Some FIXes to the QL’s power supply or additions to make the QL motherboard more stable are best described as KLUGEs. Since enough time had transpired between when I thought I knew how to read a schematic to the present time when I know I do NOT know how to read one (remember when a schematic was glued to the inside of transistor radios?), and because it seems that I have always lived in places where “odd” electronic components are not readily available over-the-counter, none of the kluges were viable for me. My trouble shooting has degenerated to replacing suspected “defective” part; and, my repairs are limited to what can be ascertained with a Volt-Ohm-Meter (VOM) and fixed with a soldering iron. Nonetheless, I managed to come up with a Four Line wiring scheme which allows you to utilize virtually any PC power supply with your QL motherboard.
WHAT YOU’LL NEED
My Four Line [ +5 GND -12 +12 ] wiring scheme allows for proper power to the SERial ports and microdrives and all (?) attachments to the 64-pin DIN edge connector. In addition to a working QL, to implement this “project” you will need:any PC-type power supply
male & female 4-pin connector 1 "length" of RED wire for +5 1 "length" of BLACK wire for GND 1 "length" of BLUE wire for -12 1 "length" of YELLOW wire for +12 solder (w/flux) soldering iron (preferably, 15 watts) snips (finger nail clippers are "okay"!)
I recommend “lengths” of about 12″ (or, more) of multi-stranded wire.
As they say [this is a disclaimer], you attempt the described modification at your own risk and neither I nor ZQA! can take responsibility for muffs. The skill level you will need is modest, but you do need to have some previous soldering experience since the space may seem limited if you are not used to soldering on electronic boards. If you don’t know how to solder, or your idea of soldering is with a torch on copper pipe, then either don’t do this, or find someone who can use a pencil pointed soldering iron.
Since all soldering is done to the bottom of the motherboard, at some point, you will need a Philips head screwdriver to open the QL case and remove the motherboard. Again, if you have trepidation, then DON’T do it.
Look at the diagrams. All four diagrams are representative views of the back edge of a QL motherboard. For clarity, the majority of the diagrams have been rendered simply as lines, with the relevant portion a closer representation. The enlarged darkened dot is the suggested point on the motherboard to solder the particular colored wire.
Do not begin this project until you have compared the bottom of the motherboard with the diagrams and have a good sense of what is represented.
WHY I DID IT
The first time my QL went dead I was obviously perplexed. Several months of use had familiarized me with the fact that the position of the QL’s case behind the microdrives would always get warm when running, and mine was stone cold. After deciding to void the very limited warranty, I opened the case and confirmed that the 7805 voltage regulator to which the heat sink was attached was dead by replacing it with a new one and having my QL come back to life.
Time passed, and after replacing the 7805 for the umpteenth time, I knew I had to come up with an alternative power supply. It seemed that all the “standard” power supplies which were available provided three voltages ( +12 +5 -12 ). Because the output for QL power supply is AC, the QL Service Manual that I bought was of little assistance to me. Time for the VOM.
WHAT I DID
Obviously, I felt that I needed to come up with a simple Four Line wiring scheme which only depended on the available voltages from a standard power supply.
[Figure: Motherboard diagram, Red wire (+5 volts)]
Beginning at the point that I knew the best, I soldered a RED wire (+5 volts) to the trace that the 7805 voltage regulator output was connected. Use the flux to tip the ends of the four wires before attaching them to the motherboard — that is, strip about a quarter-inch from the ends of the wire, dip them in flux, add heat them from the soldering iron, then apply a light coat of solder. Snip ends so that about 1/16″ of wire remains exposed before soldering to the motherboard.
[Figure: Motherboard diagram, Black wire (Ground)]
I did consult the QL Service Manual to confirm that the middle pin on the power connector socket was the ground, and soldered a BLACK wire to it. This is a tight space, and perhaps other points on the motherboard could be used.
[Figure: Motherboard diagram, Yellow wire(s) (+12 volts)]
Using the QL Users Guide and a VOM I found the pin closest the QL’s power connector socket which corresponded to the +12 volt pin on the 64-pin expansion connector and soldered a YELLOW wire to it. Since this was not the input pin on the power connector, I later decided to also feed +12 volts to that pin to provide (stepped down) voltage for the microdrives and whatever else does not use “standard” voltages (after all, the QL’s circuitry was designed to deal with +15 volts, wasn’t it?). Do you need to add the additional jumper? I really don’t know. I can say that whether or not my logic was correct, the microdrives seem to operate as before (whatever that means!).
Wiring the -12 volt line was a bit perplexing to me. The first time, I soldered the BLUE wire onto the output pin of the small transistor (like triode(?)) which generates the -12 volts from the AC input. This was (is!) a very tight space, and I don’t think I did a clean soldering job since operation of the Serial ports seemed problematic.
[Figure: Motherboard diagram, Blue wire (-12 volts)]
HMMMmmm. Eventually, I soldered a BLUE wire (-12 volts) to the largest (trapezoidal) point near the 64-pin edge connector which connected to the long trace nearest to the back edge of the motherboard behind the Serial ports (see diagram). The Serial ports work with this arrangement.
SOME OF THE CHOICES I MADE
I happened to use the “standard” 4-pin Molex connector that is commonly used for disk drives since that was what I had.
The wire color sequence I used is: RED – BLACK – BLUE – YELLOW. Note that the wire colors “match” except for the -12 volt line.
This may be (is probably!) a bad choice if you are color blind (I am not); but, I presume that if you were to mistakenly plug your QL motherboard into a “standard” 4-pin Molex that there would be no harm since the -12 VOLT line would simply be “looking at” a GROUND line. However, if you plug in a modified power supply line to a drive, you might have a problem with the -12 Volts (minimal as it is) being where a GROUND line should be! I really don’t know.
To minimize confusion, I Braided the four lines attached to the QL motherboard and the Molex plug; and also, I Braided the power supply lines its Molex socket, too.
To further ensure visual differentiation, I Twisted the “regular” power supply output lines which supply power the drives.
Regardless, match the sequence (voltage and color) of the lines from the power supply with those of used on the motherboard. If the power supply you are using does not have leads, then solder matching colored wires to the appropriate terminals (i.e., RED to +5, BLACK to Ground, and so on) and BRAID.
Although the wire COLOR and Voltage output seems to have been standardized to what I have described, don’t make that presumption if you are not using a “new” power supply & case. For example, older Leading Edge power supplies used a proprietary color scheme; so, don’t presume anything. If-or-when in doubt, check with a VOM, or have a friend who knows how to use a VOM check your power supply’s output. If you don’t know what a VOM is, or how to use one, ask someone in your users group.
If you feel you have successfully wired your QL’s motherboard, and attached the power supply’s output lines to a matching socket, then before you re-attach the various accessories to your re-wired QL motherboard you should test the motherboard with only a monitor attached just in case you have muffed the wiring. If your bare QL works, then it should work with all its accessories attached, too.
WHY EVERY QL USER SHOULD CONSIDER THIS
It should be noted for those who have read this far and do not think that it is necessarily worth the effort of avoiding their standard, QL power supply that there is a probable cause and effect that I will suggest which makes it paramount for anyone still using the standard keyboard matrix (old or new) to consider the modification.
Some time ago, I had concluded that one of the reasons that the QL’s keyboard matrices fail is not necessarily because SRL was trying to save a hay-penny, but because of the proximity of the matrix tails to the heat sink (where the matrices tend to fail). That is, simply, that the material is prematurely aged by the heat.
Having said that, the caveat is that handling a fragile (i.e., “old”) matrix might make it fail; so, this is best done with caution unless you are already in the process of installing a new matrix.
Okay, so you’re up to the project. You can wire your QL before you have a specific power supply in hand.
You should note that there are a lot of “salvage” power supplies available. I’ve tried doing this with a lot of really strange stuff (i.e., I “wasted” a lot of money on odd-ball power supplies while trying to save money) and Dan Elliott has successfully wired a COLECO power supply to many QLs.
Dan’s UPDATE! article came too late for me, but just as well since the wiring he described employed a multitude of lines coming from a modified COLECO power supply to some cryptically described “pins” on the QL motherboard. Well, at some point, I actually got a chance to lay my baby-blues on Dan’s handiwork. HMMMmmm.. I learned that my confusion in following Dan’s article was a result of trying to use the QL Service Manual as a guide rather than just scanning an actual motherboard. I also learned what Roy Barber (QUANTA) had meant when he once remarked about engineers tending to use only one color of wire!
The lesson: Do yourself a favor and use different colored wire for different voltage values.
Multi-stranded, colored wire is available from auto supply stores or can often be found in the automotive section of some national hardware stores. Desperation forced me to use some Blue Krylon for my -12 volt line — it works.
QPlane
The QPlane is a fold-over type backplane with three buffered connectors; and, my recollection is that the original QPlane, or a close cousin, was available several years ago without the AT compatible power connectors. Learning that the QPlane now comes with P8 & P9 power connectors which correspond to an AT-type power supply finally peaked my curiosity enough that I bought one even though I probably won’t use one until I manage to find a “used” (under $250), Super Gold Card.
