Author Topic: Need Help with Sunface Nkt275  (Read 331 times)

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thomasolsen84

Need Help with Sunface Nkt275
« on: February 10, 2018, 08:35:17 PM »
Hi. Im trying to build this one, but having some trouble.
Im getting no sound when pedal is engaged.
I will attach the layouts im using for this. Both veroboard and offboard.
I conected my red battery wire to the middle lug on the input jack, and my black wire on the -9v on the diagram. Im using a DPDT stompswitch and no led.  I've tried two different sets of transistors. PNP russian gt320 and PNP mullard oOc type transistors. Same on both sets. Im getting some voltages on my transistors. Also i dont know what is q1 and q2. But my voltages on the top left transistor is:
E: 0.53
C: 6.87
B: 0.74

Bottom right transistor
C: 0.74
B: 0.19
E: 0.00

Anyone leading me in the right dirrection is much appreciated. Been searching for faults all day but im stuck. Checked for bridges and bad solder joints but cant see anything obviuos.




« Last Edit: February 10, 2018, 08:38:09 PM by thomasolsen84 »

thermionix

Re: Need Help with Sunface Nkt275
« Reply #1 on: February 11, 2018, 05:51:23 AM »
The voltages seem in "should make a sound" territory.  Can you post pics of what you've built?  Front and back, offboard stuff too.

thomasolsen84

Re: Need Help with Sunface Nkt275
« Reply #2 on: February 11, 2018, 06:13:56 AM »
Here's some pictures. Sorry for the crappy light.









« Last Edit: February 11, 2018, 06:16:09 AM by thomasolsen84 »

thomasolsen84

Re: Need Help with Sunface Nkt275
« Reply #3 on: February 11, 2018, 06:44:31 AM »
The pinout on the transistors are emitter, collector in the middle, base. Had to bend the transistor legs for the bottom right transistor.
Anyone spots any mistakes on the offboard wiring? Are the stompswitch the right way around? And is everything wired to the right places to the jacks? What about the battery wires? This is the first time i've used this kind of stompswitch. Im really stuck on this one. All suggestions are welcomed. :)
« Last Edit: February 11, 2018, 07:23:27 AM by thomasolsen84 »

thermionix

Re: Need Help with Sunface Nkt275
« Reply #4 on: February 11, 2018, 04:05:11 PM »
Probably unrelated to your current issue, but at some point you're gonna wanna untwist and shorten most of those wires.  It's best practice to keep input and output runs as seperate as you can, especially in high gain devices.  As it is right now, it makes it very hard to follow visually.  Your jacks look wired correctly, and you have the switch oriented like in the diagram you posted.  But you know, which blue wire is going where?

Edit:  Also, rotate the switch 90 degrees so you don't risk a lug shorting against the inside of the enclosure, the one with the yellow wires looks really close.
« Last Edit: February 11, 2018, 04:13:50 PM by thermionix »

thomasolsen84

Re: Need Help with Sunface Nkt275
« Reply #5 on: February 11, 2018, 05:39:00 PM »
Thanks for your reply. I checked the blue wires with my dmm and they are going to the right places. I really appreciate the tip on not twisting the wires. I guess it was an attempt to make it look nicer, but i dont wanna bring nouse or anything. Also i got a bit confused when i was wiring it up. Especially when the same colour of eires was twisted together. So im gonna rewire it and check my board really good . And hopefully i get it working after that.
Thanks a lot for your time. This forum is great for good tips and tricks. Alot of helpful people to help out a beginner like me.

slashandburn

Re: Need Help with Sunface Nkt275
« Reply #6 on: February 11, 2018, 06:29:31 PM »
Check over your switch wiring, I might be wrong here but you look to have possibly switched your bored input and output wires.  Worth double checking!

thomasolsen84

Re: Need Help with Sunface Nkt275
« Reply #7 on: February 11, 2018, 07:17:12 PM »
I've cleaned up my wiring untwisted and shortened. It didnt fix the problem. I've checked the board a couple of times. Reflowed every solder. Im getting voltages on the transistors.  Top left:
E: 0.54
C: 9.23
B: 0.63

Bottom right:
C:0.63
B: 0.19
E: 0.00

Im getting voltages on the sundial pot lugs as well. Im guessing thats right?
How about the trimpot. When i turn it dont change any voltages on any of the transistors. Is it supposed to?







