The Aussie Pinball Arcade
Aussie Pinball Forums => Technical Matters => Pinball Repairs / Problems & Assistance => Topic started by: MartyJ on March 07, 2009, 06:24:37 PM
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Hi guys,
Since getting the playfield sorted from this morning, I've got another issue.
I'm getting reports of ground short on a number of switches - which is EVERYTHING in column 3 - ie left & right sling, gear shifter hi/low, top red, middle red and bottom red targets.
I've gone over each one and cannot find any issues which are obvious. Other switches on each row (other than those in col 3) seem to be fine?
If I run the diags in test level mode - I get errors on column 8 & 3. If I remove J207 I get no errors.
I will continue working through PinRepair's guides. I understand U20 is often the failure on these....By removing J207 - does this isolate it to an actual prob on playfield?
Thanks
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OK, I've worked through PinRepairs guide with the alligator clip+diode for the row test on J207 other end to J209 - no errors
On the column test - alligator clip+diode for the column test on J209 other end J207 no errors other than pin 3 (switch 31)
So this would indicate possibly the U20 is gone?
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Dont have a schematic in front of me but if J207 is the plug leading to the playfield for these switches and when unplugged you get no error, than this proves the board is Ok and the fault is on the playfield.
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Dont have a schematic in front of me but if J207 is the plug leading to the playfield for these switches and when unplugged you get no error, than this proves the board is Ok and the fault is on the playfield.
Thats what I thought too, until I did the diode / alligator clip test as per Clay's guide with the testing of columns and rows....The same column (when tested that way) without playfield attached gives shorted error....
Me thinks it the U20. Easy enough to replace and mine looks original and is very common to go.
I found a little batt acid damage too on some resistors too....Just a little green and fuzzy, so I cleaned with tooth brush and 50/50 vinegar / water. Letting dry under heat lamp and wont be going back in for at least a week....
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Is U20 socketed ? It is a fairly common problem, as are the connectors.
But is sounds like you have isolated the problem to the board.
Why isn't it "going in for a week" ?
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From reading the guides, the U20 is aparently the most common chip to go. From looking it doesn't look to have been replaced (not socketed) but the LM339 has. I reseated it but no luck. The machine I don't believe has had a hugely hard life so it may have slipped through. I thought the clunking of the playfield on those damm hinges this morning I might have pinched something, but looked and looked and could see nothing. I tested the pin 3 (connector side) on buzz to earth and nothing. From googling it seems that the ground short error is never likely to be an actual ground short, but a 'something broke' error! More coincidence I think. But happy to get it out of the way now, the power board has been done, everything else clean.
The board will be out for a week as I won't be around (working up Marysville way)....
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Not sure if i missed something in the above reading, but have you tried wiggling the matrix connector while pressing the 'faulty' switches on the playfield???
Your problem might be as simple as a corroded row/col pin and not the I.C at all???
I've had this myself on a few pins now.....
MM.
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Thanks MM,
Unfortunately I don't think that will help...I'm 90% sure I've isolated it to the board, without connectors plugged in. I will replace U20, which according to PinRepairs is the most common fault with these...
I've come across some further batt damage (far right batt had let go)...I've cleaned and re-flowed what I can and buzzed out what I can. I'll replace the U20 and see how it goes...I don't want intermittant faults, so I may look at a Rottendog replacement, if they can be sourced locally happy days!
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OK U20 is out and socketed. I'm happy with the socket and solder. I'm still very much a novice in this area but I do enjoy it. In the top r/h/s you can see some of the batt damage around the resistor's. This is what concerns me. I've scrubbed and scrubbed with tooth brush and don't think it will get much cleaner. I know any PCB under macro 5 megapixel shots will look not good, but hmm.....
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U14 out and replaced with a new socket & 74LS374. I couldn't find any ways to test U14, so for the sake of $4.00 and about 1/2 hr better to be safe. The guide states U14 can go depending on how the U20 died?
