**<>**¢ Improving Your 1050 Disk Drive.¢ by Ron Fetzer member of¢ OL' HACKERS AUG¢¢ The inspiration and ideas for¢ this article came from Ben Poehland,¢ recently retired A.C. Managing Editor,¢ and a member of OL' HACKERS.¢¢ AGEING?¢¢ Most 1050 disk drives by now are¢ getting older and showing their age.¢ Performance signs of age are¢ occasional failure to format a disk,¢ failure to read a good file, noise and¢ sometimes inserting strange symbols¢ into your text.¢ Before you make the upgrade you¢ might want to check the condition of¢ your power supply. Read the section¢ DEVICES NEEDED and section VIII,¢ VOLTAGE MEASUREMENT. This will give¢ you a good idea of the condition of¢ your power supply and if the upgrade¢ is needed.¢ Once you have made the upgrade¢ the 1050 will be just like new again,¢ very reliable, quiet and will last you¢ a very long time.¢ There are two types of 1050 disk¢ drives. One is the TANDON and the¢ other is the WORLD STORAGE. They are¢ identical in most respects and are¢ upgraded the same way.¢¢ LABOR OF LOVE¢¢ You must have skills in soldering¢ and unsoldering. Budget about 4 hours¢ for each drive upgrade. This is a¢ labor of love and I would hesitate to¢ impose on a friend with this project.¢ The description of the parts¢ position is always with the disk drive¢ front facing you. The Printed Circuit¢ Board will be referred to in this¢ article as the PCB.¢¢ DEVICES NEEDED¢¢ There are a few devices that you¢ have to make yourself. You need TIE¢ POINT EXTENDERS to read the voltages.¢ You cannot reach the tie points¢ otherwise easily. Take a 5 in. black¢ piece of thin solid hook up wire.¢ Remove 1 in insulation from one end¢ and 1/4 in insulation from the other¢ end. Take the end with the longer¢ exposed wire and wrap it about 5 or 6¢ times around a sewing needle so it¢ forms a little spring. You will now be¢ able to slip this over the tie points¢ on the PCB and be able to measure the¢ voltages easily. Make two more exactly¢ the same way with different color¢ wire.¢ You will also need 4 SPLICERS.¢ Take a very thin copper wire and wrap¢ it about 10 times around a darning¢ needle so it forms a spring about 1/4¢ long. Cut off the ends that are¢ sticking out. Splicers are used to¢ connect together wire components for¢ soldering. They are also commercially¢ available as COLMAN SPLICERS #1345-H¢¢ DISK DRIVE AGEING¢¢ What deteriorates in your disk¢ drive is the internal power supply.¢ The power supply is like the heart of¢ a human being that pumps blood to the¢ organs. The power supply pumps D.C.¢ voltages to all the I.C.'s and chips.¢ This voltage has to be almost pure¢ D.C. If there is a substantial A.C.¢ component riding on top of the D.C.¢ then your I.C.'s get confused and¢ think they are receiving information¢ pulses. A.C. or Alternating Current¢ has a high and a low potential just¢ like data pulses. That is the reason¢ you have to upgrade your power supply¢ to eliminate the A.C. ripple current¢ on top of the D.C. voltage.¢ The solid state I.C.'s and other¢ solid state devices will stay¢ virtually like new if they receive the¢ proper D.C. voltage and are protected¢ from excessive heat.¢ While your disk drive is¢ disassembled you should also clean all¢ contacts, read-write head, belts,¢ pulleys and moving components etc.¢ At the end of this article I will¢ give you a list of tools needed,¢ supplies required and replacement¢ components needed, and also where to¢ get them.¢¢ FILTER CAPACITORS GET OLD¢¢ As they age, the filter¢ capacitors in the power supply dry out¢ and develop a high power factor. This¢ results in letting A.C. pass through¢ on top of the D.C. voltage. This¢ voltage is usually called the ripple¢ voltage.