25 amp Pyramid pwr supply keeps blowing fuses

[949Jake]

Hey all,

My buddy was running his rig off of a battery charger so to get him on the air more I loaned him a 25 Amp Pyramid power supply that was just sitting around. I've had it about 4-5 years and hadn't used it in about the last year. I'm not sure what the model numbers are.

He has been using it for about a month with no problems, until a few days ago. I only talked to him briefly about it on the telephone before I went to work, but I believe that he had a 2950 and a small 40-60 watt amplifier hooked up to it. I think he blew a fuse while operating, but again I'll have to check with him again on the details.

He replaced the fuse, turned the power supply on, and that fuse immediately blew. He says he had nothing hooked to the power supply at that time. He replaced the fuse again and this time it shook a little (did a little dance) and that fuse blew.

I have a feeling he probably did something like hooked the black wire to the red post and doesn't want to tell me ...I have a few other possibilities in mind, but I wonder what others think. I'd just like to find out what is wrong with it for curiosity's sake and to maybe fix it.

I thought it sounded like an interesting problem, but I've been out of ham/cb for a little while now so perhaps I am overlooking something. I have not yet seen the power supply in person and will not be able to until Thursday.

 

[190]

jake, i bought a brand new 46 amp pyramid power supply and it had a simular problem. one day i just turned on all my stuff and poof, the fuse blows in my month old power supply. put in anoth fuse,poof, same thing. hummm. well i took it to the local radio guy and he found that one of the solder joints on a wire was actuallly touching the frame of this thing. cant remember which one. maybe it was the transformer.??? im not sure. was a factory screw up. he resolved this problem and its been working ever since. he might of even had to replace something,i dont remember for its been a couple years. sorry.

 

[Captain Kilowatt]

Could be a shorted filter capacitor or rectifier diode causing that.Lift the leads of the transformer secondary from the rectfier and see what happens. Next attach them to the rectifier and lift the cap and try it again. That will help you get a start on what the problem is.

 

[TonyV225]

What has happen is the bridge rectifier has went CAPOOT. Its the little square piece thats bolted to the bottom rear of the Supply it has 3 wires running to it and usually has 1 terminal left empty.

The one in there is a KBPC3501 I replace all mine with KBPC5010 50 AMP unit the inrush current usually takes the 3501 (35 amper) out after time the 50 amper will handle more of the beating presented by the inrush.

Take note of the wires in how there hooked to the rectifier or lable the wires with masking tape and a marker or atleast lable them so you know exactly how they go back on or you will just make more of a mess for yourself. If you decide you dont want it let me know and I maybe interested in it for myself.

As far as the part radio shack out here didnt have them like they did years ago so when I bought them I bought a few extra so I wouldnt have to search for them. If you have any question dont hesitate to PM me I will help anyway I can. Good luck.