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U18 & U19 (LM339's) done as well. U19 previously socketed and changed (most likely due to batt damage) but checked under socket and buzzed out ok. Replaced LM339 and replaced U18 - socked and IC. That should complete it.
Jumpers existing repairs. All tested and working. The dodgy looking resistor also buzzed out OK. I don't like the colour of the solder on all the resisters touched by batt leakage, but I reckon the solder pads will be gone, so not worth re doing.
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Good Stuff Marty !
How long did it take ? - One hour of your time !
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Good Stuff Marty !
How long did it take ? - One hour of your time !
Probably about 1/2 to 3/4 hour per chip, including removal, desoldering, cleaning with isocol, new socket, solder buzz....
I used my new station to solder too. For some reason, I didn't get as much flux (I think it is - brown stuff around solders) as I did with my old iron? Same roll of solder too? Temp around 380deg.
I don't rush pcb's at all, I like to take my time. Setup on the kitchen table, used my new weller PCB holder (an absolute must), bright lamp behind and slowly slowly.
Although most likely to be only the U20, whilst the board is out it was worth doing all four. At least I'll know when I put pcb back in if it fails again to look elsewhere....
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Nice, Look at it this way "every chip re-socketed, is 1 less next time around " !*!
MM.
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New U20 went in and no apparent switch matrix issues (will req. further testing), however direct switches now causing a few funny things....Its like the enter button is being pressed down constantly...I've checked for broken wires....The guide states generally an earth issue but not sure?
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Hmm,
OK, black (earth) from switch to plug looks and buzz's out fine.
Corresponding earth pin on direct switches plug J205 buzz's out fine to earth...
U17 replaced.
No value thus far....
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Hmm,
OK, black (earth) from switch to plug looks and buzz's out fine.
Corresponding earth pin on direct switches plug J205 buzz's out fine to earth...
U17 replaced.
No value thus far....
Just recheck your work - especially solder bridges between pins.
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I've gone over it again. No obvious solder touching other sockets...A few solder pads looked a little suss , I'm thinking this is the problem....I will look for a schematic for U16....
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OK, I suspect there is a damaged solder pad (poss batt damage after resocketing) for my U16 which controls direct switches.
The schematics are available from IPDB which is good, I've had a read and this is where I fall down. Is someone able to assist me in working out where the pins from U16 should come / go so I can jumper them to see if this fixes the problem? I'm still learning reading schematics and this is above me (again what I don't know could fill a warehouse!)...
The schematics were available from IPDB and I downloaded a copy, but I'm fearful to upload in case of copywrite issues etc...
Any help would be greatly appreciated!
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noted battery acid damage, did you first sand back the corrosion before treating it with the water/vinegar? I normally remove all components in the corrosion area, then sand and treat before replacing parts.
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From what u describer, it kinds reaks of a pin being held HI or Low due to a nearby shorting pin/track...
Try metering between adjacent pins on the chip(s) you replaced, and see if there any obvious shorts there.
MM.
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noted battery acid damage, did you first sand back the corrosion before treating it with the water/vinegar? I normally remove all components in the corrosion area, then sand and treat before replacing parts.
No I didn't do this..From looking at where it had gone, it would have been a lot of resistors. I suspect if I had removed them the pads would have gone too.
I will mostly likely get a Rottendog replacement. They're not super expensive but no one has them at the moment..I get the feeling I will be chasing my tail in the long term.
From what u describer, it kinds reaks of a pin being held HI or Low due to a nearby shorting pin/track...
Try metering between adjacent pins on the chip(s) you replaced, and see if there any obvious shorts there.
MM.
You might have to dumb it down a bit for me MM...I've buzzed out the suspect pins with other pins around it if this is what you mean?
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Yep, just go thru each pin on the IC, and meter onto the pin either side of it, and work your way along the whole I.C.
The short may be on the 'other' end of the resistor(s) away from the I.C end, so you might also meter between resistors too.
MM.
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Yep, just go thru each pin on the IC, and meter onto the pin either side of it, and work your way along the whole I.C.
The short may be on the 'other' end of the resistor(s) away from the I.C end, so you might also meter between resistors too.
