(Topic ID: 249880)

Gottlieb Road race indicator burning between contacts

By JReedie

4 years ago



Topic Stats

  • 8 posts
  • 4 Pinsiders participating
  • Latest reply 2 years ago by hjh632
  • No one calls this topic a favorite

You

Linked Games

Topic Gallery

View topic image gallery

15664096864295500529161140255398 (resized).jpg
15664096408737629901632306986059 (resized).jpg
#1 4 years ago

My project road race is having a few issues still mainly associated with the central spinning indicator. I have 2 points where the machine is starting to burn between traces on the bakelite boards. Firstly it's burning between every contact on the indicator disk. Secondly between 2 contacts on the BS relay.

Along side this is having plenty of scoring issues which I think is associated with this indicator mech. Scoring for that seems to be all over the place.

Help would be appreciated as this is supposed to be at a show this coming weekend!

James

15664096408737629901632306986059 (resized).jpg15664096408737629901632306986059 (resized).jpg15664096864295500529161140255398 (resized).jpg15664096864295500529161140255398 (resized).jpg
#2 4 years ago

Any ideas anyone?

#3 4 years ago
Quoted from JReedie:

I have 2 points where the machine is starting to burn between traces on the bakelite boards.

Is it starting to burn, or could this have happened a while ago?

Scorching like this could be caused by:
- dirty contacts that increase resistance and generate heat
- a high current circuit (e.g. to a pop bumper or other solenoid) that cuts off power without a bleeding resistor or some other place for the residual current to go
- having a contact land between two pads (as your BS relay) and barely making contact with either one of them which could increase resistance and generate heat.

If your contacts are landing in the center of the pads the scorching may no longer be an issue. Without a schematic it's hard to be more specific.

/Mark

#4 4 years ago
Quoted from JReedie:

Along side this is having plenty of scoring issues which I think is associated with this indicator mech. Scoring for that seems to be all over the place.

The scorecard gives a hint that scoring of the indicator varies "mysteriously" but only scores when you move the pointer. The BS relay tries to stay in sync with the indicator target. When you move the indicator to a different pad, they are out of sync, and some arcane circuitry is involved for the BS relay to search for the new location along the way. It scores 50 per cycle of the score motor while searching, then more (plus spotting the number) when it finds the new location. There is deliberate scrambling of the 10 wires that connect the 10 segments on the indicator to the 10 segments on BS, so a short move of the indicator may require a long search, and vice versa.

A good test at this point would be to start a game with the glass off, ensure that all numbers 1-10 are UNspotted, then manually move the indicator to each number and see if it gets spotted. You may find that your BS relay has trouble finding some numbers. When moving the indicator manually, move it to the center of each segment, so that you are not causing any high-resistance edge contacts.
.................David Marston

#5 4 years ago
Quoted from JReedie:

I have 2 points where the machine is starting to burn between traces on the bakelite boards.

Steve Young of The Pinball Resource contacted me offline about this problem and offered me some clarity:

"....the phenomenon is called carbon tracking and is caused by repeated tracing and particulates building up between lands...eventually will conduct and burn....must be removed and can be filled with epoxy or the disc replaced. Disc is available."

"Seen alot on this disc because wiper can stop between patterns and create a bit of an arc and deposit debris. Seen also on AS discs as patters are close together and maintenance difficult and ignored. Common on Williams ball count discs that are foil (not rivet) type. Common on Chicago Coin everywhere where they used fiberglass board material....believe a bit more abrasive and more prone to leaving debris."

"Keep disc clean and properly lubricated. Where adjustments are available, make them to keep stopping position centered on the pattern center."

Thanks Steve. I learned something new.

2 years later
#6 2 years ago
Quoted from MarkG:

"....the phenomenon is called carbon tracking and is caused by repeated tracing and particulates building up between lands...eventually will conduct and burn....must be removed and can be filled with epoxy or the disc replaced. Disc is available."

I had this problem on a Hearts and Spades where scoring either the 2 or 3 lit BOTH the 2 AND 3, and I could see arcing between the copper pads. You advised me to clean the area between the copper pads and that solved the problem, but a year or two later it's back to scoring both numbers again. My question is: fill with what kind of epoxy? Do you think I can just put a thin layer of super glue between the newly cleaned space between the copper pads? I have super glue in my shop but not epoxy.

#7 2 years ago

Did you just clean the board, or the whole assembly? I'm curious where the carbon is coming from if the problem returned.

I haven't repaired a board myself that way nor do I know how super clue holds up compared to epoxy. Give it a try and maybe order a spare just in case.

#8 2 years ago

I cleaned the whole surface where the pads are and scraped out the small spaces between the copper pads with a needle. I did not remove the whole unit, or disassemble and clean. I’ll try the super glue and post if it holds up after a few weeks or months.

Reply

Wanna join the discussion? Please sign in to reply to this topic.

Hey there! Welcome to Pinside!

Donate to Pinside

Great to see you're enjoying Pinside! Did you know Pinside is able to run without any 3rd-party banners or ads, thanks to the support from our visitors? Please consider a donation to Pinside and get anext to your username to show for it! Or better yet, subscribe to Pinside+!


This page was printed from https://pinside.com/pinball/forum/topic/gottlieb-road-race-indicator-burning-between-contacts and we tried optimising it for printing. Some page elements may have been deliberately hidden.

Scan the QR code on the left to jump to the URL this document was printed from.