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please help me diagnose this fault - fixed!

cooldan

i like pizza
10 Years
Joined
Jul 21, 2011
Messages
7,157
Location
Ealing, London
TOTAN cages are a thing that grabs the ball - when it is lit and when it recognises the opto switch has been broken, a coil is supposed to fire, sending some spikes up to trap the ball in a cage.

the right one works fine, the left one i never saw working (though others told me they saw it working a few weeks back at a shindig in my living room). in switch test, the opto registers just fine, but in coil test i cannot get the coil to fire (the right one i can make it fire ok and they both use the same fuse so it's not a fuse issue). in game play the game even recognises that it messed up, as (when the cage is lit) when the ball triggers the opto but then triggers the outlane switch, the game gives the ball back as a temporary ball save. 73V at all three lugs of the coil, same as on the right.

i pressed the start button during this coil test and it told me the wire colours, connector and pin numbers, fuse number and type, and transistor numbers:

L cage violet-brown and red-brown, fuse 104, J116-1 and J133-1, transistors Q72, Q60, Q56
R cage violet-red and red-brown, fuse 104, J116-2 and J133-1, transistors Q68, Q64, Q55

kids with chalk.jpg

now here's the problem - a month or so ago, just before my little party, i had the board out and tested all those transistors and all seemed fine, so i'd decided to leave it ..... then later that day i heard it was working (i never saw it, but this was someone who understands pins) so i forgot about it. now i just want to sort it out.

so. ..... is there anything i should check on the playfield?
should i get the board out again, retest, and get replacing those transistors even if they test good again?

and what is that clever trick to distinguish between a problem on the board vs one on the playfield?

here is the switch matrix (the opto switch is on the matrix) and the coil chart (which by the way refers to J133-2 and not the J133-1 reported by the game itself). all help gratefully received, and if you can explain your reasoning as well, i'll be super thankful.

TOTAN switch matrix.JPG TOTAN coil chart.JPG

edi
 
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What I would do, is move J116 over one pin to the right, then test the right cage, the left one should fire.

If not there's an issue with the coil as we know the transistor for the right cage works fine.
 
You can momentarily ground the tap of Q60, to see if it fires the coil. If it does, then the fault most likely lies with Q56 or Q60

If the coil does not fire, then you most likely have a bad connector or wiring from the driver board to the coil.

Annoyingly in this instance, you have a TIP36C in the way, so you can't ground that one to test it, unless you like sparks and smoke

If the coil doesn't fire, check your wiring and replace your TIP36C at Q72


May the force be with you
 
"move J116 over one pin to the right, then test the right cage, the left one should fire." - you sounded confident so i looked at this, but there's a blocked hole in the connector to stop this from being possible. maybe just as well, as i didn't understand why or what i was doing there.

"momentarily ground the tap of Q60, to see if it fires the coil." i tried this and nothing happened. then i had a 'duh' moment and did it again with the door closed - perfect, the coil fires.

so this means the fault lies with Q56 or Q60 you say? how did you know to test that one and not Q56 or Q72? very clever. so i need to get the board out and replace one or both of those. thanks!

edit: colour coding posts, red for transistors, blue for diodes, yellow for resistors
 
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Q56 and Q60 are your most likely fault(s), so I'd replace them as it's quick and easy. If that does not cure it, test the associated resistors and diode. If you are really unlucky it's IC U7

edit
Probably the most sensible thing is to test the resistors and diodes first if you want to avoid possibly unnecessary transistor replacement, so it's up to you how you tackle it. I tend to go with the most likely first so that I can keep the repair time down, but it just occurred to me, you are not working on the clock, so you don't have to copy me ;)
 
"test the resistors and diodes first"

ok. diodes i can test, i just put the black lead on the banded side, right? and in reverse it should be open i think. i will just test all the ones i can see around those two transistors.
reistors are not something i tested before but presumably i just put my meter on ohms and hope for the best?

i'm not very good at schematics, are these the right bits i should be looking at?
should i be looking at something else? (TOTAN manual here, thanks for your help)

TOTAN components.JPG TOTAN schematic.JPG

edit: colour coding posts, red for transistors, blue for diodes, yellow for resistors
 
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ok. diodes i can test, i just put the black lead on the banded side, right? and in reverse it should be open i think. i will just test all the ones i can see around those two transistors.
reistors are not something i tested before but presumably i just put my meter on ohms and hope for the best?

This article explains how to use your DMM to test resistors and diodes, note the procedure on diodes that if out of range then test again out of circuit (you'd probably be replacing it then anyway)
http://www.pinrepair.com/begin/#howdmm

In the manual, I can only find the PCB assemblies not the circuit diagrams to tell exactly which diode and resistor is connected.

I enjoyed flipping through the manual though, the playfield assemblies look awesome!
 
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right, i'm getting somewhere:

took the board out, identified the components from here
manual parts list.JPG

transistors: tested Q60 and Q56 with my multimeter after looking them up here so i knew which leg to put where and what numbers to expect
all looked good. i thought i found a problem that one leg value was not the same as the other, but it was the same as all the others of the same type so all good.

resistors: tested with multimeter using the link from @astyy above (thanks) after finding out what the values should be - some were 68 ohms, some 220, one 470, one 4700 and one 2700. again i thought i'd found a smoking gun when the 2700 one only gave me 2100 or less, but again i tested all the other ones that were supposed to be 2700, and they were all the same as my test one.

diodes: i found one that is different to all the others, when the manual tells me it should be the same ! all the rest read 0.5 but this one reads 0.9 - so i'm gonna desolder and replace that one now, D76. wish me luck

edit: colour coding posts, red for transistors, blue for diodes, yellow for resistors
 
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curiouser and curiouser, said Alice:

ok so i put the board back in and played a game trying to light and then activate the left cage, but gave up and went into solenoid test - and was pleased to see the cage pop up.
but then i decided to have another game, and the ball wouldn't come out of the trough. coil test shows a collection of coils that weren't responding - 9 to 15 in this chart

TOTAN coil chart - v2.jpg
so i reseated J113 and J133, but no change. presumably i buggered something up, but what?
 
fuse F102 on the driver board?
 
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all the fuses are good. i agree that a batch of coils out together sounds like something basic like a fuse
TOTAN fuse list.JPG

actually it's F104 for my dead coils, but since the fuses are all good, i reckon i reconnected something wrongly.

gonna disconnect all the connectors to that board again and reconnect them one by one.
if anyone knows a good shortcut to this because they can tell which one it is, please let me know
 
yep, that sorted it. so my problem was a dead diode D76 on the power driver board, a 10p part.
found it, removed it, replaced it, fixed it; with the help of the forum.

before.jpg after.jpg

awesome feeling :clap:
 
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So after you replaced the diode, was the bank of coils out because something wasn't connected right?
yep, basically. i have no idea what it was, but i reconnected everything again and this time it worked.

i always thought diodes only went bad on the playfield switches, that's me learning a new trick
 
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