(Topic ID: 229076)

WPC/WPC-95 GI from Secondary Transformer

By DumbAss

5 years ago

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2 posts
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Latest reply 5 years ago by Ronkz650
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Please educate me! I only did basic (secondary) high school physics which included basic electricity (essentially V=IR).

I fried a tantalum capacitor by incorrectly wiring (not correctly grounding a transformer secondary to a board). I want to prevent further board damage before I wire something up and enable the flow of electrons.

I am trying to understand the purpose of WPC J115-1 (or WPC-95 J103-1). This is a pin connected to one side of the 6.3VAC secondary transformer output and directly connected to ground on the power driver board. I am working on bench testing GI.

- Is this just to provide a known reference (ground)? It's still 6.3VAC between the two points but not to any known reference point.

- The AC current in the GI circuit is never rectified so what is the purpose of this? The AC voltage is still 6.3VAC regardless of whether it's grounded.

- Is it safe to not bother connecting any of the secondary transformer output (i.e. just connect the five pairs of AC input on J115 and leave J115-1 not connected)? Will it affect the triacs and therefore the GI?

- If it is NOT safe to do this (requires grounding) ... is there any danger to connecting the center tap of a VCT to ground and using both sides of the secondary transformer output (split across the five pairs of AC input)? I have a 12VCT transformer with two 6V secondary outputs but they are opposite phase due to the center tap. If the AC is never rectified does the phase mismatch cause any problems?

If it is not safe to ignore the ground connection and not safe to connect the center tap to ground I can use one side of the center tap but that will limit my capabilities (probably only able to test three simultaneous GI circuits instead of all five) due to incandescent current draw.

Thank you to all the experts out there that can provide any knowledge and information!

Not sure exactly what you are doing, or did wrong before, but the way it works in the game is one side of each gi string is grounded to turn on the lamps, the other side of each string is always 6.3vac. The strings controlled by triacs vary the ground basically, so they can turn on full ground for full brightness or zero ground for no brightness of the bulbs.
J115 pins 1,7,8,10,11,12 are all ground pins. In you disconnect pin 1, that would leave all the triacs without a ground, and I doubt any string would light. The other ground pins each go to one triac, so I believe if any of them were disconnected that string would not work.
Of course the other pins on J115, pins 2,3,4,5,6 are all power at 6.3vac all the time.
If you wanted to wire an aux transformer to power all the strings at once, you could by wiring one side of a 6.3vac to pins 1,7,8,10,11,12 and the other to pins 2,3,4,5,6. If many bulbs were going to be lit though it would take a large transformer.

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