Do I Have Excessive Voltage? (WPC89)

I have excessively powered coils in my TZ. The ball-release coil, for example, punts the ball clear over the diverter into the shooter lane. I have bought/installed a few replacement coils, each with a higher resistance than the last, but none has been week enough to release balls properly. I spoke to Steve at The Pinball Resource about this and he suspected my game voltage is somehow excessive. My household voltage is 122VAC and the voltage at the ball-release coil is 77VDC. 77VDC is weird. I looked in the manual to learn more. The ball-release coil is solenoid #9, powered by J127-1 on the Power Driver Board (see photos). When I look at the schematic of the PDB, it shows 50V at J127-1 (see photo). In fact, there is no voltage anywhere in any of the diagrams (excluding the main power diagram) that is more than 50V. I asked a seasoned op about this and he said my coil may meter 77VDC, but it’s actually 50V under load. I metered his coil on his machine and, sure enough, his coil at rest is also above 70VDC. His ball-release coil works fine, however. The stock coil is a 12-2600 with 10 Ohms resistance. The replacement coil in there now is a 30-3000 with 69 Ohms resistance and it’s still too powerful!
Steve told me to consult the manual for information on the “jumpers” in the power box, as these are configured in response to where the machine is on location. In places outside the U.S. where the voltage is different, these jumpers are important. I found nothing in the manual but I did find the three voltage diagrams in the schematic manual (see photo). There appears to be a “strip” in the cabinet for games designed for foreign markets through which one can adjust the game’s voltage management. I have no such strip. Is there any chance my game is a re-import and still set to 100V? If it were set to handle 100V and I’m presently giving it 120V, would that make my coils hyperactive? Any insight into this problem would be much appreciated.

Thanks for reading my long post!

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#2 2 years ago

ZAC

zacaj

RPC

Rochester, NY

11y 158K 10,385 85 122 1

There isn't a strip, you need to look at the wiring of the connector between the transformer and the power box. Which jumpers are installed on that 9 pin connector determine what voltage your transformer is set for.

To avoid the "under load" question, you can chdck the ac voltage coming into the power driver board. It should actually read around 50v ac, and isn't affected by the caps, etc like the DC is

#3 2 years ago

FNG

DumbAss

Pinside+ Frequent

9y 109K 2,978

Here's the arithmetic (math):

50VAC produces 70VDC.
Nominal outlet 115VAC transformer primary input to produce nominal 50VAC transformer secondary output is a ratio of 2.3.
Your outlet 122VAC transformer primary input with that ratio produces 53VAC transformer secondary output.
53VAC produces 75VDC.

If you want to learn more then research "root mean square" and prepare to have your head spin.

#4 2 years ago

J_G

Jason_Jehosaphat

Pinside+ Frequent

Quoted from zacaj:
There isn't a strip, you need to look at the wiring of the connector between the transformer and the power box. Which jumpers are installed on that 9 pin connector determine what voltage your transformer is set for.
To avoid the "under load" question, you can chdck the ac voltage coming into the power driver board. It should actually read around 50v ac, and isn't affected by the caps, etc like the DC is

Thanks for your help.
Where do I meter the inbound voltage to the PDB? Manual shows a slew of low-voltage connections from the transformer.
And how do I check the jumpers? What do you see in these photos?

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#5 2 years ago

LTG

Pinside member

OP
Quoted from Jason_Jehosaphat:
And how do I check the jumpers?

The jumpers circled in red are the ones to change voltage. Don't mess with them until you find out which ones go where.

LTG : )

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#6 2 years ago

J_G

Jason_Jehosaphat

Pinside+ Frequent

Quoted from DumbAss:
50VAC produces 70VDC.
Nominal outlet 115VAC transformer primary input to produce nominal 50VAC transformer secondary output is a ratio of 2.3.
Your outlet 122VAC transformer primary input with that ratio produces 53VAC transformer secondary output.
53VAC produces 75VDC.

If you want to learn more then research "root mean square" and prepare to have your head spin.

Oh. Then my coil voltage is apparently normal. The "50V" shown in the schematic is AC and becomes 77VDC at the coil?
Thanks for your help.

#7 2 years ago

LTG

Pinside member

OP
Quoted from Jason_Jehosaphat:
Manual shows a slew of low-voltage connections from the transformer.

Page 3-32 - J105 pins 1 and 2 50VAC

LTG : )

#8 2 years ago

J_G

Jason_Jehosaphat

Pinside+ Frequent

Quoted from LTG:
The jumpers circled in red are the ones to change voltage. Don't mess with them until you find out which ones go where.
LTG : )[quoted image]

Great. Thank you, LTG, but where do I look for these jumper-configuring details when there is nothing in my service manual?

#9 2 years ago

LTG

Pinside member

OP
Quoted from Jason_Jehosaphat:
but where do I look for these jumper-configuring details when there is nothing in my service manual?

Wiring schematic. Other manuals.

Since your 50VAC is right. I'd leave it alone.

LTG : )

#10 2 years ago

J_G

Jason_Jehosaphat

Pinside+ Frequent

Quoted from LTG:
Page 3-32 - J105 pins 1 and 2 50VAC
LTG : )

Interesting. I didn't realize all the coil power goes through the Fliptronics board.

#11 2 years ago

J_G

Jason_Jehosaphat

Pinside+ Frequent

Quoted from LTG:
Since your 50VAC is right. I'd leave it alone.
LTG : )

Should I expect to meter 50VAC at my ball-release coil?

#12 2 years ago

LTG

Pinside member