The QPlane may not be the answer for everyone who wants to use a PC-type power supply. While a Super Gold Card does not need to be modified to take advantage of the QPlane’s power connectors, modifications are necessary when used in tandem with either a Trump or standard Gold Card disk interface. Call me crazy, but in a worse case scenario I would rather have to replace a QL motherboard than a disk interface.
Another QPlane observation I want to make for those who are not familiar with IBM compatible PC hardware is that PC & AT power supplies (to my knowledge) are not wired the same. I “forget” what the precise difference is, but after physically modifying my sister’s first generation IBM PC case to accept an AT motherboard, the motherboard didn’t work when I plugged the power supply into it! The problem was apparently in the power connector output lines being sequenced differently than that of an AT power supply. Since I didn’t have any reference material with me to put the power lines in the proper sequence, I re-installed the original PC motherboard back into the case (and, of course it worked); and yes, the AT motherboard did work when it was plugged back into an AT power supply.
I cannot say that your QL equipment will successfully survive having a QPlane plugged into a “regular” PC power supply. When in doubt, check line voltages.
DO IT YOURSELF FOLD-OVER
Part of the downside of the QPlane is the additional cost created by the “extra” two connectors which you probably won’t need. The extra connectors are a throw-back to when some expansion cards did not have Thru-Ports. Of course, the alternative to “store-bought” is to make one yourself.
Over a half dozen years ago, after much trial-and-error (“gnashing of teeth” is probably a better description), I can say that a fold-over type board should be relatively easy to cobble up; but, it requires acquiring the necessary parts (connectors, perf board, tinned wire, solder, soldering iron); and, knowing the easiest way to fabricate it.
Initially, I tried the “original” Foldover board (Adman Services) which failed miserably (for me) for a couple of reasons — the primary being my tardiness in ordering (my issues of QUANTA came about a month after they apparently were received in the UK), thus receiving the last one (literally) on the shelf which unfortunately had some broken traces that necessitated hand wiring some of the connections. HEW. Apparently, during soldering at least one other trace must have broken (they were very, VERY thin), or I had an undetectable solder splash. Regardless, I just could never get it to work despite extensive continuity checks.
Okay, so I pulled the connectors, and decided to hand wire a “clean” piece of perforated board (Radio Shack). Well, I made the mistake of following the lead set by the single-sided, printed circuit of the Foldover board, and tried to hand wire the 64 (x2) pins on the same side. Let me just say that using insulated, wire-wrap wire it got very crowded in a hurry. In the end, my “first” home-made fold-over board didn’t work either; but, I keep it around as a reminder of what not to do.
In a flash of this-is-really-obvious-in-retrospect, I determined that the key to successfully hand wiring and soldering a fold-over board is to use both sides of the perf board. Really. Double-sided soldering can be done with the end result being physically quite stable.
So, all you need to do is to take the first connector and straighten the “lower” row of pins (or, bend the “upper” row) so they can be inserted into an appropriately spaced piece of perforated board. If you do the same for the other connector, you will find that if properly bent/straightened and inserted into the perf board, the bent pins will be pointed toward one another on one side of the perf board and the straight rows will be accessible on the other. I allowed for nine “rows” between connectors. The QPlane’s first connector appears to be similarly spaced.
Of course, you want to ensure that the DIN connectors are snug to the perf board before soldering. I decided to use tinned wire for the connecting wire since its slightly heavier gauge is less fragile than the wire-wrap you can get from your local Radio Shack (of course, you can use insulated wire wrap if you prefer). If you follow my suggestion of double-sided soldering, you simply need to solder a connecting wire between each pin of one connector with the one that lines up with a pin on the other connector.
If you have made your fold-over board with tinned wire (as I have), I recommend that you “paint” the outer, exposed wires to provide some insulation.
Since 64-pin DIN connectors are rare in North America, if you want to try to cobble up a fold-over board, you might consider salvaging a matched pair of DIN connectors from a QL memory expansion which has a Thru-Port since these boards are periodically available for a very small amount (try Mechanical Affinity). Removal of the DIN connectors from the circuit board is best done with either a razor saw or a Dremel-type tool (of course, you will want to cut as close to the board as possible).
YOU CAN DO IT
I have an internally expanded (512K) QL [motherboard modified by Nazir Pashtoon] with the described Four Line wiring configuration. Because the 512K QL is in the standard QL case, I have left the 7805 voltage regulator in place so that I can power it using either a PC power supply OR a QL power supply — there have been no perceived conflicts.
My “primary” QL (with an unmodified Gold Card) has been wired to a Sperry PC case (100 watt PS) for years. Before I bought either the Sperry case or the Gold Card, the “same” motherboard was installed in an AT case (230 watt — excessive for the hardware configuration) and the original connector attached to the QL motherboard was a salvaged pin set that I recall plugging only into P8 from the power supply.
