getting ~4.39 instead of 5.333... help!

[guest]

using 4.88v will make it not 1v/octave on the cv
it will also have slight sound differences
it might be more difficult to tune as well

does the trimpot have any effect on the 4.88v

you can use regular resistors for the thermistors
but it will drift out of tune faster

[Danx]

The thermistors were pre-installed
Nop the trimpot doesn´t have any effect on the 4.88 (J4) (Ic23)
Only affects the IC22
1.73 to 2.27 (adjusting the TM6-2k checked btw-)

I´m using a 1K R5 instead the 2.5k and the voltage remains 4.88

[guest]

thats a bummer
ic22 is completely busted then

what is the part number on it
and is it orientated correctly
and are you measuring the voltage on its pin or on the trimpot
its possible there is a bad connection to ic22

[Danx]

The part number on IC22 is F KK45 LM336 z5
Correct orientation.
All connections seems fine.
I`m measuring on the IC22 pins.

Pin next to TM6 1.39 to 2.10 using the Tm6

middle pin 4.70v

pin next to D45 0v

[guest]

ok
its definitely busted

[Danx]

O.k.

So i need to replace it.
Meanwhile can i continue with the main board or should i wait...i`m finishing the first part of the VCO.

Thanks

[guest]

yes you need to replace it
you can continue to build though
just dont bother tuning until you get it replaced

[Danx]

I have replaced the IC22-LM336 and everything seems fine now.
The TM6 adjust the middle pin and i`m having J4 at 5.333 and 11.93

Thanks for your support

[Chris72160]

Hello,

i only can measure between 4.6-4.9v after the TM6 (see picture).



d44 d45 juncture = 0.57v
d45 r5 juncture = 1.12v
r5 tm6 juncture = 1.88v
tm6 r4 juncture = 2.51v
r4 d46 juncture = 4.22v
d46 d47 juncture = 4.78v
d47 r3 juncture = 4.94v
r3 r2 juncture = 25.8v
r2 r1 juncture = 28.8v

I measured all resistors before i soldered them.

When soldered in i measure following values:

R2 = 973ohm
R3 = 6800ohm
R4 = 5580ohm
R5 = 2380ohm

Maybe someone can help me!!

Greetz Chris

[mmm]

I'd recommend installing IC23 first and then measuring its output (pin 7).

From my own experience the IC23 input (pin 5) cannot always be trusted because to seems to be dependent on the internal impedance of the multimeter. If the problem persists we'll look further.

[Chris72160]

Thank you!

This was the solution!

Greetz Chris

[diplowave]

Hi,
I have a problem with the trimmer TM6, the setting is in 4.60 and 4.90 v v only. Not around 5,333V.
I checked all resistors and diodes ... The trimmer turned fully, happens only 1.86 k it's not up to 2k. I measured it before soldering. Perhaps the trimmer is busted?

I made some measure:

->IC22 test:
-TM6/IC22 juncture: 1,88V
- center IC22: 4,9V
-D45/IC22 juncture: 0V

I think IC22 is OK.

->other:
-D44/45 juncture: 0,551V
-D45/R5 juncture:1,101V
-R5/TM6 : 1,780V
-TM6/R4: 2,3V
-R4/D46: 3,90V
-D46/D47: 4,42V
-D47/R3: 4,61V
-R3/R2: 25,2V
-R2/R1: 28,30V


This is not my first DIY, i soldered the components in the right direction and at the right place. I really don't understand why I can not calibrate correctly TM6. I assemble another x0xb0x in the same time and the other is OK!
Help please.

[mmm]

From my experience the measurements pre-IC23 are not reliable because they depend on the impedance of the multimeter.

While IC23B is technically just a buffer I frequently get different readings for its input (pin 5) and output (pin 7). I'd install IC23 first and then check again at its output.

[diplowave]

I soldered IC 23 and i have always tm6 around 4,60v and 4,90v.

[substyler]

R5 is really a 2.4K resistor on your I/O?