WG6100 issue

[level42]

Anyone an idea what is wrong with this WG6100 ?

http://youtu.be/pL6oqDfWipU

[Etienne MacGyver]

it looks like its malfunctioning 

[level42]

We need more technicians here ! Or those who have some experience should write a bit more.....

Anyway, since the vectors were influenced in both horizontal and vertical direction I thought that the cause would be in the low voltage section on the deflection board. I checked the caps there but they were fine.
Then Dokert on KLOV forum said it would probably be a cap on the HV board so I checked all of them. Turned out there are two filter caps for the low voltage section of the HV board too and sure enough one of them was dead acording to my ESR meter. It had almost no capacity anymore and very high (over 100 ESR). It was a strange looking cap, it turned out that it was an old-fashioned Bakelite capacitor from a German brand. Googling a bit learned me that on one hand they are popular with audiophile fans because of the "audio" qualities but also that they don't last long in hot circumstances and you can bet that a HV cage in a Tempest gets pretty damn hot....

Of course I checked all the other caps while I was at it and I found that C914 was also completely dead.

I've replaced both. Now I still need to redo all the solderings on the deflection board connectors because when touching it the lower half of the screen disappears, and when touching it again it returns. This is very indicative of bad solderings on the connectors that run to the power transistors on the frame, or even cracked tracks around those connectors as I've experienced before.

To be continued....

[level42]

I redid all the connector solderings but before that I checked them with my DVM. It was really funny as I found one pin that did not make contact with the track (measured right at the "top" (on the solder side) of the pin to the track. However with the bare eye you wouldn't have guessed it was bad.

I also made some macro shots, it's always fun to see the (start of a) ring that is indicative of a broken soldering.

I used a 470 uF 35V for C901, can't see why it would need 50V, there is only 25V there so the 10V extra should be enough.

Decided I wanted to know the results so I just reassembled the boards and:

http://www.youtube.com/watch?v=alCXvv_6UvM&feature=youtu.be

The lower left area seems to be not the correct color. Might need some degaussing or maybe redoing the convergence (hope the first, less work )

[Etienne MacGyver]

Good job ! 

[level42]

Oh, in case anyone wonders...this is Thwocker's monitor out of his Tempest. In exchange for fixing this he promised to bring it to RGE/Eurocade 2014 !  

(I don't think he did...but Tempest would be great to have !!!   )

Now....I fully realize I still have another 6100 to work on (plus a deflection board)....however I have a good reason for those too to fix this first:
It is great to have a fully working monitor to compare with the non/bad working stuff so I hope to fix those next......fi-na-ly.....

...and this one was easy to fix, the others not so easy....

Checked the poor color: it is only on the pure red so it's a purity issue....well I'm not scared of working on that anymore

[level42]

Ahhhhhh, I love it when convergence comes together !!!! This may be the nicest 6100 I've ever seen ....... lucky Thwocker !!!

This is about as good as it gets on a 30 year old tube.....the corners are not 100% but WAY within factory spec

The pincushioning should be fixed by the Tempest PCB....SW doesn't do pincushion correction. The story was that they corrected it in the yoke well.....don't you believe it

[level42]

Nice example of how a bad purity can influence the picture.

Notice on the first video that all colors looks fine EXCEPT red. The red text has a purplish look in the lower left area (about 1/4 of the screen). Since it only influences one color it can't be a degaussing issue.

So I put up a cross-hatch signal and checked all colors, yes only red was bad.

This meant there was a purity issue. I had to move the convergence ring set a little bit to get the purity fixed. Of course, after that I fixed the convergence too, first the center area using the convergence rings, and then with the famous "convergence strips for the edges and corners.

OK here the videos.

Before:
http://www.youtube.com/watch?v=gdfNwFm8xqM&list=UUn47kbEAlRBSmWmdae45P2w&feature=share&index=1

After:
http://www.youtube.com/watch?v=NxJoEuG5o7c&list=UUn47kbEAlRBSmWmdae45P2w&feature=share