MM.
Will do.
MM if you get time, are you able to look at the schematics for U16 (LM339) and see if you can decipher what goes to what. I've found the earth pin - easy but the others seem very confusing.
Thanks
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No probs, this is Getaway isn't it?
You might need to scan/email me a page or 2, i can't find an easily downloadable one at the moment...
MM.
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File is 2mb so I cannot upload and not sure if I can?
http://www.ipdb.org/files/1000/Williams_1992_The_Getaway_High_Speed_II_WPC_Schematics_Revised_May_17_1993_.pdf
Or PM me your email and I will forward.
I just need a hand to work out whats going on? I'm very confused as to what should be going where @@^ @@^ @@^
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ok, got it.
b4 i look thru the whole pdf, which page/diagram am i looking for?
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Thanks MM,
Page 2. Its U16 I'm looking at (LM339). U16 & U17 control the direct switches.
I found one track which was done, that I've repaired. But its hard to work out what goes where.
IF we can work out that pins 1 to 14 are suppose to go, I can buzz each one out. I think there is one which still is broken that I need to find.
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I found some stuff on RGP & hopefully is correct.
I should be getting solid 5v on pins 4, 6, 8, 10 on LM339 at U16 & U17.
On U17 - all correct
On U16 - all 5v except pin 6.
Further states should get 12v at pin 3 on U16 & U17.
On U17 - 0.01v
On U16 - 0.01v
??
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Cool, looking at it now, pretty straight-forward operation.
Which part of the diagram dont you get, when trying to trace the tracks?
IF you buzz the output pins of the LM339 (U16 pins 1,2,13,14) which goto the 74LS240 (U15a pins 8,6,4,2 respectively)
then you've proved that much.
Each of these 4 pins ALSO connect to a 10k resistor, and the other ends of those 4 resistors will (should) be all joined together which is the 5v pullup for them.
Confirm that LM339 pin 12 = GND (ground), and that pin 3 = 5v.
http://pdf1.alldatasheet.com/datasheet-pdf/view/3064/MOTOROLA/LM339.html (http://pdf1.alldatasheet.com/datasheet-pdf/view/3064/MOTOROLA/LM339.html)
Inputs (-ve) to the LM339 are pins 4,6,8,10 and should be connected to 5v.
Inputs (+ve) to the LM339 are pins 7,5,11,9 and should wire to 1K resistors, the other ends of these 4 resistors should connect to diodes D14,13,12,11 respectively, to their 'Anode' ends.
At the join where the resistor connects to the Diode, there will ALSO be a 1.2K resistor connected too.
The other end of this 2nd lot of (1.2k) resistors connect to the 12v supply.
Buzz the diodes with a diode-check function on your meter too.
Assuming everything above checks out, you may have an external wiring error? a shorted/missing diode on your switch somewhere? or possibly lost a connection AFTER the output of your U20 chip.
There's a signal on the 'Direct Switches' connector named 'Enable', buit oi'd say that is ok if all the other direct switches are working?
Otherwise, replace Transistor Q1 (2N3904) and/or confirm U5f (74LS14) also works too.
I'll leave it here for now until you've eliminated all thse, then we'll dig deeper, as there's more chips that control U5f (enable signal).
Good Luck,
MM.
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You just confirmed a problem then....
Inputs (-ve) to the LM339 are pins 4,6,8,10 and should be connected to 5v.
Good Luck,
MM.
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Cool, looking at it now, pretty straight-forward operation.
Which part of the diagram dont you get, when trying to trace the tracks?
IF you buzz the output pins of the LM339 (U16 pins 1,2,13,14) which goto the 74LS240 (U15a pins 8,6,4,2 respectively)
then you've proved that much.
Each of these 4 pins ALSO connect to a 10k resistor, and the other ends of those 4 resistors will (should) be all joined together which is the 5v pullup for them.
Confirm that LM339 pin 12 = GND (ground), and that pin 3 = 5v.
http://pdf1.alldatasheet.com/datasheet-pdf/view/3064/MOTOROLA/LM339.html (http://pdf1.alldatasheet.com/datasheet-pdf/view/3064/MOTOROLA/LM339.html)
Inputs (-ve) to the LM339 are pins 4,6,8,10 and should be connected to 5v.
Inputs (+ve) to the LM339 are pins 7,5,11,9 and should wire to 1K resistors, the other ends of these 4 resistors should connect to diodes D14,13,12,11 respectively, to their 'Anode' ends.
At the join where the resistor connects to the Diode, there will ALSO be a 1.2K resistor connected too.
The other end of this 2nd lot of (1.2k) resistors connect to the 12v supply.
Buzz the diodes with a diode-check function on your meter too.
Assuming everything above checks out, you may have an external wiring error? a shorted/missing diode on your switch somewhere? or possibly lost a connection AFTER the output of your U20 chip.
There's a signal on the 'Direct Switches' connector named 'Enable', buit oi'd say that is ok if all the other direct switches are working?
Otherwise, replace Transistor Q1 (2N3904) and/or confirm U5f (74LS14) also works too.
I'll leave it here for now until you've eliminated all thse, then we'll dig deeper, as there's more chips that control U5f (enable signal).
Good Luck,
MM.
Firstly, Thanks MM for your help...I am more trying to get this working now not to beat me!
I was just having trouble working out what goes to where? I've looked at ones where the tracks are drawn from each pin (numbered) to where it goes...I find this easier..
Outputs of LM339 U16 - :
pin 1 buzzs to 74LS240N U15 to pin 6 (you had 8?)
pin 2 buzzs to 74LS240N U15 to pin 8 (you had 6?)
pin 13 buzzs to 74LS240N U15 to pin 4
pin 14 buzzs to 74LS240N U15 to pin 2
Respective pins buzzs to R35 to 38
Inputs (-ve) to LM339 (U16) 4, 6, 8, 10 5v.
OK. I am guessing that these pins would share the power rail 5v in common. If I buzz from U16 to U17 on pins 4, 8, 10 - it buzzs but NOT pin 6- which is where I was lacking voltage before..
Inputs (+ve) to LM339 (U16) 7, 5, 11, 9
pin 7 buzzs to R?? (this has broken pad)
pin 5 buzzs to R43
pin 11 buzzs to R45
pin 9 buzzs to R46
Diodes D14 to D21 test good.
Sooo...I need to jumper pin 7 to the right resistor and sort out power to pin 6. Can the power for pin 6 be jumpered off pin 6 on U17?
pin 12 = ground (tested ok) pin 3 = is this 5v or 12v.?
Pin 12 U16 - ground
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Sooo...I need to jumper pin 7 to the right resistor and sort out power to pin 6. Can the power for pin 6 be jumpered off pin 6 on U17?
Provided the pin 6 is meant to be permanently tied to +5V it can be jumpered from anywhere that has +5V permanently including pin 4 or 8 of the same device (assuming these too are permanently tied to +5v).
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Sooo...I need to jumper pin 7 to the right resistor and sort out power to pin 6. Can the power for pin 6 be jumpered off pin 6 on U17?
Provided the pin 6 is meant to be permanently tied to +5V it can be jumpered from anywhere that has +5V permanently including pin 4 or 8 of the same device (assuming these too are permanently tied to +5v).
I've jumpered it from pin 4 to 6, which ties the 5v to it. Both U16 & U17 now buzz out identical and getting correct voltages to those pins.
Still no 12v on pin 3.
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From that same RGP article (similar prob) their solution was to jumper 12v from pin 3 on U20 to pin 3 on U16 (which then carries to U17).
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Outputs of LM339 U16 - :
pin 1 buzzs to 74LS240N U15 to pin 6 (you had 8?)
pin 2 buzzs to 74LS240N U15 to pin 8 (you had 6?)
pin 13 buzzs to 74LS240N U15 to pin 4
pin 14 buzzs to 74LS240N U15 to pin 2
I re-checked the schematic, it's DEFINATELY what i said, but what you found might highlight an error in the manual (wouldn't be the 1st time) or a late board-design change.
