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SOLVED : Help with troubleshooting a Hypex SMPS400A400

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rfengg:
Hi All,

May I request anyone who has experience or has access to the schematics of the Hypex SMPS400A400 power supply module, some help and advice?
I have a Rotel RKB-D8100 amp which has 2 of these Hypex SMPS400A400 modules......while one of them puts out the correct voltages, the other is dead.  :horse:
While I can start comparing the working vs the non working one, if anyone has access to the schematics or has experience on these, it would be most helpful.

thanks

fzabkar:
Is this of any use?

HYPEX SMPS400V11 PSU service manual:

https://elektrotanya.com/hypex_smps400v11_psu_sch.rar/download.html

rfengg:
Thanks fzabkar....already found this at the same url.

MathWizard:
Other than how tight it's packed, it probably should be a pretty standard layout SMPS with a chip or two, having most of the circuitry, inside them.

That little 8 pin chip on the top side, next to a small transformer, that should be the primary side controller, that gets some trickle of current from after the rectifier, as it's startup Vcc, then once it gets going, some winding on one of those transformers, will generate the working Vcc of the chip, and circuits around it.

Does it have a Standby voltage on the secondary side ? That little transformer by the 8pin DIP could be for STBY, or it could be some gate drive transformer, but it looks big for that.

That chip could just be for STBY 5V, and there's another chip doing the main switching of the big transformer.

You don't have to plug it in, to check a bunch of stuff like for shorts or diode voltages, from the plug, inwards, to those big transformers. And same with the output side, starting from the transformers.

Then if there's no apparent shorts,etc, I would solder on a few wires here and there, and power it up and check some voltages, like after the rectifier, and Vcc of any IC's.

So does the other one do anything at all ? And noise, or does it try to make some voltages and then restart over and over ? If it's totally dead, something near the plug should be broken, like a fuse, or the rectifier.

rfengg:
Thanks for your reply MathWizard.


--- Quote from: MathWizard on April 17, 2024, 11:16:35 am ---Other than how tight it's packed, it probably should be a pretty standard layout SMPS with a chip or two, having most of the circuitry, inside them.

That little 8 pin chip on the top side, next to a small transformer, that should be the primary side controller, that gets some trickle of current from after the rectifier, as it's startup Vcc, then once it gets going, some winding on one of those transformers, will generate the working Vcc of the chip, and circuits around it.

Could you please let me know which pic you are referring to here? I believe that that the 8 pin DIP is a dual opto.......




You don't have to plug it in, to check a bunch of stuff like for shorts or diode voltages, from the plug, inwards, to those big transformers. And same with the output side, starting from the transformers.

Checked for shorts on the active devices but no luck so far.Will do more tests during the weekend.

Then if there's no apparent shorts,etc, I would solder on a few wires here and there, and power it up and check some voltages, like after the rectifier, and Vcc of any IC's.

So does the other one do anything at all ? And noise, or does it try to make some voltages and then restart over and over ? If it's totally dead, something near the plug should be broken, like a fuse, or the rectifier.

No hiccuping or any audible noises at all. Just plain dead. The primary 5A fuse is good.

--- End quote ---

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