Working on a Bally SDB - Solenoid Driver Board Tester.

This follows on from the Lamp Driver Tester board I did a couple of years ago:
https://pinside.com/pinball/forum/topic/bally-stern-lamp-driver-board-tester

Here is my V1.0 Prototype Tester Board:

board design (resized).png

It will test:
1. The 15 Momentary Solenoid Driver Circuits, Q1-Q14, Q16
2. The 4 Continuous Solenoid Driver Circuits (Including the Coin Lockout and Flipper Enable Relay) Q15, Q17-Q19
3. The Two Flipper Relay Switch circuits
4. The 5v Regulator Circuit
5. The HV circuit

There will be an option to still be able to test, even if the SDB 5v regulator circuit has failed. (By providing 5v supply to the SDB from the tester itself, instead of from the SDB).

Prototype board is in production and should arrive in a couple of weeks.

There are 5 Jumpers on the SDB board, with a ton of connections. The tester needs 39 connections to the board in order to run all the tests, so the main complexity for this project is making up 5 separate wiring harnesses. J1,J2,J5 are 3.96mm and J3,J4 are 2.54mm.

J3 is a 25 pin housing which are not easy to get ahold of. I got some 3D printed in Nylon to a design specification that allows them to house the Molex 2.54mm HIGH PRESSURE Crimps - these make a really good contact with the pins, much better than the standard crimp pins - but also 20X the cost! (We don't really need this level of quality for this tester, but given these are the only 25P housing I have available, I'll use it).

I've already started working on the code:

1. Start up - reset all outputs and initialise the LCD display, display Opening Message and firmware Version No. for 2 seconds.

2. 5V test - If the 5v regulator on the SDB is generating 5V the "5v SDB Test" Led should be lit. No other leds should be lit on a working board.

3. Lock On test - Display a message warning that any lit "Q" number Led means the corresponding driver transistor/circuit is faulty and locked on. These should be fixed before proceeding any further.

4. All Q Test - will flash all the Q circuits quickly in sequence. If a Led doesn't flash, it's a faulty circuit.

5. Q Number test - Runs through each Q number from Q1 to Q19 and flashes the corresponding Led. If the Led doesn't flash then the drive transistor/circuit is faulty and should be fixed.

Q15 is the Flipper enable relay. The Tester will test both relay switches for the left and the right flippers, so both Q15 Leds should light whilst Q15 is being tested, the flipper enable relay should also click on and off and be audible as it does so.

6. HV Test - At any time the user can press the "Test HV" button on the right hand side of the unit to test the SDB High voltage circuit. If the circuit is operational, the "HV test" LED should illuminate when the test button is held down. it will go off as soon as the button is released.

The Momentary Solenoids are Q1-Q14 & Q16 (15 of them) are controlled by the 74L154 IC. If this is faulty then expect to see issues with these Q circuits.

The Continuous Solenoids are Q15, Q17, Q18, Q19 - these are directly controlled by the MPU in the game.

The HV test is conducted using the highest voltage we have on the tester board which is the "43v" circuit. In reality, this is going to be less than 40v because the buck boost circuit boards I am using can only generate around 39v max. I have labelled the circuit 43v just to be compatible with the nomenclature in the Bally/Stern schematics.

The HV circuit is usually powered by 230V DC, but I didn't want to have such a high voltage on my tester board. I have tested a few on my boards (good ones and faulty ones) and they all worked at the lower voltage of around 40v. i.e. a faulty circuit didn't light the Led and a good circuit did!

The wiring harnesses will consist of 5 cables from the tester to the SDB, J1-J5: Here is the mapping:

pasted_image2 (resized).png

If this all works, I'll make kits available. Probably 2 options:
1. Tester Kit + Harnesses : Full kit to make up the tester board plus all the parts to make up the 5 wiring harnesses.
2. Tester Kit : Full kit to make up the tester board, but without the wiring harnesses.

I'll update this thread once I've got the PCB in hand.

prototype boards arrived today
IMG_8360 (resized).jpeg

so i built one up
IMG_8361 (resized).jpeg
IMG_8362 (resized).jpeg

Did some testing and realised q1 and q2 have an incorrect footprint and the connections reversed. so i desoldered and turned around. i’ll correct that in the production board

got all my headers out ready to make up the 5 wiring looms
IMG_8363 (resized).jpegIMG_8364 (resized).jpeg

got lots of two colour wire from an old wiring loom i had

these are the high pressure crimps for the 25w j3 connector. they’re much better than ordinary 0.1” crimp
pins
IMG_8365 (resized).jpeg

ps no 20k pull up resistors on the board because i’m not sure if i need them. will find out once ive wired up an sdb and completed the software! i’m away from tomorrow so have to leave this until monday now…. i can’t wait!

wiring connectors all done. i’ve triple checked them.

Just a bit more coding to do before the first test of the tester!

IMG_8388 (resized).jpeg

IMG_8389 (resized).jpeg

IMG_8390 (resized).jpeg

IMG_8391 (resized).jpeg

IMG_8392 (resized).jpeg

The 45v is coming from the buck psu board. i’m using 3 of them to get 5v, 11.9v and 43v
the sdb tests out ok if you use less than 43v, ie 30 is fine too.

Quick video of the tester running through the 19 solenoid circuits Q1…Q19. You can hear the flipper enable relay click on Q16

A few changes needed on the prototype pcb:

1. no need for pull up resistors, so i’ll remove those.

2. There is too much current drain via the 595 shift register when it grounds the solenoid inputs, so current limiting resistors will be added.