¢ Since this is a major overhaul of¢ your 1050 disk drive we are going to¢ replace them with premium filter¢ capacitors which are larger than the¢ original, high efficient, high¢ temperature, long life types. We are¢ also going to replace the 1N4001 1¢ Amp. Charge Pump Diodes with 3 Amp.¢ heavy duty 1N5400 Silicon Rectifier¢ Diodes. This will beef up the power¢ supply so it that it is a new heavy¢ duty long lasting supply.¢¢ THE JOB STEP BY STEP¢¢ I. DISASSEMBLY¢¢ 1a) Turn your drive on its back¢ and with a Phillips screw driver¢ remove the 2 screws in the black front¢ bezel. Then remove the 4 screws in the¢ corners. Slide the top forward and¢ out. Place it aside.¢¢ 1b) Next we must disconnect all¢ the jacks from the PCB so we can¢ remove the mechanical motor assembly.¢ The motor assembly rests on 4 pins¢ with rubber cushions. Lift the front¢ to see it. In the front on the right¢ side of the PCB is a jack. Mark it and¢ the PCB with White Out so that you¢ know how to insert it again. Remove¢ the jack. Do NOT pull on the wires but¢ use the body of the jack to pull up¢ on.¢¢ 1c) In the back where the power¢ supply is, there is a large jack on¢ the left, and a smaller one on the¢ right. They have to be removed. The¢ left hand jack is really 5 jacks next¢ to each other and they will come out¢ individually. If you look next to the¢ jacks on the PCB you will see the jack¢ markings. On Tandon drives the body of¢ the jack is also marked. On World¢ Storage drives the jacks are¢ corrugated and they are not marked.¢ The easiest way to mark where the jack¢ belongs is to take a piece of masking¢ tape, write the jack number on it and¢ glue it around the appropriate wires.¢¢ Here are the left handed jacks,¢ front to back and the number of wires¢ they have.¢¢ J11 has 4 wires¢ J12 has 2 wires¢ J1 has 4 wires(motor control)¢ J10 has 4 wires¢ J14 has 3 wires¢¢ On the right hand side there is a¢ single jack J15. Mark it and the PCB¢ with White Out so you know how to¢ insert in later on. Remove it also.¢¢ 1d) On World Storage drives there¢ is one more wire, a ground wire,¢ usually purple that is glued with¢ apoxy to the heat sink. The easiest¢ way to remove it is to cut it and¢ later on to solder it again when you¢ assemble the drive.¢¢ 1e) You now can lift the motor¢ assembly and remove it. Put it aside¢ for now. You now have only the PCB and¢ the bottom cover.¢¢ II PCB REMOVAL¢¢ You should wear a wrist grounding¢ strap (see Tools) or have a grounded¢ surface that you work on for the next¢ steps.¢¢ 2a) If you remove the 4 rubber¢ cushions on the motor pins it will be¢ easier to remove the PCB. On Tandon¢ drives about 2 inches from the front¢ on either side of the PCB there are¢ plastic snap holders that you must¢ push back to remove the PCB. On World¢ Storage drives you also have an¢ additional two snaps in the back of¢ the PCB. You also have 2 hold down¢ screws on the PCB in the back and on¢ on the left front of the PCB in some¢ drives. You must remove them. The PCB¢ will now come out quite easily. Put¢ the bottom aside you will work only¢ with the PCB.¢¢ III UPGRADING OF THE POWER SUPPLY¢¢ 3a) As you look at the PCB in the¢ back on the left side of the metal¢ heat shield are two IC's mounted with¢ screws and one on the right hand side.¢ The rear left and right IC's are the¢ voltage regulators. The left is a 7812¢ for 12 volts D.C.(Q8). The right is a¢ 7805 for 5 volts D.C.(Q7). Both of¢ these regulators should have a white¢ paste or heat sink compound (see¢ supplies) on their backs. If they seem¢ to have very little compound on them¢ remove the nut, bend the IC a little¢ forward. Clean both surfaces with 91%¢ Isopropyl alcohol. Put new heat sink¢ paste on them and reapply the nut.