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Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 312
Registered: 10-2002
| | Posted on Thursday, March 06, 2014 - 3:16 pm: | 
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I have a 150 amp power supply that is not doing as much as it once had. Under a load it will make a funny sound. It has 15 of the m- k70 -9151 transistor's. I was wondering how to test these to see how many are bad. The power supply still has an output of 12 to 16 volts DC but the amp output is barely 35 amp's. It has never blown any fuse. No odor or smell of anything hot. All connection's and wires are good. Now this power supply does not have a name. I had bought it off a guy out west that had made these power supply's. 150 amp constant 170 surge. It is about 10 year's old. |
Tech833
Moderator
Username: Tech833
Post Number: 2288
Registered: 8-2002
| | Posted on Saturday, March 08, 2014 - 5:32 pm: |
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My guess is that the filter capacitors have become leaky. If one or more of the regulators goes bad, they usually fail by shorting out, which would likely take out the fuse.
On the other hand, electrolytic capacitors usually fail "gracefully" by becoming leaky. That means, they will show a lower resistance than a new capacitor. As they become more and more leaky (lower and lower resistance), they will put a load on the power supply, rendering it incapable of putting full amperage to your load.
Capacitors can be checked using a multimeter with a capacitance setting, or by using an ohm meter.
Your radio 'Mythbuster' since 1998
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Charliebrown
Intermediate Member
Username: Charliebrown
Post Number: 313
Registered: 10-2002
| | Posted on Sunday, March 09, 2014 - 8:34 am: |
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Tech 833, just before I had read your answer I had done the test on the capacitor's and there is two out of three capacitor's that are showing a different reading. However, I did not know the information you had just given me about the capacitor's. It would look like I will replace some very large capacitor's to fix the problem. THANK YOU SO MUCH 833 AND MAY GOD BLESS YOU AND THE FAMILY |
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