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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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:'''Symptom:''' No trace, HV low despite maximum setting | :'''Symptom:''' No trace, HV low despite maximum setting | ||
:'''Root cause:''' HV [[Bumble Bee capacitors|PIO "Bumble Bee" capacitors]] leaky (~180 μA at 2 kV); no trace because CRT grid too negative wrt. cathode | :'''Root cause:''' HV [[Bumble Bee capacitors|PIO "Bumble Bee" capacitors]] leaky (~180 μA at 2 kV); no trace because CRT grid too negative wrt. cathode | ||
:'''Solution:''' Replace caps | :'''Solution:''' Replace caps with modern ceramic equivalents | ||
:<gallery> | :<gallery> | ||
585 HV caps old.jpg | old PIO caps in place | 585 HV caps old.jpg | old PIO caps in place | ||
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:'''Symptom:''' Trace fading after ~10 minutes operation | :'''Symptom:''' Trace fading after ~10 minutes operation | ||
:'''Root cause:''' HV resonant cap (C808) leaky, overheating (visible bulge) | :'''Root cause:''' HV resonant cap (C808) leaky, overheating (visible bulge) | ||
:'''Solution:''' Replace cap | :'''Solution:''' Replace cap with modern ceramic equivalent | ||
:<gallery> | :<gallery> | ||
585-c808-therm.jpg | Thermal image | 585-c808-therm.jpg | Thermal image | ||
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:<gallery> | :<gallery> | ||
585-neon-1.jpg | broken lead | 585-neon-1.jpg | broken lead | ||
585-neon-2.jpg | repaired leads (before encapsulation | 585-neon-2.jpg | repaired leads (before cleaning and epoxy encapsulation) | ||
</gallery> | </gallery> | ||
:--[[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 == | |||
:'''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. | |||
:<gallery> | |||
585 wavy trace.JPG | wavy trace | |||
585_wavy_trace_new_electrolytics.JPG | +12.6 v PSU with new eletrolytics. | |||
</gallery> | |||
:--[[User:Matt|Matt]] ([[User talk:Matt|Matt]]) 08:53, 5 May 2019 (PDT) | |||
[[Category:Instrument repair reports]] | [[Category:Instrument repair reports]] | ||