Mini Testbench - Fork of Frank_fjs's Minigun

[RealMFnG]

Have been working on a simple PCB that shrinks the footprint of traditional test benches like this:



Down to something like this (an early prototype):

The problem of a traditional workbench is two-fold:

1. The footprint as a result of the JAMMA harness wiring and the footprint needed for controls.
2. All the while, there is a need to make things elegant and clean for controls. Which can make costs go up.

The desire is to shrink the footprint for the harness and controls down into a small PCB. I wish to use this for both my fledgling forays into PCB repair and for CRT repair. This is intended entirely for break-fix/maintenance/testbench purposes. There will be no internal processing or scaling. Any signal processing shall be external. Momentary switches shall handle about 90% of all signal/control inputs in a test bench scenario. 2x10 multi-console header for external controls input and prolonged testing. This header is borrowed from the PS360+ and has been the standard in that arena and carried on by Brook and makers of other fight sticks.

By keeping the testbench footprint small, perhaps this allows for portability. "Consolizing" this into a briefcase and testing PCB's out the field becomes a possibility. Ultimately, I will end up with this:

+

I toyed with the idea of using a Pico PSU, but with the power brick, it does not reduce the footprint from replacing the switching PSU. The last thing to do is to figure out which onboard speaker to use which will require moving some things around in the layout. Any other feedback is welcomed.

Consolidating the discussion that I've had with several people on the subject across different threads into this one. So paging a few folks: @ic3b4ll, @xodaraP, @pacoarcade, @ekorz,@'Frank_fjs',

 

[pacoarcade]

I find a small CRT TV ideal for testing. Since it already has speakers I'd convert the audio to line level and use a Mini DIN 8 with XRGB mini / HAS / Minigun pinout.

Anyway I like the idea to have on board sound if you are using an arcade monitor in your test bench.

For the buttons I'd use ones that require low pressure in order to avoid bending the PCB.

 

[RealMFnG]

Was hoping to use an onboard speaker with PC Pins for solder mount, but attenuation becomes a problem as those speakers max out at 1mW. Found a small enough 4ohm/3watt speaker that will suit the purpose. Just will have to use standoffs to mount it though. But this speaker will be louder. I think this should be the final layout. Just need to validate and beef up the traces before sending it off to press. So here is what it does:

Spoiler

• Tactile/momentary switches for inputs
  • These are the switches this was designed for: MJTP1230A
  • Lighter pressure switches are also available that have the same footprint
• Onboard audio with a DTDP switch to output audio to a header for external connection
• All connectors use 2.50mm spacing
  • So JST NH or XH series will work. Molex KK series for US dudes
• A block of extra taps for +5v and +12v to power whatever else you may need
  • Gonbes 8200, small LCD screen, analog controls, optical controls, whatever else
• Clips to power a +5v test probe
• Voltmeter with a hole under it to calibrate the meter for accuracy
  • A DT3P switch so you can gauge all 3 JAMMA voltages
  • No extra LED power indicator. Sort of redundant I feel with the voltmeter there
• Test points for all JAMMA edge connections
• Kick harness
• 2x10 MC console header for external controls if prolonged testing is needed
  • TEST is mapped to HOME button on 1P and 2P
  • SERVICE is mapped to SELECT on 1P and 2P
  • COIN is mapped Punch 4 on 1P and 2P

 

[pacoarcade]

I'm afraid that an unshielded speaker of that size could cause magnetization to CRT screen relatively easy. At least CRT TVs, dunno if that's the case with arcade monitors.

 

[RealMFnG]

Crap. Might just go with it and keep fingers crossed. Here is the speaker: AS04004PO-2-LW152-R. Datasheet says nothing about shielding. But then again, it doesn't look sheilded at all.

 

[pacoarcade]

Apart from that I'd choose 8 ohm speaker since if the board requires 4 ohm it will work fine with 8 ohm speaker.

