Blast City - possible convergence issue

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alex2005
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Blast City - possible convergence issue

Post by alex2005 » January 28th, 2015, 4:20 pm

This is the last thing left to fix in my Blast I believe and hope :awe: , could someone confirm how to fix this?
On the edges of the monitor sometimes colours are misaligned.
See Art of fighting 2 picture below showing one of the corners, line should be white only but you can see red, blue and green colours popping out:

Image

Can this be fixed adjusting the image from the chassis potentiometers (those next to the VGA input on the left side of the Blast)?
If yes > is there a way to access them without dismantling the Blast and which ones should I focus on?
If not > do I need convergence strips? Where to find these at a reasonable quality and price in Europe?

Thanks :)

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copados33
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Re: Blast City - possible convergence issue

Post by copados33 » January 28th, 2015, 6:33 pm

You can't fix that moving potentiometers, in your case ( best case scenario ) where only that part of the screen is affected, probably due some convergence strips that have been removed, so you will have to put new strips.

Worst case scenario, a loose yoke or messed up convergence rings, as to where to get the convergence strips, I have no idea.

alex2005
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Re: Blast City - possible convergence issue

Post by alex2005 » January 28th, 2015, 9:29 pm

Thanks for the tips!
Just found this website selling strips:

http://www.endgamearcade.com/catalog/it ... 991752.htm"

I will order some and see how it goes :)

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Re: Blast City - possible convergence issue

Post by LegoYoda » February 2nd, 2015, 9:39 pm

I've got the same issue. Can you post your experiance / how long it took for the parts to arrive. I've always been a little reticent to poke around the back of the monitor.
Alec
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Owning a Blast City: Fixing and Repairing -http://retrogamingstuff.wordpress.com/

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Re: Blast City - possible convergence issue

Post by phillv85 » February 2nd, 2015, 9:42 pm

Seems to be a common thing on these monitors. Mine also has it, albeit a little less severe :problem: . I'm also interested to see how you get on :awe:

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Re: Blast City - possible convergence issue

Post by alex2005 » February 2nd, 2015, 9:58 pm

I ordered the strips and these were shipped one day later :D
I am still waiting on these to arrive, I'll see afterwards how it goes.
I doubt whether I should just leave it as it is or go on and try to fix it.... I am really afraid of breaking anything trying to fix it lol

To start with I do not know which parts can or shouldn't touch on the monitor. Anyone with a graphic schema pointing out the dangerous zones will be of great help :D

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Re: Blast City - possible convergence issue

Post by Chempop » February 2nd, 2015, 11:42 pm

alex2005 wrote: To start with I do not know which parts can or shouldn't touch on the monitor.
Be careful with that, applying the strips is all sorts of danger zone. :roboprob:
The anode wire, leading to the cap, potentially zappy. I’d steer clear from the neck especially since it’s a fragile piece.
You basically are wedging the strips between the tube and yoke iirc, and obviously it need to be running with a test grid while you do it.
I’d advice a friend to be present
[+] Spoiler...
with the police/ambulance # on speed dial :awe:

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Re: Blast City - possible convergence issue

Post by kaneda56 » February 3rd, 2015, 12:27 pm

I already did the operation some weeks ago, here's a small video:
https://www.hasntfiguredouthowtoembedyoutubeproperly.com/watch?v=rHJLrKycba0"

And the dedicated thread (with other little problems):
http://www.neo-arcadia.com/forum/viewto ... onvergence"

Sorry for the poor quality, and it's full french.
To resume my long speech:
- No big deal: your screen must be outside of the cabinet and you have to be careful with the anode wire, and that's all. When you have understand how the strip's position affects convergence, it takes 45 minutes to fix the entire screen.
-The strip must be placed between the yoke and the tube, don't hesitate to go far, to rotate it to improve the correction
- The tube MUST be cleaned, otherwise the strip's adhesive tape won't grip.
- You can use 2, even 3 strip to correct a big convergence problem.

alex2005
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Re: Blast City - possible convergence issue

Post by alex2005 » February 3rd, 2015, 10:31 pm

Thanks for all the guidance and advices! I need to take out the monitor anyway to clean inside the Blast, that should be a good timing to approach a bit on these convergence tricks.
I will keep you updated on how things go :)

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Re: Blast City - possible convergence issue

Post by alex2005 » February 11th, 2015, 11:57 am

Ready for the fun :)

Image

I read somewhere that as long as I use only one hand to put those strips, and keep the other in my pocket, I shouldnt get shocked. Is that correct?
Besides the anode wire, any other part I should avoid touching? What happens if over the time these strips fall? Can they cause any damage?

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Re: Blast City - possible convergence issue

Post by ninn » February 11th, 2015, 1:33 pm

It is easier to close a circuit with both hands, than with one alone.
You can get shocked, but less chances the current runs thru your heart.

Have fun! :thumbup: :whoa: :thumbupright:
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currently lazy. must not buy games!

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Re: Blast City - possible convergence issue

Post by RMRM » February 11th, 2015, 5:53 pm

ninn wrote:It is easier to close a circuit with both hands, than with one alone.
You can get shocked, but less chances the current runs thru your heart.

Have fun! :thumbup: :whoa: :thumbupright:
Messing with CRT chassis, gotta love it :awe:

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Re: Blast City - possible convergence issue

Post by alex2005 » February 12th, 2015, 10:28 pm

The guy in this video does touch the anode wire, obviously I will try to avoid it by all means but since convergence is on 3 corners, may be that I can't avoid it at some point.

Is it still safe to touch it, or this guy was just lucky?

https://www.hasntfiguredouthowtoembedyoutubeproperly.com/watch?v=QYB1L8AIeq4"

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Re: Blast City - possible convergence issue

Post by grantspain » February 13th, 2015, 8:47 am

unlikely to get a shock by touching the anode wire,just don't stick your fingers under the anode cap itself-you are more likely to get a shock from the deflection yoke tappings tbh

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Re: Blast City - possible convergence issue

Post by alex2005 » February 13th, 2015, 8:59 am

I will try to go to the minmum: unplug everything, remove monitor, clean the tube real well, let it dry, plug in monitor, display crt test grid, wear thin plastic gloves, and touch only the tube to move/stick these strips.
Sounds like a plan :)

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Re: Blast City - possible convergence issue

Post by ninn » February 13th, 2015, 10:59 am

I got those sicks too, but I never worked on the convergence - too afraid to faul and rin the monitor [or me] ... please report back once you did it!
Randy and Candy.
currently lazy. must not buy games!

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Re: Blast City - possible convergence issue

Post by alex2005 » February 13th, 2015, 11:46 am

Me too, surely afraid :) there is particularly this bottom right corner i MUST fix, its where most of the credits go on classic games and just want it to look better. :awe:
Will report tomorrow if i am still alive ;)

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Re: Blast City - possible convergence issue

Post by cools » February 13th, 2015, 11:56 am

Remember to let the tube warm up for half an hour before doing any adjustments.
Image

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Re: Blast City - possible convergence issue

Post by alex2005 » February 13th, 2015, 12:06 pm

Does it matter -if at all- which resolution do I pick from my 15khz setup to adjust?
Currently windows is at 640x480 interlaced, but most emulators will run around 320x240
I guess I can display the test grid with only one resolution, and whichever I pick will do?

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Re: Blast City - possible convergence issue

Post by baddy » February 13th, 2015, 3:36 pm

I did (badly) the same convergence adjustment a few month ago (blast city, ms2931)

do it in 31k, the defects are more precise in hi resolution. Even if you dont fix it perfectly you will see that in 15k is will barely show anymore.

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