CMoy Power Circuit Debugging Help

When first troubleshooting when something goes wrong, the first step is to check your current work with what's displayed on the schematic.

Sometimes, working on that type of board can get pretty confusing when trying to follow the schematic. I'm not too sure whats going on with the wiring there either, you should probably explain what's what.

Start from the top, and follow the +4.5V rail. That line should say hello with the battery, R1 and C1, is that the case with your current work? Perhaps a solder bridge connection, or four, isn't such a bad thing after all.

Don't forget that you're supposed to be checking voltages with respect to the virtual ground that you've created (which looks just fine by the way ^^).

I'd wait for somebody else to chime in before doing anything insane, I've never built a CMoy before.

The resistors are soldered to the wrong spot.

Where they solder to the middle is O.K., but they

need to solder to the same pads as the battery

wires.

In short, the positive battery wire, one side of a resistor

and the positive lead from one capacitor all go together.

The negative battery lead, one lead from the other resistor

and the negative lead from the other capacitor all go together.

The other leads from the resistors and capacitors go to the

center strip.

Hope that helps...

By the way, great pictures...

Maybe I just couldn't see the jumpers under the caps...

Try taking the caps out and see if you get the proper

voltage division. The resistors form a voltage divider.

If it works properly, put the caps back in one at a time

being careful of polarity. Check the voltage after each

cap is installed to see if is still OK.

It might be easier to feed in wires from the top of the board.  There are many things soldered together at a single point. Perhaps you can use a small wire jumper to an adjacent thru hole and insert the wires there before soldering.  There is a danger of weak joints because the thru-holes on general purpose proto boards are bigger than the typical component leads.  You should bend the component leads or insert an extra component lead so that there is a mechanical connection before soldering with a 25watt iron.

If size matters, then use lower-voltage versions of the same type of caps. They are usually smaller.

You need a suction tool for repairing errors. You can find these items at Sayal. There are several outlets in the GTA.

Whip out the multimeter and check that the jumpers are doing their jobs.

Some "tools of the trade".

63/37 rosin core solder, desoldering braid, solder sucker and

a soldering station.

In your case, you can just heat the lead and lift. repeat on

alternate sides until the component comes free.

Tangent has some tutorials on soldering here.

Quote:

Originally Posted by miceblue 

Yup, I just did that and I get the same measurements across the board, +/- 1.30 volts. The battery's voltage is 8.88 volts so theoretically the output voltages on each side of the power circuit should be around 4.44 volts. Measuring across the +/- input wires at the top of the circuit gives me 8.88 volts, but measuring from the + or - input wire to the virtual ground gives me the + or - 1.30 volt output for some reason.

Extremely odd indeed, where'd all the voltage go!
 

How much faith do you have in the multimeter's readings? I suspect it might be dodgy as when you measured both the rails together, you got 8.88V!.

If you have any spare parts, I'd throw another one together just for laughs, as I just can't figure out how'd you get +/- 1.30V.....

Quote:

Originally Posted by miceblue 


Sorry, I don't quite understand what you're trying to say. Are you suggesting adding a different power route with a jumper wire going to a different part of the circuit board?

I am trying to see it from the perpective of a novice buying a kit because that is easier than doing it from scratch. So what should the kit designer do for that person?  The main problem is that the large capacitors obstruct the view of the connections. Also, there are wires attached to the solder side of the board.. this is a no-no.  I do the same for something hacked together only for me, but I would not expect someone else to repeat my hacking.

For this board, I suggest to temporarily connect the caps to the board with extension wires that do not obstruct the view.  Install the caps only when the circuit is finally working.

Quote:

Originally Posted by miceblue 

Yeah I'm pretty sure the multimeter is correct, this battery is slightly used so it should be less than 9v.

I know, but the thing is, if those rails were at +/-1.30v, measuring the top rail to the bottom rail should yield 2.60v if that's the case.

Try measuring across each individual part to see if any strange readings pop up.