Rodotron 666 on New astro city monitor

[iori]

Hi gents,

I recently bought a 666a chassis and I successfully install it on my new astro but I have one major issue, it is the side compression on side when dispaying 15khz image.
I tried again and again to tweak all pots on the chassis but the issue is still there.

Is it a way to change cap or something else on this chassis to match exactly with my yoke ?
I think the issue is there, this 666a is not really designed for this CRT.

Thanks for your help.

[grantspain]

nothing you can do about that,you get a small amount of side compression on 15khz but it depends on the game board as some are worse than others-bet 31khz looks fine

[iori]

to be honest , I didn't test so much 31khz as by now 15khz is not acceptable for me.
I want first to fix 15khz issue before to move with the 31khz.

That's too bad because I really would like to avoid to buy a new cab just to have 31khz (but it's now mandatory as I play type x games)

[digitalsystemsdesign]

Have you set up the B+

There are generally no problems at all with 666A chassis if they are set up correctly either pre-shipping from the supplier or for you to set it up correctly yourself

Side compression on a lot of monitors can be due to incorrectly set up B+

This isn't a plug, but all of my 666As go out with a full technical manual, a CRT safety manual and an electrical setup manual - never had one problem with them in terms of geometry, compression etc etc, and they are still working fine to date

[digitalsystemsdesign]

note also that on the 666A the B+ must be set for each individual mode as they all have their own individual circuits

So set it for 15kHz, then 24.5kHz then 31kHz

Jeff

[iori]

Hi Jeff

Thanks for your reply.

To be honest, I already tried to tweak a bit this B+ pots. I only touch the one for 15Khz as I want first fix side compression issue on 15 Khz before to continue with 31Khz.

I tried to adjust it with a CPS2 crosshatch without any success. do you think that adjust 31K B+ pots will have impact on 15Khz display ?

Also, I saw a post of few years ago that one guy successfully fixed side compression issue by adding a small cap on the chassis , do you think it's feasible ?

I will anyway try tweak again this pots, and is their any other pots to play with ?
One strange things also on my 666a chassis, I have a flyback with 3 pots but one is cut to avoid to touch it , normaly I should have only 2 pots on the flyback as replacement of a MS9 ?

I'm a bit lost.

Thanks for your help.

[grantspain]

b+ don't affect compression,width yes
there is a high voltage cap in the 15khz horizontal deflection circuit that needs to be changed-sorry i do not remember where but will have a look at my achives

[iori]

That could be really great if you can found it.

If we can locate which one is the "faulty" one.

Many thanks in advance.

[digitalsystemsdesign]

Sorry Grant - I might be misinterpreting the word compression and how it is used here

Are we talking about the sides of the images being compressed and overlapping on top of themselves - as in squashing at the sides or is it another term

If this is the case, then that is a B+ issue and I have seen it quite a bit on several of Georges stuff when shipped. If we are talking about something different ie vertical compression at the horizontal sides of the picture then yes I can understand and I apologize.

But the B+ settings shouldn't be played with to be fair as they affect other parts of the circuit - all 3 circuits are independant on that front.

Your manual should stipulate the settings for your chassis and you should set it up for the fixed voltage level

J

[iori]

Sorry but maybe a misunderstanding of my issue due to my english skills

here is exactly the issue I have :


When I was trying to tweak the 15Khz B+ pots, I could notice a few improvement but impossible to get it correct even with pots at max.
Maybe interaction with other pots, or simply change a cap (I found on other topic one guy who did it, but nothing is explained unfortunatly)

That's why I'm asking you some help.

[grantspain]

C86 and C88 are most likely culprits-can't find any values of replacements so I guess it's a case of just messing with different values until you get it right
all good as long as you do not damage the chassis

what you have in your picture is the standard side compression you see on 15khz on almost all wei ya and rodotron tri syncs-some are better than others,probably something to do with the yoke being a better match

[digitalsystemsdesign]

I stand corrected - picture paints a thousand words - cheers Grant

[iori]

Great,

I found on the diagram values of those.
http://wiki.arcadeotaku.com/w/File:Rodo ... ematic.pdf

Also, I found on this thread : http://forum.arcadeotaku.com/viewtopic.php?f=4&t=3402
that this guy fixed a width issue by increasing capacitance of C85 caps. effect of this was increasing width, so maybe I should decrease a bit C86 or C88.

I was also thinking that my issue is like I would have the narrow/wide jumper incorrectly set , but this jumper does not exist on the 666a compare to the Nanao MS8. interesting things would be to find what those kind of jumper are doing technicaly (changing capacitance , or something else, ?)

I will try this evening to find couple of different values for those caps, and will try to change them to see if it's better or no, or if the chassis will burn

Anyway, by now , it's absolutly not possible for me to keep 15khz picture like this, so, I will fix it or burn it

[iori]

Hi gents,

Thanks to your help, I finally fix this bloody chassis.
No more side compression on 15 Khz

So I decided to move on with 31 Khz, and after some tweak, I have a really small issue but it's now contrary of side compression, some kind of side stretch.

Grantspain, for this time , do you know which cap I should play with ?

FYI, I just change C86 to fix side compression on 15Khz, and once I will have completely fixed my chassis, I will post a small "how to" to help other owner of this chassis to fix those kind of issue.

Many thanks.

[grantspain]

give me a couple of days to look at the schems,
i am really glad you found the 15khz problem as it will help many people so please share this knowledge

[monouchi]

Hi gents,

Thanks to your help, I finally fix this bloody chassis.
No more side compression on 15 Khz

So I decided to move on with 31 Khz, and after some tweak, I have a really small issue but it's now contrary of side compression, some kind of side stretch.

Grantspain, for this time , do you know which cap I should play with ?

FYI, I just change C86 to fix side compression on 15Khz, and once I will have completely fixed my chassis, I will post a small "how to" to help other owner of this chassis to fix those kind of issue.

Many thanks.

I am one of those other owners, It would be awesome with a "how to" with pics!

[iori]

Thanks Grantspain, I will wait your feedback about the caps before to order new one, my local dealer is running out of stock !

Don't worry monouchi, I will create a small how to with pics to help you and other, but I want to finish completly my setting of the screen before to do it.
There is an horrible mess at home with screen , chassis, computer , cable , etc ... everywhere and my girlfirend is about to solve the screen issue by herself if you see what I mean

[grantspain]

C302 on the 31khz daughter board I reckon

[iori]

Good , thanks Grantspain.

I begun yesterday to tweak but I don't have no more caps with different value, I had to find couple of caps before to move on and gave you feedback.

In the mean time , I will try to focus on the B+ setting as it seems to be important.
Do you know how to do it correctly ? I have a meter but don't know how to do.

Thanks.

[grantspain]

Good , thanks Grantspain.

I begun yesterday to tweak but I don't have no more caps with different value, I had to find couple of caps before to move on and gave you feedback.

In the mean time , I will try to focus on the B+ setting as it seems to be important.
Do you know how to do it correctly ? I have a meter but don't know how to do.

Thanks.

mate the b+ settings are in the wiki