Either way, looks like all 4 outs are going into the '240 as you found....it'll still work.
Inputs (-ve) to LM339 (U16) 4, 6, 8, 10 5v.
OK. I am guessing that these pins would share the power rail 5v in common. If I buzz from U16 to U17 on pins 4, 8, 10 - it buzzs but NOT pin 6- which is where I was lacking voltage before..
Alrighty, you definately need to take pin6 to +5v.
Yes, you can wire onto pin6 of U17, although you could use a shorter link by joining onto pins 4,8 or 10 on U16.
Inputs (+ve) to LM339 (U16) 7, 5, 11, 9
pin 7 buzzs to R?? (this has broken pad)
pin 5 buzzs to R43
pin 11 buzzs to R45
pin 9 buzzs to R46
The schematic shows pin7 is on R43, but no doubt the manual/typo has upset things, i'm assuming it's really R44 ;-)
As long as pin7 joins to that Resistor, and the other end of that resistor is joined onto D13?/D14?(typo) it will be ok.
pin 12 = ground (tested ok) pin 3 = is this 5v or 12v.?
Pin 3 is looks to be +12v according to schematic.
There's bit of a screwup in the drawing, showing +5v connected to pin12(GND) up top...
Anyway, as long as there are volts on pin 3 (5v or 12v) the chip will work.
Hope this helps.....gettin' there ;-)
MM.
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So there's NOTHING on pin3 ?????
If that's the case, YES, grab Volts from another pin and jumper it across as u said....
Before going further, just confirm which voltage is on pin 3 of the other 339's (is it 5v or 12v).
Just be sure you're about to put the right volts on U16 pin 3.
MM.
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From that same RGP article (similar prob) their solution was to jumper 12v from pin 3 on U20 to pin 3 on U16 (which then carries to U17).
U20 pin 3 is "Column DATA", don't use this!!!!
MM.
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U18 & U19 are also LM339's, measure there volts to confirm what you should put onto U16/17.
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OK MM,
It looks like I'm not getting 12v to the board. I tested pin 3 on U20. Same readings as U16 & U17....
Pin 3 on U18 & U19 are reading 12.1v!
Sooooo
I will have to check that pin 3 on U20 should be getting 12v also...Maybe there is a break in the 12v before U20?
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OK yes, Pin 3?? ^&^
Pin 10 is +12.
Tested again, so pin 10 (U20) good 12v same as U18 & U19. They all buzz out together so must share the same rail.
Jumpered PIN10 U20 to pin 3 U16.
All good.
Just letting run for a while to ensure no phantoms and will test all playfield switches again.
I suspect the cleaning and movement in / out may have caused issues where the batt damage had been. I am still going to put a Rottendog board in. I think this will be a better option for the long term.
Thanks MM, ^^^
PS. Even after you explained everything I cannot read that schematic. I will keep trying though..
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Pin 10 is +12.
Tested again, so pin 10 (U20) good 12v same as U18 & U19. They all buzz out together so must share the same rail.
Jumpered PIN10 U20 to pin 3 U16.
Yep
Yep
and Yep.
(and NEVER use U20 pin3 hehehe).
PS. Even after you explained everything I cannot read that schematic. I will keep trying though..
No probs, i'll come over someday and give u scematic tutoring.
MM.
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OK,
Tested in gameplay, no more phantom direct switches.
Direct switches all working, no aparent issues.
So as far as the cause? NFI. BUT big thanks to MM for his help decyphering the schematics.
I will slowly stock pile parts (Greg, expect more orders) and the rebuild will more than likely take place in a couple of months... (playfield+cabinet)
$#$
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Cool Stuff #*#
Glad it's all sorted.
No doubt the battery acid has done some damage that you can't even see no matter how much you clean & scrape, must have eaten a track somewhere, albeit a hairline acid etch....
Keep them coming, ready for the next schematic decode !*!
MM.