Author Topic: Help with touchstone  (Read 552 times)

ChrisTracker

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Help with touchstone
« on: August 09, 2020, 02:03:33 AM »
Im almost near to finish the pcb
Im out for 5 needed component
Please help me/guide me on what to pick on my available part that can substitue on the listed one
C10 = 2.7nf. I only got 2.2nf and 3.3nf
C11 = 180pf. I only got 150pf and 220pf
C7 = 15nf. I got 10nf and 20nf
R24 = 180k. I got 150k and 200k
Any idea on what to substitute a 2n5087?



Thank you

« Last Edit: August 09, 2020, 02:08:59 AM by ChrisTracker »

Scruffie

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Re: Help with touchstone
« Reply #1 on: August 09, 2020, 03:49:49 AM »
C10 - 3n3
C11 - 150pF
C7 - 10nF
R24 - 150k
2N5087 - Any general purpose PNP transistor.
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ChrisTracker

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Re: Help with touchstone
« Reply #2 on: August 09, 2020, 06:29:10 AM »
Thanks for the reply
Now I can finish populating the pcb
I read somewhere that capacitor has 10% tolerance but I dont know if I should go higher or lower.
Thanks again

jimilee

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Re: Help with touchstone
« Reply #3 on: August 09, 2020, 08:08:32 AM »
Thanks for the reply
Now I can finish populating the pcb
I read somewhere that capacitor has 10% tolerance but I dont know if I should go higher or lower.
Thanks again
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ChrisTracker

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Re: Help with touchstone
« Reply #4 on: August 11, 2020, 04:06:17 AM »
So I follow Scruffie replacement part. I use 2n2907 to replace the 5087 and follow the same orientation. I also use 1N914 diode cause I dont have the 4148. multilayer ceramic for 33n at the input. I dont have the reverse log as well so I use 1M log but wiring backwards (I just read from somewhere with a working small clone)

I cant make it to work still bypass signal after engaging the effect.

Here are the voltage I got:
VC - 9.7
VD - 8.9
VB - 4.29

4558:
1 - 4.35
2 - 4.35
3 - 4.51
4 - 0
5 - 4.30
6 - 4.27
7 - 4.27
8 - 9.5

LM358
1 - 1.50 to 3.0
2 - 4.80
3 - 4.80
4 - 0
5 - 2.7
6 - 2.7
7 - 8.27
8 - 9.5

MN3007
1 - 8.9
2 - 8.9
3 - 7.16
4 - 0
5 - 0
6 - 0
7 - 6.9
8 - 6.8

CD4047BE
1 - 8.80
2 - 0.02
3 - 6.88
4 - 8.8
5 - 8.8
6 - 8.8
7 - 0
8 - 0
9 - 0
10 - 0 (This is expected to have voltage rating)
11 - 8.8
12 - 0
13 - 8.8 (this is unconnected but I kept getting voltage here)
14 - 8.9

Q1 (2N2907)
C - 0
B - 5.9
E - 8.3

Q2 (2N5088)
C - 9.2
B - 6.5
E - 5.9

Q3 (2N5088)
C - 9.2
B - 9.1
E - 8.6

Ive been debugging for about 2 days now but to no luck. I already checked resistor and capacitors value. Checked for unwanted solder joints using knife/solder tip passing through each traces. I have 2 CD4047BE and used both but nothing worked. tried different dual opamp for 4558 but nothing helped so far. Or maybe I got a defective MN3007, cause I only have one. Checked all parts connected to ground and 9v supply. Please guide me on where to look as I might missing something here. I really want this one to work.

Thank You...

ChrisTracker

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Re: Help with touchstone
« Reply #5 on: August 11, 2020, 11:33:16 AM »
I made an audio probe to the circuit.
It passes ok at the pin 3 of 4558. I only got continuity to pin7 going to output. As well as pin1 but the rest of the pin, none. Then from pin1 of 4558 the signal was cut at 20k and the trimmer. The signal changes as I turn the trimmer. From there its nothing. I dont know where to look anymore

Scruffie

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Re: Help with touchstone
« Reply #6 on: August 11, 2020, 11:42:47 AM »
Your 4047 isn't working, no clock, no delay signal.
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ChrisTracker

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Re: Help with touchstone
« Reply #7 on: August 11, 2020, 10:21:54 PM »
Thanks. I'll keep that in mind
By the way, did another audio probe. From 4558, is it normal that I dont get audio signal from pins 5 and 6?
Audio signal now cuts at D1 so no signal going to 12k and 33k. Slight improvement from my last audioprobe ;D
I will check the diode

m-Kresol

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Re: Help with touchstone
« Reply #8 on: August 12, 2020, 02:19:54 AM »
you should have audio signal (at least the clean sound) at pin 6 of the 4558. Pin 5 is ok without audio as it is tied only to DC bias (Vb).

the 2n2907 has a slightly different pin layout than the 2n5087. They are both E-B-C, but make sure you have the 2907 soldered correctly
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ChrisTracker

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Re: Help with touchstone
« Reply #9 on: August 12, 2020, 05:10:42 AM »
Oh I see. I will going to check again 4558 pin 6. But I remembered that I resoldered new resistor and caps on that trace thinking of a bad component on that side.

I replace D1 that causes audio signal to pass 33k, now I have audio signal on MN3007 pin3. While 12k going to pin1 of 4047, no luck.

Do I need a new 4047? Both of my 4047 didnt work...
Im going to check Q1 as well
Thanks for pointing those out

Scruffie

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Re: Help with touchstone
« Reply #10 on: August 12, 2020, 05:15:05 AM »
Did your 4047 voltages change?
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ChrisTracker

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Re: Help with touchstone
« Reply #11 on: August 12, 2020, 06:52:18 PM »
No, it didn't

ChrisTracker

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Re: Help with touchstone
« Reply #12 on: August 13, 2020, 01:48:43 AM »
So I came to suspicion that the 4047 is the culprit. I searched on how to test a 4047 ic and came up with a schematic
I dont know if Im doing it correct as Im not that knowledgeable with electronic stuff or maybe this is not necessary.

Will this test my 4047 to be defective or not?

Here is the schematic: