Delta Elektronika E 0300-0.1 DC power supply 300V repair teardown
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- Опубликовано: 2 окт 2024
- Really nice design DC supply by Delta Elektronika from Holland,
age 1986 from schematic, this design is special, contain one PUT, and two SCR in the rectifier system, to pulse / switch -mode pre-regulate the voltage, so there is less drop and less heat loss for the final linear stage.
34V constant pre regulated over linear stage, this means at 300V 100mA 30W output
the loss in the linear stage is 3.4Watts equal to almost 90% efficiency,
it is clearly made to be assembled fast, all is so smart made, this one is quite old but still looks like brand new and it also works perfectly, only minor detail to mention is please dont load it full current at low voltage, it will be too hot, and there is no thermal protection or sensors at all.
PUT explainer : • Testing PUT Programmab...
Delta 30V 1A : • Delta Elektronika E 03...
The Saturated inductor I mention in the end of the video : 273mH 27 Ohm measured at 50Hz
be aware if you ever play with this part, there is a center tap, it is not connected on the pcb,
I think they reuse the same inductor for other voltage / current rated supplies.
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#teardown
#powersupply
#vintage
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I use auto generated subs, i am sorry there are a few spelling errors,
maybe one day they can do it better..
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Cool design and great looking boards. I like it.
38:33 no I would not have figuered an inductor would have such an asymetric behaviour. I also would have replaced the scr's. 🤔
Nice powersupplies. In school we had a couple psu's of this brand. They were the better ones we had. Good memories 🙂
I guessed it was something to do with the TX/inductor but not magnetisation.
I am assuming the designer went on energy storage for the 47n not being more than the pulsed energy of the gates of the SCR's.
Like the turning off of a line output transistor in a CRT you zener the base junction in reverse to suck out the base charge very quickly and it can be as high as 15V @ 1.5A in reverse but for a short duration i.e. less than 1uS.
As well the leads of the reference are coiled, so that there is no residual stress on the legs, and thus on the die, and as well it will be able to expand without generating any error in voltage as well.
Designers did a poor job with the regulator resistor, should be moved to the other side of the board, as the capacitor does sit below it, but the hot rising air from the resistor does cook the reference diode. Resistor should be moved to the top of the board on some leads, with new holes drilled on the board at the back away from the connector.
Inductor magnetisation I would say it was magnetised from manufacture, so would need to be degaussed and placed back in use.
i performed a few more tests with the inductor, I am able to re-magnitize it, in any current direction when turning on the psu, randomly, this tells me, the first few pulses are not perfectly symetric, and will therefore magnitize it, so i would claim the coil is wrong designed for this purpose, it should be made to handle this, maybe it will be a bit bigger, or too big for the case, if designed better for the purpose, output ripple is still amazingly low, so maybe they simply gave up solving this since it is not a big deal for the user,
@@TeardownOZ2CPU Possibly a softer iron laminate, one that will self demagnetise would be better instead of the one used.
En magnetisk spole. Hvis du vender ledningerne på den, vil den så ikke ophæve magnetismen med tiden.?
yes, but it come back, next power on cycle, random current direction saturation, so the coil is not perfect for the job,
BUT the DC output is nice and clean, so no big deal after all, i just like to understand what is going on to the last detail.