With the amount of available ROM/NVRAM space now, just implement "software settings" instead of requiring more dip-switches.
How many total playfield switches do you need? Can you get away with using more unused continuous solenoid data lines as switch strobe lines ala Fathom/Medusa - etc? The coin lockout coil data line could also be re-purposed as another switch strobe line.

Test point TP3 that's connected to pull-up resistor R70 on the Lamp Driver Board is there for manually testing SCRs. Connecting a wire from TP3 to the gate lead of any SCR should activate the respective lamp.
It's mentioned as part of the Lamp Board diagnostic procedure in the Bally Repair Procedures manual FO-560

There are also pull-up resistors connecting to test points only on the SDB that are used for similar purposes.

Correct.

$0000-007F 6810 RAM
$0088-008B 6821 PIA U10
$0090-0093 6821 PIA U11
$0200-02FF 5101 RAM (upper 4 bits only! - ROMs expect lower 4 bits to read high)

$1000-17FF U2 ROM
$1800-1FFF U6 ROM

Address lines A15, A14 and A13 are not used on the MPU board itself which means the above memory map gets mirrored all over the place. Suffice to say U6 is mirrored at $F800-FFFF in order for the 6800 CPU to read the system vectors.

The $5xxx range is related to -35 boards, not -17 boards.

Have you already come up with some alternate rule/feature plans?

Great ideas..
I can give you pointers of where to start looking. PM me if interested.

I think you might be incorrectly counting the LED flashes.

Count the flashes on the Skateball next to it and you might notice an extra flash. Both MPU boards should flash the same number of times.

The moment you switch on the game, the LED should flicker, then flash one time, then one second delay then 6 flashes. If you're seeing 5 flashes instead of 6 flashes after the one second delay the problem is most likely the F4 5amp fuse on the rectifier board is blown.

The -17 and -35 MPU boards are not directly interchangeable without making modifications.

That F4 fuse looks blown. It's for solenoid power and is required by the MPU board for the last LED flash.

Absolutely. Someone has improvised and made a discrete rectifier with those 4 diodes but they don't look like they're high enough current type diodes.

I use these that directly fit in:
KBPC810PBF made by Vishay Semiconductors.
http://export.rsdelivers.com/productlist/search?query=KBPC810
https://www.mouser.com/Search/Refine.aspx?Keyword=KBPC810

Be careful of the cheap Chinese units on Ebay/Aliexpress - they are physically bigger and won't fit.

Yes, my response was a bit lazy.

The controlled feature lamp bridge is where it might matter since it runs at high current (the other two bridges are lower current circuits). You can swap one of the other VJ248 bridges to the lamp bridge location if it's a concern and use the KBPC810 bridge in the lower current locations.

Keeping the bridges cool helps them survive during heavier loads. I use a good quality thermal paste between the bridges and the aluminum/metal plate, and make sure all three bridges are screwed down (no missing screws as you sometimes find).

A year or two ago I tried to get ADT to make me some for personal use and I tried to convince them there is a market for these. But they didn't seem overly interested. I sent them the attached slideshow. MOQ per color/type was 1000 pieces but they wouldn't make me any samples to ensure they were going to get it right first time. In the end I just modified some myself. Problem is some LEDs are full of glue in the bayonet and aren't possible to pull apart without damaging them.

output_8xk02S.gif

I saw you post that picture somewhere else and really liked the neat way you mounted that load resistor - so much so that I'll probably be employing your technique on a friends machine, thanks!

#8-32 thread, thread length about 3/8"

TP3 is connected to TP1 via an external wire on the solenoid driver board J3 connector. See below schematic.
Your fault was probably on the connector and you've essentially bypassed it.
TP3 is the 5V power test point of the solenoid logic driver side.

SDB_TP3.jpg

You mean the game wouldn't boot? If yes, you've got other problems unrelated to TP3.
No voltage at TP3 on the SDB will only cause solenoids not to work.

Since the auxiliary lamp board shares most of the lamp address/data lines with the main lamp board are any of its lamps flickering?
You haven't accidentally crossed the two lamp strobe wires at the MPU board connector or accidentally swapped a lamp address/data wire?

If you do swap the two lamp strobes at the MPU board connector do the flickering lamps follow the strobe line or stay with the lamp board?

Umm, no. The lamps on the second strobe are activated directly after all the lamps on the first strobe have been processed.

