Hello,
I got my drumstation out of the drawer yesterday but, it doesn’t turn on…
I measured the power supply voltages and there is only 0.5V out of the 7805. So I replaced it and now there is… 0.5V out of the 7805…
Does anyone have the schematics? Or any advice?
Could a bad capacitor induce that voltage drop?
thanks a lot. Nice day to all of you
A couple of suggestion that come to mind:
-Is the voltage at the input of the 7805 as its supposed to be?
-Do the electrolytic capacitors look okay, or are the bulging a little?
Hello, yes the voltage is as it should be and the capacitor seems fine.
It’s really hard to understand without a schematics, there seems to be a third copper layer in the middle of the pcb…
I tried again today to do some tests but there is almsot no voltage anywhere even with the new 7805
I made such rookie mistakes before so… can you check that your power supply provides the voltage in the first place? Does this voltage go succesfully into the board?
Is there a variable resistor anywhere near the regulator? If so, it could have been intended to manually fine tune the power regulator, and might have failed. Also possible is that there is some overvoltage protection which might have tripped. Any fuses? Shunt regulators (eg TL431)? Thyristors (eg BT151)?
The third copper layer is probably a ground plane, for the MIDI circuitry.
thanks, yes I checked. I begin to lose faith. It’s been aalmost 10 years since the last time I use it…
No there are not.
thanks anyways
So in summary, there is more than +5 V present on the input terminal of the L7805 regulator, but only 0.5 V on the output terminal of that regulator? And when you replaced the regulator that didn’t change?
Just to confirm: You’re measuring from the L7805 output terminal with one multimeter probe and the other probe on ground? And the multimeter is on the DC voltage setting?
0.5 V is an odd value — it’s not a short to ground, but it’s near it.
Can you post a PCB photo?
I’m not seeing the voltage regulator, where is it?
Q1 or Q2 at the top perhaps?
sorry I am not that quick to answer…
The voltage regulator is the ugly soldering at the bottom. I have tested it though. I usualy do nice soldering but this old pcb is not diy friendly at all.
I have to put this aside for now.
[off topic about life]
I have left the analog world for some years because I was in a totally accoustic band, streets and bars gigs… Now I am pluging all my all stuff one by one to see if everything works. There is a lot to do, a faulty HR16 keypad, a faulty gameboy (now working again), rehousing a thomas henry MPS, maybe rehousing the HR16, and so on…
This drumstation is not a simple one, I would really love to have those schematics so…
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thanks a lot, I will see to it after everything is working properly.
