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Switch problem wpc - twilight zone

DRD

DRD

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My tz has developed a switch fault

I have put into switch test mode. It occasionally registers all the switches in a column in very short order. It is too fast to see them individually.

It looks like the game is scanning and then registering all the switches in a column in a fraction of a second

Is it just case of replacing all the diodes in the relevant switch column ?

Or reflowing solder on pins on the mpu ?

Thanks
 
Great suggestions thank you.

I will investigate. So far i have just jiggled the relevant connector on the mpu
 
You could have a switch wire/connection shorting on a lamp holder on the relevant column, try banging/lifting the table and see if it occurs
or possibly a bad connection at the connector as you say ,doubt if it's multi diodes at fault if a diode fails its usually one switch that doesn't
register.
 
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Thanks for the tips

The problem is revealing more of itself and intermittent problems are becoming lasting ones

I found an intermittent fault on an opto. So I cleaned it in situ with cotton buds and ipa.

That has now morphed into three dead opto switches, all on the same column. The game now tells me to check these when I turn it on

I am also getting erroneous locks, which is again probably opto related given that lock one isa microswitch, the second lock is an opto.

So my guess is a problem with the opto board below the playfield. I can see that this has previously been worked on, chips have been replaced. The soldering on these chips looks a bit iffy

So I will take this out and get it under the magnifier tomorrow

When stuff like this happens i have to remind myself that somehow this thing used to live in the wild, taking money from strangers and somehow not breaking down
 
I quite fancied buying that baby pac-man, but when I get trouble like this it puts me right off

Still having trouble with my banzai sound despite new roms and a postal board repair

****ing things
 
DRD said:
Thanks for the tips

The problem is revealing more of itself and intermittent problems are becoming lasting ones

I found an intermittent fault on an opto. So I cleaned it in situ with cotton buds and ipa.

That has now morphed into three dead opto switches, all on the same column. The game now tells me to check these when I turn it on

I am also getting erroneous locks, which is again probably opto related given that lock one isa microswitch, the second lock is an opto.

So my guess is a problem with the opto board below the playfield. I can see that this has previously been worked on, chips have been replaced. The soldering on these chips looks a bit iffy

So I will take this out and get it under the magnifier tomorrow

When stuff like this happens i have to remind myself that somehow this thing used to live in the wild, taking money from strangers and somehow not breaking down
Click to expand...
Check the connectors of the opto board for dry joints and also suspect the LM339's.
 
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DRD said:
I quite fancied buying that baby pac-man, but when I get trouble like this it puts me right off

Still having trouble with my banzai sound despite new roms and a postal board repair

****ing things
Click to expand...
It's the fixing that I love the best. Nothing beats getting a poorly machine and making it work again.
I was beaming like an eight year old on Christmas morning when I got to play my first game on my newly acquired Vector this week. :)
 
I hadn't had any opto trouble in the 15 months or so I have stewarded the game.

But this was the opto board .....image.jpgimage.jpg
Quite a few ropey looking and very skinny joints, and a lot of hardened flux residue from a repair that predated my relationship with her. I have reflowed solder on all the connectors, chips and any other joints that looked iffy. Cleaned the board with flux cleaner afterwards, but the flux was so ingrained that i had to use a metal brush to help it on its way

When I plugged it back in the three dead optos worked. But I was still getting a residual opto problem (false lock reporting) on another one, possibly two that register locked balls. Cleaned these two with ipa

As of now it is working fine. But I have learnt never to trust over-complicated twilight zone (addams is a profoundly better game in terms of reliability) so I will wait and see before I feel confident this is sorted
 
Why would somebody go to the trouble of changing the LM339s and not socket them ? :hmm:
 
As I feared, this has not fixed it. So next stop is to replace the lm339s per @Andrew Stockdale 's suggestion

Which type of chip socket is best please given that this is a double sided board ? "Turned pin" ones ?

Thank you
 
It's that dreaded word intermittent... I have just had two and a half months of head scratching over an intermittent switch fault.

Sent from my D2303 using Tapatalk
 
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Johnnyo said:
It's that dreaded word intermittent... I have just had two and a half months of head scratching over an intermittent switch fault.

Sent from my D2303 using Tapatalk
Click to expand...
LM339s are the definition of intermittent when they start to fail. They flicker between a high and a low signal and it is very hard to detect.
 
Really helpful thank you @Andrew Stockdale

Bits ordered from farnell and ebay. I will give it a razz

I have never tried using logic probes or oscilloscopes, but hopefully my ignorant edit/ find/ replace approach with these chips might work

****ing twilight zone
 
looks like the 2 texas instruments ones are the replaced ones. definitely worth socketing them as they do go flaky from time to time.
 
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Found the fault.

Having socketed and changed three chips. Reflowed solder on the board. Tested every basic component bar the capacitor in situ.....

This b@stard game had a broken track that was hidden beneath the capacitor. I was reluctant to remove this as it would be very difficult to solder it back in again given how short the legs are. ....

So one of the opto columns received full voltage. The other was getting less. And I imagine much less under load

Twilight zone is a horrible, sneaky, untrustworthy game

image.jpg

I have done a temporary fix with the existing capacitor. Will do a permanent one with a new cap when I hate the game a bit less ...

image.jpg

All working now and a first score of 354m to start the healing process
 
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