Strobe #1 from the MPU board is at J1 pin 11 - goes to the main lamp board
Strobe #2 from the MPU board is at J1 pin 8 - goes to the aux lamp board

You can try swapping those two strobe wires around on that MPU J1 connector and see what happens.

If TP2 on the Alltek MPU board reads 43V then the bridge rectifier for solenoid power (zero crossing) should be ok. If it read half voltage then the bridge rectifier would be suspect (internal diode open circuit).

The data lines to the lamp boards also go to all the displays. Have you disconnected all displays to eliminate any effect they might be having on those data lines?

Have you disconnected the Auxiliary lamp board as a test?

Hi,
Can you post a video showing the whole playfield (both in attract mode and lamp test mode) so we can see all the feature lamps that are flickering. Please remove the fuse for the GI lamps when you do this - the LEDs in your GI are causing heavy strobing making it hard to see what's going on.
We need to try and build a full picture to see if there's a pattern.

The 22.5VDC you measured at the Zero Crossing TP6 test point on the MPU board indicates it's unlikely to be your problem. An issue here should have resulted in a much lower voltage. To confirm, measure TP2 on the Alltek MPU board - it should be around 43VDC. The Alltek MPU board divides the voltage at TP2 in half which is where TP6 is connected.

If you want to hook up your oscilloscope to visualise it, set the voltage scale on your oscilloscope to something like 10V/division and the time scale to something like 2ms/division.
Hook up the black lead to ground and the probe tip to TP2 at the MPU board.
You should see a signal that looks something like the lower "Output Voltage" waveform in the image pinfixer posted here:

https://pinside.com/pinball/forum/topic/bally-as-2518-club/page/24#post-4607509

Adjust the voltage and time scales until you can see a good overall view of the waveform. Post a picture of it.

Your videos show the first 4 outputs of each of the lamp decoders (4514 chips on the LDBs) are flashing. Logic wise it's not a data/address thing, more likely timing.

Your first two oscilloscope readings look fine (time wise) - the periods of those waveforms are around 8.3ms (the time in which they repeat) which translates to a frequency of 120Hz and is right. Does your oscilloscope probe have a "X1 / X10" switch? If yes, put the switch on X10 which basically divides the input voltage by 10. You'll then be able to see the full height of the DC waveform at TP2.

Anyway, as barakandl has mentioned, the zero crossing detector circuit on your Alltek is outputting the wrong frequency (presuming you've probed the correct pin - U12 pin6). It should be the same frequency as TP2 and TP6. The wave shape will look different but the time taken to repeat should be identical.

Have you got a working Bally MPU board you can hookup?

The Zero Crossing detector circuit output to probe on the Bally MPU board is pin 4 of U14.

BTW, I think you mentioned somewhere that before the game restoration there was no issue with the lamps. Exactly what's changed (hardware wise)?

Did you build the rectifier board or was it one barakandl pre-built?

Lets strip this down to bare minimum.
Completely disconnect the playfield from the game - I mean every playfield connector.
Disconnect any connectors to the display/lamp hinged panel in the head box.
Measure the voltage on TP1 of the rectifier board and if it's around the 6.5VDC range, grab a spare lamp socket and connect the base to that TP1. Connect the other end of the lamp socket to pin 18 of J1 header at the lamp driver board (remember the lamp driver board pins are numbered upside down from 1 at the bottom and count upwards). Pin 18 of J1 is the output for the centre target "S" lamp that's currently flickering. Power on the game and go to lamp test mode. Does this lamp still flicker with an incandescent and LED?

With no load it will be a bit higher, so no big deal.
But can you first hook up the oscilloscope to TP1 on the rectifier board and post the waveform. Adjust the volts/division on your oscilloscope so you get all the amplitude from the waveform to fit in the image - start from around 2 volts per division.

Ok, new waveforms look better About what's expected for a rectified DC voltage.
Can you confirm the 27 ohm ceramic resistor on the rectifier board is getting warm?

I know you've triple checked your connectors but can you post clear pictures of them at the following so we can see wire colors:
LDB J4
MPU J1
Aux lamp board connector J1

Sorry

While I check your wires can you do the following:
Lets manually activate the SCR driving that temporary lamp you've connected to the target "S" lamp connection.
Grab a jumper wire and hook up one end to TP3 on the LDB. Touch the other end of the wire on the "gate" leg of SCR Q14. This will manually illuminate that lamp. With the Bally lamp driver board you've got, the gate leg on the small SCRs is the middle leg going upwards.

