Try a 10 Ohm 10W first. Why such a difference between Tx? Do they have the same spec printed but one is wrong?
Thanks I will try & let you know, yes it's a big difference between the Tx, of course both are 120VA 2x21V.
Before 10R 60.9V, after 10R 60.5V & I look for 55V, I suspect the mosfets are gone due to the fact heatsink don't hot
Other channel 56.5VDC after reg.
Tx 1 44VAC, Tx 2 45VAC
Other channel 56.5VDC after reg.
Tx 1 44VAC, Tx 2 45VAC
I have gone back to post2851 but can't find your required output voltage.
Could you remind us what the reg specification is?
Could you remind us what the reg specification is?
Reg input 55VDC output 46VDC V1.0 RS
An externally hosted image should be here but it was not working when we last tested it.
R1=22r is not 500mA.
What is R1?
the CCS dissipation is [Vin - Vr1 - Vout] * Iccs
I'll guess at some inputs:
Vin =61V
Vr1 =2V
Vout = 46V
Iccs =0.5A
Pq1 = 6.5W
Ta=25degC
It would take quite a few seconds even with a tiny heatsink to burn out the CCS FET. With an small but adequate sink say 10C/W the sink rise would be 65Cdegrees above ambient.
Tc ~ 70Cdegrees above ambient. That puts Tc ~95degC
The temperature de-rating for the FET is 0.44. [150 - 95] / [150-25]
Your 150W FET is de-rated to 66W
Pq1 ~ 10% of maximum rating.
If the FET is cold it is not passing current.
It has almost certainly not been damaged by over-voltage.
It may have been damaged by soldering or handling or simply the circuit has a fault.
What is R1?
the CCS dissipation is [Vin - Vr1 - Vout] * Iccs
I'll guess at some inputs:
Vin =61V
Vr1 =2V
Vout = 46V
Iccs =0.5A
Pq1 = 6.5W
Ta=25degC
It would take quite a few seconds even with a tiny heatsink to burn out the CCS FET. With an small but adequate sink say 10C/W the sink rise would be 65Cdegrees above ambient.
Tc ~ 70Cdegrees above ambient. That puts Tc ~95degC
The temperature de-rating for the FET is 0.44. [150 - 95] / [150-25]
Your 150W FET is de-rated to 66W
Pq1 ~ 10% of maximum rating.
If the FET is cold it is not passing current.
It has almost certainly not been damaged by over-voltage.
It may have been damaged by soldering or handling or simply the circuit has a fault.
the current is ~0.5A
The dropping resistance is 150r
How hot does it get?
Have you done the arithmetic?
P=I*I*R=37.5W
Why use 10W resistor?
Why use 150r?
The dropping resistance is 150r
How hot does it get?
Have you done the arithmetic?
P=I*I*R=37.5W
Why use 10W resistor?
Why use 150r?
AndrewT you are right was a bad connection 2nd mosfet, now is all ok after adding the 150R 10W in series to lower till 54VDC after reg, this reg after 15 minutes the heatsink don't hot & the other heatsink it's hot....
It's very very hot can left the finger few seconds.
Salas told me start with 10R 10W...
To low the voltage to 55VDC after the reg.
Is it CRC or RC configuration? From bridge to filter cap (+) just a resistor is RC. Is there a capacitor before the R?
Hi Salas
For the zobel on the output, can I use 0,5w 1r resistors ?
What is the minimum power requirements ?
For the zobel on the output, can I use 0,5w 1r resistors ?
What is the minimum power requirements ?
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