the image cutoff on the top of the screen, and black space a couple inches wide on both sides and the bottom of the screen.

At least we have progress!! I am going to go over the pincushion board next, as something tells me the size issues may be related to that...

 

[modessitt]

1) your brightness is up too high.

2) decrease your vertical height until the entire picture looks normal (but small). Then see how far you can increase it before it starts messing up.

3) When you did the cap kit, did you replace EVERY cap?

4) there is a resistor (R620 I believe) that usually has another resistor on top (R620A) that is sometimes missing on these chassis, and adding R620A (or changing the value of R620 to a smaller value) can fix the size and foldover issues...

 

[SiLeNtNiNjA1]

1) your brightness is up too high.

2) decrease your vertical height until the entire picture looks normal (but small). Then see how far you can increase it before it starts messing up.

3) When you did the cap kit, did you replace EVERY cap?

4) there is a resistor (R620 I believe) that usually has another resistor on top (R620A) that is sometimes missing on these chassis, and adding R620A (or changing the value of R620 to a smaller value) can fix the size and foldover issues...

1 - Brightness is already turned down at the flyback

2 - It never gets to normal - it is continually scrolling (out of sync?) with the top larger even when height is at the minimum.

3 - Only 2 caps not changed were the np's - 4.7uf 100v and 10uf 50v (both high temp). If needed I can pull both off another parts board (single green line across the screen and burning smell...) and see what happens.

4 - I checked R620 as it controls 25 or 27in tube w/ the pincushion board... It measures 218ohm. I have no idea about r620a, so I took some photos and dropped em in my picasa album

https://picasaweb.google.com/SiLeNt...authkey=Gv1sRgCLPk2OPTp-PxpAE&feat=directlink


Thanks again for the help!

 

[SiLeNtNiNjA1]

Bumpage! If nobody has any suggestions atm, I am going to pull ic701 and 702 from my other chassis and see if anything changes...

 

[SiLeNtNiNjA1]

I added a jumper on C812 as the trace was lifting. Check Q800/802 and Z804 as suggested by Omherone. Still no change. I tried another med res game board just to rule it out, and there was still no change.

 

[StreetzKing]

sad face.

hope you get this thing going soon man, seems you know everything about the game, so the monitors screw you over

 

[SiLeNtNiNjA1]

Well, I wouldnt say I know everything about it... I didnt really figure out anything new, I just read all of everyone elses stuff and put it together to help whoever else here is having problems

But yeah, I dont have good luck with monitors at all. Im going to have to sit down for a cpl hrs this weekend and pour over all the voltages on the ic's and see what im getting. Problem is they were all done w/ a grid pattern signal generator for the service manual and all I can do is set up a game :/