Good. We can put to bed any issues with power and rectifier board.

Wire colors at the connectors look right which I'm sure doesn't surprise you.
At this point we have to check continuity from the MPU board to the lamp driver board *after* the connectors.
With the machine OFF, grab your multimeter and set it to resistance mode. If your meter is a cheap non auto-ranging unit, set it to 200 ohms range.
Check for zero ohms resistance between the following:

MPU left leg of R55 (next to J1 pin 15) <---> LDB top leg of resistor R76
MPU left leg of R53 (next to J1 pin 14) <---> LDB top leg of resistor R77
MPU left leg of R51 (next to J1 pin 13) <---> LDB top leg of resistor R78
MPU left leg of R49 (next to J1 pin 12) <---> LDB top leg of resistor R79
MPU left leg of R57 (next to J1 pin 16) <---> LDB bottom leg of resistor R74
MPU left leg of R60 (next to J1 pin 17) <---> LDB top leg of resistor R73
MPU left leg of R62 (next to J1 pin 18) <---> LDB top leg of resistor R72
MPU left leg of R65 (next to J1 pin 19) <---> LDB top leg of resistor R71
MPU left leg of R47 (next to J1 pin 11) <---> LDB top leg of resistor R75

Yep, ohms uses the omega symbol.

You also have zero ohms between the bottom left leg of SCR Q14 on the LDB and the rectifier board under the big ceramic resistor at the solder tab marked "E8"? This is checking that the lamp driver board has good ground.

While we work on this, please only use incandescents in the problematic lamps.

Some waveforms in Lamp Test mode on SCR Q14: These are steady while the lamp is on or off as noted.
My game is a 10 amp feature lamp game opposed to your 20 amp game, hence my lamp voltages are lower.
Do any of yours differ? Are your waves steady while the lamp is ON?

IMG_0021a (resized).jpg
IMG_0017a (resized).jpg
IMG_0019a (resized).jpg

Hi, sorry I should have mentioned all three snapshots I took were with 2ms/division time base.
You're getting negative voltages and lots of noise which suggests the earth lead on your oscilloscope probe isn't connected to ground on the machine.
BTW, set your voltage offset to "0V". I've positioned my waveforms so zero volts is at the bottom of the screen. Lets just leave yours with zero volts along the centre of your graph.

SCR Q14 bottom right leg image when the lamp is off should look the same as your second image from post #1274 (with the per division settings). And this is very close to mine.

FutureSpa_FeatureLampVoltage (resized).png

Yes, I've walked up to my working machine with the oscilloscope and taken the snapshots with the game as is in lamp test mode.

Any chance you can do the Q14 gate leg with the same time base you used in the second image in post #1299 so we can see more repetitions?

That second image looks like the lamp is only being switched on once every three or so Zero Crossings. It should pretty much be once *every* Zero Crossing.

Can you do the same on Q11 which is a working lamp so we can compare?

Sorry to leave you hanging but I've got to head out - maybe someone else will chime in with your further results.

What were your hands touching when this happened?
Does wiggling the J4 connector at the LDB change anything?

You can see from the snapshots of the gate pin playing up that the decoder tries to switch the gate on (where you see those skinny spikes) but for some reason cancels/fails before the SCR gate has reached switch on voltage.

Are you getting good 5V power and ground to the LDB through the J4 connector?

BTW, is it worth taking this discussion back to your restoration thread so things can return to normal here?

It's not so trivial, the Bally operating system can only process one switch at a time so while the ball is sitting in the saucer, no other switches can be dealt with. All that can happen during that time is other switches can be flagged as needing to be serviced but there's no count facility for how many times they needs to be processed.

That's not what I'm seeing in emulation. The bonus jingle being played while the ball in the globe saucer is taking precedence over servicing all the spinners.

https://www.greatplainselectronics.com/proddetail.asp?prod=LB2-48DP

Another difference between the two solenoid driver boards is that Bally fitted a 2.2 ohm resistor at R50, while Stern fitted a 4.7 ohm resistor which results in their 5V supply being a fraction higher (around 5.2 volts compared to Ballys 5.1 volts.).

