Microsoft Word - PPM

Waterbath  Repair  and  Troubleshooting    


 




Description  
#   Text  Box   Explanation  
1   Begin  Water  Bath  Testing   Start   the  diagnostic  process   for  a  work  order  on  a  Water  bath  
2   Does  the  machine  power  up?   With  unit  plugged  in,  and  power  switch  turned  on,  the  display  should  light  up  
3   Is  power  reaching  the  control  board?   Use  a  multimeter  at  the  leads  of  the  control  board  to   ensure   that   sufficient   voltage   is   reaching   the  controller.   If   insufficient,   there  may   be   a   problem  with  the  wiring.    
4   Faulty/Defective  control  board.   Replace  control  board  if  available.  
5   Troubleshoot  the  power  supply  (separate  chart)    
6   Replace  fuse  if  necessary   See  BTA  skill  under  Power  Supply  on   Identifying  a  Blown  Fuse  
7   Does  the  machine  heat  up?    


Expose   the   heating   element   by   opening   up   the  machine.   Turn   the   unit   on   and   place   hand   over  coils.   You   should   be   able   to   feel   heat   being  produced   by   coils   if   machine   is   functioning  correctly  
8   Physically   inspect   heating   element   and   its  connections  for  signs  of  cracks,  rust  or  dust  


If   the   coils   do  not   produce  heat,   turn  unit   off   and  visually   inspect   coils   for   signs   of   damage.  Reference  BTA  skill  under  Mechanical  on  Cleaning  Rust,  and  Compressed  Air.  If  cracks  are  present  the  heating  unit  will  need  to  be  replaced.  
9   Is  voltage  reaching  the  heating  element?    


Using   a   voltmeter,   measure   the   voltage   entering  the  heating  unit.  To  inspect  if  the  circuit  is  open  or  closed,   see   BTA   skill   under   Electrical   Simple   for  Building  and  Using  a  Continuity  Tester  
10   Repair  any  open  circuits  or  bad  connections   Bad  connections   can  occur  due   to  buildup  of   rust,  corrosion,   or   broken   components.   See   BTA   skills  under   Electrical   Simple   for   Soldering,   Cleaning   of  Connectors,  Loose  Connectors.  
11   Faulty  thermostat.   If   no   voltage   is   reaching   the   heating   coil,   the  problem  could  also  lie  in  the  machine’s  thermostat.  Refer   to   BTA   skill   under   Electrical   Simple   on  Replacing  Temperature  Sensing  Device  to  repair.    




12   Is  the  resistance  of  the  heating  element  less  than  30  Ohms?  
Heating   elements   work   by   having   low   resistance  between   15-­‐30   ohms.   Attaching   a   multimeter   to  the  heating  element  should  conduct  electricity  and  produce  a  resistance  in  this  range.  If  the  resistance  reads  “open”  the  heating  coil  should  be  replaced.    


13   Replace  heating  element   Refer   to   BTA   skill   under   Electrical   Simple   on  Replacement   of  Heating   Element,   and   ensure   that  new  coil  matches  resistance  and  power  rating.  
14   Does   the   bath   reach   expected   temp   within   0.5  degrees?  


Using   a   thermometer,   test   the   bath   temperature  and  determine  if  it  matches  display/expected  temp  within  0.5  degrees.  Any  difference  greater  than  this  is  not  appropriate.    
15   Ensure   temperature   sensor   is   connected   and  working  


Use   methods   described   in   BTA   skill   under  Electrical   Simple   on   Replacement   of   Temperature  Sensing   Device,   to   determine   if   temp   sensor   is  working  properly.  Replace  if  necessary.  
16   Check  calibration  and  recalibrate  if  possible  


