Univibe build debugging

Started by mitiliray, August 17, 2012, 07:55:00 PM

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mitiliray

Hello!
i am a new member i just finished my 3rd NON working neovibe..!!  :icon_biggrin: :icon_biggrin:

this time i bought ggg pcb.(previous times i made my own pcb)
then followed the parts as stated in mr. RG's pdf.
Carefully i soldered all components.
Almost religiusly i tested every resistor and transistor before placement
Same with the wiring...
my joints are very good,no cold joints or anything.
i used 2n5210BU transistors and 2n3904 as driver and a 18Vac 500ma wall transformer
after 3 builds i thought this time i will succeed!!

i plugged it aaaannnndddddd  :icon_idea: :icon_idea:



nope...
lamp is not flashing and my voltages seems weird compared to other measurements i read here in forum...
my lamp driver is not hot at all
of course not sound at all...

Q1
C =0.9
B =0,8
E =1.9

Q2
C=1.4
B=1.9
E=3.9

Q3
C =3.4
B =3.9
E =10.2

Q4
C=4
B=3.9
E=13.9

Q5
C =3.4
B =4.0
E =10.4

Q6
C=3.99
B=3.96
E=13.9

Q7
C =3.45
B =4.0
E =10.4

Q8
C=3.99
B=3.95
E=13.9

Q9
C =3.45
B =3.99
E =10.4


Q10
C =5.05
B =5.0
E =13.9

Q11
C=13.2
B=4.72
E=24.6

Q12
C =13.0
B =13.2
E =24.6

Q13(lamp driver)
C=3.32
B=3.86
E=20.3


what could i have done wrong....again??? :icon_cry:
Any help  would be extremely appreciated! :icon_cry:

R.G.

There are several things we could look into, but first and foremost, is the naming of C and E reversed in your list of voltages, or are they reversed on the actual board?

In an NPN, the C must always be higher than either the B or E for it to work as a linear amplifier.

(N.B. for others than the original poster; yes, I know about reversed operation, but that's not an issue here and he shouldn't be worrying about it yet.)
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.

R.G.

Over the years, people have noticed that it is sometimes hard to get good voltage readings from the bases of the transistors in the Neovibe/Univibe because some meters load down the bases they're measuring.

Can you possibly remeasure the voltage between the base and emitter on the transistors?
R.G.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.