¢ This helps dissipate the heat from the¢ IC. The front left IC usually has some¢ kind of insulating material square¢ clamped to its back. This is the¢ TIP110 (Q6). Leave it ALONE!¢¢ 3b) Next you are going to ground¢ the metal case that covers most of the¢ IC's. Cut a 5 in. piece of hook up¢ wire. Strip the insulation from both¢ sides. Find another nut that fits over¢ the right side of the screw that¢ sticks out from Q7 on the metal¢ shield. Put the wire around the screw¢ and put the second nut on top of it.¢ Solder the other end of the wire to¢ the side of the metal cage. This¢ prevents RFI from your drive.¢¢ 3c) Next we desolder the 3 big¢ black filter capacitors C67, C68 and¢ C71. On Tandon drives they have only 2¢ leads + and -. On World Storage drives¢ they have 3 leads +,- and a dummy¢ lead. You must desolder all of the¢ leads to remove the capacitors. I used¢ the SOLDAPULT desoldering tool from¢ Radio Shack (see tools) and found it¢ quite effective. After the capacitors¢ are removed clean out the holes. To¢ clean the holes put a little solder¢ over it and suck it out again with the¢ SOLDAPULT tool. The old capacitors¢ were 4700 uf at 35 volts or less. The¢ new ones we will install are going to¢ be larger 6800 uf 35 volt, 105 degree¢ C temperature, long life, high¢ efficiency types.¢¢ 3d) Remove the charge pump diodes¢ CR15, CR16. They are in the middle¢ between capacitor C71 and C68. They¢ are clearly marked on the PCB. We are¢ NOT going to desolder them, instead we¢ are going to clip them near the body¢ of the diode so we have two leads¢ sticking up for each diode. The new¢ diodes will get attached to these¢ leads. The 3 Amp. diodes have thicker¢ leads and would not fit into the holes¢ on the PCB. Besides this is the easier¢ way of doing it.¢¢ IV INSTALLATION OF NEW PARTS¢¢ 4a) The first thing we are going¢ to do is install the new 3 Amp. charge¢ pump diodes 1N5400 in place of the¢ CR15, CR16 1 Amp. diodes. Cut the lead¢ of each new diode about 1/2 in. from¢ its body and bend it 90 degrees. Take¢ a solder splicer and fit it over each¢ leg of the diode. Slip the other end¢ of the solder splicer over the old¢ leads of the diode sticking out of the¢ PCB. The band of the diodes faces¢ right. Solder the connections. Do this¢ for both diodes. They both face to the¢ right with the band.¢ 4b) Next take your new filter¢ capacitors, which are not wire lead¢ types, but have snap legs, and see if¢ you have to adjust the legs. They will¢ not fit flush on the PCB but are about¢ 1/8 in. above it. Adjust the legs so¢ they fit into the holes of C67, C68¢ and C71 and solder them. The negative¢ band faces to the right on all 3¢ filter capacitors.¢¢ V CLEANING¢¢ To clean the jacks contacts and¢ I/O contacts use CREMOLIN R100 and¢ B100 (See CN Oct. 90 page 24 "THE¢ MAGIC JUICE") or if you do not have it¢ use 91% alcohol (see supplies)¢¢ VI REASSEMBLY¢¢ 6a) Put the PCB in the bottom¢ cover and snap in the plastic¢ retainers on the side of the PCB (4 on¢ World Storage drives). If you had hold¢ down screws for the PCB reattach¢ them.¢¢ 6b) Put the rubber cushion back¢ on the 4 motor resting pins with the¢ flat side up Before putting the motor¢ assembly back look at the belt on the¢ bottom. Clean it with soap and water¢ if it seems greasy. Clean the motor¢ pulley and the flywheel with alcohol¢ and reattach the belt.¢¢ 6c) Take the motor assembly and¢ put it on the 4 pins so they match the¢ holes in the housing.¢¢ 6d) Twist the wires around a few¢ times and attach jack J15 on the right¢ rear side. Twisting prevents RFI.