Commodore Projects

The Dell model 6Y667 Monitor Stand is part of a docking station I happen to use at work. At one point I wondered if it might also be suitable for use with my flat Commodore 128 at home. A quick Web search found them to be in plentiful supply from a number of computer surplus outlets and parts recyclers, and I ended-up buying one on eBay (used, but in relatively good condition) for just $5.99 (USD) plus shipping.

When the monitor stand arrived, a few preparatory steps were needed before attempting to use it with my 128 – there is a sliding docking mechanism located on the bottom-interior of the stand, designed to latch-onto the laptop’s port replicator. Since it protrudes about half an inch, it needed to be removed. By gently lifting the right side, it snapped-out without much effort and without anything breaking. A cable connects it to the stand. Since I intended to re-use the cable later (see below), I cut it as closely as possible to the sliding mechanism, to maximize its available length, then tucked it away into the slot it was protruding from. With the bottom-interior of the stand now free from obstructions and flush with the natural curvature of the stand sides, the 128 could now be placed inside. The image on the right is how the stand looks at this point. The interior of the stand has a shallow slope of about 5-10 degrees. My 128 is positioned so it extends about 3 inches forward of the base, where it meets the desk surface, and to me the slope isn’t even noticeable (see final photos below).

Overall, I was impressed at how well this stand lends itself to being used not only with a different system but one designed nearly two decades earlier! While not wanting to sound like a salesman, I found this unit offers several advantages over other monitor stands I’ve seen or used with Commodore hardware over the years:

• Holds monitor in a far-forward position, reducing eye strain.
• Elevates monitor, promoting good posture, while providing ample clearance for ventilation and access to keyboard.
• Unique ‘U’-shaped design keeps sides free and open architecture leaves plenty of room behind for the 3 C’s: cables, connectors & cartridges.
• Stand edges are constructed of durable aluminum tubing, giving the unit a hefty weight rating of 100 pounds.
• In my opinion the stand is also aesthetically pleasing, since the dark brown plastic molding won’t clash with Commodore case colors. As a side-note, the width of the stand pretty closely matches the base width of most Commodore monitors. For monitors using the flip-down type access panel, the panel door can also be left open without obstructing access to the buttons on the face of the stand (see photo on right) – it’s almost as though they were designed to be used together!

While the stand works great with the Commodore 128, there shouldn’t be any reason why it wouldn’t work equally well with any of the other ‘flat’ Commodore computers. The next section discusses the LED-backed buttons on the face of the monitor stand and how they might be exploited – this may be of particular interest to Amiga owners, since it would eliminate the need to reach for the switch on the power supply ‘brick’, allowing it to be situated in a more convenient location.

Soft-Touch Power Control

Like many modern docking stations, this stand includes a few status LEDs and a couple soft-touch switches that were of course designed originally for use with a laptop. As any PC-user with an ATX-based power supply knows, the soft-touch, momentary-on power switches offer a real convenience. After setting-up the 128 and monitor, I thought it would be great if the unused electronics on the monitor stand could somehow be exploited to serve a similar purpose by controlling power to the 128 and monitor, while also providing visual feedback as to the power state &#150 so I started a part-time project to see if I could put something together toward that end. It took about three weeks to reverse-engineer the wiring in the monitor stand, settle on a schematic and wiring scheme, gather the parts and essemble everything. Having only taken one year of Electronics in High School, I don’t consider myself electronically-inclined, but the idea was too compelling not to try.

A hole was drilled in the back of the stand and the cable that was tucked-away earlier was run out through it (see photo on left). There are 4 LEDs total on the face of this monitor stand, but for this project I was only interested in wiring the two pushbuttons and the LEDs behind them, so 8 lines needed to be tapped (see wiring diagram). I thought about using a panel of four adjacent RCA jacks, but settled instead on CAT5 networking cable with RJ-45 terminators, since it provides a single 8-conductor cable, rather than four individual or two pairs of RCA-terminated cables. The caveat to this approach is that the shield is used as one of the lines for the ‘Power’ switch. Since the black and red wires weren’t being used, I snipped them off, ran one of them alongside the other 7 in the RJ-45 plug before crimping, then soldered the end back onto the shield (see photo on right). Not the most elegant solution, but it served the purpose of making the connection. The cable only extended about a foot from the stand, so I added an RJ-45 coupler and standard CAT5 network cable to extend it another 6 feet so it reaches the power control box.