Measure the voltage at TP3 on the solenoid driver board. If you don't measure 5 volts then re-terminate the brown-green wire that runs between pins 13 and 25 at connector J3 or just solder a wire from TP1 to TP3 on the back of the solenoid driver board.

As everyone said, you've got a connector issue on the signals between the MPU board and the Solenoid Driver Board (SDB) that indicate which solenoids to activate.
I don't have facebook so can't see your video but from your first description, the signal with issue is the red-white wire between MPU J4 pin 1 and SDB J4 pin 3. You should just re-terminate all wires on those connectors though.

Exactly which solenoids are not working in solenoid test mode - are any still activating at the wrong time?

Glad you're saving this ol' girl. Keep at it! Sounds like the terminals at the MPU J4 connector got hit with battery corrosion from the original MPU board.

Good eyes Inkochnito ^^^
Inspect the soldering on the other pin headers in case more need to be resoldered.

https://www.greatplainselectronics.com/proddetail.asp?prod=LB2-48DP

As is, Harlem Globe Trotters has no concept of millions scoring. So upgrading to simple 7 digit displays requires mods.
There's a seven digit scoring mod here:

http://www.pinball4you.ch/okaegi/pro_soft.html

It requires a ROM upgrade to support millions scoring plus and a bit of hardware circuitry to be built to enable the millions digit on the displays.

Otherwise XPIn make a simple plug'n'play solution called 7volution:
https://xpinpinball.com/product/xp-7volution/

The side with the metal tab should face the same way as the other SCRs with metal tabs.

Note: on the lamp board, the connectors start with pin 1 at the bottom, not the top. Rather unusual that the lamp board connector pin locations are "upside down" compared to the other boards in the system.

Yes the tilt lamp wire is at pin 10. Pin 18 is actually the key position.

Not your bad at all, nearly all the early Stern lamp board schematics have that particular smudge making that 10 look like an 18

Consider the side that has the model number printed on it is the front for all SCRs/transistors. The metal side can be screwed to a heatsink for thermal transfer such that the model number on the front side is still visible. In other words the new SCR and the original SCRs you have should have the model number face on the same side.

Grab a jumper wire. Connect one end to ground and touch the other end on the metal backing of the SCR. Does the tilt lamp light? This will test continuity from the SCR to the lamp and that the lamp & lamp socket are working. It does not test the SCR.

Next hookup one end of the jumper wire to test point TP3 on the lamp driver board. Touch the other end of the wire on the "gate" leg of that SCR. The gate leg is the one on the right when you look at the front side of the SCR (that shows the model number). Does the tilt lamp light? This test manually activates the SCR to tell you if the SCR is working.

Your tilt switches are working, right?

Post a picture of your lamp driver board so we can see which variant you have.

Thanks, ok you've got the original design lamp driver board with the buffer chips between the big decoder chips and the SCRs.

Have you got a logic probe?
If yes, hook it up, put the game in lamp test mode and probe pins 14 then 15 of the buffer chip at U8.
What does your logic probe indicate is happening on these two pins?

Put the game in display test mode (where no lamps are being lit) and measure the voltage on both those pins at U8.
Then put the game in lamp test mode. Do you get a slightly different voltage reading? Maybe the readings change as the lamps switch on and off?

TP3 is a test SCR enable voltage, it's not ground.
TP2 is a ground point on that lamp driver board, so redo the measurements with the black meter lead on TP2.

Ahh, sorry just looked again at your pic and you have a Stern lamp board. For whatever reason Stern swapped TP1 and TP2 around. TP1 is ground on their board. Can you redo the measurement again with the black lead on TP1?

You were measuring those voltages on pins 14 and then 15 of the buffer chip at U8 and these results were the same on both?
The values themselves don't mean much (a multi-meter is not really appropriate for checking high speed logic signals), but is indicating there is movement.
What voltages do you measure on the gate leg of SCR Q47 (right most leg when looking at the front of the SCR) in lamp test mode?

In lamp test mode, check pins 3 and 2 (8k bonus lamp drive) of U8 to compare against pins 14 and 15 respectively. The multi-meter activity should be the same.

You measured 3.75 volts on the right leg or the center leg?
3.75 volts on the right gate leg would have switched the SCR on and the Tilt lamp should've illuminated.

