Strange line filter mod?

Toxik Bones

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While checking voltages on my MK II restore, I was getting 130v when testing line and neutral. When testing from ground for both line and neutral separately. I get 35v through the neutral and 64v through line. I know this is not correct but it's also original wiring. But upon further inspection I found this and have yet to see this type of mod. After sniping it out I get 10v through the neutral and 30v through line.
c1a98d77513d3e4ca93eab22d6ae7d18.jpg
 
Pretty sure that's normal and that all the 90's Midway games I have seen have that. It's just a capacitor between the hot and neutral lines, likely to reduce hum and interference, which ironically is the filter's job anyway. I've also seen that mod on many switching power supplies for that same purpose.
 
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Pretty sure that's normal and that all the 90's Midway games I have seen have that. It's just a capacitor between the hot and neutral lines, likely to reduce hum and interference, which ironically is the filter's job anyway. I've also seen that mod on many switching power supplies for that same purpose.
could that also be the cause in the flux of voltage?
 
That is a standard setup. That is not a capacitor. It's a MOV (metal oxide varistor). It provides over-voltage and transient-voltage protection. Basically, the higher the voltage, the lower the resistance of the MOV and prevents that extra voltage from going into your game. They do go bad, usually from too many voltage spikes. I would recommend searching the part number and replacing it.
 
I don't see a mod there - looks standard to me.

The green MOV, as the commander said, is to absorb transient voltage spikes. They normally have visible damage when hit but not always. Wouldn't hurt to replace just in case of internal, non-visible damage from previous voltage spike. Replace with Littelfuse V130LA20AP. Don't forget to reuse the red insulation!

Assuming you live in the US: If testing the 120VAC, normally check power across the hot/neutral lines, not with respect to ground. Ground should be...ground. But Neutral...well, it should also be ground for most localities. Since ground and neutral are typically bonded together - you should be able to measure 120VAC between hot and neutral and between hot and ground.

You should not be measuring a voltage across neutral and ground. If you do, you have 'leakage' somewhere. But since this machine plugged into mains power shared by your entire house - you could actually be measuring the leakage between hot and neutral of your Air Conditioner even though you are measuring it inside your machine.
Odds of that are rather slim and frequently frowned upon by GFCI outlets. If testing for internal leakage, test with respect to ground. Internally within the line filter, there are special "X" and "Y" capacitors between hot, neutral and ground. These will play havoc with high input impedance DVM meters. Do not use a DVM here. Get a real, analog meter with a real needle (remember those?). Quite often you get ghost readings with DVMs when checking neutral lines. My meter of choice for this type stuff: the nearly indestructible Simpson 260.
 
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Good video on Phantom voltages when measuring power using a DVM.
They also demonstrate one of the new DVM's which has a setting to eliminate phantom voltages but most meters do not have this funciton.

https://youtu.be/mRwsxmn2P-s
 
I don't see a mod there - looks standard to me.

The green MOV, as the commander said, is to absorb transient voltage spikes. They normally have visible damage when hit but not always. Wouldn't hurt to replace just in case of internal, non-visible damage from previous voltage spike. Replace with Littelfuse V130LA20AP. Don't forget to reuse the red insulation!

Assuming you live in the US: If testing the 120VAC, normally check power across the hot/neutral lines, not with respect to ground. Ground should be...ground. But Neutral...well, it should also be ground for most localities. Since ground and neutral are typically bonded together - you should be able to measure 120VAC between hot and neutral and between hot and ground.

You should not be measuring a voltage across neutral and ground. If you do, you have 'leakage' somewhere. But since this machine plugged into mains power shared by your entire house - you could actually be measuring the leakage between hot and neutral of your Air Conditioner even though you are measuring it inside your machine.
Odds of that are rather slim and frequently frowned upon by GFCI outlets. If testing for internal leakage, test with respect to ground. Internally within the line filter, there are special "X" and "Y" capacitors between hot, neutral and ground. These will play havoc with high input impedance DVM meters. Do not use a DVM here. Get a real, analog meter with a real needle (remember those?). Quite often you get ghost readings with DVMs when checking neutral lines. My meter of choice for this type stuff: the nearly indestructible Simpson 260.
Thank you for the info! I am still learning a lot of it. I do have an analog meter as well and will use that to check it. Would it be wise to just swap it with a a new one, Both the Line filter and the MOV?
 
