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Bride of Pinbot Power issue

i went ahead and swapped out Q2 in case there was an issue - no change.
I am getting 18 v in to Q2 and hardly anything out ( measuring at F115) - so am i a complete idiot - have i got the wrong VR in there? I have a LM7812CT/NOPB, Linear Volt Regulator.
PDF here

its also worth idiot checking that the orientaion is correct - cos i can be an idiot
 

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maybe a short on the output - that 100uf cap is directly across the output, could be dodgy? Also could possibly be the 339 ic as that takes power from the 12v - that is easy to isolate as you can remove fuse 115 and see what happens to the output of Q2 then?
 
i think the cap is fine - its showing 99uf

i took q2 out and had a look at the board... it seems the problem is on the output - when i check continuity off the points for the input and ground and their associated paths - it tests ok
However the output does not check out between c1 or F115 - attached is a pic of the board - the output doesnt have a pad and furthermore i cant seen a trace between it and F115 and C1 - is this the issue
when i put the board back in the machine im getting 12v on the output but nothing at F115 ( which i assume supports my findings above) - i am new to all this so very much learning as i go.

There is no differnce in readings with F115 in or out
 

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should the missing pad connect to the point just to the right of it?? I cant really see from the photo. Other possibility is that the trace is on the topside of the pcb maybe?
 
perhaps i have no idea - the trace to its right is connected to the ground - can the output and Ground share a trace?
 
There are traces topside. And q2 needs a heat sink.
 

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Asiapinball said:
Yes and one end of c2.
Click to expand...
I get nothing between the output on q2 and c2. I do get continuity between the ground on q2 and ground on c2. I assume they share a common earth.

I went ahead and tested continuity between the cap and F115. No problem here. I have continuity

At this stage I think I need to replace c2 and see what happens. It seems it’s either a faulty cap or the trace between it and q2 output.

I’ve ordered a replacement and will get back to this on Monday as I’m away this weekend.

Thank you for your help
 
kamalackarie said:
I get nothing between the output on q2 and c2. I do get continuity between the ground on q2 and ground on c2. I assume they share a common earth.

I went ahead and tested continuity between the cap and F115. No problem here. I have continuity

At this stage I think I need to replace c2 and see what happens. It seems it’s either a faulty cap or the trace between it and q2 output.

I’ve ordered a replacement and will get back to this on Monday as I’m away this weekend.

Thank you for your help
Click to expand...
 
kamalackarie said:
I get nothing between the output on q2 and c2. I do get continuity between the ground on q2 and ground on c2. I assume they share a common earth.

I went ahead and tested continuity between the cap and F115. No problem here. I have continuity

At this stage I think I need to replace c2 and see what happens. It seems it’s either a faulty cap or the trace between it and q2 output.

I’ve ordered a replacement and will get back to this on Monday as I’m away this weekend.

Thank you for your help
Click to expand...
Do you have continuity between output of q2 and f115? If you don't the trace is broken and you will need to reinstate. Easiest way is a jumper wire between the 2 but do ensure you get the correct end of f115 to jumper to otherwise you could bypass the fuse.
 
Asiapinball said:
Do you have continuity between output of q2 and f115? If you don't the trace is broken and you will need to reinstate. Easiest way is a jumper wire between the 2 but do ensure you get the correct end of f115 to jumper to otherwise you could bypass the fuse.
Click to expand...
Good morning.
I checked and i did not have continuity between the Output of Q2 and F115. I jumpered a wire between them on the back of the board and now have continuity.
On power up:
I have 1.9vdc readings on both the q2 output and at F115.

If i remove F115 I have 12vdc on the q2 output and 12vdc at the end of the fuse holder that the Jumper connects to ( the Right hand side as you look at it).

the only thing i have yet to do is to replace the C2 - not sure if this is relevant.
 
C2 seems ok, if output is measuring 12v with fuse removed, but then drops significantly, then it's possibly something after the fuse that is dragging the voltage down. Try unplugging J114 and put the fuse back in - whats the voiltage then?
if it;s around 12v then the issue is whatever is connected via J114. if it drops again to 1.9v then I'd look to replace U6
 
when i remove J114 i get the 12Vdc no problem. J114 links over to J210 on the CPU board and when i connect J114 and remove. J210 - i get 12vdc

so its something on the CPU i imagine. J210 has 12vdc on lines 6 and 7. again i assume its somewhere in this path - where might i be looking - the schematic only points to it being 12v - but doesnt show its path
 
So the 12v powers the uln2803 ics and the lm339 ics and also feeds the switch matrix.
It could be one of those ics or something in the switch matrix circuit on the board or in the switch matrix itself on the playfield. You could try unplugging the 5 connectors that go out to the switches.

You can see the 12v points marked on the schematic and the ics power is mentioned top right as well
 
Thnak you - unplugged all 5 connectors - no change. Popped Uln2303a out and bingo 12V - will order a new one online now.
Quick question is there - game requires a uln2803a - i am seeing those and also uln2803apg online - is there a difference ? if so what is does the PG mean
 
APG is compatible with A suffix.

The A suffix was a revision where they added internal pull up resistors to the design of the original ULN2803.

the PG is : P for plastic case and G = Green (i.e. lead free construction). APG is originally a toshiba suffix, but other manufacturers now use it.

I have used APG most recently as they are easier to get.
 
morning! I swapped out Uln2303a and now have 12v - result! However issues remain.
Game not booting up. LED 5 ( +20v) is on and should be off.
I took readings of the plugs and resistors on the CPU - the attached PDF shows the findings. From what i can see U14 (74LS374) needs replacing as values on R66-R74 are bad.
R28/32/34 low readings. which as i understand lead to the low readings on J212
I have ordered a new 74LS374 and resistors for 28/32/34 plus a few random extras just in case ( 74LS240N - U13 )

am i on the right track?
 

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