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Posted on Aug 03, 2010

I have a Pyramid phase 111 model: PS-25 adjustable power supply. After a lightning strike the voltage is high. 25 volts and will adj. down to 19 volts.Is it reparable? Thanks, Dan.

2 Related Answers

BJ Russell

  • 214 Answers
  • Posted on Nov 14, 2008

SOURCE: pyramid ps-15kx

Unplug the PS-15KX 120V AC cord !! Then take cover off. DO NOT plug the AC cord in unless you are used to working around a lethal voltage and current !!!!!!!!!!

If you can use a Multimeter, then measure resistance across each pair of the 3 leads of the output transistors. You will probably find fractions of an ohm across a pair of leads. One or both may be shorted. NOTE: Do not ever measure resistance in a powered up circuit, kiss meter bye-bye and maybe burn you too.

By putting more robust transistors in this supply, you may not gain much reliability. The supply is rated at a continuous current draw, which is less than the intermittent current they advertise. Read the spec's of any power supply you get and look for continuous current ability.

There are several better transistors that will substitute for the 2N3055. You will need to look at a transistor substitution book and check specs. The internet is great for this. I used to use all kinds of data books, and still have them! But looking up info on-line is nice. Motorola has some that will fit and have higher current and voltage ratings,

Get someone who is a ham or geek if you aren't sure about sticking your fingers in the power supply.

Be Careful, Work Safe, it is a factor of longer life.

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Tom Carson

  • 3083 Answers
  • Posted on Sep 01, 2010

SOURCE: pyramid ps25 phase 111 power

Here is a site that suggests things to check, and has information about this device.
http://forums.qrz.com/showthread.php?t=170144
Apparantly, the schematics are not easy to get, and maybe not that accurate, so not sure if even they will help much. You might try to ohm out the regulators and pass transistors like the article suggests, I would think that's your best bet.
Good luck, thanks for using FixYa, and hope this helps.

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