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Author Topic: Nanao MS9 pots, watts and ohms...  (Read 502 times)

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RadRush

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Nanao MS9 pots, watts and ohms...
« on: December 25, 2019, 12:22:29 pm »
Hello!

Sweden calling! I'm new to this forum and I hope to get some answers here from you rockers!

I have a Sega New Astro City with its Nanao MS9 monitor in it. Long story short, I recently hooked up a Mame PC to it and the picture was really crisp and clear. Only thing to do was some minor horizontal and vertical adjustments on the pots, to perfect it. Being a total noob I had no idea there was such thing as a remote adjuster, so of course I hunched myself through the coin door to adjust the pots on the chassis. Turning the  V.LIN just the slightest did wonders. Then...I was turning the H.S. LIM pot on the board...and... CRACK...the knob snapped and fell off.  The picture now looks pinched and compressed like it is beyond the point of no return. I'm absolutely devastated.

1. How bad is this? I keep telling myself a new pot should do the trick.

2. I need a new pot anyway. What values do this particular pot have? I believe it is the VR452 pot. Or rather, what are the values for all pots on the chassis board? And what are the values on the pots on the remote? I want to know Ohms, Watts and any other value I can get my hands on.

I have googled so much the last few days I keep coming back to the same forums, discussions, youtube clips etc, but with zero information on this. All I've found are some 10kOhm pots people use on the remote, but Im not sure that's what I'm looking for? Is there anyone kind in here who can tell me what I need to buy?

Thank you very much!
/ Jonas

lilshawn

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Re: Nanao MS9 pots, watts and ohms...
« Reply #1 on: December 25, 2019, 05:17:51 pm »
while i don't specifically know the value of the damaged part (i'm sure I could find a schematic and look it up...) but you can place an ohmmeter between the 2 outside legs of the pot to find (approximately) it's value.

if you wish to replace them, the values of the pots are printed right there on the front of them.

the value is decoded as AAB with AA being a value in ohms.... and B being how many powers to raise this number

for instance "103" would be 10 and 3 zeros. so 10 000 ohms or 10K ohms..so on and so forth.

i believe the wattage on those small pots is  125 milliwatts and of the carbon variety.

that said, it looks like the wiper contact in your damaged pot appears fine. it probably still functions okay. you would just have to insert a tiny flat blade screwdriver in there to turn it. (the plastic bit that has come out just makes this easier to adjust.) you can actually buy trimmer pots without all the extra stuff on them, and they are often called "skeleton" timmers. used internally some something that needs to be set, then never touched again, they can be had for fractions of a cent each.

i'm not sure if you could find an EXACT replacement for that style of pot (as these parts become obsolete fairly fast as the companies who make them come and go), but something like this.......

https://www.ebay.com/itm/10pcs-WH06-1A-502-Side-Adjust-Carbon-Track-Trimmer-POT-1-Turn-5K-Ohm/400988400436?hash=item5d5cc56b34:g:8LQAAOSw0JpV5d-~

is much more common and should slot into its place without issue...you just have to order the proper values.

search for "right angle carbon trimmer pot _______"(the value you need such ad 10K or 200)

RadRush

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Re: Nanao MS9 pots, watts and ohms...
« Reply #2 on: December 25, 2019, 05:51:56 pm »
Thank you very much for your reply lilshawn! I will definitely have a look into this.

When that plastic little bit snapped and fell off, I'm afraid I accidentally kind of stabbed the pot with the screwdriver. Is it possible to short a pot? Could I have damaged it? You really think there is hope for it being still functional? I mean when turning the pot it shrinks/expands the picture and when it first fell of the picture was really crammed into the center of the screen, making up about 1/3 of the full screen. I turned everything off, but later when I booted it all up again, the picture was a real jittery wobbling mess.

The plastic bit has a printed number on it that says 289. Is that the number you referring to with AAB? If so, what is 289? This makes no sense to a long lost guy like me...

Also...after another few hours (yeah really!) of googling I believe it is a 3.3 kohm pot. Really hard to find apparently. So in desperation, what would happen if I put a 5kohm pot there instead? Could it do any damage?