You should be getting a similar behavior on the gate leg of the SCR in lamp test mode - voltage goes from 0ish when the lamp is off to something when the lamp should be on.

Pin 15 of U8 (Tilt lamp enable signal) goes to resistor R49. The other leg of R49 goes to the gate leg of the SCR Q47. Do you measure zero ohms continuity between the SCR gate and R49?

LDB_SCR_MCR106.jpg

The center leg of the SCR goes to the lamp. When the lamp is off you should be measuring about 5.5 to 6 volts there. 3.75V is too low - not likely your issue but I'm curious why it's low. When you get to the game, can you also measure the voltages at the lamp socket on both the braid connected side and on the tip where the lamp wire is attached? Also remeasure the center leg of the Q47 SCR again. Do these voltage measurements with the game in attract mode.

Compare the voltage/behavior on the gate leg of another SCR in lamp test mode. If the result is the same, Q47 is being told to switch on.

With the confusion on where the gate leg was on the SCR, please redo the jumper test from test point TP3 on the lamp board to the gate leg of Q47. Does the Tilt lamp illuminate?

Are you using LEDs or incandescent lamps?

Ok, maybe doing these tests in lamp test mode wasn't a good idea since it doesn't help your multi-meter to give steady readings.

Please open up a support thread for this in the "Tech: Early solid State" subforum so this thread can return to normal discussion about the games.

Try the following and answer in your new thread.

Install normal incandescents in the Tilt lamp socket and also the Ball In Play lamp sockets.
Start a game and put it in Tilt mode.
Measure the voltages on the lamp driver board at the following locations (black multi-meter lead connected to TP1 GND on the lamp driver board and leave it there).

Measure these locations for the Tilt lamp:
U4 Pin 14
U8 Pin 14
U8 Pin 15
Q47 gate leg

Measure these locations for the Ball in Play lamps:
U1 Pin 14
U6 Pin 11
U6 Pin 12
Q16 gate leg

.
Both these lamps should be lit so we're comparing voltages for their selection and drive circuits.

The following images are to clarify IC pin leg numbering anti-clockwise:

Pin_Numbering6a.jpg
Pin_Numbering2.jpg

Hi sinus and welcome to Pinside

There are many different conversations happening in this thread so may I suggest you create your own new thread in the early solid state tech support sub-forum and post your question there:

https://pinside.com/pinball/forum/forum/tech-early-80s-solid-state

In your new thread please give us some more details about the actual switch problems you're having.

Cheers.

Generally most 2732 (not all) have flat faces, while most 2532 have a square raised section in the middle where the window is. This isn't strictly true for all manufacturers but most of them are like this.

Probably best you confirm with the ebayer that supplied you the EPROMs.

2x32_EPROMs.jpg

Can you post some clear high res pics of this board in question?

Make sure the 4049 chip at U14 is an unbuffered version "4049UB" and not a buffered "4049B" version.

I think you're right. Until someone produces real evidence:
The NVRAM test is only nibble wide (4 bit) during power on self test. PinMAME appears to be using SB100 emulation and they're using 1MHz CPU clock but looking at some game time delays it matches older MPU-100 CPU clock times based on 500kHz. ROM addressing is MPU-200/Bally-35 based.

If the 50 point switches is the only switch issue you have then most likely one of those eight 50 point rebound/dead bumper switches is stuck closed. You can confirm if it's the issue by going to switch test mode. Remove the ball from the outhole. See if the game reports switch #34 (50 point switches) is closed.

Yes, a likely bad connection on either/both of those pins. There is a brown-white jumper wire between those pins on J3. A common mod for redundancy on these solenoid driver boards is to solder a wire on the back of the board between TP1 and TP3.

SDB_TP3.jpg

I do the mod inconspicuously

5V_Mod_TP1_to_TP3.jpg

The wire gauge is a similar thickness to the other factory jumper links on the board. Holes are 0.8mm drill diameter.
You can use component lead clippings similar gauge to the jumper links already on the board to do the job.

I do the same with the C26 and C23 capacitor ground mods although I use thicker gauge component lead clippings for the C23 mod because of higher C23 surge currents on power-up.

The C26 negative trace is too thin to drill through so I drill next to it and bend the wire along the trace and solder. Of course you need to scrape the green enamel off the traces to expose bare copper first for the solder to take.

