**<>**›     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 **››