The Aussie Pinball Arcade
Aussie Pinball Forums => Archived Threads => Homepin => Topic started by: Homepin on June 17, 2014, 06:32:17 PM
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I have had numerous requests over the years for the MOV and Thermistor commonly used in DMD machines. I have actually been supplying these for several years to a few pinball repairers and thought it was about time others had the opportunity to get the correct 230V parts.
I have them available as a single pack (one of each and I include high voltage/temperature insulation) and also a five pack for those with more machines.
They are available here:
http://www.homepin.com/mov.html
(http://www.homepin.com/pics/1pack.jpg)(http://www.homepin.com/pics/5pack.jpg)
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great deal,there is so much miss info about this product and were to buy.well done mate.
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might be worthwhile explaining the importance of these parts mike,with so many inports comming in.
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might be worthwhile explaining the importance of these parts mike,with so many inports comming in.
You're right....
The MOV (Metal Oxide Varistor) acts like a zener diode in that when a voltage is sensed that equals or is higher than its rating it quickly short circuits and forces the mains fuse to blow (as long as it isn't a nail!).
Sometimes if it is just a transient spike in the mains it will not permanently short but just do so momentarily to protect the machine and trust that the fuse will do its job. Other times the MOV will short circuit and must be replaced but be happy that it has very likely protected your machine from much more serious damage.
The Varistor is placed in series with one side of the mains and when cold (power off state) it exhibits a high resistance and so slows the inrush of current when the machine is first switched on. This initially limits the current flow basically to offer a "soft start" to the machine and allow things like the main filter capacitors time to charge to capacity gently without stressing them. As this part warms up the resistance drops to quite a low value, typically a couple of ohms and so the full mains potential is applied to the machine after the initial start.
Thermistors, as they age, lose the ability to switch down to very low resistances and can typically only go down to around 10~20 ohms. This can cause random resets and can be a tricky fault to find.
Machines wired for 110V (USA and Japan) will have the incorrect value MOV installed that will usually have a breakdown voltage of around 150~170V. If you plug this machine into 230V the MOV will instantly conduct and you will be greeted with a shower of sparks and then silence.
It is my recomendation that if you are going to the trouble to open up the machine and gain access to the MOV you may as well change both parts at the same time.
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Nice mate so many games are left without them
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Nice, needed last week @.@
It seems my ST TNG blew the thermistor as a result of a faulty line filter. Replaced thermistor firstly before she burned up with smoke and all.
New line filter, thermistor and added a varister ( had been cut out!) fixed the problem.
What about a third pack including the line filter?
Cheers
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What about a third pack including the line filter?
I would love to as I can get filters at very attractive prices BUT Australia Post kills the deal as the cheapest postage option for something of that thickness is OVER $10.
I might be able to do a package posted from Hong Kong as the postage would only be about $3 air mail and registered!
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Even post at 10 bucks, you still will be competitive with PSPA. line filter at almost 20 plus 3.68 for a thermistor and varister 1.00 and their postage 7.95.
I reckon you will find plenty of buyers here ^^^
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Nice one Mike, i just placed an order for the pack of five ^^^
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Mike, aren't these somewhat low in voltage rating? 230v?? they would short at switch-on with regular 240v present.....
Do you have deeper specs on their idle voltage versus spike voltage to indicate what voltage fluctuations these will handle?
I only ask this, because i've had to repair endless industrial equipment that some tech before me fitted out with 220v-240v MOVs, only to find all the machines blew fuses at powerup.
In that particular case i had to replace all the MOVs with the original versions being 300v rated according to the manual/tech guidlines.
Most pinny sites/mods i've seen have used the 275v versions for Aus.
Also to note, for anyone powering on a USA 110v pinny on 240, the MOV will short and blow the fuse...if there's any "sparks" it's just the mov+fuse exploding, NOT your pinny/boards ;-)
MM
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The MOVs I supply are rated at 250V RMS which I conceed is a little low if you live in WA as that is close to the (sometimes) maximum supply.
In practice I have never had a problem and have sold over 1000 in two years and I suspect that both the idle rating of the device (390V) and the tolerance of 10% both play a part.
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Are these suitable for any pre DMD games Mike? From your description I'm guessing this is the likely problem with my BoP machine. I thought it was fixed but I'm still having intermittent issues and this is the last thing left to chance out.
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Fantastic work Mike !
I've had a few really badly "repaired" games that have obviously come out of the USA and they have needed both replaced. Great idea to have the EMI filter as a "kit". I've replaced the EMI Filters in FIFTEEN games since March.
Just placed an order ^^^
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All orders received by 9am 18th June (today) have been packed and will post today.
I will certainly look into packs that also contain the EMI filter but these would have to be posted from Hong Kong as Australia Post has priced itself out of this market. How is it possible to post a package from HK to be delivered in Australia (by Australia Post) for $6 when the exact same item costs $12 to post between Australian destinations AND it is often delivered faster and registered from HK? Bloody ridiculous IMO.
My apologies for not responding individually to buyers but I have been overwhelmed with orders for these and I have a plane to catch in two hours so I was scrambling to get them all packed. My usual packing and posting person will resume duties tommorow.
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I would grab a few packs with the line filters. The slower postage from hong Kong wouldn't worry me.
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might be worthwhile explaining the importance of these parts mike,with so many inports comming in.
You're right....
The MOV (Metal Oxide Varistor) acts like a zener diode in that when a voltage is sensed that equals or is higher than its rating it quickly short circuits and forces the mains fuse to blow (as long as it isn't a nail!).
Sometimes if it is just a transient spike in the mains it will not permanently short but just do so momentarily to protect the machine and trust that the fuse will do its job. Other times the MOV will short circuit and must be replaced but be happy that it has very likely protected your machine from much more serious damage.
The Varistor is placed in series with one side of the mains and when cold (power off state) it exhibits a high resistance and so slows the inrush of current when the machine is first switched on. This initially limits the current flow basically to offer a "soft start" to the machine and allow things like the main filter capacitors time to charge to capacity gently without stressing them. As this part warms up the resistance drops to quite a low value, typically a couple of ohms and so the full mains potential is applied to the machine after the initial start.
Thermistors, as they age, lose the ability to switch down to very low resistances and can typically only go down to around 10~20 ohms. This can cause random resets and can be a tricky fault to find.
Machines wired for 110V (USA and Japan) will have the incorrect value MOV installed that will usually have a breakdown voltage of around 150~170V. If you plug this machine into 230V the MOV will instantly conduct and you will be greeted with a shower of sparks and then silence.
It is my recomendation that if you are going to the trouble to open up the machine and gain access to the MOV you may as well change both parts at the same time.
Cool, I thought they were cake testers.
Thanks for the op to buy, Mike
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I would grab a few packs with the line filters. The slower postage from hong Kong wouldn't worry me.
That's the thing - it probably wouldn't be slower anyway......but much cheaper.
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I would grab a few packs with the line filters. The slower postage from hong Kong wouldn't worry me.
That's the thing - it probably wouldn't be slower anyway......but much cheaper.
Great. Let us know if they become available.
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I would grab a few packs with the line filters. The slower postage from hong Kong wouldn't worry me.
That's the thing - it probably wouldn't be slower anyway......but much cheaper.
Great. Let us know if they become available.
I bought some filters today - now to get some more MOVs and Thermistors......
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Maybe also offer a 240v plug and fuse along with the MOVs as package for a "one-stop" solution for people changing 110v machines to 240v.
just a thought...