Q*bert. A man and his grail... FINISHED !!!

[Laszo]

Here's the schematic Leo.

As mentioned, I removed diodes D21 and D24 (well, soldered them loose on their cathode side, which is the same thing) and I shorted D23 with a jumper wire.

You tied 35v ac to the logic ground. Your half bridge has been combined zenerdiode at D26 which is tied to the same ground. Together they form a bridge...... i think

[level42]

Good thinking....yes I can see The zener will be conducting in the negative puls of the AC from the transformer when there is a load connected, but even when I didn't have one connected it was still 47Vdc.....

In my thinking, D22 prevents any current from flowing in the negative pulse.....as long as there is no load.

Another thing.....I did have some second thoughts about hooking up the negative side of the tranformer to the ground....but it is the only way to create the half wave rectifier. The big problem is however, if that ground is also tight to the other grounds in the system, I'm also pumping negative pulses into f.i. the 5V circuit.


Gotta check the wiring and board connections etc......REALLY don't feel like blowing anything up on this precious Q*bert hardware....

There's a good chance that on the PSU board already the grounds are tied together and that would force me to "loosen up" all negative sides of the components. ......that may start to be too complicated for a simple hack...

[level42]

Oh......OF COURSE the other voltage supplies are also connected to the same ground......what was I thinking ??

In order to have it work the negative side of the entire 30V section would have to be floating (=not connected to any ground).
However the knocker is triggered by drawing a pin to ground (the plus side is fixed to the 30Vdc) and I guess the sound amp on the sound PCB is also hooked up to a common ground.


I think this is the end of the half wave rectifier idea....would be too much hacking.

In fact.....I wonder why nothing blew up on the soundboard while I tested it this way.....yikes !

[Laszo]

No more hacking for you today mister  those powersupply parts can easily be changed for new.... Your soundboard and main mpu are not easy to repair when blown....

[Etienne MacGyver]

keep it Original, mount the diode more far from the board and install a fan there. done

[level42]

Mmmmm....dont want fans in Q*bert but we'll see.


Today I had planned to take the cab to the DIY store but when I woke up there was nice layer of snow.....and I really didn't want to drag the cab through that....also I was pretty limited in time because we had to compete in the Dutch championships with the drumband....and today was the only day with 40% off for the good quality brand paint.....

Sooooooo......I had a good look on a lot of Q*bert side pics and I maybe wrong but to me it looks like the yellow of the side-art is a total match to the yellow on the cab....

So I simply brought one of the side arts and removed the pre-mask a little bit.

The DIY store had a color scanner but only for their store brand....weird. However, I've seen color scanners fail and I've seen perfect matches done by the eye (Ms.Pac Blue !!) although I must say the scanner at Bruno's DIY store seems to be absolutely spot on....


Anyway,....lets do this....guy asks if I want water or oil (terpentine) based......duhhhh.......oil of course.
Color matched and mixed.....the guy at the counter said yellow is pretty tough to get a good cover and that he could also mix a primer in the same color.......well @-40% what the hell, let's do it.

[level42]

While we're there, let's ad a Dutch touch to the cab.....can't believe these are actually still being produced in this country.....can't last long.....already heard Philips now wants to sell off their lighting division and since they already sold the TV/Audio division, chip division and a number of others too I wonder what the heck Philips will be left with......o well....can't change it.

One tip for newbies......always get cool white tubes, not warm white, I made the mistake of thinking warm white would look better but in fact, it makes the colors of the marquee look muddy...

[level42]

Oh for those who wonder....and for what it's worth, it's Flexa f8.60.80

[Etienne MacGyver]

Strak in de lak ! 

[level42]

I hope so Etienne !

Did some color matching. I am very happy. Compared to the CP (original) it looks spot on. Compared to the part that was uncovered from the side art sticker it looks to be a tad lighter yellow but on the eye it was spot on.
Maybe due to flash, I really don't have good light in the gameroom to compare.....but I'm happy.

The only thing...........I don't know why but I got gloss paint....thought the sides were pretty shiny on Q*berts but now I look at it again it looks more like satin......arrgh.....O well, can't return the stuff so we'll see how it works out.

[level42]

Do you guys think Q*bert approves ?

[level42]

I have also reached a verdict over the original vs. repro CPO.

The repro CPO looks AMAZING...it is SO close I'd think it could be a NOS one....I can't see a fault in the colors, nor the appearance of the black areas nor the look of the material itself. The only "flaw" would be that some of the texts on the right side are a bit thinner, but that could easily be a screening issue on the original.

And.....see the macro shots I just took.....the black areas have a lot of scuffs and scratches.

Cigarette burns on the edges. There are more lighter one's....this picture also shows the "grubby" look of the yellow. I've tried about everything I could think of to get rid of it but it just sticks somehow...

[level42]

More grubby yellow....

[level42]

The front edge has cracking all along and one really bad spot.

[level42]

.....and so, the verdict stands..........it has to go.

I mean, if there wouldn't be repro's etc. I could have well lived with it but the repro's are top-notch AND there will be spanking new repro marquee, bezel and control panel front art installed so it wouldn't make sense to keep this one....