3. If testing an SDB that has had the 5v supply mod (ie tp1 connected to tp3), then allow the testers 5v supply to tp3 to be disconnected, otherwise might cause issues, although this will be less of an issues due to 4 below.

4. Powering the 11.9v supply continuously, drawns too much current via the buck psu board, so will change the 11.9v/5v test to become a momentary test using a push button.

I made all the changes to the PCB and the V1.1 production board is now being produced. Should be here within 12-14 days.

New pcbs just arrived. I’ll make one up and test it out.
IMG_8523 (resized).jpeg

Video of the full tester in action

Link to construction instructions / operation instructions
https://drive.google.com/drive/folders/12aZ3fSyBVv6dnGWxjE80GImThVph5_HL?usp=drive_link

Just a few parts still to arrive for the kits. Yesterday I received my order for 1,200 connector wires (enough for 30 kits), I made up a set of cables to test everything out. All worked fine.

IMG_8632 (resized).JPG

Good news! All the components have now arrived, so I can start shipping kits.

Here are pics of the kit:
IMG_8703 (resized).JPGLeds, Resistors, Male Header pin strips, power jack, push buttons, IC socket, IC, jumpers, female sil sockets, standoffs with nut and screws.

IMG_8704 (resized).JPG
0.156" PCB headers, wiring connector housings, keying pins, cable ties, molex high pressure crimp pins.

IMG_8705 (resized).JPG
PCB and esp32s MPU

IMG_8706 (resized).JPG
3 bagged Buck/boost psu boards, 1 bagged LCD display

IMG_8709 (resized).JPG
pre-crimped wires 0.156" and 0.1", Mains PSU with interchangeable Pins to suit UK, EU, USA, ROW.

IMG_8710 (resized).JPG
The whole lot!

Will be in pinside shop very soon. https://pinside.com/pinball/market/shops/1464-retro-electro-designs

Now shipping - see my pinside shop: https://pinside.com/pinball/market/shops/1464-retro-electro-designs

First check the wiring is correct. To enable the relay we need 43v going out on Pin2 of J3A

5v test light could be on if the SDB has been modded to connect TP1 to TP3 or similar mod. This effectively bridges the 2 5V circuits on the SDB, so the LED will light becuase we are powering 5v via J3 Pin 25. Remove the "5v supply" jumper bottom left of the tester and the LED should go out.

Hi Randy, there is nothing special about Q4 and Q5 - if you look at a SDB board schematic, you can see these 2 are controlled by the 74L154 Decoder IC, just like all the other 15 Momentary Solenoid Circuits:
sdb schematics, centaur (resized).png
So, not sure why there should be an issue on those 2 circuits? Strange only happening on weebly boards?

If you have a board that doesn't light up any of the circuits, then I would suggest:
a) check you are getting 5v at TP3
b) U1, U3, U4 are transistor array IC's and they drive every solenoid circuit - both momentary and continuous. It is unlikely that all 3 have blown, but not impossible, especially if the board has had the wrong voltage applied to the 5V circuit (which is possible if someone mis-wires, or mis connects J3 - as this is carrying 11.9v, 43v and 200v as well as 5v. I have fixed a couple of boards where 2 out of 3 had blown.
c) U2, the 4 to 16 bit decoder IC controls the 15 Momentary solenoids. Again that IC can fail, but if that was the case then the continuous solenoids should still work (as long as U4) is not faulty too. So it could be faulty U2 and U4 that gives the symptoms you have.

PS - the other thing to also check is that there are no broken traces on your board. I had a board that was badly corroded and some of the traces had just got eaten away.

I just tested on a weebly board and Q4, Q5 light up as they should. The 5V test light comes on all the time - I guess this is because on the weebly board the 5v in and out are wired together, so the 5V supply from the tester is going into the SDB on Pin 25 J3, but is internally connected to Pins 13-17 which is the 5V output from the rectifier circuit. I removed the "5.0v supply to SDB" jumper on the tester and the led faded and went out. I then pressed the "5v test" button and it relit, as expected, and then faded once the button was released (there is a big 12,000uf smoothing cap that keeps it on for a while).

Ok so you have enough voltage at the J3, Pin5 - I have tested various boards, original bally, stern, weebly and they all trigger the relay using 36v (which is the max my tester buck board will give out), so that looks ok. Next the flipper enable relay is triggered by a signal from j4 Pin 8, via U4, P10 in, P9 out (u4 is a transistor array), then to Q15. You could try testing the circuit with a logic probe. Check the signal from J4A-P7 on the tester is being generated and is getting to J4-P8 on the SDB, then follow through the U4 and Q15.

Ok, if the 5V test LED lights immediately, it means we have a bridge between the 5V rectifier circuit on the SDB and the 5V logic circuit on the SDB. On the original boards, there two 5V circuits are separate and are joined by a wire jumper on J3 that comes out of P13 and back into P25. I.e P13 is the 5V rectifier output, TP1 and P25 is the 5V supply into the logic circuits on the bottom of the SDB board, TP3.
To then test the 5V rectifier circuit, you should remove the "5.0v Supply to SDB" jumper to prevent the tester putting 5v via P25 (& P13). You can then press the 5v test button" and if the SDB rectifier circuit is working, the Tester will send 11.9V to the Board and we should see 5v come out the other end of the voltage rectifier circuitry and light the LED. One some boards the initial current rush (because of the large smoothing cap, can make the tester reeboot, but usually pressing a second time is ok as the capacitor holds the charge).

Ok, try powering up the tester with no SDB connected, what happens?

Bob, I'll post you a new ESP32 board, I think that has failed.