Potentiometre on Neo25 board is damaged. Halp

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kazuo
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Potentiometre on Neo25 board is damaged. Halp

Post by kazuo »

Hey all,

Picked up a Neo 25 cab from a local recently and threw in a four slot. No go, psu worked, monitor worked but the 4slot would not start up. Tried a single-slot in there that I know is good (came out of my other cab), same deal. Nothing.

Checked voltage on the +5v pins, was getting 3.3v from the psu. Okay, I've been told by several users (channelmaniac from the neo forums in particular) that the four slots need around 5.1-5.2v to operate properly. Okay, I go to adjust the potentiometer on the psu.. oh, great, an empty hole.

So I unscrew the psu from the case and take it out, and I immediately hear a rattling sound. Must be the pot. I open up the casing, sure enough, there's the pot, ripped to shreds and broken clean off the board.

Pics are below.

Where can I get a replacement pot that will work properly with this psu? I figure the psu is still good, so I can just solder in a new pot and I am good to go, right?

If not, where the hell can I get a new (or used) psu? I searched a bit and I found that most people are chopping up Happ psu's or whatever to work.. not really interested in soldering a bunch of wires, thanks, so I'd like to avoid that if possible.

Thanks in advance for all the help!

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Pic of the PSU. Hole in the top-left is where the pot should be.

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Two different close-ups. Top left is where the pot should be on the pcb.

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Pics of the pot. As you can see, the previous owner hired a bear or perhaps a woodpecker to perform the pot adjustment.
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Devil Soundwave
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Re: Potentiometre on Neo25 board is damaged. Halp

Post by Devil Soundwave »

Having googled VR51, the only electronic component that comes back is the VR51B varistor by Shindengen. Obviously a varistor is not what you need.

Having said that, there is reference to a VR51 potentiometer on a Radioshack cassetter recorder here:

http://support.radioshack.com/support_v ... /30285.htm

Radioshack part no: 1072123

Although the Radioshack site returns nothing for this - give them a call.

Further googling tells me that the VR51 is a 1k Trim Pot, so perhaps this would do:

http://www.radioshack.com/product/index ... Id=2062300

But you'd need to get that confirmed by one of the more technically minded bods on the forum.

VR51B datasheet if this is at all useful:

http://pdf1.alldatasheet.com/datasheet- ... VR51B.html

God knows where you'll get one in Thaliand though...
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grantspain
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Re: Potentiometre on Neo25 board is damaged. Halp

Post by grantspain »

to match a pot you need to look at the number printed on it,i think your says 201 there its 2 0 and one x 0,that should be 200ohms
other examples 202= 2 0 and two x 0 2000= 2 kohms
401= 4 0 and one x 0 400ohms
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Devil Soundwave
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Re: Potentiometre on Neo25 board is damaged. Halp

Post by Devil Soundwave »

Guess you can discard my answer then as it would appear it's all ****... ;)
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yosai
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Re: Potentiometre on Neo25 board is damaged. Halp

Post by yosai »

The silk screen on the PCBs is there for the people that assemble them. It also makes it easier for fault finding and refering back to forth to the schematics.

In this case the VR stands for Variable Resistor. The 5 is common to all of the components, probably because the PCB is named S8XA-500 and the 1 means it's the first variable resitor on the board.
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Re: Potentiometre on Neo25 board is damaged. Halp

Post by Devil Soundwave »

Good to know. :)
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kazuo
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Re: Potentiometre on Neo25 board is damaged. Halp

Post by kazuo »

grantspain wrote:to match a pot you need to look at the number printed on it,i think your says 201 there its 2 0 and one x 0,that should be 200ohms
other examples 202= 2 0 and two x 0 2000= 2 kohms
401= 4 0 and one x 0 400ohms
Wow, nice pick-up grant, I didn't even see the number when it was staring me right in the face. Thanks for the info! it does in fact say "201," so your assessment should be correct.

Now I need to find a 200-ohm pot somewhere reputable... Radio Shack does not have anything suitable.

BTW I don't really live in Thailand. lol. I live in the US :)
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grantspain
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Re: Potentiometre on Neo25 board is damaged. Halp

Post by grantspain »

try ebay or is it mauser you have in the u.s
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kazuo
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Re: Potentiometre on Neo25 board is damaged. Halp

Post by kazuo »

grantspain wrote:try ebay or is it mauser you have in the u.s
I checked ebay and didn't find anything that looked like it would work.
http://www.mouser.com/Search/Refine.asp ... er&FS=True
None of those look correct, either...
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grantspain
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Re: Potentiometre on Neo25 board is damaged. Halp

Post by grantspain »

ebay.uk
http://shop.ebay.co.uk/items/?_nkw=200r ... &_osacat=0

ebay.usa
http://cgi.ebay.com/25-Allen-Bradley-20 ... Components

when searching use trimmer pots,variable resistor,potentiometer and value as 200 ohm,200r or 201

europe usually uses 200r whereas the u.s uses 200 ohm
I reckon your best bet is the u.k listing as that seems the correct fitting and i guess the shipping will be cheap for such a small item
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grantspain
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Re: Potentiometre on Neo25 board is damaged. Halp

Post by grantspain »

here you go,contact this fella
http://www.therealbobroberts.net/pots.html

he has what you need
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kazuo
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Re: Potentiometre on Neo25 board is damaged. Halp

Post by kazuo »

Thanks for the help, grant!

A fine gent on another forum has suggested the following:
I think you want Mouser part # 594-63X201

It is Vishay part # M63X201KB40

Datasheet: http://www.vishay.com/docs/57027/63.pdf

You want the X not M part # (63X not 63M)
Seems agreeable to me. Anyone else care to chime in?

Looks like I might get this thing fixed after all!
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kazuo
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Re: Potentiometre on Neo25 board is damaged. Halp

Post by kazuo »

Just a quick update - got it fixed! The pot worked perfectly, aside from the fact that it sat facing backwards--that is, the adjustment screw faced into the PSU, rather than toward the outside due to the orientation of the feet. But it worked perfectly. Got it set to 5.09v and my MVS boards work fine!

Thanks to grant and channelmaniac for the excellent information!!
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