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Power  Supply  (Transformer)  Repair  and  Troubleshooting    


Description  #   Text  Box   Comments  
1   Begin:  Transformer   Begin  diagnostic  process  for  a  work  order  on  Transformer.  Testing  and  maintenance  is  advised  when  a  device  using  a  transformer  fails  to  turn  on.  
2   Ensure  that  the  transformer  is  appropriate  for  the  desired  input  and  output  voltages  by  inspecting  its  specifications.  

Transformers  typically  print  the  required  input  and  desired  output  voltages  on  its  surface.  It  is  necessary  to  adhere  to  these  requirements  for  safety  and  appropriate  transformer  performance.  
3   Is  this  a  wall  transformer?   A  wall  transformer  converts  AC  input  voltage  to  a  DC  output.  It  is  also  known  as  an  “AC/DC  adapter.”  
4   Using  a  voltmeter,  ensure  the  wall  outlet  is  outputting  the  proper  voltage.  Plug  in  the  wall  transformer.  

As  a  precaution,  it  is  always  good  to  ensure  that  the  input  to  the  transformer  is  of  the  correct  voltage  before  plugging  it  in.  

5   Using  a  voltmeter,  check  the  output  voltage  and  current  of  the  transformer.  
After  plugging  in  the  transformer,  place  one  probe  from  the  voltmeter  on  the  interior  DC  output  connector,  and  one  on  the  exterior  of  the  connector.  

6   Are  voltage  and  current  measurements  appropriate?   After  checking,  ensure  that  these  measurements  match  the  wall  transformer’s  specifications.  
7   Replace  wall  transformer.  Go  back  to  beginning.   If  accurate  voltage  and  current  outputs  are  not  obtained,  replace  the  wall  transformer.  
8   Wall  transformer  is  working  properly.  See  power  supply  flowchart  for  further  instructions.  

Move  on  to  the  next  step  of  the  power  supply  flowchart  if  device  still  does  not  turn  on.  Always  check  with  clinician  before  putting  a  piece  of  equipment  back  into  use.  
9   Ensure  that  the  input  voltage  is  being  inserted  into  the  proper  side  of  the  transformer.  

It  is  absolutely  necessary  for  the  input  voltage  to  enter  the  correct  side  of  the  transformer  for  safety  and  appropriate  transformer  performance.  
10   Does  the  transformer  output  the  proper  voltage?   Using  a  voltmeter,  check  the  output  voltage.  Ensure  that  these  measurements  match  the  transformer’s  specifications.  
11   Transformer  is  working  properly.  See  power  supply  flowchart  for  further  instructions.  

Move  on  to  the  next  step  of  the  power  supply  flowchart  if  device  still  does  not  turn  on.  Always  check  with  clinician  before  putting  transformer  back  into  clinical  use.  

12   Is  the  output  voltage  zero?   If  the  voltage  is  zero,  absolutely  no  potential  is  being  emitted  from  the  transformer.  This  is  indication  of  further  damage.  
13   Troubleshoot  transformer  fuse.   Use  a  voltmeter  to  assess  whether  or  not  the  fuse  shorts.  A  shortage  indicates  a  functioning  fuse.  
14   Does  the  transformer  fuse  short?   If  the  fuse  shorts,  it  is  still  functioning  and  the  transformer  is  not  functioning.    
15   Replace  Transformer.  Go  back  to  the  beginning.   If  the  voltage  is  zero  and  the  fuse  is  working  properly,  the  transformer  is  should  not  be  repaired.  
16   Replace  the  fuse.  See  fuse  troubleshooting  flow  chart  for  appropriate  actions.   Refer  to  the  fuse  troubleshooting  guide  to  appropriately  replace  the  transformer  fuse.  
17   Go  back  to  beginning.   Troubleshoot  entire  transformer  when  fuse  has  been  replaced.  
18   Use  BTA  skills  to  assess  proper  resistances  of  coils,  between  coils,  and  between  the  coils  and  the  frames.  

If  the  voltage  is  not  zero,  but  also  not  the  appropriate  voltage,  use  the  BTA  skills  to  assess  the  resistances  within  the  transformer  to  determine  which  parts  may  need  to  be  recoiled.  Complete  this  step  only  if  recoiling  is  possible.  Otherwise,  the  transformer  will  need  replacing.  
19   Rewind  transformer  if  possible  and  necessary.  Otherwise  replace  transformer.  

If  resistances  indicate  that  the  transformer  needs  recoiling,  rewind  if  coils  are  exposed.  Otherwise,  the  transformer  will  need  replacing.  

Copyright 2016, Engineering World Health