(Topic ID: 207553)

Gottlieb Sys1: Replace dead small transformer with LED displays & power supply

By ForceFlow

4 years ago


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  • 31 posts
  • 11 Pinsiders participating
  • Latest reply 7 months ago by toblave
  • Topic is favorited by 12 Pinsiders

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#1 4 years ago

This discussion came up in the "project games for sale" thread about what do to when a system 1 game has a dead small transformer since small transformers (B-17921) are difficult to find.

The small transformer carries a bit more than just the high voltage for the displays:
The two transformers convert the 120 volts AC input to other voltages needed for the game. [...] The small transformer outputs the main score display voltage (60/42 volts), the computer board voltage (12 volts which ultimately ends up as +5 volts), and the score display offset/reference voltages (8 and 4 volts).
Source: http://www.pinrepair.com/sys1/

It sounds like can use Boston Pinball's LED displays:

http://www.bostonpinballcompany.com/displays.htm

According to boston pinball, the displays do not require 69vac (60vdc & 42vdc), the offset voltages, or 5vac.

The (original) MPU requires +5vdc and -12vdc at J1.

So, it sounds like you can use an arcade power supply for the +5vdc and -12vdc, and bypass the Gottlieb power supply.

Desolder the wires for the small transformer. Put ring terminals on the hot & common wires, and connect those to the power supply. Add a ground wire from the power supply ground terminal to the EMI filter's middle terminal. Get a J1 connector (09-01-6061), and connect +5vdc and -12vdc to the appropriate pins.

1: Spare
2: -12vdc
3: DC GND
4: DC GND
5: +5vdc
6: +5vdc

Since it's not common to have -12vdc on arcade power supplies (but they are readily available on ATX computer power supplies), options are limited. There are -12vdc 0.5A, 1A, and 2A Mean Well power supplies available:

https://www.digikey.com/products/en/power-supplies-external-internal-off-board/ac-dc-converters/133?k=&pkeyword=&pv1527=6&FV=fffc074a%2C2dc1d7b%2Cffe00085&mnonly=0&ColumnSort=0&page=1&stock=1&quantity=0&ptm=0&fid=0&pageSize=25

I'm not certain on how much draw there actually is on -12vdc.

The pinout of the 4-digit display uses +5vdc at pin 18, which is fed by the MPU (from J3) and isn't a problem.

The pinout of the 6-digit display might be problematic. It appears to take +60vdc at pin 17 from the Gottlieb power supply, and uses a 15k 1/2w resistor to drop to +5vdc. I'm not sure yet how exactly the boston pinball displays handle this. Here's two versions of the original display schematic:

pasted_image (resized).pngpasted_image (resized).png

Any thoughts?

#2 4 years ago

In looking at the installation documents, it looks like the boston pinball displays are powered by a separate power supply, with a power adapter plugged into the service outlet. The 69vac line fuse is removed.

http://www.bostonpinballcompany.com/install.htm

#3 4 years ago

What is the -12v used for?

#4 4 years ago

Trying to zoom in on the BPC display boards, and they look like they have GND, 5V and 4V silk screened on their J2 and maybe the same on J3?

Quoted from zacaj:

What is the -12v used for?

The -12V is for the original MPU board - something about the Rockwell chips needing this voltage.

#5 4 years ago
Quoted from zacaj:

What is the -12v used for?

http://www.pinrepair.com/sys1/#tools

Looks like it's involved in some way with the spider chips, some transistors, and digit/segment output lines for the displays.

#6 4 years ago

Technically, the 11660 (Rockwell PPS-4/2) runs on 17VDC. But, by using somewhat standard power supply inputs (+5 and -12) it uses various components to interface with 5V logic.

#7 4 years ago

From what I can tell, both the NiWumpf and Pascal Janin PI-1(X4) boards only use +5V so the -12 is not necessary if you have already dumped your original Gottlieb MPU board.

#8 4 years ago
Quoted from CactusJack:

From what I can tell, both the NiWumpf and Pascal Janin PI-1(X4) boards only use +5V so the -12 is not necessary if you have already dumped your original Gottlieb MPU board.

Good to know

[edit]: I looked into the boards a little bit. I sent David an email about his board. And since I'm not sure if the Pascal board requires all the original voltages or not in order to boot, I dropped him an email as well.

#9 4 years ago

I got confirmation that the nii-wumpf MPU only needs +5vdc.

#10 4 years ago

Also the LISY1. More on that later...

#11 4 years ago

hello everyone

my PI-1 board uses +5V only.

my all-in-one PI-1 X4 board uses 11VAC and 14VAC taps from the small transformer, but not the 69VAC.
therefore it could still run on a damaged transformer whose 69VAC tap often blows due to reverse insertion of A2P1 connector on the original GTB power supply..

in addition to this, my all-in-one PI-1 X4 board generates enough current on the 12VDC output available at the screw-clamp connector J1, so that it can directly power Boston Pinball's excellent displays without need for an additional power supply block.

see the attached picture: direct power to the displays or to the dimmer provided with each displays kit.

