I have one of those china IRS2092s based amp boards that uses a xl7005a regulator fed from the Gnd to negitive rail through 3 parallel 20v 1w Zener diodes to drop the negitive rail of about 60 volts to 40 volts. I removed the zeners and replaced them with 1 120 volt 5 watt zener to the positive rail to run at 80 volt rails (160-120=40 volts). Powered it up and it worked for a second then blew the regulator.... Can't figure what went wrong, did this twice so far..... I want to equalize the current draw on the rails at idle and run at higher voltage...the rest of the amp survives 80 volt rails just fine. Checked the voltage after and it was 40 volts, what gives?
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Hi!
Could you show the schematic of what you did (original and modified)?
We need to understand which parameter was exceeded.
See that this IC cannot handle more than 100V at Vin and it mentions 20V to 80V for normal operation.
This is the typical application found in the datasheet:
Could you show the schematic of what you did (original and modified)?
We need to understand which parameter was exceeded.
See that this IC cannot handle more than 100V at Vin and it mentions 20V to 80V for normal operation.
This is the typical application found in the datasheet:
I think my intuition failed me, I chose the 5 watt zener out of my head without doing the math. The regulator is drawing aprox 50 ma, so original 20 v zener would be 20x.05=1 watt, fine....my mod of a 120v zener 120x.05=6 watts and it was a 5w zener...so the zener heated up until it failed short...
Ok! First issue detected. Zener power exceeded.
But check also if voltages are within what is supported.
I didn't understood exaclty what you did in terms of topology.
But check also if voltages are within what is supported.
I didn't understood exaclty what you did in terms of topology.
https://www.diyaudio.com/community/attachments/irs2092-500w-module-pdf.1010
You can see in this schematic that the regulator is connected to the Gnd through 3 parallel zener diodes (20v) i replaced them with a 120 5w zener to the positive rail.
You can see in this schematic that the regulator is connected to the Gnd through 3 parallel zener diodes (20v) i replaced them with a 120 5w zener to the positive rail.
Maybe 2 60 volt 5 watt zeners to give 120v at 10 watts, but over 5 watts continuous will heat up my small enclosure....hmmmm
Hi!
Ah ok, zener in the Vin.
So with 120V zener you kept same same original 40V on Vin.
You resolved - it was only too much power on the zener.
It is good to not use the zener at maximum current/power, since it gets really hot.
2x60V/5W seams a better option or even 3 x 40V/5W.
50mA x 60V = 3W
50mA x 40V = 2W
What about a small heatsink (just a small aluminum piece) with thermal paste?
Ah ok, zener in the Vin.
So with 120V zener you kept same same original 40V on Vin.
You resolved - it was only too much power on the zener.
It is good to not use the zener at maximum current/power, since it gets really hot.
2x60V/5W seams a better option or even 3 x 40V/5W.
50mA x 60V = 3W
50mA x 40V = 2W
What about a small heatsink (just a small aluminum piece) with thermal paste?
Ya it looks like 3x40 is the way to go as I can't think of another solution that is easier, Could use a separate 12v supply but that's too much...all of tis is to use the amp on a power supply that has no center tap on the transformer and I want to keep the current draw on the rails equal at idle.