I use Zero Delay Encoders for MAME-to-JAMMA controls. I skip the J-Pac. I just don't like the quality of the onboard video amp (it's 10+ years old now); find it to be lacking in contrast. I liken the image produced from the J-Pac to looking at an arcade monitor with sunglasses on. The whites are crushed. In most US-based cabs, I can get away without an amp entirely on MAME builds. But if not, I use a THS-series RGB amp and made
a PCB project for that to suit my needs. Also, don't like keyboard emulation that J-Pac uses and find it to be a bit laggy across different PC's at times. Don't know why that is so. But the Zero Delay Encoders take care of that entirely. Also, I like to keep MAME builds as low cost as possible. A J-Pac is $60. An ArcadeVGA is $80+. I always use a HD5000-7000 series Radeon card. I buy them in large batches from eBay for $5 each. Zero Delay Encoders are $5 each, sometimes less. I always buy these things in bunches when I see good deals on them on eBay.
If I have a cab where I know it will always be used for MAME, I just gut the wiring harness and repurpose that harness for other things. Remove the PSU and keep it for stock/a rainy day, or sell it to recoup some cost. Then, I'll wire video output right to the chassis after breaking out RGB/VGnd/H&V Sync (tied together) with a
VGA breakout terminal. I tap AC from somewhere in the cab to power a 12v DC adapter to power a stereo amp. Then rewire the cab for stereo output from the PC. Always, always I fashion a splitter or use a power distribution block when tapping power. Once I build a MAME cab and send it off, I don't want it burning down someone's house. Also, I keep everything powered from one AC input which is controlled by a rocker switch. To achieve this, I go into the PC's BIOS to setup 'Power On' after 'AC Restore'. I'll hack up an AC power cord and wire that to a power distribution block, along with the monitor AC power, stereo AMP AC power, and marquee AC power. The marquee's AC power is very important. Because to turn off the MAME cab, I set the front end to shut down the PC upon exit. Once the PC is shut down, the monitor goes black and you wouldn't know the cab is on if there is no marquee light. So after the PC shuts off, the swich is flipped off cutting power to everything. Then powering it back on is just a matter of flipping the AC switch on. You'll always know the cab is on if the marquee light is on in my builds. I think others use smart power strips. Those things cost $30. Why have that expense?
If I need to keep the harness intact (like when setting up MAME in Candy cabs), I'll solder all non-controller inputs to a JAMMA fingerboard. Then use Dupont wires for controller signals after soldering a 2x10 console header to a finger board. That is why I like the PB.JAMMA so much for this purpose. Plus, I can tap 12vdc from the PB.JAMMA to power the stereo amp. PB.JAMMA allows me to use multi-console PCB's for consoles and such, so I dig the flexibility it affords over the J-Pac. Sometimes, I will create a harness and wire it right up to the CP,
like I did here.
Get a load of this "ghetto" setup I am working on right right as of this moment:
This may seem really ghetto with a Windy II's CP being propped up by Coke cans. But this ghetto setup belies a truly functional application for this purpose. That CP is getting ready to be stripped of its CPO. The panel repaired as rust is eating away at it. But before it gets that TLC and since we are at my buddy's office, it makes for a good make shift rig to config MAME cotroller inputs as well as the front end's navigation inputs. All of this shall be thrown into a Sega Versus cab later. Once I have MAME and the the front end's inputs configured (in this case AttractMode), I can just copy the config files over and over. Those LCD's you see there are displaying a misaligned impage are displaying a 15khz signal from a single Dell Radeon 5450 card ($5 bucks shipped!) running CRT Emu. Such LCD's are a god send if you ever setting up MAME. I wouldn't even dare setup MAME without such an LCD. Too troublesome. It is worth your time to find an LCD that can display a CRT Emu hacked 15khz signal through VGA. With it, you can set everything up from the comforts of your desk. Then once done, shut it down and all you need to do is wire in your PC to your cab and you are good to go.
All of this is pretty simple once you've mastered the software setup of MAME. Anyone on this forum can do the rest. I am sure there are much more experienced people at crimping and soldering then me here.