Even shielded speakers may cause problems with CRTs, I magnetized a philips TV some time ago

 

[brad808]

maybe you already know but just in case you don't something extremely similar exists ready to buy https://riddledtv.com/arcade/jamma_testers.html#Tester

I use one but there is few problem after much use that look same on yours:

- those small momentary buttons are not most reliable. Everything on test bench beds to be 100% all the time. Thankfully riddletv one has leds so you can see if switch not make each time. If yours has little crappy switches but no indicator that are crappy then would be headache

- Having jamma connector on board causes stress and intermittent loss of connectivity with numerous boards. Would be much better with small harness to jamma board to remove stress point. How it is now it's total pain in the ass. Have to be very very careful and aware otherwise you push down on little button and top pins on jamma lose connection etc, board resets etc etc. Very annoying.

 

[RealMFnG]

Good points @brad808. I have seen those JAMMA testers before but notice they require actual harness wiring which is what I want to eliminate. I really want to keep the footprint small. Also, I've also noticed those JAMMA testers use the cheapest edge card you can find. But you are right, connectivity at the edge connector is a problem that will likely pop up. Don't want that problem either. Paramount to having a small footprint is having proper functionality, especially in a test bench scenario.

Perhaps it is best to move the momentary switches to a detached remote board. If the harness is kept short, would still keep a small footprint while still allowing the user to make the harness as long as they desire.

 

[pacoarcade]

Another idea could be to make the Mini Testbench PCB pluggable to the Minigun through both DB15 connectors to check controls.

 

[RealMFnG]

That would require a Minigun (Captain Obvious I know, wink, wink). Test benches are inexpensive, normally cobbled together things made of spare/misc. parts. So requiring a Minigun would go against that spirit.

But moving the momentary switches to a remote board does afford the space to put in DB-15 headers. So I'll explore doing just that. Give folks options if you already have supergun controllers.

 

[djsheep]

If there’s a way to figure out how to generate colour bars or a test hatch screen that would be great.

Wouldn’t it be awesome if the guy who made the 240p test suite made a JAMMA version @Artemio

 

[RealMFnG]

Heh, beyond my skill level. Next best thing, just plug a CSP2 into it. But port 240p Test Suite to Raspberry Pi, then we can work something out.

 

[Derick2k]

By keeping the testbench footprint small, perhaps this allows for portability. "Consolizing" this into a briefcase and testing PCB's out the field becomes a possibility. Ultimately, I will end up with this:

Something similar to this?

 

[djsheep]

There's this: http://www.chrismcovell.com/dottorikun.html

I have two copies of Dottori-Kun to hopefully mod one. Does anyone happen to know what chip to use and if my Top 3000 will burn it?

 

[RealMFnG]

So @brad808, I will go to press with this version with the momentary switches on the PCB; no remote board (yet). Will get really soft momentary switches and see how it works out.

 

[brad808]

So @brad808, I will go to press with this version with the momentary switches on the PCB; no remote board (yet). Will get really soft momentary switches and see how it works out.

Yes. Can use jamma extension loom to resolve.

 

[RealMFnG]

By keeping the testbench footprint small, perhaps this allows for portability. "Consolizing" this into a briefcase and testing PCB's out the field becomes a possibility. Ultimately, I will end up with this:

Something similar to this?

Hah! Yeah, that is the idea. Portable test rig. Could turn an old GAEMS case into a portable test rig.

 

[AlxUnderBase]

This is an awesome project ! Need to jump on it and make a test rig !

 

[Derick2k]

By keeping the testbench footprint small, perhaps this allows for portability. "Consolizing" this into a briefcase and testing PCB's out the field becomes a possibility. Ultimately, I will end up with this:

Something similar to this?

Hah! Yeah, that is the idea. Portable test rig. Could turn an old GAEMS case into a portable test rig.

That would be cool, lets do it

 

[Artemio]

If there’s a way to figure out how to generate colour bars or a test hatch screen that would be great.

Wouldn’t it be awesome if the guy who made the 240p test suite made a JAMMA version @Artemio

Since each PCB has its own levels... It would be better to have platform ports fo teh suite, so that teh levels are form each PCB family. That is in the future, but I am slow at this and have been busy with MDFourier.

BTW, I love this porject! It looks awesome @acblunden2