Macron (HiPo) MPT-4012/5002 pooter PSU

Just been asked to look into a batch of these units which all expired the same day, during power fluctuations and brownouts.

Initial observations are fuse blown, caps all look OK and no signs of distressed components. Bridging the fuse lights the series lamp fully i.e. short present on input side. Main suspects are the pair of 2SK2765 FETs.

The trouble with this design - aprtf rom the obvious lack of a schematic - is the lack of space to access any components. There's arguably a 2mm gap between heatsinks and the main tfmr, with components mounted under an overhang on the 'sinks. To remove for example one of the FETS would require removing an entire heatsink assembly with three semis attached.

Before I embark on this probably uneconomic task, I thought I'd ask on the extremely remote chance that someone may have a schematic for any of this family of MACRON psu's, as deep googling has turned up zip.

Interestingly, on the HiPo website the -4012 is listed as 115/230V while the PSU label states only 230V. There is no sign of even the potential for a voltage selector switch on the pcb trackwork, so I'm forced to wonder if it is one of those auto-sensing dual voltage types which traditionally get confused and die during 240V system brownouts.

Reply to
who where
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"who where"

** Due to a raging electrical storm by any chance ??
** Poor diddums......

** Sounds like bad news.

..... Phil

Reply to
Phil Allison

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Have seen worse than that in some gear. Most switchmode power supplies everything is jammed into a small space like you describe.

You have no choice but to just desolder all devices and pull the whole heatsink assembly out. If the things use clips to attatch to the heatsink, you may be able to get them out and use tweezers to remove the device

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I had a problem with a series of Panasonic units like that in the

1990s. I simply removed the Triac that was used (when turned on by the control logic) to change the main filter capacitor pair bank from series (240v) to voltage doubler. (120v). Never had another problem after this. (note - Im assuming you will use this on a 240v supply.)

Any arrangement like I have just described is pretty easy to identify, and deal with except for the very inexperienced

Failing that, you will need to look at external brownout protection. Im sure such devices are available for commercial electrical installs. They are needed for things like fridges etc where the compressor motor can burn out at lower voltages.

If its physically possible to mount, and to wire it to your system, it might be a good idea to give these MACRON PSUs the boot and use a regular PC power supply. These normally dont give much trouble, and are cheap.

Reply to
KR

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