The schematic for the power control board is based mainly on Bill Bowden’s MOSFET Toggle Circuit, driving a relay to switch 120 VAC power to the 128 power supply and monitor. The LEDs could have been driven in parallel to the load (relay) in Bill’s schematic, with green for ‘ON’ and unlit for off. Since the LEDs on the stand are bidirectional, with amber indicating “Standby Mode”, additional circuitry has been added to exploit this capability, based in part on the following Bi-directional LED driver. Here is the combined, final schematic and board layout used in this project.

Since space was at a premium inside the project box housing the circuit and outlets, the 9-Volt power supply remains external and plugs-into a jack (I didn't really want to butcher it up anyway). There are two independent pairs of switching circuits and relays on the circuit board – the original intention being to use them independently for the computer and monitor. However, I didn’t realize until hooking-up the power receptacle that the outlets are wired in parallel. So for now, the control box switches both the computer and monitor in tandem... which isn’t really such a drawback when you think about it. After all, who uses their Commie with the monitor switched-off, anyway?

With some of the video converters that have appeared in the marketplace recently, it's now possible to use a Commodore 128 with a VGA monitor, without too much hassle or expense. Below are two products I've configured for use with my system, allowing 40-column and 80-column video modes to be selected at the flip of a switch:

• RTV Veg Lite Composite-to-VGA Converter (for 40-column mode).
  • Appx. cost: US $40-60 (as of 5/07)
• Highway CGA (RGBI)-to-VGA Converter (for 80-column mode).
  • Appx. cost: US $90-140 (as of 5/07)

Wiring Diagram:

There is a bypass switch on the back of the RGBI-to-VGA converter that, when used with a Composite-to-VGA converter, allows you to toggle between 40-column and 80-column modes. This switch is in an awkward location (between the power and bypass cable connectors), so for convenience I've added a toggle switch to the front of the project box.

Thanks to members of the Commodore 128 Alive! forum for information and suggestions instrumental in making this possible. Special thanks goes to Mangelore for providing information necessary to overcome the lack of Intensity pin on the RGBI-to-VGA converter, thereby allowing all 16 distinct colors!

Below are some pictures of the final configuration.

I recently ordered and received the new Y-Plus model A-22 RGB-to-Composite Converter. A lot of people have been curious to know how it compares to some of the other options such as RGB-to-VGA, when connected to the Commodore 128 in 80-column mode. It is said a picture is worth a thousand words, so I've included a few pictures below.

The kit was pretty modestly priced at only $25 on eBay, and included not only the board and information leaflet, but also the power cable, RGB cable, composite cable and even S-Video cable! The only caveat was that the RGB cable fits the 5-pin connector on the board, whereas the 6-pin type was needed due to the C128 outputting the vertical and horizontal sync lines separately. Fortunately, the cable I needed was included in the CGA-to-VGA board kit I bought last year. Since I'm no longer using it, I simply unplugged it, snipped the intensity line and in less than five minutes I was able to see the results with the new board!

Using the S-Video output, the quality is much better than I expected, if not as good as with the CGA-to-VGA adaptor, pretty close – especially since up-scaling is usually involved, and most LCD monitors only render distortion-free when viewed at their maximum supported resolution. Some of the colors look rather heavily-saturated – hopefully that can be corrected using the individual R-G-B trim pots on the board, although I haven't test this yet.

In my case, the advantage this board offers over the Highway board is that my LCD TV includes both composite and S-Video inputs. I'm using the composite line for 40-column output, and S-Video for the more signal-intensive 80-column output. It's also one fewer component in the chain, compared to the CGA-to-VGA solution, which required not only the Highway board, but also the Composite-to-VGA converter.

I haven't yet routed the intensity pin to the circuit, so what you see below is what you can expect if you decide to use the board with no modifications. Check back periodically as I'll be posting the results once the intensity pin mod has been made, although the difference should involve mostly just the color mapping – the overall image quality should still remain roughly the same.

Wiring Diagram: