Author Topic: Damn GI.... (Read 4691 times)

Toadie · « **on:** June 01, 2013, 11:01:55 pm »

So after a few weeks of playing and tweaking, things were going well until tonight. I was replacing a #47 bulb on one of the top bumpers with an LED 47 and when I twisted the bulb the metal underneath hit a screw and shorted out my GI track. Now none of my playfield GI's are working and interestingly enough, none of fuses blew.

Honestly I wish they had but I tested them all and they all work. There was the typical electronics smell after the short but I'm at a loss. All the other lights work and all the game functions, I just have no GI.

Thoughts?

Toadie · « **Reply #1 on:** June 02, 2013, 02:52:12 pm »

I think it's the new rectifier board. I'm not getting a voltage off of TP4 but I didn't blow a fuse which is odd

ChadTower · « **Reply #2 on:** June 03, 2013, 10:20:33 am »

If it's the repro board then call the seller. They should be able to advise.

Silverball84 · « **Reply #3 on:** June 04, 2013, 11:14:06 pm »

What style rectifier board do you have? I always rebuild the original boards with more reliable parts. Probably number one thing on early solid state pins that fails are cold solder joints. Primarily at header pins. I would isolate your power supply and check for GI voltage. If the voltage is missing and the fuse ohms out good then a component on the rectifier board has most likely failed.

smartbomb2084 · « **Reply #4 on:** June 05, 2013, 09:00:41 am »

What game is this? SPACE INVADERS?

If so isn't GI in this game AC voltage? So why does it need RECTIFIED?

Have you possibly damaged the transformer winding for your GI?

Are you absolutely sure fuse F5 is good?

ChadTower · « **Reply #5 on:** June 05, 2013, 10:33:10 am »

Not everything routed through the recitfier board actually gets rectified. Some just gets fused there and passes through.

smartbomb2084 · « **Reply #6 on:** June 05, 2013, 05:08:51 pm »

EXACTLY... Thank You Mr. Obvious...

More going on here than 'meets the eye' I think...

How could just quickly 'touching a screw' cause transformer damge without blowing the properly rated circuit fuse?

Toadie · « **Reply #7 on:** June 05, 2013, 07:57:45 pm »

Yeah it's a space invaders pin so it's a 2518-54. It's a new board with newer components. I can't say I have all the answers as this is my first pin so I'm not sure if anything happened to the transformer. In terms of how it happened...

Took working #47 out of the top bumper (second from the left), placed a #47 back in, gave it a twist to lock it in, and pop... no more GI

When it happened I could see the metal touching the screw so I know that was it. I tested the continuity in all the fuses so yes, they were all good.

I've sent the board off to the supplier to get it tested.

Toadie · « **Reply #8 on:** June 05, 2013, 08:01:53 pm »

While the board is out, is there a way for me to test the transformer?

ChadTower · « **Reply #9 on:** June 06, 2013, 12:28:15 pm »

Quote from: smartbomb2084 on June 05, 2013, 05:08:51 pm

How could just quickly 'touching a screw' cause transformer damge without blowing the properly rated circuit fuse?

I've seen stuff like this happen when there is more than one short. Not all shorts are across circuits. Sometimes they are in the same circuit and they just allow a different current path to do something like bypass a fuse.

smartbomb2084 · « **Reply #10 on:** June 06, 2013, 03:45:52 pm »

I measured resistance across transformer lugs 17 and 18 on two different Bally transformers and got .3 Ohms on one and .4 Ohms on the other....

Did you perhaps short GI Voltage to +43V Coil Voltage?

Toadie · « **Reply #11 on:** June 06, 2013, 05:45:40 pm »

Good question but no, it's a regular bumper not a thumper bumper. Also the short occured from the top and not underneath. There would technically be no way for me to trigger the 43 coil

That I can think of that is. Later tonight though I'll go check the wiring and see what I have going on. Cross short is a concept I didn't think of

Toadie · « **Reply #12 on:** June 06, 2013, 09:48:00 pm »

nah I was right just two wires, one red, one white. The same wires that tie all the GI's together when I follow the chain.

ChadTower · « **Reply #13 on:** June 07, 2013, 10:06:48 am »

Are you following the chain with your eyes or a DMM?

Toadie · « **Reply #14 on:** June 07, 2013, 10:40:02 pm »

Just with my eyes. Right now I have no power. The rectifier board has been sent back for testing. In terms of the short I took out that screw and moved that light piece back to where it should have been.

smartbomb2084 · « **Reply #15 on:** June 07, 2013, 11:26:54 pm »

Now the plot thickens...

Just exactly WHAT light piece did you move to where it SHOULD have been?

And where WAS it before you moved it back?

Also...Did you 'Ohm out' the transformer yet?

Toadie · « **Reply #16 on:** June 09, 2013, 11:01:12 am »

I'm not sure how exactly the plot thickens or what I would have to gain but not telling the full story up front like I did but you go on with your bad self Pinball Wizard

Before you do though you may want to go back to the statement in my first post "I was replacing a #47 bulb on one of the top bumpers with an LED 47 and when I twisted the bulb the metal underneath hit a screw and shorted out my GI track."

If you look at the picture you will see that the standard light bracket has a wavy pice on the bottom. That piece has the ability to turn due to the fact that it looks like it's connected by a rivet type thing. I would guess that over time (machine is from 1980) that it loosens and turns more easily. Ie. Like when a guys is replacing a light bulb and twisting to lock it in.

To be more specific with my answers...

The WHAT, the the wavy metal piece and the WAS is directly under lamp socket.

As for testing out the transformer, I asked how to do that and never got a response.

Posted by: Toadie
« on: June 05, 2013, 08:01:53 pm »
Insert Quote

While the board is out, is there a way for me to test the transformer?

I'm not sure how to do it

smartbomb2084 · « **Reply #17 on:** June 09, 2013, 11:11:14 am »

So you shorted the bumper lamp socket to one of the bumper body mounting screws?

Screws that are just through plastic and wood and that touch nothng else?

As for the transformer test... I told you already...

Measure resisitance across lugs #17 and #18 WITH A DMM....You should get .3 or .4 Ohms..

This is the winding that delivers GI AC voltage to the game.

If you can't do this simple thing you may be selling the game to some one who can.

ChadTower · « **Reply #18 on:** June 09, 2013, 06:38:06 pm »

When you short a lamp lug it's very easy to figure out what you shorted it to. Go back in and spin it. You shorted it to whatever is within reach of the lug.

Toadie · « **Reply #19 on:** June 09, 2013, 11:16:02 pm »

Hey Smartbomb... you can stop replying any time. I'd rather hammer my way through it than deal with someone like you. The fact that I have more than enough money to buy 10 of these things pales in comparison to the point of me trying to learn something because I'm curious. Congratulations, you know about electronics, I'm really impressed

I'm sure you're a joy to be around.

Hey Chad, I haven't tested it since I've been pretty busy today but I'm wondering if maybe this is happening...

For sure it's that screw and in theory our little troll is correct. Technically the screw that just goes through plastic and wood should not short it but... what if it's touching a staple from the underside of the play field? if I recall correctly the lamp holders are bent as they go through the playfield and tied back with metal staples. If the screw somehow touched that staple then technically it could be touching one side of the lamp.

Since I'm not an electronics genius like Mr. Wizard

I'm not sure what the effect could be but logic would dictate that it could result in a short no?

ed12 · « **Reply #20 on:** June 10, 2013, 12:06:13 am »

your logic is 100 % correct
yes they staple in the wire's and yes a screw can and will short over to the high side winding's
so go slow and see if it did ?

ed

smartbomb2084 · « **Reply #21 on:** June 10, 2013, 08:25:44 am »

Man, why the hostility? I am sure you are even MORE of a joy to be around than me.

That's what happens when you try to help the clueless....they cop an attitude and don't do the things you recommend to fix their problems. And then, they blame you for their ineptness

It's always a good practice to bash the people who are trying to help you out....You're welcome...and Good Luck...

ChadTower · « **Reply #22 on:** June 10, 2013, 10:29:00 am »

If you think it's that type of short then do a continuity check from that screw to all of the other potential circuits. If there is a short you'll find it.

Then cut the wire off that lamp lug and cover it with some heat shrink so this doesn't happen again.

smartbomb2084 · « **Reply #23 on:** June 10, 2013, 06:27:02 pm »

Damn, Chad... I was hoping you had my back on this one....

I did nothing but try to help the TOAD and got sh*t canned for doing so.... You could be next...

Let Mr. Moneybags buy ten of these games and while he is at it he can have his kitchen remodeler fix this one because he knows all about electronics and nothing about wood...

Toadie is the perfect name for this clown ... the WARTS aren't just on his ass...

Toadie · « **Reply #24 on:** June 10, 2013, 08:54:16 pm »

So Chad / Ed,

I took an initial look and tried a continuity test but it didn't seem to connect. I think I'm going to need to pull the bumper and see what I can see. The one thing I did notice was that the light from the bumper also seems to be soldered to the light right in front of it and the push switch. I'm positive it's touching something I'm just not sure what. I'll find it though.

ed12 · « **Reply #25 on:** June 10, 2013, 09:30:41 pm »

this is quick feild fix
reomve coil >2 screw's< to the top bracket
lay it to the side.. isolate the to termials so they cannot short
unsolder the light socket,remove it
see if this fix's the gi problem
if not remove thumber asambley,and chk again
this is called working through the problem

ed

Toadie · « **Reply #26 on:** June 10, 2013, 09:48:07 pm »

Hey Ed, it's just a regular bumper, no coil. Here's what I did though, I pulled the bumper assembly, unsoldered the lights, and I hate to say this but I couldn't see anything that the screw would have touched. I did however put a pick in the hole and I swear I hear something metal in that hole. I also checked the other hole and there isn't a metal sound at all. I think there's something metal in the bottom of that hole but it's not attached to anything.