Most   digital   water   baths   have   the   capability   to  reset   their   calibration.   After   ensuring   the   temp  sensor  is  working  properly,  recalibrate  the  system.  Determine   water   bath   temperature   with   external  thermometer   and   make   sure   the   machine   is  calibrated  correctly  to  this  value.  
17   Is  the  temperature  too  low?   The  bath  temperature  is  not  reaching  the  set  temp.  
18   Was  bath  recently  turned  on  or  water  added?   If  the  machine  just  turned  on,  or  room  temp/colder  water  recently  added  to  the  bath,  it  might  not  have  equilibrated  yet.  
19   Allow   for   2   hours   for   bath   temperature   to  equilibrate   Leave   at   least   2   hours   after   start   or   addition   of  water  for  the  bath  temperature  to  rise  to  set  temp  before  continuing  with  flow  chart.  
20   Safety  temperature  is  set  too  low  


Ensure   that   the   safety   temp   (or   maximum  allowable  temperature)  temperature  setting  is  not  lower   than   the   desired,   set   temperature.   The  machine  will  never  exceed  the  safety  temp,  even  if  it  is  lower  than  desired  temperature.  
21/22   Controller  Failure   The   PID   controller   is   not   providing   correct   or  sufficient   feedback   to   the   system.   Troubleshoot  controller  circuit  (include  rust  check).  
23   Does  display  remain  stable?   After   the   equilibration   time   (2   hours)   the   bath  temp   should   remain   stable   (within   0.5   degrees   of  




the  set  temp).  
24   Check  bath  placement  and  room  conditions   Ensure   that   the   bath   is   not   placed   near   a   heat  generator  or  distributer  (i.e.  fan,  window,  radiator,  air   conditioner).  Ensure   that   room   temperature   is  not  fluctuating.  
25   Ensure  that  bath  has  at  least  2”  of  water   The  water  must  completely  cover  the  temperature  sensor,  which   is  generally  about  2”  on   the  base  of  the  bath.    
26   Check  controller  circuitry  for  rust  or  buildup.   Visually   inspect   all   controller   circuitry.   If   rust   or  buildup   has   formed   on   connections,   clean   using  BTA  skill  under  Electrical  Simple   for  Cleaning  Rust  and  Cleaning  of  Connectors.  
27   Check  connection  to  temperature  sensor     Use   methods   described   in   BTA   skill   under  Electrical   Simple   on   Replacement   of   Temperature  Sensing  Device  to  determine  if  temperature  sensor  is  working  properly.  Replace  if  necessary.    
28   Does  the  water  remain  in  bath  without  draining?   Other   than   because   of   evaporation,   water   height  should  remain  relatively  constant  over  time.  Check  to  see   if  water   level   is  changing  drastically,  due  to  cracks  or  leaks  
29   Ensure  that  all  fittings  and  connections  are  tight   Drain   bath.   Using   BTA   skills   under   Plumbing   for  Connections  tighten  all  connections  and  fittings  to  ensure  leak-­‐proof  seal.    
30   Check  for  cracks  in  tank  and  repair  with  epoxy   Look   for   cracks   in   the   bath   tank.   Using   BTA   skill  under  Plumbing  on  Epoxy,  seal  any  cracks.  
31   Ensure  that  circuitry  does  not  have  water  damage   If  leaks  have  occurred,  disassemble  bath  and  check  electrical   circuits   to   ensure   no   damage   has  occurred.  
32   Does  the  rack  shake  as  expected?   If   bath   has   a   shaking   feature,   this   motion   should  occur  without  obstruction    
33   Is  power  reaching  the  motor?   Using  a  multimeter,  check  the  leads  of  the  motor  to  ensure  voltage  is  reaching  the  motor  
34   Repair  any  open  circuits  or  bad  connections   Refer  to  steps  9  &  10  for  BTA  skills.  
35   Check  for  obstructions   Visually   inspect   the   bath   and   rack   connections   to  find  any  objects   that  may  be  hindering   its  motion.  This   could   include   rust/calcium   buildup,   rack  deterioration,  or  solid  particles.    




 
 


36   Ensure   that   weight   on   rack   doesn’t   exceed  maximum   The   rack   itself   can   only   accommodate   a   limited  amount   of  weight.   This   varies  with   bath   size,   but  generally  should  not  exceed    
37   Clean/lubricate  motor   See   BTA   skills   under   Motors   on  Cleaning/Lubrication.  