Thanks again for your reply!
/ J.

grantspain

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Re: Nanao MS9 pots, watts and ohms...
« Reply #3 on: December 25, 2019, 06:27:59 pm »
vr452 is either 6.8k or 3.3k depending on chassis revision and what tube/yoke it was used on
you sure your old pot does not say 683?

lilshawn

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Re: Nanao MS9 pots, watts and ohms...
« Reply #4 on: December 25, 2019, 06:36:28 pm »
289 looks a lot like a 682 when viewed upside down.

 :lol

grantspain

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Re: Nanao MS9 pots, watts and ohms...
« Reply #5 on: December 25, 2019, 06:48:58 pm »
yes 682, i blame the bourbon for my number misprint

RadRush

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Re: Nanao MS9 pots, watts and ohms...
« Reply #6 on: December 26, 2019, 05:06:55 am »
..ehrm.. well, could very well be 682 of course, haha. Those numbers are sooo small. So, ok...now what does 682 mean? If 103 means 10.000, 682 is probably 6.8 Kohm, just like grantspain says. Now I'm getting somewhere. But how do I know the watt? lilshawn tells me 125 mW. How do you know that? Is it something you just happen to know, or where/how do you find out? Again, what happens if I pick a pot with another ohm value? Could it be dangerous to the board?

Thanks a lot guys!

grantspain

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Re: Nanao MS9 pots, watts and ohms...
« Reply #7 on: December 26, 2019, 06:00:26 am »
they are 125mw, i know because the manual says they are and they match that physical size parameter
the actual part number is RH063LCW3R-6.8KB  although you will not find any info, they were made by ALPS

you could probably use a 5k

RadRush

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Re: Nanao MS9 pots, watts and ohms...
« Reply #8 on: December 26, 2019, 06:27:32 am »
Thank you grantspain!

One final question (at least for now): what happens if I mount say a 5 kohm pot like you say, but it's 0,5 watts instad of 0,125? Or even 1 or 2 watts? What harm would it do?

I seriously have no clue about watts and I know nothing about what wrong values will do. Im asking because it's really hard to find 0,125 watt pots.

Mike A

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grantspain

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Re: Nanao MS9 pots, watts and ohms...
« Reply #10 on: December 26, 2019, 06:50:10 am »
watts not massively important if higher but of course its about physical size and fitting onto the chassis and lining up with the through holes
ms9 use a couple of very hard to get value presets, 3.3k and 6.8k

this one should be ok, might have to bend the rear leg outwards
https://www.arcadepartsandrepair.com/store/components/trimmer-potentiometers-pots/5k-ohm-trimmer-potentiometer-p1066/

this one looks ok as well although higher watts but leg spacing looks correct
https://www.arcadepartsandrepair.com/store/components/trimmer-potentiometers-pots/5k-ohm-trimmer-potentiometer-p1042/

RadRush

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Re: Nanao MS9 pots, watts and ohms...
« Reply #11 on: December 26, 2019, 06:55:05 am »
Thank you Mike A!

No, Ive never seen that page. Thanks! They dont have 6.8kohm pots but do have 5 kohm which should be fine. However they are 0.5 watt rather than 0.125 that Im looking for. Would this do anyway? Still wondering what happens if I have the wrong watt value.

RadRush

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Re: Nanao MS9 pots, watts and ohms...
« Reply #12 on: December 26, 2019, 06:58:23 am »
Wow thanks a lot grantspain!

I did find that one myself, with the correct leg spacing, but missed the one with the better watt value. I'll grab a few of those.

Thanks a lot to all you guys. I really appreciate your help!!

grantspain

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Re: Nanao MS9 pots, watts and ohms...
« Reply #13 on: December 26, 2019, 07:02:10 am »
because the pot you are replacing controls the h s limit its not as important as let say a horizontal or vertical frequency pot, they tend to be pretty critical and on some chassis if you get the horizontal frequency pot completely out of spec you will kill the horizontal deflection circuit

RadRush

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Re: Nanao MS9 pots, watts and ohms...
« Reply #14 on: December 26, 2019, 07:36:11 am »
Again, thank you grantspain. Just ordered a couple of those pots now and also added an MS9 cap kit to safe up my future gaming life in case something blows or start leaking. Really good thing to know the H and V freq pots are that sensitive too. I have a lot to learn!

Cheers!

Mike A

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Re: Nanao MS9 pots, watts and ohms...
« Reply #15 on: December 26, 2019, 08:14:28 am »
yes 682, i blame the bourbon for my number misprint

Pour yourself some more bourbon. You helped another person keep a CRT alive. :cheers: