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THE AM BULLETIN BOARD => Technical Forum => Topic started by: WA1LGQ on May 12, 2010, 07:46:57 PM



Title: Heathkit MP-1 Power Supply
Post by: WA1LGQ on May 12, 2010, 07:46:57 PM

      I picked up a Heathkit Cheyenne with MP-1 power supply at Nearfest and tried to fire up the supply. The thing had a 10 amp fuse in it and after a second of humming and drawing about 12 amps or so the fuse blew. It was not connected to the Cheyenne yet as I don't have a cable or connectors to do so. My question is what is the fuse supposed to be? Don't have a manual or schematic. Thanks!.........Larry


Title: Re: Heathkit MP-1 Power Supply
Post by: WQ9E on May 12, 2010, 08:46:43 PM
Larry,

I believe that is basically the same as the UT-1 which was the original supply to match the MT-1/MR-1 mobile pair.  If so it requires only a 3 amp fuse.

I believe I also have the manual for my MP-1 and I will dig it out and make a copy of the schematic for you if no one else has it handy.

If it were mine, I would disconnect the line bypass caps and also the connections to the HV secondary.  Then try the rated 3 amp fuse and see what happens. 


Title: Re: Heathkit MP-1 Power Supply
Post by: WA1LGQ on May 16, 2010, 05:32:22 PM
    Roger, the MP-1 is not an ac powered supply, it runs on 12VDC. I guess I should just go ahead and check and/or replace all components, especially the electrolytics and try it again. Thanks..........Larry



Title: Re: Heathkit MP-1 Power Supply
Post by: KC4VWU on May 16, 2010, 06:03:22 PM
Larry,
          Check for info at mods.dk. No need in flying blind unless you absolutely have to. However, fresh filter caps is definately a good place to start.

73, Phil
       


Title: Re: Heathkit MP-1 Power Supply
Post by: WQ9E on May 16, 2010, 06:08:57 PM
Larry,

Sorry about that.  I think that the MP-1 was replaced fairly quickly by the HP-10 which is the DC supply that came with my MT-1/MR-1 pair.  It might be worth buying a manual before you throw much money and time at that since you may have one or both bad switching transistors or a bad transformer.  I believe the HP-10 DC supply is considerably different than the earlier MP-1 DC supply.

If you aren't going to actually run them mobile, the AC powered UT-1 or later HP-20 would be more practical and both are common and cheap.
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