Devi Ever Hyperion Debugging help

[ragingben]

Hi guys,

Building a pretty simple build, a clone of the Devi Ever Hyperion from this layout:



I've modded the layout to have a 10k pot for starving the circuit, here's the updated layout:



When the circuit is engaged it is really quiet. With an input voltage from lug 2 of the sag pot of around 9v I get around 9v as expected at Q1's collector, however I only get around 1v at Q2 and Q3's collectors. If I probe with a wire connected to a jack I get audio as expected at the end of C4 (B11 on the vero) but hardly any at E11 on verro, which is the base of Q2. Any ideas? Could it be a bad transistor (I don't have any replacements). I'm guessing something is acting as a voltage devider and sending the rest of the voltage to ground? I think that if Q2 and Q3 had 9v on their collectors the circuit would act as expected. I'm stumped (quite late here and been on it for hours!) as it is such a simple circuit!

Any help or advice is greatly appreciated, I'm still pretty new to electronics in general.

[sidewalk]

Also speaking as a beginner; when I built a Soda Mieser it had a volume drop issue after first putting it together. I added a lot of electrical tape to make sure no metal was touching other metal including the enclosure and the problem went away.

[ragingben]

OK I'll check that out just in case that's the problem. There is hardly any gain which makes me think the problem is related to the lack of voltage

[PRR]

> I get around 9v as expected at Q1's collector

I would expect 3V at all three.

> I get audio ... at the end of C4 ... but hardly any at ... the base of Q2.

These two points are connected with 0.2 inches of solid copper. They "have" to be the same. If they aren't, there's a bad joint.

[ragingben]

Ah OK I'll check all voltages. Will I have killed Q1 by giving it 9v?

Regarding the audio at the end of cap C4 I don't think I was clear - I have audio a B11 on the vero at one leg of cap C4 but not on the other leg of cap C4 at E11 on the vero.

Out of curiosity why would you expect 3v on all the transistor collectors?

Thank for your help

[ragingben]

I've just checked all the voltages across the circuit. For the caps and the resistors I've put the voltage at the left or top most leg of the component first, then the right or bottom most:

R1   0      0
R2   0.51      7.98
R3   8.87      7.98
R4   1.14      0.57
R5   8.87      1.14

C1   0      0.51
C2   7.98      0
C3   0      7.98
C4   0      0.57
C5   0      1.14

Q1   C: 7.98    B: 0.51    E: 0
Q2   C: 1.14    B: 0.57    E: 0
Q3   C: 1.14    B: 0.57    E: 0

Any ideas? I've remelted all the solder joints and they all look OK. Checked the resistor values and they are fine too, as are the caps.

[ragingben]

I just tried a different vero layout:



Which appears to be fine from the posts here



I swapped out all three transistors from the old layout and I am getting the same readings! I'm leaning towards a dodgy transistor? If I overheated it could it fail in a way that could give these readings?

[slacker]

Check that the transistors are the correct was round, if Q1 was backwards that might give the voltages you have. Don't just assume that the way the layout is drawn matches your transistors.

[ragingben]

If they are all TO-92 transistors they should have

C
B
E

layouts where the curved side is to the left and the collector is at the top shouldn't they? On my vero I have them all facing the same direction.

[PRR]

> why would you expect 3v on all the transistor collectors?

I would expect "same" on all collectors because Q1 and Q2 are DC-biased the same (10K and 2.2Meg), and Q3 is "off" but forced to follow Q2 collector. Great discrepancy suggests bad joints.

> If they are all TO-92 transistors they should have

TO-92 comes in various pinouts:

[ragingben]

Thanks for posting that the very interesting. I've found a data sheet for the MPSA18 (Q1 and Q2) and they are correct but I'm having trouble locating one for the 2n2907a for TO-92 (on my phone not a pc!) I'll look more tomorrow but if not ill try switching around Q3 and checking all the joints. I cheers for your help much appreciated

[ragingben]

So I've removed the 3 transistors from the circuit and now all 3 spots where the collectors should be have 8.6v so the at least I know nothing weird is going on with the voltage getting split funny before them. I

Just to verify - it is ok to have all grounds - board, led, ground from volume pot and sleves from the jacks all connected together isn't it?