On Tue, Feb 8, 2011 at 5:03 PM, Tony Firshman <[email protected]> wrote:
> Plastic wrote, on 8/Feb/11 22:30 | Feb8: > > Hi all, >> >> During my time at Sandy, I learned microdrives (the part inside the case, >> not the cartridge) were surprisingly reliable and fault-free. The only two >> faults that came up on a regular basis were dirt, and damaged capstans. >> >> The capstan, for those not in the know) is the rubber wheel on the motor >> which contacts the tape. The microdrive capstan has one advantage over >> capstans from tape decks. Tape deck capstans contact a metal pin when in >> position. If left for a long time, the capstan rubber acquires a "dent" >> which makes the tape change speed as it passed through - also, it slightly >> stretches the tape. The microdrive design contacts a plastic wheel in the >> cartridge, so it only touches something when a cartridge is left in. >> However, some people leave a cartridge permanently in the drive when not >> in >> use, and this can cause problems eventually. >> > I found a large number of QLs I repaired had migrating capstans. They had > nothing other than friction to hold them onto the metal shaft, and they rose > up in the majority. Maybe the ones that didn't had unused microdrives! In > extreme cases the capstan actually touched the top case - I saw many like > this. I did see that often. If you pulled the capstan off, and rubbed the motor shaft with a little rubbing alcohol to degrease it, the capstan was far less prone to sliding up. Also, it should be put on upside down afterward - it may have warn slightly unevenly and if so, it needs to spend the next interval wearing unevenly the opposite way - like rotating your tires. > The wires that enter the motherboard are just tinned stranded wire and >> quite >> fragile. I always soldered pins on these as a first act of owning a QL - >> often, soldering on the pins was quicker than trying to fit that floppy >> mess >> of bent wire. I have tons of these pins so if anyone wants some for their >> QL, I'll happily mail them at no charge. >> > If I had to remove microdrives, I always did this. Better than pins though > is a SIL socket strip. I cut sections off a DIL turned pin socket. That > way re-fitting is a doddle. What I have is the single rows of turned pins that we used to use on the SuperQBoard for the riser 512k memory daughter card. They're like a pre-cut sockets of very high quality. They used turned pins on all the boards I saw until I saw a US QL with the flat blade type socket - ick. > At Sandy, we also found that cartridges would become error prone if not >> spun >> once in a while. I got into the practice of, once a month or two, spinning >> up every cartridge through at least one full loop (about 20-30 seconds) >> just >> to prevent print-through and to redistribute the lubricant. >> >> You'd be amazed how often we'd get "mad microdrive" complaints and we'd >> ask >> them to send in the computer and the problem cartridges, and they'd ALWAYS >> have fingerprints, or the computer smelled of cigarettes. Smoking kills >> cartridges! So does finger grease. >> >> If you pen your case to clean anything, >> > .... or even 'open'. You are coming up with some brilliant mistypes, Dave. > Wasn't it you who talked about 'dinky cars'? Sorry :) My hands are a little numb still and don't co-ordinate very well, and my eyes don't spot the missing letters. it's always a good idea to remove >> and refit the voltage regulator. That's the small 3-pin device screwed to >> the heatsink right behind the microdrives. It gets warm regulating the >> voltage, but a poor connection can also create heat, so reseating the >> regulator in its socket helps it stay cool. While you're at it, if you >> have >> any PC thermal paste/crease/ >> > .... and another good mistype (8-)# > > arctic silver, replace that little plastic shim, >> if there is one, with a tiny dab of that and you'll find it transfers heat >> to the heatsink FAR better. >> > Yes indeed. I did that to *every* QL I repaired. I'm thinking that by now a lot of the regulators and IC pins will be quite oxidized and could use a good cleaning. I use a PEN eraser to gently remove the oxide. Pen erasers don't generate static charge when rubbed. ICs do run a little cooler when they have good socket connections. One, the socket to pin contact has lower resistance. Two, better contact conducts heat away into the PCB slightly better. Additionally, a cooler IC draws less current than a hotter IC anyway, so it could make 20-30ma each difference on the 68008 or the copro. > SOME people would get a tiny fan, hook it across >> the +9v and ground pins, and have it draw that air out the slots at the >> back. Nice if you can make it fit, but I don't think it makes much >> difference - it moves heat, but doesn't make sure it's being generated >> efficiently in the first place - just addresses the symptom. >> >> If I ever designed a QL PCB, it would have a far better power supply (but >> then, the PCB wouldn't be long and thin like that - it would be a eurocard >> or double eurocard - 100x160mm or so. I would also give it a proper bus >> with >> 4 or 5 expansion sockets. Hindsight. >> > ... and not require the wire connection 5v rail mod that Sinclair added to > issue 5 boards! > > >> I know this is obvious to many, but not to all, so my apologies to those >> who >> consider this obvious. >> > > Always worth repeating good advice. You will be amazed at how many still > don't know. > > Tony > > -- > QBBS (QL fido BBS 2:257/67) <+441442828255>+44(0)1442-828255<+441442828255> > [email protected] http://firshman.co.uk > Voice: <+441442828254>+44(0)1442-828254 <+441442828254> Fax: > <+441442828255>+44(0)1442-828255 <+441442828255> Skype: tonyfirshman > TF Services, 29 Longfield Road, TRING, Herts, HP23 4DG > _______________________________________________ > QL-Users Mailing List > http://www.q-v-d.demon.co.uk/smsqe.htm > _______________________________________________ QL-Users Mailing List http://www.q-v-d.demon.co.uk/smsqe.htm
