madbeanpedals::forum

Projects => Tech Help - Projects Page => Topic started by: nicotina74 on August 13, 2021, 03:13:46 PM

Title: Harbinger 1.5 - not working
Post by: nicotina74 on August 13, 2021, 03:13:46 PM
hi guys, i need some help.  i finished assembling the circuit but it doesn't work properly.  i am not expert but i could verify that the voltages on transistor mspa13 - Q12 has variable voltage values ​​when it should have stable voltages.  do you have any idea where the problem might be?  thanks for any help you can give me.
Tanks
Nicola
Title: Hambiger 1.5 - not working
Post by: jimilee on August 13, 2021, 03:25:26 PM
Hey hey, welcome! We’re absolutely happy to help, we just need some information please.

To get tech help, in the first post of your thread, you must include:

(1) Project Name
(2) General description of the problem
(3) Steps that you have taken to try to resolve the issue
(4) List any substitutions you used for parts/values


Clear close up in focus pictures of both sides of the board.

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Title: Re: Hambiger 1.5 - not working
Post by: Zerro on August 13, 2021, 04:35:54 PM
Some schematics would help too, if available :@)
Title: Re: Hambiger 1.5 - not working
Post by: nicotina74 on August 13, 2021, 11:18:10 PM
Hi, sorry I thought that the name of the project shown on the title of the discussion was sufficient.
1) Project name: Harbinger 1.5 (Univibe (TM) for 1590BB) - the version with 9v power supply.
2) The pedal turns on, the speed and depth controls work because the lamp responds to the two controls, but connecting the pedal to the guitar and the amplifier the pedal does not work. I try to explain myself better: in vibrato mode the sound comes out but without effect, in chorus mode the sound is distorted and is perceived as soon as the effect is very low in volume. Switching from modern / vintage mode seems to have an effect as I perceive the sound to lighten or darken.
3) What was I able to check?
a) I double checked the values ​​of all resistors (with color codes)
b) I checked the capacitor values ​​and polarity in the case of electrolytic capacitors.
c) I checked the diodes
d) I checked that the transistors were of the type indicated on the project and that the pinouts were correct.
e) Finally I checked the voltages of the transistors, of the IC1 LT1054 and of the LM7815 voltage regulator with the tester, with powered pedal, and compared with the voltage table of the project.
The voltage readings I have found that are suspect are as follows:

from project: Q12 (MPSA13) C = 9.2 B = 9.08 E = 8.13
detected: Q12 (MPSA13) C = varies B = varies E = varies

from project: Q14 (2n5457) D = 17.5 S = 2.77 G = 0
detected: Q14 (2n5457) D = 17.14 S = 1.47 G = 0

from project: IC1 LT1054
1 = ~ 2.1v
2 = 4.94
3 = 0
4 = 0
5 = 0
6 = 2.56
7 = 1.38
8 = 9.26

found:
1 = 1.37
2 = 5.01
3 = 0
4 = 0
5 = 0
6 = 2.57
7 = 1.42
8 = 9.11

I did not use equivalent components but those indicated in the project.

The rest seems okay to me.

Thanks, any advice or suggestion is precious !!

Title: Re: Hambiger 1.5 - not working
Post by: Bio77 on August 14, 2021, 12:58:51 AM
Can you add pictures of the top and bottom of the PCB? 
Title: Re: Hambiger 1.5 - not working
Post by: nicotina74 on August 14, 2021, 02:57:56 AM
Here are the pictures!
Title: Re: Hambiger 1.5 - not working
Post by: Zerro on August 14, 2021, 09:21:22 AM
Reflow that copper side from tin dust and controll it from udesirable bridges between points. I see at picture minimally 2 sufficient places. Thats for a start.

BTW, hambiger and harbinger are two different words. For those skilled in electronics but not in possible names of projects it will be confusing and junk work to look for schema at web.
Title: Re: Hambiger 1.5 - not working
Post by: jimilee on August 14, 2021, 10:22:55 AM
Here are the pictures!
Thank you, that’s helpful. Checking your components is a great starting point. It looks like several solder joints are starved. Solder should flow through the board eyelets and look like little silver Hershey kisses. If you would, please go back over the board and reflow, adding solder where needed. Also, yes, watch out for solder bridges.


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Title: Re: Hambiger 1.5 - not working
Post by: nicotina74 on August 14, 2021, 10:29:30 AM
BTW, hambiger and harbinger are two different words. For those skilled in electronics but not in possible names of projects it will be confusing and junk work to look for schema at web.
sorry I corrected!
Title: Re: Hambiger 1.5 - not working
Post by: nicotina74 on August 14, 2021, 10:32:35 AM
Reflow that copper side from tin dust and controll it from udesirable bridges between points. I see at picture minimally 2 sufficient places. Thats for a start.

could you mark the colon on the image?  I would be very grateful. Tanks
Title: Re: Harbinger 1.5 - not working
Post by: Zerro on August 14, 2021, 12:53:55 PM
I assigned the most suspicious. But with some needle try to clear all, and from rosin rests too.