Bally Triac Questions

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By Hop-Pac

3 months ago


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  • Started 3 months ago
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  • Latest reply 2 months ago by wayout440

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1200px-Triac.svg (resized).png
IMG_20170226_040122285 (resized).jpg
IMG_20170226_050007 (resized).jpg
large_330_BT136-1 (resized).jpg
Goodpath_zps9c0e01b5 (resized).JPG


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#1 3 months ago

Does anybody know much about Triacs?
From what I can read they control GI and make them flash, are prone to fail, are no longer made, and are "easily" bypassed.
My questions are...
Does a Triac work with an Aux. Driver board? Does it require both?
Is there anything that can be used to replace a bad one?
What happens when a Triac goes bad...Do all GI lamps stay off?
And how are Triacs bypassed?

#2 3 months ago

In simplest terms, because the GI is AC (sinusoidal, current flows in two directions) a Triac is used. A regular transistor or SCR is basically constructed with diodes, so it can be used as a simple DC switch. A triac is preferred in AC circuits because it allows current to flow in both directions. The triac is just a solid state switch substituting what can be done with a mechanical relay. I have noticed that in early solid state pinball, we tend to see relays used for GI switching in Williams and Gottlieb games, and triacs often used in Ballys.

A possible replacement: http://www.marcospecialties.com/pinball-parts/BT138-600E

Hi Everyone.
I have been advised the following will work so this may help anyone else with this issue.
"I would use Jaycar ZX-7149 which is actually a BT-137-600V-8A Triac because it has an isolated tab meaning you don't need to use any insulating washers to mount the part - much easier."
You need to get the pin outs of new and old triacs so you can solder the wires in correctly. You can also drill a hole in the metal plate and screw the new triac in as it is isolated.

Regards
Clive

#3 3 months ago

So the triac, being a switch, is turned on and off by the small square Aux Driver board? If the triac goes bad, does it stay off? No GI?

#4 3 months ago

I don't have a Pac, but looking at the schematics there is a page which shows a GI flash driver board, that is the small board that turns on and off the triac. The schematics show A9J2-5 with the description "To pin 3 GI flash driver board".

What I see is: Aux driver J2-5----> GI flash driver pin 3 ----> triac.

If the triac is dead, then the GI doesn't have any return so the lamps are stuck off.

#5 3 months ago

If you search Pinwiki for "triac" there are a few articles that appear to be about making a test fixture.

#6 3 months ago

Recommend you check the bulb first:

To make the GI lamps flash on and off, Bally used a Triac bolted to the power supply board in the cabinet. The triac is cycled by the GI lamp flasher board mounted under the playfield. This flasher board is similar to a solenoid expander board. The output of a lamp SCR driver is used to drive a MOC3011 opto coupler that drives the Triac. As with the solenoid expander board, a dummy 555 lamp is connected to the SCR output on the flasher board to insure there is enough current draw to drive the MOC3011. Most likely this 555 bulb is burned out, and causing your problem. Also check the flasher board for bad (cracked or cold) solder connections. Check all the cable connections to the triac too. Lastly you can replace the MOC3011 chip.

#7 3 months ago

Great info. Thanks. I think I have triac issues on both machines.
On Pac-Man, the GI stays on for the pac-maze.
And on Gold Ball the backglass lights are always out. The playfield lights work and blink as they should. There are 2 Triacs in Gold Ball. I'm guessing one for pf and one for bg.

#8 3 months ago

Ok, hope that info helps. I had Elektra, which had triacs for the backglass, playfield and mini-playfield. Good luck.

#9 3 months ago

Does anybody know how to bypass a triac so I can see if the lights turn on?

#10 3 months ago

Near the power supply (in the cabinet) there should be two similar connectors.
One going to the triac and the other going to the transformer/power supply.
Those two connectors should fit together.
One would have a green and white wire, the other should have a green, white and a black wire.
The green and white wires should line up turning the GI on.

In this image you can see the connector going to the triac in the hand.
The other connector you can see near the large resistor.

Goodpath_zps9c0e01b5 (resized).JPG

#11 3 months ago

I'm not sure how you conclude that "triacs are prone to fail"?

I have found them to be one of the most reliable and robust semiconductors ever made?

#12 3 months ago
Quoted from Inkochnito:

The green and white wires should line up turning the GI on.

Cool. Thanks Inkochnito. Will try that

Quoted from Homepin:

I'm not sure how you conclude that "triacs are prone to fail"?

Just did a search about Triacs, and see a lot of the same type of posts about Triacs not working. And I seem to be having trouble with both of my games. I just figured they were prone to fail. Maybe I jumped the gun on that? Are they reliable? I don't know

#13 3 months ago

Yes you can jump the center pin to the left pin facing the front of the triac to make it switch on, the 3rd pin is controlled by low ground voltage which will switch it on. In this pic shown you would jump A1 to A2 to turn on the GI string.

large_330_BT136-1 (resized).jpg

#14 3 months ago

Triacs are tough to burn out most likely you have a problem in the switching circuit (G)

#15 3 months ago

Also the pins are commonly known as B(base A1)E(emitter A2)C(collector G) the transistor should have its value printed on the front of it. Tip 102, BTE 500E ect. What is the value?

#16 3 months ago
Quoted from Hop-Pac:

Just did a search about Triacs, and see a lot of the same type of posts about Triacs not working. And I seem to be having trouble with both of my games. I just figured they were prone to fail. Maybe I jumped the gun on that? Are they reliable? I don't know

I think what you are most likely seeing is threads discussing GI failures that just happen to include a triac in the circuit. Almost always there is something else at fault
http://www.pinballrevolution.com/threads/do-gi-triacs-ever-fail.674/

1 week later
#17 89 days ago

I took pictures of my boards in my machines. So looking them over, I found this. A broken wire in Gold Ball.

IMG_20170226_050007 (resized).jpg

#18 89 days ago

So I checked it out. And a quick fix = Backglass Lights!!!
And they flash when the gold ball comes out. Turns out, it wasn't the triac! One fixed, now on to the other.

IMG_20170226_040122285 (resized).jpg

#19 89 days ago
Quoted from gmkalos:

Also the pins are commonly known as B(base A1)E(emitter A2)C(collector G) the transistor should have its value printed on the front of it. Tip 102, BTE 500E ect. What is the value?

Triacs are not transistors and so they do not have a "base, emitter or collector" and do not have pins marked EBC.

They work in an entirely different way to transistors.

Well done to the OP for finding the problem. As usual, it is best not to overthink the problems and start blaming things when really most issues are common connector or cabling problems.

#20 88 days ago
Quoted from Homepin:

Triacs are not transistors and so they do not have a "base, emitter or collector" and do not have pins marked EBC.
They work in an entirely different way to transistors.
Well done to the OP for finding the problem. As usual, it is best not to overthink the problems and start blaming things when really most issues are common connector or cabling problems.

Correct. A triac has 3 pins: Anode 1, Anode 2 and Gate. Congrats to the OP for finding the problem. The poor triac always gets the blame, lol.

1200px-Triac.svg (resized).png

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