Author Topic: Manson, Velleman, etc, PS 613 bench power supply repair - Schematics needed  (Read 1790 times)

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Offline AndersJ

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I inverted the leads when charging a battery.
I blew the PS and the output is at the full rectified DC, 48V.



Easy, I thought.
Replace the pass transistor and I'm up and running again, in 5 minutes.

Wrong!

The pass transistor and associated circuitry is OK.
The problem seems to be in the feedback loop or reference.

It is a nightmare to disassemble,
and without disassembling I only have access to the solder side,
and the only schematic I have is from a similar but different PS.

Q1: Does anyone have experience reparing the PS-613?
Q2: Does anyone have a schematic diagram?
Q3: Does anyone have a component placement diagram or a picture so I can probe from the solder side, without disassembling?
Q4: Other suggestions?

Thanks,
Anders J












« Last Edit: July 18, 2018, 06:08:24 pm by AndersJ »
"It should work"
R.N.Naidoo
 

Offline coromonadalix

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Offline floobydust

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In something this cheap, you will not find good service/repair docs.

I have these schematics, the one I fixed was an old B&K Precision 1670 or 1671. Sch does not include the ICL7106 panel meter portion.
Inside is a rat's nest of wiring and hodge podge of parts.

Like many of these Taiwan/china bench PSU clones, they blow up charging batteries.
If the output voltage ever goes around 7V above the setpoint, backfeed kills the pass transistor+driver, then the op-amp shorts and damages other parts.
The red Current-limit LED usually explodes across the room.
Switch off power or a power outage occurs with a battery connected, power comes back on and you have a bonfire happen. Kinda creepy.
Reverse-voltage also kills some models without a big diode there.

You have to add a few protection diodes to really fix the design, and the driver transistor needs heatsinking.


I would recheck the pass transistors, the red LED, and replace the dual 4558 op-amp or LM741's if that is what got used.

When making voltage measurements to troubleshoot, note that PSU output (+) is circuit common for all the control circuitry.
Use DMM (-) to PSU OUT (+) and voltage readings will make more sense. The entire control circuit floats with the PSU output (+).


In the same family of these re-labelled bench power supplies:

Manson EP-601, analog panel meters, 0-30VDC 2.5A
Manson EP-603, analog panel meters, 0-30VDC 2.5A, Aux 5V 12V 0.5A
Velleman PS-603, analog panel meters, 0-30VDC 3A, Aux 5V 12V 1A

Manson EP-611, LCD panel meters, 0-30VDC 2.5A
Manson EP-613, LCD panel meters, 0-30VDC 2.5A, Aux 5V 12V 0.5A
Velleman PS-613, LCD panel meters, 0-30VDC 3A, Aux 5V 12V 1A
Circuit Test PSA-2530D, LCD panel meters, 0-30VDC 2.5A, Aux 5V 12V 0.5A
Jaytech MP-3082, LCD panel meters, 0-30VDC 2.5A, Aux 5V 12V 0.5A

Manson EP-3050 ?, LCD panel meters, 0-30VDC 5A, Aux 5V 12V 1A
Dick Smith Q1760, analog panel meters, 0-30VDC 5A, Aux 5V 12V 1A

The 5A and 2.5A are the same design, just beefier pass-transistors. I also have schematics for the one's with a fan.

Mastech HY-3010D, HY3005 is a bit different circuit design, also missing protection diodes and blows up just as easily.


https://www.eevblog.com/forum/beginners/manson-ep-613-dc-power-supply-troubleshooting
« Last Edit: July 18, 2018, 09:32:24 pm by floobydust »
 
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Offline coromonadalix

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normally on the schematics:  Q1 should have an reversed  power diode between the collector emitter,   kathode on collector, anode on the emitter ...   that would give better protection against reverse voltages, you have D4 who doing some protection too
For me i would have put another 2n3055 in the circuit in parallel of Q1,  but the heatsink must support it ... and have an thermally controlled fan on them, depends of the psu brand.


I have an Kepco 75-8 , a 864 watt psu,  it gives 80vdc at 8 amps,  boy this puppy gets hot when pushing its full power, it has an very big fan in it, but has an very huge wire wound filament resistor on ceramic plates made like an clothe dryer.

When i charge batteries ex:  (an 12v 5 amps) i set 14v -16 volts, connect it, slowly rise the output current up to 500ma-800 ma, or around 1/10th the battery maximum current, the psu goes into constant current, and you charge the cell/battery.

But you have to constantly check the meters, when the battery charge the current will drop down and the voltage will rise dangerously if you forget it, and you may blow it.

My psu is really bad for inductive loads, i dont know how, but sometime if the inductive surge current protection kicks, it will dissipate 864w of heat ????  its build like 2 huge series pass transistors, the second will short to the ground but the first transistors series thru the big wire wound resistor will heat as hell.

All i have to do is disconnect the load ??? and everything goes normal.

 
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Offline AndersJ

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Fixed!

After replacing the op-amp, the output capacitor and reverse protection diode,
and reparing a burned out pcb trace from the negative output terminal,
I'm up and running again.

Thanks for the schematic diagram, suggestions, miscellaneus information and support.

/Anders J
"It should work"
R.N.Naidoo
 


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