Manson SSP-8160 PSU repair, help needed.

[CyberChris]

Hello,

after charging a lead acid battery with my Manson SSP 8160 PSU the output of the psu is damaged.  The control part seems to be working, but turning on/off the output has no effect, the output stays at 0V.

A google search found some hints that some Manson PSU designs do not like to be backwards powered. 

Sadly I can't find any schematics for this type of PSU on the internet.
Any useful hints for the schematics (or repair) are welcome.

Regards,
 Chris

[floobydust]

Yes, they do not like a battery there if the power supply is off.

It usually takes out the TL494 or a control op-amp so the main switcher does nothing, and the aux. switcher (MCU, panel meters etc.) run ok.
I do not have your 8160 but the internals are similar I think throughout the SPS family. Check PCB numbers.
Compare to the SPS 9400 service manual.

I consider Manson power supplies "disposable", as they blow up easily, service manuals hard to find, and Manson advises "please contact the company where you buy the product for spare parts and repair service."
You could try email them for the service manual but I got the PFO.

[alm]

In my opinion charging batteries or large caps from a bench supply without a series diode is abusing the power supply. You can kill plenty of power supplies by turning down the output voltage (or turning off the supply) while having a charged battery at the outputs. This can also be due to a power glitch. Bonus points if an overvoltage crowbar protection or down programmer gets triggered.

Saying the supplies do not survive it well is like complaining about Keysight multimeters because they survive getting hit with a hammer less well than other brands.

[floobydust]

The PSU designers have not thought of this operating mode.
Having an output voltage present above your PSU setpoint  or if the PSU is off easily blows up cheap-ola analog power supplies from china.
The fix is to add a diode/resistor. Pure rocket science.

[alm]

Adding a series diode degrades the output impedance and degrades regulation. It also defeats any down programming circuit, slowing down decreasing the output voltage. If you want something designed for battery charging, buy a battery charger. If you want to use a bench supply for that purpose, add a series diode yourself.

It is not just cheap power supplies that can be damaged that way. For example, see attached snippet from the recently introduced Keysight E36300 series manual. Designing a multimeter against hammer blows is not rocket science either, but I would not blame Keysight engineers for not investing time in it.

[floobydust]

The back-feed diode/resistor I speak of are not in the output circuit and do not degrade the PSU. They connect to the CV, CC error-amplifiers to prevent IC damage. Some PSU designs already have them in place. There's no output OVP in this unit that I know of.

I'm not sure why you think a design for no hammer blows is acceptable, given the $0.25 cost hit  

The problem sending this out for repair is shipping and repair costs will be at least 1/2 at the price of a new PSU.

[CyberChris]

Last week I spent some time for disassembling the SSP8160 PSU . The design is totally different to the 9400 series PSUs.

On the PCB I found this parts:

FAN7930C PFC controller driving 2*11N80C switching FETs on the primary side.
UC2843A PWM controller driving a FAN73711 high side driver that drives a FDB150N10 switching FET
TL082, TLE2142C OpAmps

TNY274 for a 9V auxilary power supply.

After probing around with my meter and scope I found out that the PFC circuit doesn't start up. The PWM circuit was working. So I came to the conclusion that charging the lead acid battery was not the main reason for the fault.

There were no pulses on the gates of the two 11N80. When I touched the source pin of one of the 11N80 with the probe of my scope the circuit started up? I could repeat this several times, but now the PSU is working as soon as I switch on the power. Maybe it was/is a faulty cap?

For those that are intrested I have included some photos.

[eurofox]

Hello,

after charging a lead acid battery with my Manson SSP 8160 PSU the output of the psu is damaged.  The control part seems to be working, but turning on/off the output has no effect, the output stays at 0V.

A google search found some hints that some Manson PSU designs do not like to be backwards powered. 

Sadly I can't find any schematics for this type of PSU on the internet.
Any useful hints for the schematics (or repair) are welcome.

Regards,
 Chris

Hi,

I have a schematic of a Manson PSU but not the same model but maybe this will help.

[floobydust]

I hate to lead you on a second goose chase, but those capXon electrolytic capacitors are known junk.
forums at Badcaps.net has good for advice on capacitors and repair too.

I would suspect the PFC controller start-up power, U1 Vcc is pin 8 FAN7930C which needs 12-13V to start. So C10 is suspect but I cannot see around D8 what is powering the PFC controller IC.
My guess is your touching the scope probe might give an extra blip and raise Vcc so it can start up.

You can try run it for a while, cheap electrolytic capacitors seem to act up cold and in their last days, work somewhat when warmed up.
I would test/replace all the electrolytic capacitors in this PSU as capXon is pretty bad.

Best to clean off flux using IPA and cotton q-tip, the high voltage needs a clean PCB.