EEVblog Electronics Community Forum
Electronics => Beginners => Topic started by: iampoor on November 04, 2015, 07:57:30 pm
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Hi
Recently I got some Macom PS1517 Power supplies. These were used for Video Gear. Of course, I cannot find ANY info on the rated output current or even what a few of the rails on the transformer are rated at (I know it has +-24v rails, but a few are unlabeled).
I was thinking of reverse engineering the Power supply Boards (each rail has a seperate board, they are just paralleled 2n3055's as series pass transistors) to figure out an approximate current output. Are there any other ways of getting a ballpark figure? It has a 4 amp circuit breaker on the input. I was also thinking about maybe running it no load and then seeing where the voltage drops at a particular current, but thats probablly not a very useful metric without any other detail.
TLDR: Figuring out the voltages is easy, but how can I figure out the approximate output current of each winding? :-+
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The wire size will give you a little clue so will the core cross sectional aria.
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You only need to reverse engineer the power circuit, not the control system. You could check voltage drop across each 2N3055 and work out the dissipation, + measure the heatsink temperature increase Also, do not exceed 10% drop from unloaded at the transformer's secondary.
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:-+ :-+
What He Said.
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Got some info, it is a 280va transformer....its a good start. :-+
You only need to reverse engineer the power circuit, not the control system. You could check voltage drop across each 2N3055 and work out the dissipation, + measure the heatsink temperature increase Also, do not exceed 10% drop from unloaded at the transformer's secondary.
I will be back with a schematic shortly. Great idea :-+The wire size will give you a little clue so will the core cross sectional aria.
If only it didnt have 6 windings.. :(
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If you have a decent selection of power resistors you can try loading down each secondary (one at a time) until the voltage drops by 3-5%; that will usually give you the full load current rating for that secondary.
A helpful site to reference on sizing unknown transformers in general: http://www.smoke.com.au/~ic/ham/transformers/used_transformers.html (http://www.smoke.com.au/~ic/ham/transformers/used_transformers.html)