ICOM PS-125 Switching Power Supply No Output!!

[N8QBY]

Well, I was using this PS-125 power supply the night before last, and it was working properly. I went to use it tonight, and there was no DC output. The proper ac voltage is going into the plug-in at the back, (good cord). The L.E.D. on the front of the supply won't even light. The only thing that I have checked was the 25 amp fuse inside the supply. I figured I would check other peoples opinions before I delve into this. The only thing I can think of as far as what might have caused it, is that the power went out temporarily during a snow storm, and it might have gotten a voltage spike. And when I tried to use it tonight, nothing. I have not had this supply very long, and was wondering if anyone else has had any, "loss of output", issues with the PS-125. Any idea's/comments are welcome. Thankyou in advance. Pat N8QBY

[wa8mea]

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[N8QBY]

Bill, I checked the fuse with my meter, and it checked good. The fuse is white, so you can't just visually check it. Also, the power cord is just a plain 3-conductor cord for 117vac, with no fuses.
It will give me something to do, but I just thought I would ask for others input to see if they have come across the same problem.

Thanks for your input.


Pat N8QBY

[wa8mea]

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[N8QBY]

Bill, the ICOM PS-125 has a pig-tale coming out the back of the power supply with the matching plug for many Icom radio's. It is about 14" long, and plugs into the back of the radio. There aren't any fuses in the cord. The actual power-cord for the radio is not used. Anyway, the next time I get bored, I am going to look for the obvious, then check the not so obvious. I am going to have to download the schematic for the supply, and go from there. There haven't been many responses, so it must not be a common problem.
Thanks for your comments.

Pat N8QBY

[ee4u]

Have you been able to resolved this yet?

In searching around on this I have learned that one cause for this can be components/circuitry associated with the start-up control of the main control module HC1 (a module with a part number of MB1023A).

Unfortunately, if this part has failed, the cost of just this one special module can be quite expensive! Very little can be found on this module! This is not your standard IC replacement component.

I will let you know if I uncover anything on this later.

73

Doug

[N8QBY]

Doug, thanks for the info. I haven't had time to check out the PS-125 yet. I did download the manual/schematic, so when time permits, I am going to check things out. I guess by having another supply, I haven't had to rush into the repair yet.

Thanks, Pat N8QBY

[va3jwp]

Hi Pat, just a thought for you. Mike has a brand new PS-125 in his shack, he got it as a free-bee with the 746 PRO he bought a while back. I'm thinking maybe you can arrange a visit with him, and use his supply as a test?. Good luck to you in finding out the problem.

73.
James (VA3JWP)

[W7TE]

Pat,
I wish you luck, I have had 2 of these, both died under like conditions 2 weeks apart with identical problem that you have. Sent one off to Burqhardt and they said not economical to repair. I liked the units but I understand why it is free with radio. I live way out in the country and get power spikes without fail. Won't last worth beans. Too bad ICOM won't stand behind them. LOL

73
Alan (W7TE)

[N8QBY]

W7ET- Alan, thanks for your story. I was wondering if Burqhardt's mentioned what the actual problem was, as far as what part was bad?? Anyway, it will give me something to putz around with, if I could ever get it on my, "to do" list.

73 Pat N8QBY

[ee4u]

Doug, thanks for the info. I haven't had time to check out the PS-125 yet. I did download the manual/schematic, so when time permits, I am going to check things out. I guess by having another supply, I haven't had to rush into the repair yet.

Thanks, Pat N8QBY

Pat,
I recently repaired one of these supplies. It had no output, but the input fuse and associated components all appeared to be good. Did a bunch of VOM readings with the unit cold, and found two bad components in the secondary side VCC circuitry - IC11 (dual op-amp LM2904) and Q13 transistor. Ordered these parts & replaced thinking all would be well again. But only would get output for about 1/2 second and supply would shutdown again! Finally traced problem to a flaky zener diode D26 (15v). This zener would start to go into avalanch at about 13.2V instead of its15v spec. Replaced this an all was well again with this PS .
Let me know if I can help you out with your PS after you have checked it over.
73
Doug

[N8QBY]

Doug, thanks for the info. I will post again when I find out the problem.
73 Pat N8QBY