Would that cause a short though? GI on, bulb goes in, lamp touches screw? My gut says no but I don't know enough to say either way.

Thoughts?

Toadie · « **Reply #27 on:** June 10, 2013, 09:53:24 pm »

ed12 · « **Reply #28 on:** June 10, 2013, 11:45:23 pm »

i can see your :short's:
there is from the look of them 3
but 1 def.
u see the diode's in your first and second pic's ?
make sure they are not touching the braid wire >gi< wiring,
then remove the bumper..your #47 socket is broke
plus it has heat shrink on it
tell's me quick feild fix
try that first.
look's like the play feild was pulled all the way out and layed flat on the :contact side:,bad bad move

ed

Toadie · « **Reply #29 on:** June 11, 2013, 07:42:44 pm »

Hey Ed,

The picture might be misleading. The diodes are all up away from the playfield but the picture makes it look like they're lying flat. On the socket, are you looking at the top one? That socket actually works and is part of the light underneath the shield in front of the bumper but behind the target switch. If you look further down you see that vent like shape with the plastic plunger piece and the two lamp socket legs coming out of it? That's the bumper assembly.

As for the field being laid down, that might have happened with the guy that I bought the machine from but all in all it seems to look ok and everything plays well.

Silverball84 · « **Reply #30 on:** June 12, 2013, 09:26:05 am »

I apologize for inaccurate info. GI power doesn't get rectified it is ac power. However being a standard bump Target tells me that touching that mounting screw would short nothing. It mounts directly to the wood. The leads in the picture look securely fastened. If anything in this problem is related to a short check your led 47 bulb. If the socket would have shorter to a switch chances are it would have killed the switch matrix...thus preventing the mpu from even successfully booting. I never got in to the whole pin led thing. I like the nostalgic look. If everything checks good go back to incandescent bulbs in the GI. See of that solves it.

ChadTower · « **Reply #31 on:** June 12, 2013, 09:43:50 am »

Quote from: smartbomb2084 on June 10, 2013, 06:27:02 pm

Damn, Chad... I was hoping you had my back on this one....

No need. You appear to be able to handle the issue yourself.

Toadie · « **Reply #32 on:** June 12, 2013, 01:33:05 pm »

I'll get some better pictures today and put something together. I agree though, technically it shouldn't have shorted anything which is really odd. I haven't heard back from the board tester yet so I'm sort of just in limbo but the feedback is great. It certainly helps think through the solution.

As I think back, on the very first day I got the machine I noticed that the light in that bumper didn't work but everything else did... so I did a bunch of things, then replaced the bulb and then I heard a pop... the F5 fuse blew. Hence why I was wondering why it didn't blow. Anyway here's where it might get kind of interesting.... because I was a new I didn't know what was going on or how to disassemble right? So I took out both bumper screws and then realized I needed to do a lot more to get it out. Lifted the playfield, noticed the fuse, replaced it and it all worked... replaced that bulb and it worked. Put in screw one with no issues... put in screw two and when I got to a certain depth the light would flicker so I stopped. I'm not sure why I'm recalling this now but I was thinking... why would that piece have touched the light... well it's because I didn't put the screw all the way down.

It doesn't fix the issue or help me understand it but it does confirm that for some reason that screw did something

Silverball84 · « **Reply #33 on:** June 13, 2013, 12:10:28 am »

The only reason I can think to cause a flicker would be just bumping the socket and due to its age its probably not making the best of contact with the light bulb. I will suggest to turn the power off when removing or installing parts. Just reduces risk for accidental shortage. Just wait to hear what the board company says, and go from there. This should be an easy fix.

Toadie · « **Reply #34 on:** June 14, 2013, 05:53:18 pm »

So I spoke to the board guy today and he's fixing the board but he couldn't say why the fuse didn't blow. He said I was right though that fuse F5 should have triggered. He said that he could follow the trace and verify it?

Silverball84 · « **Reply #35 on:** June 16, 2013, 11:47:12 pm »

So there's either a short in the GI somewhere or the board had a weak spot which opened instead of the fuse. I would check resistance on the GI circuit at that bumper. Something I didn't think of til just now...Is it possible that the tip of the light bulb got shorted to the body by the head of the screw? In the picture above the screw head looks really close to the socket. If the tip of the bulb touched it that would have shorter it for sure.

Toadie · « **Reply #36 on:** June 20, 2013, 11:29:51 pm »

Looks like their was a fault in the rectifier board that should have been caught by the fuse but for some reason it didn't catch. Transformer appears to be ok, and I'm back up and running. Thanks Chad and Ed for the insightful tips and hints, much appreciated and helpful.

ChadTower · « **Reply #37 on:** June 24, 2013, 09:59:18 am »

Hrm. All I can think of there is that the fuse holder was shorted or the circuit was overfused. Overfusing a circuit is way more common than it should be in older games when someone can't quite figure out how to fix it. Also just shorting the fuse with a nail or aluminum foil.


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