My QL’s motherboard is held in place within the Sperry case with two screws whose posts were inserted in a 3/4″ thick piece of pine cut to fit the bottom of the case; and, the edges of the QL motherboard “rest” above the wooden platform on 1/8″ thick strips of perforated hardboard that happened to be handy.
A home-made ribbon cable extension connected a keyboard which used the original QL matrix until I bought a Falkenberg keyboard interface a couple of years ago. The new, DI-REN keyboard interface (available from Mechanical Affinity) would be my first choice, now.
If you have questions, contact me:
AL FENG
914 RIO VISTA CIR SW
ALBUQUERQUE, NM 87105
READTHIS_TOO
I would like to think that the foregoing is useful information for many people within the QL community; and, I have to apologize for the delay in getting it into print.
Prior to the inception of ZQA!, I believe I put out a general query regarding interest in an article on putting a QL in a standard PC case; but, the only response I got was from Peter Hale (then editor of NESQLUG’s newsletter). The problem with NESQLUG’s newsletter was my perception that the article would necessarily need to be broken up (i.e., re-written) into episodic installments due to its length. So, for various reasons, I never got around to re-writing (nor, sending) a version of the original draft. My belated apologies.
Shortly thereafter, I spent my “lost year” in the hinterlands of New Mexico. My QL was packed away for the majority of my sojourn. Time passed, and the article was pretty much forgotten.
Eventually, I must have interpreted a written comment by Tom Robbins that he was having power supply problems; and so, I re-drafted my original article, drew up a diagram, and sent it to him since he co-authors “QXL in Command” (in IQLR). I requested that Tom advise me if he could not follow it; otherwise, if he had no problems to send it off to Bob Dyl (IQLR’s editor/publisher). That was November 1994. Well, I never heard back from Tom, so I can only presume that he didn’t have a problem with following the instructions in the article.
While I could only presume that the article was sent to Bob Dyl, I eventually re-sent the article in April along with three others directly to IQLR. The US Postal service did NOT return my envelope, so I can only presume that IQLR received the articles. Well, that certainly makes Bob Dyl’s lament about the lack of articles a few months ago ring hollow, doesn’t it?
Of course, in theory, it is the perogative of any editor to exclude information from their publications, particularly if the writers are being paid for their articles; but, it seems obstructionist to the better interest of the Sinclair (particularly, QL) community to omit an article such as this one unless the information was found to be grossly inaccurate-or-incorrect.
Well, perhaps Bob Dyl has a “vision” of how the QL community should directed. Perhaps he thinks that information which “competes” with commercial products should be suppressed. Perhaps he thinks that only articles written by his by his friends should be included. Or, is it something else?
Perhaps you bought a QPlane and are satisfied with the idea of cutting and soldering on your Gold Card. Perhaps you have unlimited funds that don’t infringe on any portion of your household budget so that you would prefer to buy one of the over-the-counter QL-in-a-box packages instead of saving some money. Perhaps you consider yourself simply a regular person to whom the way of the world can be dictated by those who would like to be thought of as the cognoscenti.
Regardless, I know that I would be miffed if I had been looking for this information on wiring a QL motherboard to a PC power supply, and later found out it was excluded from print because of some unwritten, quixotic editorial policy.
And, that is the real pity because IQLR has apparently provided an excellent forum to a geographically diverse number of QL users. It seems that most of the articles are informative — even if many tend to hawk particular products — since they are usually written by end-users. Still, this episode begs the question: How many other articles and how much other information has been excluded for reasons that one can only speculate upon?
IQLR’s editorial policy is ambiguous at best (I remember once reading the proclamation that every article submitted had been printed just about a year before the lament that there was a dearth of articles) and has certainly become provocative at worst.
You have “one side” of the story about the history of this article. If you want more information [i.e., the “other side” (if there is one)], put your queries in the proper (and/or, telephonic) forums. Discuss this with other members in your users group. In particular, you owe it to yourself to get explanations and answers if you are an IQLR subscriber.
I don’t tele-communicate since I try to spend most of my time in the Upper Paleolithic and early Holocene — in other words, I can only shout what I know from the house tops and hope that someone else hears what needs to be said; and hopefully, those of you out there who do care about the direction of the QL community make it a consensus — rather than an individual — decision.
If I did tele-communicate, then I would be posting this information about Bob Dyl’s exclusionary policy on QBox and the appropriate site(s) on the INTERNET. Perhaps some of you out there will do so. The Sinclair community needs to hear from all voices about all its facets. What I know is that sometimes the emperor isn’t wearing any clothes; and, someone has to point it out.
HAPPY TRAILS,
AND COMPUTING, TO YOU …