Water  Bath  
Flowchart  


 




Description  
#   Text  Box   Explanation  
1   Begin  Water  Bath  Testing   Start   the  diagnostic  process   for  a  work  order  on  a  Water  bath  
2   Does  the  machine  power  up?   With  unit  plugged  in,  and  power  switch  turned  on,  the  display  should  light  up  
3   Is  power  reaching  the  control  board?   Use  a  multimeter  at  the  leads  of  the  control  board  to   ensure   that   sufficient   voltage   is   reaching   the  controller.   If   insufficient,   there  may   be   a   problem  with  the  wiring.    
4   Faulty/Defective  control  board.   Replace  control  board  if  available.  
5   Troubleshoot  the  power  supply  (separate  chart)    
6   Replace  fuse  if  necessary   See  BTA  skill  under  Power  Supply  on   Identifying  a  Blown  Fuse  
7   Does  the  machine  heat  up?    


Expose   the   heating   element   by   opening   up   the  machine.   Turn   the   unit   on   and   place   hand   over  coils.   You   should   be   able   to   feel   heat   being  produced   by   coils   if   machine   is   functioning  correctly  
8   Physically   inspect   heating   element   and   its  connections  for  signs  of  cracks,  rust  or  dust  


If   the   coils   do  not   produce  heat,   turn  unit   off   and  visually   inspect   coils   for   signs   of   damage.  Reference  BTA  skill  under  Mechanical  on  Cleaning  Rust,  and  Compressed  Air.  If  cracks  are  present  the  heating  unit  will  need  to  be  replaced.  
9   Is  voltage  reaching  the  heating  element?    


Using   a   voltmeter,   measure   the   voltage   entering  the  heating  unit.  To  inspect  if  the  circuit  is  open  or  closed,   see   BTA   skill   under   Electrical   Simple   for  Building  and  Using  a  Continuity  Tester  
10   Repair  any  open  circuits  or  bad  connections   Bad  connections   can  occur  due   to  buildup  of   rust,  corrosion,   or   broken   components.   See   BTA   skills  under   Electrical   Simple   for   Soldering,   Cleaning   of  Connectors,  Loose  Connectors.  
11   Faulty  thermostat.   If   no   voltage   is   reaching   the   heating   coil,   the  problem  could  also  lie  in  the  machine’s  thermostat.  Refer   to   BTA   skill   under   Electrical   Simple   on  Replacing  Temperature  Sensing  Device  to  repair.    




12   Is  the  resistance  of  the  heating  element  less  than  30  Ohms?  
Heating   elements   work   by   having   low   resistance  between   15-­‐30   ohms.   Attaching   a   multimeter   to  the  heating  element  should  conduct  electricity  and  produce  a  resistance  in  this  range.  If  the  resistance  reads  “open”  the  heating  coil  should  be  replaced.    


13   Replace  heating  element   Refer   to   BTA   skill   under   Electrical   Simple   on  Replacement   of  Heating   Element,   and   ensure   that  new  coil  matches  resistance  and  power  rating.  
14   Does   the   bath   reach   expected   temp   within   0.5  degrees?  


Using   a   thermometer,   test   the   bath   temperature  and  determine  if  it  matches  display/expected  temp  within  0.5  degrees.  Any  difference  greater  than  this  is  not  appropriate.    
15   Ensure   temperature   sensor   is   connected   and  working  


Use   methods   described   in   BTA   skill   under  Electrical   Simple   on   Replacement   of   Temperature  Sensing   Device,   to   determine   if   temp   sensor   is  working  properly.  Replace  if  necessary.  
16   Check  calibration  and  recalibrate  if  possible  


