MS9 weird behavior

[grantspain]

does your horizontal hold pot do anything?

[zumbito]

does your horizontal hold pot do anything?

Ok, that made something, I turned it on back again, and quickly turned the H Hold 15k pot. I got a recognizable image, but it was huge for the screen. I turned the remote control size pots all the way down, but still was too big. Tuth be told this time it lasted more than a minute, I was running a multigame and had enough time to turn on, play with h hold, take some pictures, size it down, get into a game to get a more familiar screen, change game, and then when I noticed some image flickering, like trembling up and down I was going to record a video and suddenly shut down.

Pics I took before the video (I know, the image is flipped):





Short video, I didn't have time for much.



Colors look awesome though, hope I can get this running

[grantspain]

odd fault, perhaps your chassis pots are damaged or your vertical ic is failing

[zumbito]

odd fault, perhaps your chassis pots are damaged or your vertical ic is failing

I think is the vertical IC, cause this time it suddenly colapsed on the video, I will add it in a moment.

[zumbito]

Ok, so this is the video:



I waited couple of min and when I turned it on again it was just out of synch, moved the pot a bit, and synch again, kept turning and went out of synch, kept turning and shut down, like if it was so out of synch it shut down, if that makes any sense...

[grantspain]

vertical ic breaking down
ic U401

[zumbito]

vertical ic breaking down
ic U401

Ok, I understand I must replace it. Will order one.

[grantspain]

use solder mop on the ic tracks- do not use a solder sucker

[zumbito]

use solder mop on the ic tracks- do not use a solder sucker

Too late... I didn´t have mop either, will order some. ATM waiting for the IC to arrive, hope that was the problem. Will let you know when it arrives.

[zumbito]

Today the IC arrived, and hurried to replace it . At first the image looked really nice (a bit dark, but no image adjustment)



I noticed some flickering but wasn´t nothing big, so connected a board and try to adjust the image, when it suddenly turned off.

Turn on again, and image all weird again:



And now again vertical collapse. Why!?

I have noticed that the IC has what I think is a ceramic capacitor attached to the third pin, is that normal?

[grantspain]

you need to replace 5 caps near the vertical ic, 3 x 100uf 35v, 1 x 47uf 25v and 1 x 470uf 16v
you should change all your power supply capacitors as well- in fact you should change all the electrolytic caps

and you will likely need to change the vertical ic again

[zumbito]

you need to replace 5 caps near the vertical ic, 3 x 100uf 35v, 1 x 47uf 25v and 1 x 470uf 16v
you should change all your power supply capacitors as well- in fact you should change all the electrolytic caps

and you will likely need to change the vertical ic again

I already changed the caps before changing the IC, shall I change them again?

By power supply capacitors, you mean the caps in the cab PSU?

[grantspain]

you have not changed the important caps as I can see the soldering is original in the photo
c408,c407,c958,c402 and the one under the glue which I think is c409
also there is a bad solder joint on d401

[zumbito]

you have not changed the important caps as I can see the soldering is original in the photo
c408,c407,c958,c402 and the one under the glue which I think is c409
also there is a bad solder joint on d401

Oh!, that photo I took it before the recap. I was just showing that orange thing. Al the chassis caps (except the biggest one) are replaced.

[grantspain]

maybe a fake la7837 ic then, lots of fake ones on the market

[zumbito]

maybe a fake la7837 ic then, lots of fake ones on the market

Any idea where to buy original ones? I bought it in Ebay from the UK.

[grantspain]

I get mine from cricklewood electronics

[zumbito]

I get mine from cricklewood electronics

I just tried another one from the pack I bought, same thing, straight into vertical collapse. Can it be the chassis frying the IC? I´m going to buy from same shop as you Grant, hopefully this ones will last.

[grantspain]

could be something killing the ic, corroded yoke could do it-possible one of the diode in the vertical circuit

[zumbito]

could be something killing the ic, corroded yoke could do it-possible one of the diode in the vertical circuit

Ok, I think it will be better to replace everything and see what happens, I have no way to check what could be... How do I identify which parts belong to the vertical circuit?

BTW this is embarrassing, but I don't have a very clear what a diode is...