small stone not phasing

[saxtim]

I've just completed a small stone using the schematic at Tonepad (using CA3080s and two 2n5088s instead of the CA3094).  I've used my own layout (something I've been doing with all my effects lately for the learning experience.)

I tripled check the layout and used PCB express' schematic link function to design the board and I'm happy that is most likely not the source of the problem.

I wired everything up, without bypass, and tried it - I get sound coming through perfectly, just with 0 effect.  The colour switch and the rate pot have 0 effect on the signal - it just comes through clean.

I've checked that all the IC's and other points on the schematoc have the appropriate voltages (v+, vbias and ground.)

My vbias is only around 1.8 volts - does that seem too low?  

Where else do you think I should start looking?  I'm assuming the fact that I'm passing audio ok must mean it's close to working (I hope!)

thanks
tim

[smoguzbenjamin]

Did you match the FETs? And the bias voltage does seem a little low... :?

[puretube]

Ben: no FETs in there/nothing to match!

Tim: you hear audio: this means, that the first 2 transistors, R`s around it, and the 1st cap "transmit" to the output...
(the "effect" itself will - if it works - only be added at R13/C7);

btw.: it`d be nice, if people having Q.s about circuits, would add a link http://www.tonepad.com/getFile.asp?id=7 there...
(not ev`ryone knows what`s the talk about, & it`s a hassle to get there, s.t....)

[smoguzbenjamin]

Oh ok, I heard 'phaser not phasing' so my mind went 'unmatched FETs'

[mattv]

Vbias should be about 3.6V

[saxtim]

I rechecked my bias voltage - it's actually at 3 volts.  I originally check my bias and v+ with out the IC's in the sockets.  3 volts may still be a little low?

I'll start measuring all the transitors and I'll post the voltages I find

thanks
tim

[saxtim]

Ok, I've done some voltage measurements.

As commented by puretube the schematic may be located at:

http://www.tonepad.com/getFile.asp?id=7

Firstly, my V+ is sitting at 7.6 volts

This seems low no?  I'm getting 9.16 out of the battery, but the first resistor, the 470 ohm one, drops it to 7.6

V bias is at 3.06

I've got vbias, v+ and ground at the appropriate points of the circuot

Transistors - they're not labelled in the schematic, so I'll do the best to point out whcih ones I mean.

The first pair after the input (NPN and PNP)

(NPN)
E2.46 B2.87 C6.95

(PNP)
E7.6 B6.95 C4.65

Two transistors off IC1:

E3.62 B4.05 C7.57
E3.04 B3.62 C7.59

Off IC2:
E3.64 B4.05 C7.55
E3.62 B3.64 C7.58

Off IC3:
E3.62 B4.04 C7.56
E3.04 B3.62 C 7.58

Off IC4:

E3.65 B4.07 C7.55
E3.05 B3.65 C7.55

NPN's of IC5:

E4.67 B5.19 C5.70  ----------- This looks like trouble?
E5.19 B5.68 C7.57

PNP's of IC5:
E5.88 B5.69 C5.20
E5.87 B5.20 C5.86

Both of these look no good?

The ICs:

IC's 1-4 I get the same readings:

1 0
2 3.03
3 3.03
4 0
5 .61
6 4.02
7 7.59
8 0

IC 5:

1 0
2 5.16
3 5.68
4 0
5 .68
6 5.66
7 7.04
8 0

Ok.  I think that the first four stages - IC1-4 are all ok no?

Any suggestions what the problems may be around IC5? I'll start checking for shorts/wrong component values around there

thanks
tim

[saxtim]

Located the probelm -

there is a resistor marked at the tonepad site and at general gadgets only as '100'

I assumed 100k, but obviously it should've been 100 ohms.

Now it appears to be working...

however the colour switch seems to do next to nothing!  It basically seems to add a tiny bit more speed when on to the current speed setting, and perhaps a fraction more depth.  It's hardly noticeble though and you actually have to listen really carefully for it - I didn't think it was doing anything at first.

Is it supposed to do more than this?  Is there still another problems perhaps!!

thanks

tim

[puretube]

congrats! you solved the prob yerself while others are sleeping.

Use a fresh(-er) battery, or reduce the 470ohm R (R2) at the bat+ to about 100ohm;
this should get your V+ / Vbias up, and enable the effect of the colorswitch to be fully exploited:
a change in speed, and a noticeable different depth and "position" of the sweep,
which should make it sound "deeper", or you may call it "wider".

The other half of the col-sw. introduces the feedback option, and should be even more noticeable: check the values of R9, 10, 11, 12, and C6, and especially the trace from the not-grounded side of that sw.-half to R4/C2 (near the first transistor). (maybe that one is omitted in the PCB-layout?)...