powering up old unused electrinics equipment

[paulmars]

I remember in electronics school in the 1980s we learned that the
best way to damage a very old piece of electronic equipment was to
power it on with full voltage. After a long time with no power caps
go to zero ufd, which will pass the full voltage and burn out other
components. Something like that. Im looking on the internet for
info about this, but I cant find any. Do you know of any?

tks,
pa

 

[Smart $]

https://www.google.com/webhp?source...spv=2&ie=UTF-8#q=unused capacitor degradation

 

[paulmars]

applying low voltage and slowly increase it over time to bring them back into spec?

 

[Jraef]

Do a search on the term "capacitor reforming procedure". The term "reforming" refers to forming the oxide layer on the capacitor film again, because over time with no power supplied it decomposes back into its base elements in solution with the electrolyte. So you have to re-power it by slowly increasing the voltage while the oxide layer re-forms on the film surfaces. Does not apply to dry film capacitors by the way.

 

[Curious nerd]

Ask your local ham radio community about "boatanchor" specialists

Ask your local ham radio community about "boatanchor" specialists

Cleaning will be the first issue. Get rid of any deposits that might be conductive.

The presentation I went to, if I remember right, talked about running at a few volts for hours or days, and pre-emptively changing out capacitors.

 

[junkhound]

applying low voltage and slowly increase it over time to bring them back into spec?

Dont we wish! You want to bring the voltage up slow primarily to avoid collateral catastrophic damage.

By 'very old', assume you mean vacuum tube equipment? If so, there are many effects on power up. Also, if a cap blows at full voltage, there is likely to be collateral damage. Many old tube sets have badly carbonized linen wire (due to tube heat), that often touches and can be a short on start up - another cause of collateral damage.

An internet search would need to hit a few key words, listed some below for you to search, extensive topic.

a. Inrush - can blow caps that have corroded internal connections, can blow tube filaments due to overvoltage if any overshoot due to inrush, and can blow old SiC NTC inrush limiters. Any of the terms in the above sentence can be used for search.

b. Overshoot

c. Transformer inrush

d. Capacitor charging (e.g. I=C*dv/dt; aka depends on where in the 60 Hz waveform the switch is closed)

e. Fuse crystallization

f. Arrhenius equations

g. Mil-hdbk-217

h. dielectric formation; burn-in.

I. Insulation degradation, see also f.

etc.....

 

[paulmars]

not that old. Its an AKAI CS-F33R that has not been used in over am decade.

 

[junkhound]

AKAI CS-F33R that has not been used in over am decade.

Eh, new stuff, low voltage.
No problem powering up at full voltage with that age equipment, as there are likely no electrolytics over 50V. Main problem with caps in that vintage would be a cap seal leak if stored in really cold or hot areas (<-40C or >55C).

Your biggest problem with the recorder in general would be the capstan rollers having a hard polymerized surface or having taken a set if stored with the play button engaged, electronics should be zero concern if it worked when stored.

 

[mxslick]

Beware of cold temperatures and high humidity in storage....

Beware of cold temperatures and high humidity in storage....

I have had a lot of my electronics that have been stored over the winter in an unheated outbuilding fail upon power-up. I moved to my new place in December and had a lot of my stuff stored in that building. Temperatures often went well below 0deg f (several days of -20 or more too) and it has damaged a lot of my electronics.

Some was older gear (15-20 years old) and others were relatively new.

All have obvious electrolytic cap failure symptoms.