are you johnny L? The famous drum 'n bass musician?

Hi,
as a rule of thumb, you cannot rely on board's led because they can go bad. To check if it's a board issue or a psu issue you must measure the voltages coming from the psu on the connector first, then on the game pcb. If the voltages are there (in particular the 5V line) it's likely that you have a board issue (or a monitor issue).

Nice to see it found the love it deserves

Wow, the dedication you and your friends are putting on this is incredible, congratulations! I like very much arcades like this, where classics, more recent machines, pinballs, candys etc can live togheter... it's marvellous. Maybe you have the right place for eurocade 2016

Keep this topic updated!

No, i know, but it's also true that synonym9 didnt mention to install 6 or more buttons on a dedicated cab, nor a 60-in-1

As far as your work is reversible , i do not see any problem using MAME to revive a classic. Its' way worse to strip an original art and replace it with a repro because it's not perfect or doesnt look good... there are different points of view as you can see, and the forum is the right one

Uh, I have just noticed that I have not updated this post for years!

I don't want you to think that those two games have been trashed: they are fully working now!
In particular, I had the opportunity to work on them starting from this summer.

WGP was the first of the line because it was 90% working and not too much work was predicted. After a good cleaning i replaced the (linear) not working secondary PSU with a switching PSU. As it was juicing the rumble motor, this (and reconnecting the cables) was all it needed to have it back to work. Another problem was the audio: only one channel was working. After some google i noticed that TAITO's are known for audio problem caused by the op-amp going bad. Piggybacked the old IC and the channel started working right after... yes! Last problem was mechanical :the springs that keep the wheel in place where broken, so i had to replace them.

Race Drivin' was another story: i knew it had some board problem, mechanical and the monitor had color issues. This board is incredible: it gives you the position of defective RAMs and you can bet that replacing them the pcb will work! I had 2 defective VRAMs and by replacing them the PCB was fixed! I would never be able to fix it without those self test, great work ATARI! While doing this, the monitor died. It had xray shutdown, but trying to fix it i shorted the EAT (and i am not a noob on this ). Being a zenith K7000 (K7000a) i had to replace it. Found that MTC9110 is a good replacement for those (you need to swap the neckboard socket and place a higher value resistor in series with the filament, 2.2 ohm if i remember well, i wrote this somewhere else so if someone need the correct value i can source it and replace some connector) and it really is
Some additional work (greasing of the pedals, cleaning of the cab, a good revision of the "new" monitor) and now it works great!

I have some pic on the phone, let me see if i can upload them...

That monitor don't  need an iso transformer: if you look close at it you will see that the psu is a switch mode psu.   Pay attention though: the primary  side of the psu is "hot", so in the case of servicing it while working you need a 1:1 iso