Look Sam No Smoke - Module Power up

Ok no pictures , but I got my MicroBus PSU powered up and then finally started to fit the power connectors on the modules, power them up chipless and then with chips…

These are all power tested… No pops , bangs or smoke…
LFO
ASDR
DUAL VCA
Performance Filter

These ones to finish off tomorrow.
QUAD VCA
VCO

Just leaves the Molex to Jack wires to do…
And swappinf out the wrong prescion regualtor on the VCO…

SO CLOSE!!!

Rob

6 Likes

Care to elaborate on that one?

I was thinking, since on the #1222 the regulated 5V is connected to the Arduino’s Vin instead of 5V pin and doesn’t go anywhere else, maybe it would make sense to use a 7808 8 volt regulator instead of the 7805.

The 4040AIZ 4.1 - I was not paying attention when buyingand got a 10V, only realised during the thread on the little begger the other week.

Not looked at the schematic in terms of the 5V line, I do’t see why you could not put a 780x in and run to VIN. I am not sure what advantage there would be either way, you could just run in the +12v line I guess and dispense with the reg altogether… I alway use +5 . I guess of board regulation will let the chip run cooler.

1 Like

it is not bad for the circuit to put the current in a module without chip ?

2 Likes

Yeah, you probably could, I just feel it would look cleaner with a regulator since that’s what the PCB calls for.

2 Likes

Usually it’s not a problem as the chips are what is the most likely to be damaged if the power supply is inverted or connected to the wrong place.

3 Likes

You could probably use a 10 V, since the 4.000 V reference voltage is taken from the other side of a voltage divider trimmer; you just end up with the trimmer in a different position. You may have to tweak the R42 series resistor, though, but iirc someone did the math and the current value (220 ohm) is too low for 4 V anyway so might work as is for 10 V.

EDIT: (12 - 10) / 220 = 0.9 mA max through the reference, which is so nicely positioned between the 100 uA min and the 15 mA max that you’d think it was designed for 10 V :slight_smile:

2 Likes

I guess it’s a gamble either way.

Other two modules now have the power.

Spent half the live stream crimping molex connectors.

2 Likes

What makes you think so?

it was a question, I was wondering if it could be bad for some components, but now I understand that no

1 Like

You could design a circuit that can damage some passive components if not all active components are there, or even damage the missing components when you add them later, but that requires effort :smiley: I don’t think you have to fear this for your usual DIY stuff.

(well, ok, if you power things up and insert the missing components in a powered circuit, all bets are off.)

4 Likes

Now that you mention it, didn’t someone (you?) link to a video of the Super Simple Oscillator where that actually happened? You had to make sure to discharge the capacitor or you’d blow the transistor when adding it to the circuit.

3 Likes

burnt up components and circuit traces usually only happen on high power stuff like power amps. a friend of mine repairs music equipment , etc. he has shown me some real cooked shit over the years . like whole circuit boards lost [ no way to id the components ] . you talk about bad smelling , that stuff reeks .

I had a cheap Hi-Fi Amp that came to me wiith a blown track. I am no diagnostics expert but as it was a dead loss anyway I repaired the track… And it held, more than long enough for another track to blow…

Both tracks were easily traced to one of a pair of large Darlington Drivers, 3 in the stereo pair were seemingly ok, this one was fully shorted… £3 later, one more track repair and I was in business :slight_smile:

The comments on the live stream for the Quad VCA mention Sam powering up with the chips in 1st Go.

I think the biggest risk we have seen here is either sockets being soldered in the wrong way so the chip is in back to front, or just putting the chip in back to front… Fortunately I have been playing with socketed IC’s for 30 years ( ouch ) so I am reasonably proficient…

Rob

2 Likes

Yeah, I’ve posted the avalanche disaster video here a couple times, and I have a big bold section about discharging in the simple oscillator post, so I guess “takes effort” wasn’t entirely accurate :smiley:

(his circuit was powered on, though, so strictly speaking that falls in the “all bets are off” category, but on or off doesn’t matter that much if you have a low leakage 100 uF capacitor charged to full supply voltage in the circuit… 1.5 mC might only be 1/10000 of a lightning bolt, but can be a bit too much for a single transistor…)

4 Likes

My Frequency Central MicroBus will power the LED’s for minuets with no other load when disconnected. So I always remove the Module from the power and let it sit a little…

Rob

1 Like

LOL is that a technical term for what happens when we F@#* up .

1 Like

Yeah, thats normal. Those are some chungus caps.

2 Likes