585/Repairs: Difference between revisions

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:<gallery>
:<gallery>
Electrolytic repair 1.jpg | Remove defective cap
Electrolytic repair 1.jpg | Remove defective cap
Electrolytic repair 2.jpg | Cut can near base, remove guts
Electrolytic repair 2.jpg | Cut can near base (using a small hacksaw or a pipe cutter), remove guts
Electrolytic repair 3.jpg | Fit modern cap
Electrolytic repair 3.jpg | Fit modern cap
Electrolytic repair 4.jpg | Epoxy cap onto base
Electrolytic repair 4.jpg | Epoxy cap onto base
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:--[[User:Peter|Peter]] ([[User talk:Peter|talk]]) 02:45, 4 May 2019 (PDT)
:--[[User:Peter|Peter]] ([[User talk:Peter|talk]]) 02:45, 4 May 2019 (PDT)


==wavy trace ==
==Wavy trace ==
:'''Symptom:''' wavy trace
:'''Symptom:''' Wavy trace
:'''Root cause:''' C786 (100µF 25V) has high internal resistor (ESR ~ 20 ohms). -12.6 v regulator ciruit is oscillating
:'''Root cause:''' C786 (100 µF 25 V) has high internal resistance (ESR ~ 20 Ω) causing +12.6 V regulator circuit to oscillate
:'''Solution:''' Replacing of  electrolytic capacitor C786 with new part.
:'''Solution:''' Replace C786 with new part.


:<gallery>
:<gallery>
585 wavy trace.JPG | wavy trace
585 wavy trace.JPG | wavy trace
585_wavy_trace_new_electrolytics.JPG |  -12.6 v PSU with  new eletrolytics.
585_wavy_trace_new_electrolytics.JPG |  +12.6 v PSU with  new eletrolytics.
</gallery>
</gallery>
:--[[User:Matt|Matt]] ([[User talk:Matt|Matt]]) 08:53, 5 May 2019 (PDT)
:--[[User:Matt|Matt]] ([[User talk:Matt|Matt]]) 08:53, 5 May 2019 (PDT)

Latest revision as of 03:43, 29 March 2020

Supplies out of regulation

Symptom: Several supplies out of regulation
Root cause: dry HV electrolytics
Solution: Rebuild caps using modern replacements
  • Remove defective cap

  • Cut can near base (using a small hacksaw or a pipe cutter), remove guts

  • Fit modern cap

  • Epoxy cap onto base

  • --Peter (talk) 02:45, 4 May 2019 (PDT)

    HV low and trace invisible

    Symptom: No trace, HV low despite maximum setting
    Root cause: HV PIO "Bumble Bee" capacitors leaky (~180 μA at 2 kV); no trace because CRT grid too negative wrt. cathode
    Solution: Replace caps with modern ceramic equivalents
  • old PIO caps in place

  • old PIO caps removed

  • new ceramic caps

  • --Peter (talk) 02:45, 4 May 2019 (PDT)

    No trace

    Symptom: Trace invisible
    Root cause: Wiper of focus pot not in contact
    Solution: Disassemble focus pot, clean and re-seat wiper
    --Peter (talk) 02:45, 4 May 2019 (PDT)

    Trace disappearing

    Symptom: Trace fading after ~10 minutes operation
    Root cause: HV resonant cap (C808) leaky, overheating (visible bulge)
    Solution: Replace cap with modern ceramic equivalent
  • Thermal image

  • bulging cap

  • --Peter (talk) 02:45, 4 May 2019 (PDT)

    Time base inoperative

    Symptom: No trace
    Root cause: Lead of neon bulb in Miller integrator (B171?) broken
    Solution: Solder replacement lead after grinding away some glass (or replace neon)
  • broken lead

  • repaired leads (before cleaning and epoxy encapsulation)

  • --Peter (talk) 02:45, 4 May 2019 (PDT)

    Wavy trace

    Symptom: Wavy trace
    Root cause: C786 (100 µF 25 V) has high internal resistance (ESR ~ 20 Ω) causing +12.6 V regulator circuit to oscillate
    Solution: Replace C786 with new part.
  • wavy trace

  • +12.6 v PSU with new eletrolytics.

  • --Matt (Matt) 08:53, 5 May 2019 (PDT)