MS8-26 clarification

[Kevin Mullins]

Can someone verify whether or not an MS8-26A-SU monitor requires an isolation transformer?

The only schematics I have found so far doesn't show one.
And of course haven't found an actual manual on them yet either.
I just want to test this monitor before I wire up the cabinet I'm putting together, but I don't know if it even works yet.

[grantspain]

i am sure you need an iso with this,obviously in europe we have to have a transformer to get the 100v(though i am sure mine are running at 110)
see if this link helps
http://files.filefront.com/Nanao+Schematicszip/;8697391;/fileinfo.html

[Kevin Mullins]

Thanks Grantspain..... those are the same schematics and such I was trying to compare to see if I could figure it out also. The closest schematic I saw just showed a plug going into the chassis.

But now you bring up a second question.... Are the bigger Nanao monitors supposed to be 100V?
I know the older smaller models are 100V, but I don't think the machine this came out of had a step-down transformer, so I figured it was 110-120V. (could be wrong though)

[Wade]

Can someone verify whether or not an MS8-26A-SU monitor requires an isolation transformer?

The only schematics I have found so far doesn't show one.
And of course haven't found an actual manual on them yet either.
I just want to test this monitor before I wire up the cabinet I'm putting together, but I don't know if it even works yet.

Doesn't need one, I have this model and it worked fine without an isolation transformer.  It was wired with an AC plug when I got it.

Wade

[Kevin Mullins]

Cool.... I plan to put one in the cabinet just so that it's a bit more universal, but I wanted to at least test this monitor before I go using it

Is yours powered by 110V, 120V?

And does it have a manual degauss button like the smaller Nanao monitors did?
The schematic looks like it has a seperate degauss set-up like my smaller KZ-20EN model.

[northerngames]

mine is from a dedicated machine and it runs on 100V and the isolation transformer is built into the PSU.

the psu I have is around 4X the regular size of the arcade PSU's.

I will check the game manual and if I find anything useful I will post it.

the per standard voltage/amperage is 100-120V/5A

current consumption is 2.1A 250 watts, 120VAC, 60HZ

my psu looks different then what it shows in the manual though  mine is all incased in a metal box.

[Rickn]

100 per cent- sort of, an Isolation transformer is not required, both the MS8 and the MS9 utilized switch mode power supplies.

In this case the primary input, (the 120 volts from the line cord) is isolated from the secondary circuit through the switch mode transformer.

So in the cabinet, you do not need an isolation transformer.

If you are going to prod around in the board in the "Hot side" or "primary Circuit" then use one.

Simply put, if you are doing repairor service work an ISO is always strongly urged.

Rick

Rick@Niemandisplays.com

[Zebidee]

Hey Grantspain, thanks for the link to the schematics!  That is so very, very handy

Sorry to hijack the thread, but right now I'm just looking at my MS8-26A with emerging vert. deflection problems.  Seems to be common with this model.  I'm getting thin white horizontal lines near the top of the screen.  Not critical at this point, but symptomatic of coming vertical collapse.

So, where does one buy a capkit for this (other than Bob Roberts, whom I've asked by email already but is probably sleeping)?  Jomac simply don't offer capkits, instead offering to replace individual components.  Even the employee that told me this on the phone seemed to have his doubts about the wisdom involved, but there you go.   

[grantspain]

hey zebidee,
i have about 30 of these in cabs and had some problems but not the one you describe-in saying that i looked at one of my chassis today and identified one or two possible culprits.
are you seeing any signs of a foldover at the top?and how much of the screen is affected by the lines?

[Zebidee]

Grant, sounds like you have hada bit of experience with these monitors then!

Here are a few pics I took today. Currently has Soul Edge PCB in there, so couldn't pause it.  Other than the horz lines at the top of the screen, it looks great!

The lines come down the screen about an inch or so - it varies slightly.  It seems larger/more apparent on brighter backgrounds.

You can tell from the screenshots that the lines only appear in brighter parts of the display.  It appears to affect all colours, but maybe blue more than others???  I'm probably imagining this because of the sky background that is apparent in most bright scenes.  To dispel my own private theory I included one shot of the title screen that has little blue in it, but still shows the lines in bright areas.

An arcade monitor technician, one of the better ones in my area, had a quick look at it when he was here a couple of months ago for something else.  He seemed pretty certain that it was showing early signs of vertical collapse and was in need of a capkit, at least for the relevant vertical part of the chassis.

BTW, Bob Roberts is sending me a capkit for the NS8-26A/SU, along with some other stuff, including capkits for my WG K7000 and Neotec NT2515C monitor chassis.  Looks like I'd better get my soldering gear ready ....

thanks again for looking at this
Zebidee

[grantspain]

def a good idea to change the caps in the psu and deflection circuit,i had an almost identical fault on pentranic chassis(common fault) whereby the picture would start to show what almost seems to be flyback lines(but not) and after a while you would get a small foldover followed by complete frame collapse and ic failure.it turned out to be in the primary stage of fault the smoothing cap on the frame ic voltage feed which then made the frame ic unstable therefore causing dry solder joints from the high level of heat and finally ended with the diode on the frame ic feed blowing pooless and then the chip exploding.
best to get in now and change those caps

[Zebidee]

Thanks heaps!  A stitch in time saves nine.  You certainly need a keen soldering hand in this hobby.

[grantspain]

also there are two small transistors on heat shields that i am sure are common component failure,i can't remember the numbers but there are two mounted opposite each other and i am sure they could have problems that relate to yours

[Zebidee]

thanks again Grant  - If you happen to be looking at one sometime (and actually remember to note the numbers!), then let me know and I'll check them out when I get to doing my capkit (in a couple of weeks after it arrives, I guess).

[grantspain]

no worries zebs,actually most of my ms8 are the "su" chassis but i have a few "a" chassis so i will check out the transistors(i think they begin bd something or other),i will have a look tomorrow as i have a few monitors i want prat about with anyway,its quite a long time since i have any serious failure with this chassis(the last time i remember a big prob was back in 1995 when i worked for a company on the south coast of england-bit i cannot remember the prob(old age mate)

[grantspain]

looking at an old ms8-a chassis today i believe the most likely culprits will be:
q401,402    2sd1571
c437            50v 120uf
c913             16v 220uf
c431            100v 33uf
c332             250v 10uf(neck card)
c433             25v 10uf
also change any caps around the frame ic and check the connections

[Zebidee]

Wow, that's great Grant.  Now I know where to focus my efforts!

I can't wait until my no-so-small Christmas present arrives from Bob Roberts (the capkits & other gear) so I can start getting busy!