Connect_PI1X4_eng_s (resized).jpg

#12 4 years ago
Quoted from Pascal_J:

my all-in-one PI-1 X4 board uses 11VAC and 14VAC taps from the small transformer

Would you be able to use these 12v and 15v transformers along with your PI-1 X4 all-in-one board?

http://www.antekinc.com/an-0212-25va-12v-transformer/

http://www.antekinc.com/an-0215-25va-15v-transformer/

Or would the extra voltage for each circuit be too much?

8 months later
1 month later
#14 3 years ago

I’m gonna bump this. Has anyone had to do what force flow is describing to skip the small transformer?

1 year later
#15 2 years ago
Quoted from northvibe:

I’m gonna bump this. Has anyone had to do what force flow is describing to skip the small transformer?

I ended up selling my joker poker that needed the small transformer replaced. But I had installed Boston pinball led displays and a pascal PI-1 all in one board. So the 69v was not needed, however there was another voltage needed, 14v I think from the small psu.

5 months later
#16 1 year ago

Alrighty! Fixing my friend's two gottlieb sys1's and a neighbors sys80a and it seems like we may have some bad transformers. So I'm back in this dead small transformer solution and I think I've been narrowing it down to parts and how etc. I'll document and list as much info as I can after I get this going. There are a few ways to do it and parts to use, so I hope we can make it fairly easy for anyone else in the future and stop the parting out of old sys1's that have a bad transformer.

Roller disco - no power from 69vac, 42vac and 5v, 12v. no displays or volttage to the head. Only playfield and backbox lights. Resistance testing of small xformer is showing low resistance on all windings except 69v and 115v.
Dragon - need to get more testing
jakes to open - no displays or volttage to the head. Only playfield and backbox lights.

4 months later
#17 1 year ago

Another bump. I built 5VDC LED displays and have a NiWumpf for my Close Encounters. My manual and schematic are currently MIA. If I only need 5VDC, can I ditch the backbox power supply and my dead small transformer and just add a 5VDC power supply? Does the backbox power supply just feed the MPU and the displays?

#18 1 year ago
Quoted from toblave:

Another bump. I built 5VDC LED displays and have a NiWumpf for my Close Encounters. My manual and schematic are currently MIA. If I only need 5VDC, can I ditch the backbox power supply and my dead small transformer and just add a 5VDC power supply? Does the backbox power supply just feed the MPU and the displays?

in theory yes. You'd power the displays.You'd have to see what the cpu board takes for power 12 and/or 5?

1 month later
#19 1 year ago

Hey gang,

I am very new to pinball and recently got a Sinbad machine. Being an idiot, I plugged the unkeyed power cable in upside down and completely melted my Small Transformer - what a design!

Someone had already replaced the main board with a Ni-Wumpf and after reading all the comments on this thread and the pinwiki, attempting to bypass the Small Transformer seemed like the best option (especially when they are so hard to find). So I ordered a Boston Pinball Company LED kit v8, which arrived yesterday.

Here is what I did today:

- Cut all the wires to the small transformer, terminated them all and then removed the small transformer
- Unplugged and removed the power board, which was toast. I also desoldered the A1-J1 connector from the board so I could reuse it
- Removed all the old displays and installed the new LED displays
- Installed the Brightness Control Board as instructed (except there is no power board to plug A2-J3 in to - come back to this)
- My machine didn't have a service port wired in for some reason, so I hard-wired a small powerboard in temporarily (I will swap this for a proper double power point later)
- Found an old 5V/2A switching DC power supply, plugged in to power board and checked the voltage and polarity. Then I soldered the +5 to pins 5-6 and ground to pins 3-4 pins of the A1-J1 connector, which sorts out the Ni-Wumpf
- While I was there, I also added two more leads from the +5 and ground, which had to be connected to pin 7 and pin 5 respectively on A2-J3, which sorts out the displays
- Plug in power pack supplied with the LED kit and connect it to the Brightness Control Board

Machine boots and plays! Displays are super sharp, couldn't be happier.

