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| Lambda LPT-7202-FM Triple Output Power Supply |
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| Chuy:
Hello everyone. I just got this used Lambda LPT-7202 but it doesn't deliver enough current on all 3 outputs. I calibrated all 3 voltages and was able to bring the voltage to the maximum value but on the Current calibration, I was short 1 amp even though I rotated the R102. R202 and R302 to the maximum. The problem is when I connect a load even a small motor or light bulb, the voltage drops down to 3 volts and the motor bearly rotates or the lights barely light up, this happens on all 3 outputs. I also put a jumper to the V+ and V- to adjust the current to the maximum and it does the same thing. For example; I turn on the power supply without load and adjust the voltage to 10 volts with the maximum current then I connect a car light bulb (12 v) immediately the voltage drops to 3 volts and the light bulb bearly lights up. Gif attached. I can turn the voltage knob to a higher voltage but it doesn't go up, stays on at 3 volts. Happens on all 3 outputs. Any suggestions/advice on what to do? |
| edavid:
When you connect the lamp and the voltage drops to 3V, what does the current meter read? |
| Chuy:
About 10ma Photo attached. |
| Chuy:
100ma Correction |
| alm:
Can you measure the voltage going into the pass transistors (at the collector side) with a scope? I wonder if the filter caps are dry and the regulator is dropping out due to excessive ripple. Also measure the voltage rails for the regulation circuit while you're at it. |
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