Generic switchin power supply

Ye Olde Pioneer Magnetics PM3329BP-5 power supply

Had one of these units go bad recently. These are the OEM power supplies for the BE FM C series solid state transmitters.

Broadcast Electronics FM 5C

This series of transmitters has been extremely reliable over the years. Rarely have I encountered an issue, other than a cabinet fan going bad, that has caused an off air incident.

Pioneer Magnetics PM3329BP-5 power supply

They seem to be a fairly standard medium voltage high current power supply. I think these run at 48 volts and can put out a maximum of 42 amps.

In a clever BE design feature; all of the supplies are paralleled onto one DC buss which feeds all of the RF modules. The current from all the supplies is balanced with a single wire current sharing circuit. This means that the loss of any one supply does not cause a complete shut down of an RF module, which in turn would cause an imbalance in the RF output combiner causing a lot of wasted power being dissipated in various reject loads. Rather, if a power supply is lost, the overall DC current to each RF module is reduced. The transmitter power may go down, depending on the TPO setting, but it does not dump a bunch of heat into the room.

Pioneer Magnetics PM3329BP-5

This power supply has been repaired and returned to the client at a significant reduction in cost and time. It takes some degree of knowledge and fortitude to dig into the guts of a high current switching power supply. After all, anybody (or almost anybody) can be a module swap guy, although some people can’t even to that right. Many broadcast engineers these days are running around in circles trying to get everything done that their employer demands of them. Not the best environment for learning and growing.

2 thoughts on “Ye Olde Pioneer Magnetics PM3329BP-5 power supply”

  1. I am interested in finding someone to repair these. I had 3 of them fail last week. The cost to swap with BE is too big for our budget. Please contact me if you know anyone who can repair these.

  2. An old CE once told me that, “if it worked before, it can work again.” Never forgot that.
    Hey, they’re having secretaries doing module swaps these days. Scary!

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