I am sure this is a repeat, Sorry..

THEDJ

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Can some one give me the basics on repairing a QBERT power sply.

My 30v side led is dead. other one are on..

I have not repaired one of these todate..


Thanks in advance.

chris
 
The 30v power supply only has a few components total. It rectifies and filters the 35v input, then uses a zener-diode regulator bringing it to 30v. Unplug connector P3 then trace your way through the circuit:

  • Measure voltage at output pin on P3 (pin 6 to ground). Confirm if the supply is generating 30v or not.
  • Check F21. If it's blown, replace it with 1.5A SB.
  • Measure voltage across R21. If the voltage isn't around 48v, check BR.
  • Measure voltage across D26. If it's not 30v, replace replace D26 and maybe R23. Look for PCB damage (burn marks) around D26/R23.
  • Measure voltage again at output pin on P3. If the voltage isn't around 30v, replace Q21. Can't remember if this transistor has a mica insulator.
 
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