Pretty rare for a line filter to fail. But that one is a Chinese Taishing version so...
 
What voltage are you getting coming out of your wall jack?

I've seen 124v out of mine and the last time I checked it was 123.
 
What voltage are you getting coming out of your wall jack?

I've seen 124v out of mine and the last time I checked it was 123.

Straight out of the wall is a solid 118.9v

Pretty rare for a line filter to fail. But that one is a Chinese Taishing version so...
Probably will look for a replacement for it as well then. I did find the exact MOV that was in the assembly here- http://www.radwell.com/en-US/Buy/TNR/TNR/15G211KM

Would it be beneficial to use the one you had suggested over this one?
 
Straight out of the wall is a solid 118.9v

Probably will look for a replacement for it as well then. I did find the exact MOV that was in the assembly here- http://www.radwell.com/en-US/Buy/TNR/TNR/15G211KM

Would it be beneficial to use the one you had suggested over this one?

The original TNR15G221K is made by Nippon-Chemicon, the V130LA20AP (very common replacement) is made by Littelfuse. The Littelfuse part is better.

I have the Littelfuse part here:
https://www.greatplainselectronics.com/proddetail.asp?prod=V130LA20AP
I'm sure the other parts sellers in this forum also carry equivalent parts.

They are both rated at same varistor and max voltages:
TNR has "221" in part number which is 'varistor voltage', Littelfuse has "130" in the part number which is 'maximum continuous voltage'. If you compare varistor voltages and continuous voltages to each other - they are the same. That difference in numbers just adds to the confusion factor.

The real difference between the two is Littelfuse part is a 20mm diameter part, Nippon-Chemicon part is 15mm diameter.
That extra 5mm difference will provide a bit of extra protection because the "clamping current" is considerably higher for the bigger part (6500A versus 4500A). This clamping current is a sudden surge of current due to 'clamping' or cutting off excessive voltage spikes.

Note -- the TNR15G221K has been discontinued by Nippon-Chemicon. Their replacement is a TNR14V221K. Smaller diameter part but thicker than original. Closer but still lower clamping current rating than Littelfuse.

I carry the Littelfuse part as found here:
https://www.greatplainselectronics.com/proddetail.asp?prod=V130LA20AP
Can also find a better Corcom (Tyco) filter here:
https://www.greatplainselectronics.com/proddetail.asp?prod=5VB1
But it is pretty rare for the filter to fail.

I'm sure the other parts sellers on this forum have them as well.
 
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The original TNR15G221K is made by Nippon-Chemicon, the V130LA20AP (very common replacement) is made by Littelfuse. The Littelfuse part is better.

I have the Littelfuse part here:
https://www.greatplainselectronics.com/proddetail.asp?prod=V130LA20AP
I'm sure the other parts sellers in this forum also carry equivalent parts.

They are both rated at same varistor and max voltages:
TNR has "221" in part number which is 'varistor voltage', Littelfuse has "130" in the part number which is 'maximum continuous voltage'. If you compare varistor voltages and continuous voltages to each other - they are the same. That difference in numbers just adds to the confusion factor.

The real difference between the two is Littelfuse part is a 20mm diameter part, Nippon-Chemicon part is 15mm diameter.
That extra 5mm difference will provide a bit of extra protection because the "clamping current" is considerably higher for the bigger part (6500A versus 4500A). This clamping current is a sudden surge of current due to 'clamping' or cutting off excessive voltage spikes.

Note -- the TNR15G221K has been discontinued by Nippon-Chemicon. Their replacement is a TNR14V221K. Smaller diameter part but thicker than original. Closer but still lower clamping current rating than Littelfuse.

I carry the Littelfuse part as found here:
https://www.greatplainselectronics.com/proddetail.asp?prod=V130LA20AP
Can also find a better Corcom (Tyco) filter here:
https://www.greatplainselectronics.com/proddetail.asp?prod=5VB1
But it is pretty rare for the filter to fail.

I'm sure the other parts sellers on this forum have them as well.
Thank you for the wealth of info! I shall be placing an order soon!
 
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