Most   digital   water   baths   have   the   capability   to  reset   their   calibration.   After   ensuring   the   temp  sensor  is  working  properly,  recalibrate  the  system.  Determine   water   bath   temperature   with   external  thermometer   and   make   sure   the   machine   is  calibrated  correctly  to  this  value.  
17   Is  the  temperature  too  low?   The  bath  temperature  is  not  reaching  the  set  temp.  
18   Was  bath  recently  turned  on  or  water  added?   If  the  machine  just  turned  on,  or  room  temp/colder  water  recently  added  to  the  bath,  it  might  not  have  equilibrated  yet.  
19   Allow   for   2   hours   for   bath   temperature   to  equilibrate   Leave   at   least   2   hours   after   start   or   addition   of  water  for  the  bath  temperature  to  rise  to  set  temp  before  continuing  with  flow  chart.  
20   Safety  temperature  is  set  too  low  


Ensure   that   the   safety   temp   (or   maximum  allowable  temperature)  temperature  setting  is  not  lower   than   the   desired,   set   temperature.   The  machine  will  never  exceed  the  safety  temp,  even  if  it  is  lower  than  desired  temperature.  
21/22   Controller  Failure   The   PID   controller   is   not   providing   correct   or  sufficient   feedback   to   the   system.   Troubleshoot  controller  circuit  (include  rust  check).  
23   Does  display  remain  stable?   After   the   equilibration   time   (2   hours)   the   bath  temp   should   remain   stable   (within   0.5   degrees   of  




the  set  temp).  
24   Check  bath  placement  and  room  conditions   Ensure   that   the   bath   is   not   placed   near   a   heat  generator  or  distributer  (i.e.  fan,  window,  radiator,  air   conditioner).  Ensure   that   room   temperature   is  not  fluctuating.  
25   Ensure  that  bath  has  at  least  2”  of  water   The  water  must  completely  cover  the  temperature  sensor,  which   is  generally  about  2”  on   the  base  of  the  bath.    
26   Check  controller  circuitry  for  rust  or  buildup.   Visually   inspect   all   controller   circuitry.   If   rust   or  buildup   has   formed   on   connections,   clean   using  BTA  skill  under  Electrical  Simple   for  Cleaning  Rust  and  Cleaning  of  Connectors.  
27   Check  connection  to  temperature  sensor     Use   methods   described   in   BTA   skill   under  Electrical   Simple   on   Replacement   of   Temperature  Sensing  Device  to  determine  if  temperature  sensor  is  working  properly.  Replace  if  necessary.    
28   Does  the  water  remain  in  bath  without  draining?   Other   than   because   of   evaporation,   water   height  should  remain  relatively  constant  over  time.  Check  to  see   if  water   level   is  changing  drastically,  due  to  cracks  or  leaks  
29   Ensure  that  all  fittings  and  connections  are  tight   Drain   bath.   Using   BTA   skills   under   Plumbing   for  Connections  tighten  all  connections  and  fittings  to  ensure  leak-­‐proof  seal.    
30   Check  for  cracks  in  tank  and  repair  with  epoxy   Look   for   cracks   in   the   bath   tank.   Using   BTA   skill  under  Plumbing  on  Epoxy,  seal  any  cracks.  
31   Ensure  that  circuitry  does  not  have  water  damage   If  leaks  have  occurred,  disassemble  bath  and  check  electrical   circuits   to   ensure   no   damage   has  occurred.  
32   Does  the  rack  shake  as  expected?   If   bath   has   a   shaking   feature,   this   motion   should  occur  without  obstruction    
33   Is  power  reaching  the  motor?   Using  a  multimeter,  check  the  leads  of  the  motor  to  ensure  voltage  is  reaching  the  motor  
34   Repair  any  open  circuits  or  bad  connections   Refer  to  steps  9  &  10  for  BTA  skills.  
35   Check  for  obstructions   Visually   inspect   the   bath   and   rack   connections   to  find  any  objects   that  may  be  hindering   its  motion.  This   could   include   rust/calcium   buildup,   rack  deterioration,  or  solid  particles.    




 
 


36   Ensure   that   weight   on   rack   doesn’t   exceed  maximum   The   rack   itself   can   only   accommodate   a   limited  amount   of  weight.   This   varies  with   bath   size,   but  generally  should  not  exceed    
37   Clean/lubricate  motor   See   BTA   skills   under   Motors   on  Cleaning/Lubrication.  




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