XY Pattern generator worklog

[Zitt]

Several months ago I posted in my Star Trek Captains' Chair worklog that I intended to modernize a old XY Pattern Generator design on the interwebs. Many of the guys on VectorList provided valuable insight into the interworkings of the circuit... and provided many layers of helpful advice.

The result was the following schematics and a set of FabA prototype boards from BatchPCB.com as a dual sided board.
Surface Mount ( yes; I can hear the screams of horror ) as I wanted to minimize PCB size – thereby cost.

If your interested in the prototype schematics; they are here:
http://pinball-mods.com/blogs/wp-con.../XYPattern.pdf

I'm pleased to report that tonight I finally debugged the last problem (that I know about).
There is a small list of issues I had to work thru; but for the most part the design worked almost out of the box.

1) The clock generator circuit (3.578MHz xtal) and U1ABC was not "locking". This was due to the buffered logic of the newer 74HC* logic. Some research on the internet indicated I needed a 150pf cap from pin1 U1A to ground to allow the clock generator to exite enough to lock. Another recommendation was to use a Unbuffered HC inverter... which I'll incorporate into the next revision of the schematics.

2) The -12V buck converting power supply wasn't outputing the correct voltage. It'd start out at ~11V.... the drop to ~5V over several minutes. On my debugged board; shorting R26 (10meg ohm) allows the -12V to become rock steady at -11.8V. Unsure here; the Maxim EE sim was very specific on the 10meg ohm value... but the maxim datasheet indicated two modes for VL to operate in. So for now will error on the practical side.

3) The 5V regulator did not have enough copper to heatsink to. Next revision of the FAB will have a large 5V copper heatsink built into the board. For my prototype; I thermal epoxied a small heatsink from a old motherboard onto the top of the regulator to give it some thermal sink.

4) The Linear POT datasheet was missing details regarding the LED side of the POT. One hole was off and will need to be moved.

Things I still need to do:
1) Hook it up to my G08 and align me some guns.
2) check the +12V portion of the buck converter. Right now I'm using the backup +12V linear regulator (U9).
3) Modify schematics and board for FabB (learnings above).
4) Create an enclosure to house the unit.

Nice to haves:
A) Retrofit EPROM sockets to toggle A11 for a 27C32 eprom(s)... allowing for more user designed test patterns.
B) Rename topside adj pots to indicate X and Y.
C) make 3pin jumpers so the jumpers can be mecahnically sound output swing is not shorted

So; what does the prototype look like?

Click to see higher rez pictures


This is the primary side; which faces the workbench in normal operation.


This is the secondary side. It becomes the "top" of the unit so the user can adjust settings and the like.

More on the way - stay tuned.

[dezbaz]

Awesome work

So if I read correctly, this is for testing a Vector monitor?

[Zitt]

Originally Posted by dezbaz

So if I read correctly, this is for testing a Vector monitor?

yes sir!

Here's the X & Y black-n-white output over time when displaying Box and Cross:

X swing +/- 10 and Y swings +/- 7.5V.

When displaying H&V Lines:

[Zitt]

The real test is how the various test patterns show up in X-Y mode on the oscope:

BOX:


Cross:


Box&Cross:

[Zitt]

And the final 3 test patterns:

H Lines:


V Lines:


H&V Lines (crosshatch):


That's all I have for now...I'll post more data when I have it.

[dezbaz]

Fantastic!

I would buy one of them , if you decide to make them

Very Cool indeed. I have searched the net for one of these for ages, and then one drops onto KLOV one day (Thank you)



I could always use the diagram to make one, but there are a few things I do not understand. Some of the diagram symbols are different to normal

[Zitt]

Exactly the reason I modernized the existing design - haven't had any real luck getting a real unit.

I'll post schematics, a bom, and a link to the batchPCB order link when I've had a chance finish debug, correct the issues, and post some general calibration processes.

I do not; at this time, intend to build these... for many reasons; but lets go with I already have plenty of projects to complete.

[freeplayinc]

I too would like one of these, that's awesome work right there!!

[dezbaz]

Originally Posted by Zitt

Exactly the reason I modernized the existing design - haven't had any real luck getting a real unit.

I'll post schematics, a bom, and a link to the batchPCB order link when I've had a chance finish debug, correct the issues, and post some general calibration processes.

I do not; at this time, intend to build these... for many reasons; but lets go with I already have plenty of projects to complete.

Fantastic, that will be just fine, and did I say, Thank you

I was going to do a combo Amplifone Deflection / HV, for a test rig, and this would compliment the whole project

[Zitt]

Originally Posted by dezbaz

Fantastic, that will be just fine, and did I say, Thank you

I was going to do a combo Amplifone Deflection / HV, for a test rig, and this would compliment the whole project

Your welcome.
The real thanks go Mr Fish - he created the original schematics years ago.
I figured it was the least I could do to share my results / corrections to my fellow community of collectors.