how is digam powersoft. what is it secret ?

[slshellas]

Dear maydaydeejay
VERY good information. Can you tell us what is the frequency of the SUMPS and what is in PFC circuit.?
http://www.diyaudio.com/forums/members/maydaydeejay.html

 

[gatabil]

hi maydaydeejay !
thank you very much for the information, and what is 3xigbt/mos! of pfc ?

 

[gatabil]

thanks,

It's been a while since I've been working on this, but I though, I'd share some info about.
Powersoft Digam series, in particular digam 7000.

Some time ago, I went across that amp on eBay, it happend to be faulty - "fault unknown" I thought, why not to give it a try... I won the auction for relatively low price as for this amp...
Once I've received the amp - obviously - "don't turn it on, take it apart"
The fault was really obvious - auxiliary supply rails have +/- 25V rail caps, that been shorting each other via amplifier top cover, since the caps did not have shielded cans at the top...
I' guessing that this fault w'd be pretty common to the Digam series.
So the short caused the auxiliary bridge rectifier to fail / kinda exploded but just a little bit, and as far as I could see, that was the only problem.
Caps and diodes replaced, assembled back together, powered up and... TADA! No big bang, no magic smoke, so far so good, lets give it some sine wave and squize some juice out to the load...
I must say, I was very impressed of what it was doing with my dummy load Obviously next step was the func gen, scope, another one, couple of DMM's, clamp meter and Schneider PM710...
Honestly, all measurements within the spec that the Powersoft provided so it was worth a try i must say.

Few days later... well, yeah, but how ? Soo small, soo powerfull, how... ?
So i took it apart once again just couldn't resist.
I've drawn a quick schematic of the power inverter, to give You guys an idea how do they do this, pls don't mind the symbols, I just couldn't care less


And no, there's no mistake about the primary side rail caps - only two 4u7/275Vac that's one of the ways to achieve high power factor. I've seen such topology few months ago in an industrial 40kW - single phase Induction Heater.
As U can tell - two stage topology, with the boost on the secondary side.
Good thing about this power supply is that it does not have any uC - everything it totally analog'ish And the board is self containing - it can work on its own, without amplifier stage connected - that makes me thinking

The amplifier - again quite simple, two full bridges, 'non' bridgable, however I've just figured out how to parallel them, so it is however 'strapable' to drive 1ohm loads - further tests will be done obviously
The PSU board as well as amp board is labeled 40/98 so as for over 14Y.O. amplifier, i must say it was quite piece of equipment back in these days.
The amplifier board, similar as supply, needs only two tiny supply lines plus power rail obviously, and is ready to go - so again, it makes me thinking... where w'd I... hmm, or mayB I'd... hmm
What I don't like about this particular amp is that the output stage filters have been embedded in a small plastic cases and filled with poly resin, and I'm sure there's something else inside... but without schematic, no1 can tell.


The amp as well as PSU is quite efficient as the only bit of radiator is the bottom part of the chassis - 5mm aluminium plate, more less of the size of the whole amp, no fins, no anything, just a single aluminium plate, and the fan for all the time is working at very low rpm, it is however PWM driven.

If I'll find anything worth 2 mention... surely I'll make it happen.
Any specific Q about the amp / inverter, feel free... as long as I have it disassembled

kind regards
mark

Thank you very much. it was late, but thank you for explanations.