¢¢ 6e) Attach jack J6 on the front¢ right side.¢¢ 6f) Attach jacks J11, J12, J1, J¢ 10 and J14 to their pins on the left¢ hand side. Twist J1 a few times¢ around. This prevents RFI. J1 is the¢ motor jack. It is sticking out a bit¢ on Tandon drives.¢¢ 6g) If you had cut the purple¢ ground wire re-solder it and put¢ insulation tape over it.¢¢ You are now finished with the¢ major part of the reassembly of your¢ drive. Plug the power transformer in¢ to the drive, turn it on and see if¢ everything is O.K. and the read/write¢ head goes into the park position.¢¢ VII SPEED ADJUSTMENT¢¢ Use DOS 2.6f (black DOS) or any¢ other disk drive speed checking¢ program to see if the speed is¢ correct. The 1050 is very stable in¢ this regard and usually does not need¢ to be adjusted. The correct speed is¢ 288 RPM for an unmodified drive. The¢ range can be from 280 to 296 without¢ an adjustment.¢ If you have to adjust the speed¢ look for the potentiometer VR2. It is¢ just to the right of jack J11. It is a¢ small rectangular block with a tiny¢ screw on top. Use a jewelers type of¢ screw driver to adjust the speed to¢ the right RPM.¢¢ VIII VOLTAGE MEASUREMENTS¢¢ Take the black TIE POINT EXTENDER¢ LEAD that you made previously and slip¢ it over TP15. TP15 is the ground. It¢ is located in front of C68 and¢ slightly to the left of it. It is¢ clearly marked on the PCB. to the¢ right of TP15 is TP13. Take the other¢ extension and slip it over TP13. To¢ the left of TP15 is TP14. Slip another¢ extension over this tie point also.¢ You now have 3 wires sticking out of¢ your disk drive, 1 black and 2¢ others.¢ Take your Digital Volt Meter¢ (DVM) or VOM and attach the ground¢ probe to the black extension and¢ attach the positive probe to the¢ extension of TP13. Set the range¢ switch to 10 volts D.C. Turn on the¢ drive. It should read 4.9 - 5.1 v.¢ D.C. Now attach the positive probe to¢ the extension of TP14. It should read¢ 12.01 - 12.03 v. D.C. These are not¢ the most important voltages that you¢ will measure. The most important¢ voltage is the A.C. ripple voltage¢ that is riding on top of the D.C.¢ voltage.¢ To measure the A.C. ripple¢ voltage get about a .1uf 100v or¢ higher mylar capacitor and with clip¢ leads attach the capacitor to the¢ extension of TP13 and the other end of¢ the capacitor to your positive probe.¢ Set your meter to its lowest A.C.¢ range. The capacitor will block the¢ D.C. and will let only the A.C.¢ voltage pass. You should get a reading¢ of .001v. A.C. or less. That is what I¢ got. Do the same thing with TP14. That¢ is 1 millivolt of A.C. RMS ripple¢ which is excellent. I think it is even¢ less than what I measured because my¢ probe leads are not shielded. This¢ voltage may be partly stray A.C. being¢ picked up by the probe leads.¢ If you use an analog meter you do¢ the same thing. On the A.C. ripple¢ measurement the needle should not move¢ or barely move at all.¢ The A.C. ripple is the quality¢ measurement of your power supply. It¢ should NOT have more than .002 v. A.C.¢ RMS ripple riding on top of your D.C.¢ voltage. The command signal to STOP¢ READ on the Floppy Disk Controller¢ Chip WD2793 on pin 27 is only -30¢ millivolts. If your power supply had¢ an A.C. ripple voltage of only 11¢ millivolts RMS which translates into¢ 30 millivolts Peak-to-Peak ripple A.C.¢ it would be the same amplitude as the¢ command signal and could easily¢ confuse the chip. There are even¢ smaller voltages in your disk drive.¢ You can see why the power supply has¢ to deliver clean D.C. voltages to your¢ IC's.