jets
05-02-2014, 11:20 PM
Hi All,
I have a few VS9K here and I have done some serious testing on them. I have one unit that has a “no signal” problem. If I disconnect the 8PSK the signal comes back. If I swap the power supply with the working unit the signal comes back and the 8PSK works.
This leads me to believe the power supply is the problem so I tested further. I found that when the 8PSK’s ribbon cables are connected that the 24 VDC and the 30 VDC voltages “pulls up”. In the working unit both the 24 and 30 VDC are a bit high already 26.5 and 32.5 respectively. Once the 8PSK is connected the voltages pull up to 33.8 and 27.8 VDC.
I tried to a diode in series with the load to drop the voltage but it did not work. I have tried an extra ground from the 8PSK to the PCB ground but no luck. So I am thinking there might be too much ripple voltage?
The power supply circuit on the output side of the transformer is a diode a cap an inductor and then another cap tied to a resistor. I have replaced all the caps with good one and still no luck. I think the problem is on the primary side of the transformer but all the components look good.
Anyone got a schematic of the PSU or ideas how to fix this?
TIA
I have a few VS9K here and I have done some serious testing on them. I have one unit that has a “no signal” problem. If I disconnect the 8PSK the signal comes back. If I swap the power supply with the working unit the signal comes back and the 8PSK works.
This leads me to believe the power supply is the problem so I tested further. I found that when the 8PSK’s ribbon cables are connected that the 24 VDC and the 30 VDC voltages “pulls up”. In the working unit both the 24 and 30 VDC are a bit high already 26.5 and 32.5 respectively. Once the 8PSK is connected the voltages pull up to 33.8 and 27.8 VDC.
I tried to a diode in series with the load to drop the voltage but it did not work. I have tried an extra ground from the 8PSK to the PCB ground but no luck. So I am thinking there might be too much ripple voltage?
The power supply circuit on the output side of the transformer is a diode a cap an inductor and then another cap tied to a resistor. I have replaced all the caps with good one and still no luck. I think the problem is on the primary side of the transformer but all the components look good.
Anyone got a schematic of the PSU or ideas how to fix this?
TIA