C23_GroundModB.jpg
C26_GroundModB.jpg

Sounds like a problem in the 43V to 12V circuit on the sound board - the sustain pot normally has 12 volts across it and likely it got hit with 43 volts. Check the Q1 TIP29C transistor for a short and the 13V zener diode at CR4.
Power on very quickly and measure the voltage at TP3 (next to the sustain pot) on the sound board. Should be 12 volts.

I would stick with the original transistor - they should be easy to get. It must be C version as barakandl said. A and B versions are lower voltage spec.
Note the 555 Timer at U7, the pre-amp at U9 (LM741) and the output amp at U10 (LM380) are also powered by the manufactured 12V rail on the sound board - they might now be suspect.
Check diode CR3 (1N4004) while you're there.

The -17 MPU board supports up to 4k bytes of ROM code.
The -35 MPU boards were enhanced to support double the ROM address space up to 8k bytes.
A 2732 EPROM is 4k bytes in capacity.

The electronic sound games were coded under the enhanced ROM address space layout.
You can't jumper a -17 board to run standard game code from a -35 game without performing the FO-597 modification to give it the enhanced ROM addressing support.

Yes, @barakandl's replacement Bally/Stern MPU board has a socket for an optional 27512 ROM that gives you 61k bytes of usable ROM space (up from the standard 8k bytes) and also increases the standard RAM size from 384 bytes to 3968 bytes.
If you're writing custom code you won't have to worry about running out of ROM/RAM space.

No other after market native 6800/6802 MPU board offers these expanded ROM/RAM features.

Refer to the Playboy schematics on IPDB for a clear MPU board circuit diagram - same board.

One capacitor lead goes on the lug that has the diode alone (no wires) where the banded diode side is connected.
The other capacitor lead goes on the lug with the two brown-white wires and no diode is connected.

The picture below is from another thread but should help - ignore the wire colors and use the switch on the left as your reference.
Playboy_TargetSwitch1.jpg

Ignore those extra two lugs. Connect the wires/diode/cap onto the same lug positions as your old switch.

Try it again but this time use the actual ball against the skirt to make sure the spoon closes the switch at all angles. It could be a mechanical issue on the top deck like someone installing shorter ring/rods causing the ball not to fully action the skirt.

Use your 4 battery holder and solder a blocking diode across the 4th battery position. The diode is needed so the MPU board doesn't try to charge the batteries, otherwise you're asking for trouble.

See here:
https://www.pinwiki.com/wiki/index.php?title=Bally/Stern#AA_Battery_pack

Yes, a 1N4004 diode can be used.

A 1N5817 diode is usually recommended because it has a smaller voltage loss across it which means the batteries will hold memory a little longer when they've nearly gone flat.

Put that 1N4004 in and enjoy your game!

Is that power on flicker and 5 flashes or power on flicker and 4 flashes? i.e. are you counting the initial power on flicker as a flash? because the flicker isn't part of the LED flash self-test process.

5 LED flashes is a problem with the 6821 PIA at U11 receiving interrupt requests from the display interrupt generator at U12 on the MPU board.

A blown F4 fuse will cause the Power On Self Test (POST) to stop after the 6th LED flash as a failure to receive Zero Crossing interrupts via the 43V solenoid power rail.

7 LED flashes are required to complete the boot process.

The under playfield fuse (a 1 amp slow blow) next the the flipper mechs should be blowing well before the F4 5 amp fuse on the rectifier board blows.
First make sure the playfield fuse is the correct type. It protects against playfield coil over-current faults except for flipper coils.
If the playfield fuse is correct, it's likely an issue surrounding the flipper coils since the playfield 1 amp slow blow fuse is wired *after* the flipper coils on the solenoid power rail.

Original is a 2N5060, but a 2N5064 is perfectly fine as a replacement (it can operate at higher voltages).
Atari_Daze the MCR106 SCRs are the ones marked on the circuit diagram with two stars ** and are the physically larger ones. It's strange the notes you posted don't mention it because I'm sure I've seen it in other lamp driver board schematics.

Ah, I see what's happened, the notes you posted are from the auxiliary lamp driver board which only has MCR106 SRCs. The main lamp driver board schematic on IPDB has the notes section partly chopped off.
It should look like this, so all good

LDB_Notes.png

Has the game reached maximum credits?
i.e. if you have the maximum credit dip switches #25 and #26 set to 10 credits, and the game already has 10 credits then you can't be rewarded any more.