Just wanted to say thanks to everyone who commented - I would probably still be looking for a Small Transformer otherwise

#20 1 year ago

Good to hear that someone was able to do this successfully

#21 1 year ago
Quoted from fileoffset:

Hey gang,
I am very new to pinball and recently got a Sinbad machine. Being an idiot, I plugged the unkeyed power cable in upside down and completely melted my Small Transformer - what a design!
Someone had already replaced the main board with a Ni-Wumpf and after reading all the comments on this thread and the pinwiki, attempting to bypass the Small Transformer seemed like the best option (especially when they are so hard to find). So I ordered a Boston Pinball Company LED kit v8, which arrived yesterday.
Here is what I did today:
- Cut all the wires to the small transformer, terminated them all and then removed the small transformer
- Unplugged and removed the power board, which was toast. I also desoldered the A1-J1 connector from the board so I could reuse it
- Removed all the old displays and installed the new LED displays
- Installed the Brightness Control Board as instructed (except there is no power board to plug A2-J3 in to - come back to this)
- My machine didn't have a service port wired in for some reason, so I hard-wired a small powerboard in temporarily (I will swap this for a proper double power point later)
- Found an old 5V/2A switching DC power supply, plugged in to power board and checked the voltage and polarity. Then I soldered the +5 to pins 5-6 and ground to pins 3-4 pins of the A1-J1 connector, which sorts out the Ni-Wumpf
- While I was there, I also added two more leads from the +5 and ground, which had to be connected to pin 7 and pin 5 respectively on A2-J3, which sorts out the displays
- Plug in power pack supplied with the LED kit and connect it to the Brightness Control Board
Machine boots and plays! Displays are super sharp, couldn't be happier.
Just wanted to say thanks to everyone who commented - I would probably still be looking for a Small Transformer otherwise

What displays did you use? What driver board? Congrats on having a sys1 with no small transformer! We’ve been waiting for confirmation

#22 1 year ago
Quoted from northvibe:

What displays did you use?

The boston pinball displays. I linked to them in the first post.

Quoted from northvibe:

What driver board?

The driver board doesn't matter since it doesn't connect to the small transfomer. Any original or aftermarket one will do.

#23 1 year ago
Quoted from ForceFlow:

The boston pinball displays. I linked to them in the first post.

The driver board doesn't matter since it doesn't connect to the small transfomer. Any original or aftermarket one will do.

Ahhh sure, I didn’t read it all just skimmed.

4 months later
#24 9 months ago

See the following link for info on building your own displays that require 5v only:

http://pinballwiz.org/index.php/system-1-led-display/

Link includes demo of a Close Encounters with the Original System 1 Power Supply replaced by a cheap Arcade Power Supply and the Original Small Transformer disconnected. MPU Board used is a Lisy1 which also only requires 5v.

Lisy Build info available at https://lisy.dev/lisy1.html

#25 9 months ago

Did you build the lisy displays?

#26 9 months ago

There are System 1 Displays available on the LISY Website at the following link and these are by Bontango:

https://lisy.dev/gottlieb.html

These displays are a plug and play design (more info at the Lisy.dev site)

The Pinballwiz.org displays and associated PCB design are by me and all info is available on my site at:

http://pinballwiz.org/index.php/system-1-led-display/

Important Note: All of the above System 1 display designs can be used with original or aftermarket System 1 MPU Boards like the LISY1 board.

2 weeks later
#27 8 months ago

Working on a Cleopatra that melted the small transformer, but want to test the MPU that came with the game since it's not the original one.

Anyone have a ballpark range on required current for the -12V rail?

1 week later
#28 8 months ago

I built the pinballwiz displays and the game seems to function and play normally, but all of my displays are blank and they do have 5vdc sent to them. As I posted a few months ago, I'm running a NiWumpf with a 5VDC power supply after my small transformer lost all of its smoke and stuff started oozing out of it. Any ideas on what to check next?

#29 8 months ago

Just a thought which came into my mind and maybe someone thought of this before.....what about using a Bally E122-125 transformer? Those used in the classic Bally solid state games like Mata Hari, Star Trek. This *might* be an option for 120VAC areas. Configure the transformer for 220VAC or 240VAC and connect it to 120VAC. The secundary voltages are now about half as specified. Use the 7VAC outlets and/or 12VAC outlet (normally for GI/controlled illumination/Logic) for display offset voltages. Use the 173VAC for the displays (now about half this value). The 43VAC (lugs 2 and 6) has an additional lug (4). Use Lugs 2 and 4 for the logic voltage now. This might be worth trying. First measure the secundairy outputs before your first attempt please! The values may be to far off. I never tried it ( I live in an 230VAC area also) but maybe it is a solution.

#30 8 months ago
Quoted from toblave:

I built the pinballwiz displays and the game seems to function and play normally, but all of my displays are blank and they do have 5vdc sent to them. As I posted a few months ago, I'm running a NiWumpf with a 5VDC power supply after my small transformer lost all of its smoke and stuff started oozing out of it. Any ideas on what to check next?

The individual displays can be checked easily on the bench by providing DC 5v and gnd connections from any suitable 5v dc power source like a PC switching power supply or similar ..... then simply connect 5v to one of the segment pins and also to one of digit pins to test.

#31 7 months ago

I'll try checking them on the bench, but since none of the displays are working in the machine, something is either inherently wrong with all of the displays I built, or the displays are not getting told to show anything due to potential damage to the NiWumpf or something else when the transformer decided to give up.

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