¢¢ IX LUBRICATING THE MECHANISM¢¢ 9a) Use LUBE GEL (see supplies)¢ and with a swab stick (see supplies)¢ that is broken in the middle. Apply a¢ small amount on the rails of the read-¢ write head. Smooth it out with the¢ cotton swab. DO NOT use Q Tips or oil¢ in your drive. Q Tips are glued to the¢ stick and when dunked into alcohol the¢ glue then will spread over every¢ surface you touch.¢¢ 9b) Put Lube Gel on all the¢ moving surfaces that eject the disk¢ and are rubbing such as the tang that¢ lowers the spindle to the disk etc.¢¢ 9c) Take the cotton swab and with¢ 91% Isopropyl Alcohol clean the read-¢ write head.¢¢ 9d) Rotate the pressure pad about¢ 30 degrees with a screw driver to¢ expose a new felt surface. The¢ pressure pad is right over the read-¢ write head and holds the disk to the¢ head. 1/16 in. of felt should be¢ showing below the plastic. If it is¢ worn down to the plastic replace it.¢ You can get a new one from BEST & CO.¢¢ 9e) Clean the two I/O connectors¢ in the back and the power supply jack¢ with Cremolin or alcohol.¢¢ 9f) To install the cover move it¢ from the front to the back and install¢ the 6 phillips head screws and tighten¢ them.¢¢ Your disk drive is now¢ reassembled. Try it out and see if it¢ works O.K.¢¢ X COSMETICS¢¢ On the back of your disk drive on¢ top of the I/O connectors there is¢ raised lettering. Mask the top and¢ bottom with Scotch Tape and take a¢ permanent type black felt tip marker¢ and gently swipe over the lettering.¢ Remove the Sotch Tape and the¢ lettering will now stand out in¢ black.¢ Mask the lettering on the front¢ black bezel with Scotch Tape "OFF¢ POWER ON". Also put tape in front and¢ the back of the word "POWER". Take¢ some White Out and put a little on a¢ piece of plastic and with a smooth¢ sponge pick up the wet White Out.¢ Gently swipe it across the lettering.¢ If you mess up you can remove it with¢ alcohol. You now have the raised¢ lettering in white on the front of¢ your disk drive.¢ Your disk drive is now in tip top¢ shape. It is probably better than when¢ it was new. It will work quietly and¢ reliably for you for a very long time.¢ In addition you have improved its¢ appearance.¢¢ TOOLS REQUIRED¢¢ * A 30-40 watt pencil type soldering¢ iron with a chisel tip.¢¢ * A desoldering tool like SOLDAPULT¢ from Radio Shack #64-2120 $5.95. Use¢ Lube Gel to re-lubricate it and¢ establish vacuum.¢¢ * A long nose plier and a wire¢ stripper and cutter¢¢ * A phillips screw driver¢¢ * A Static Drain Wrist Strap. Radio¢ Shack #276-2397 $3.79¢¢ SUPPLIES NEEDED¢¢ * LUBE GEL from Radio Shack #64-2326¢ $2.79 (Do not use oil)¢¢ * 91% Isopropyl Alcohol from your drug¢ store $1.00¢¢ * Heat Sink Grease from Radio Shack¢ #276-1372 $1.49¢¢ * Long stem cotton swabs from Radio¢ Shack (Do not use Q Tips)¢¢ * Thin hook up wire.¢¢ REPLACEMENT PARTS¢¢ * For each disk drive you need 3¢ filter capacitors. They are not¢ available from Radio Shack. Order them¢ from¢¢ DIGI-KEY CORP.¢ 701 Brooks Ave South¢ Thief River Falls, MN 56701-0677¢ Tel: 1-800-344-4539¢ Fax: 218-681-3380¢ They are 6800 uf 35 volt capacitors.¢ Digi-key #P6465ND each costs $4.04¢¢ * You will also need two 3 Amp. diodes¢ for each drive. They are 1N5400¢ Silicon Rectifier Diodes. Digi-key¢ #1N5400GI. They cost $.38 each.¢¢ If you order $25.00 or more of¢ merchandise then you do not pay the¢ $5.00 shipping charge.¢¢ The diodes are also available from¢ Radio Shack #276-1141. They are 2 for¢ $.99¢¢ If you have done the upgrade you¢ now can pat yourself on the back for a¢ job well done. Your disk drive is now¢ as good as you can make it. It will¢ last a long time and you will now have¢ the peace of mind knowing that you¢ have done all that is possible to do.¢ ** end **¢¢