Otherwise, what are you being rewarded when you get 10,000 points? Extra Ball or nothing?

Yep, all five displays are the same and you can interchange them into different positions.

You can get away with less voltage, the Zero Crossing detector on the MPU board just needs to see the Z.C voltage swing up above 5 volts (note the MPU board halves the voltage between the J4 input pin and the Z.C detector).

You should be able to use an off the shelf 24V transformer hooked up to a bride rectifier.

BTW, +1 on the Weebly board, you'll be able to put custom test ROMs on it.

The trimmer pot is electrically before the amplifier on the sound board. If you wire a volume pot within the cabinet connected to the trimmer pot location, you will likely pick up electrical noise that the amplifier will amplify.

It's better that you follow the way it was done from Xenon onwards using a 100 ohm 5 watt potentiometer connected to the speaker output. It will also save you running wires to the sound board in the head.

The old version is on PinWiki:
https://www.pinwiki.com/wiki/index.php?title=Bally/Stern#Accessing_Bookkeeping_and_Diagnostic_Modes
Direct link:
https://www.pinwiki.com/wiki/images/3/36/Sco_testrom.zip

It's been updated since though.

Yes it does From the readme:

individual lamp test - advances through Q1-Q60 on lamp driver board, pause with s33 press
press test switch

*if dip #9 set ON:
aux lamp driver test - advances through Q1-Q32 on aux lamp driver board, pause with s33 press

Switch #06 is the start button on the coin door.

What happens if you start a game or go into switch test mode then disconnect J3 from the MPU board while the machine is on? Does that inline standup target suddenly start working?

Post some clear pictures of the wiring on that switch - the more angles the better.

You've got the wires soldered on the wrong lugs (backwards). Swap them around so the white-red wire connects to the diode lug on the side and the brown wires go where the white-red currently are.

Which game is it for?
And which bridge on the rectifier board are you replacing?

There were two different rectifier boards used in classic Bally and they had different bridge rectifiers.

Give us some background - is one of them faulty, and which one?
If they're not faulty, I would not replace them.

The originals are 10 amp bridge rectifiers. They're long obsolete. The ones Marco is selling model KBPC802 are 8 amps, not 10 amps.

Physical size wise, these are all drop in replacements but are only 8 amps max (highest you can get in this physical size)

https://au.rs-online.com/web/c/semiconductors/discrete-semiconductors/bridge-rectifiers/?applied-dimensions=4294809338,4294565700,4294876504,4294874820,4294876509,4294874899,4294874849

If the BR1 feature lamp bridge has blown, replace it with one of the originals from BR2 or BR3 and install an 8 amp at BR2 or BR3. You really want a 10 amp bridge at BR1 because of the high current draw.

Screw the rectifier board with bridges in place first, then solder them so there's no stress on the joints.

Alternatively some people solder the big 35 amp bridges on the top side of the board, but you must make sure to effectively thermally cool it with a decent heatsink because it will get HOT.

Yes, the burnt connectors are potentially your problem. But it's easy enough to confirm if you have voltage at the rectifier board and no voltage at the playfield/backbox.

BTW, it looks like someone has hooked up an external bridge on BR3 (for the solenoids) so I presume that bridge is faulty. Replace it with any of the 8 amp bridges linked in my previous post.

Also, to properly test BR1 and BR3 you should temporarily unsolder one leg of resistor R2 and R1 respectively - they are across the bridges and will tamper with the readings.

They never left the factory that way. The bridges are mounted on the backside of the rectifier board. Any bridge you see on these machines mounted off board with wires is somebodys attempt at a repair.

I just checked about 15 old MPU boards in my stock and they all have 1kV caps there except for one Stern MPU-200 board that has a 100V cap fitted there from factory.

In any case, I think you should be ok to use a 0.0022uF 1kV cap for C32.

You mean CR43 still "disconnected"?
The hardware of the PIA port A pins vs the port B pins is different. Note the below paragraph in the 6821 PIA specs.
An external short on one of the port A pins will cause the PIA to fail the Bally power on self test. However an external short on a port B pin will pass the test.

PIA_Ports1.jpg

Any corrosion on that capacitor?
It's rare, but I've seen them fail - also happens to the 470pf capacitors on the PIA port pins.