« Last Edit: February 11, 2018, 07:39:26 PM by thomasolsen84 »

thermionix

Re: Need Help with Sunface Nkt275
« Reply #8 on: February 11, 2018, 07:54:53 PM »
Okay the switch wiring looks correct.  I'm not seeing any errors on the board.  But your Q2c voltage has jumped up to full supply voltage, I don't know how.

thomasolsen84

Re: Need Help with Sunface Nkt275
« Reply #9 on: February 11, 2018, 08:14:32 PM »
Yes I noticed that as well. Maybe i did fry a resistor or something? When i follow the path from the 9v on the board it is 9.27v from the battery onto the top row on the vero.
9.27v into the 33k and 470r.
From 1 row to row 4 on the 33k resistor i get 0.87v.
Through 470 at row 5 i get 9.03v
From row 5 to row 1 at the 2.2k i get 7.90 measured at row 1
Through 10nf cap measured at row 3 i get 0v
Zero volts at all the legs of the trimpot
Negative side of the 22uf i get 0.50v
Dont know if this is any use?
« Last Edit: February 11, 2018, 08:19:41 PM by thomasolsen84 »

thermionix

Re: Need Help with Sunface Nkt275
« Reply #10 on: February 11, 2018, 08:45:32 PM »
From row 5 to row 1 at the 2.2k i get 7.90 measured at row 1

Then you should have no more than 7.9 at Q2c, depending on where the sundial is set.

Quote
Maybe i did fry a resistor or something?

Highly unlikely.  Maybe even impossible.

thomasolsen84

Re: Need Help with Sunface Nkt275
« Reply #11 on: February 12, 2018, 03:28:27 PM »
So i couldnt find out the problem with my pedal, so I scrapped the old board and made another one. Enirely with new parts except trimmer and sockets. I got the exact same problem. My voltages at the same levels basicly. Top left transistor
E:0.66v
C:9.24v
B:0.76v

Bottom right transistor.
C:0.76v
B:0.20v
E:0.00v

Voltages on sundial on max:
Lug 3: 9.24v
Lug 2: 9.24v
Lug 1: 9.17v

Sundial on min:
Lug 3: 9.24v
Lug 2: 9.24v
Lug 1: 9 24v

Im completely lost. Anyone have a clue? I thought the 2.2k resistor was supposed to lower the voltages on the sundial? How would a broken trimmer or a pot effect the pedal. There is nothing i can see visually but apperently sonething isn't right.
I cant believe i pull off way more complicated veros and this tiny low part count has me been stuck to my workdesk for 3 days. :) haha

thermionix

Re: Need Help with Sunface Nkt275
« Reply #12 on: February 12, 2018, 04:34:08 PM »
The trimmer isn't the issue, as far as DC voltages go, it's only connected to the input signal.  I'm confused as to what may have changed between the time you had <7V on Q2c and now >9V on Q2c.

Look over everything with a magnifying glass, including the sockets.  Look for any little speck that might cause a short.  Test the complete circuit outside of the enclosure.  Test your sundial pot, disconnected.

duck_arse

Re: Need Help with Sunface Nkt275
« Reply #13 on: February 13, 2018, 09:37:08 AM »
I wish to make a pedantic observation. the layout diagram would suggest that this is a positive ground build. that said, when you take the voltage measures, you'd put the black probe to ground (in this case +9V) and probe about the circuit with the red probe, as is standard practise. and all your meter voltages would read as negative. none of your posted readings are negative.

that is all.
"I almost saw the singer panty in 1:36" - GiovannyS10

thermionix

Re: Need Help with Sunface Nkt275
« Reply #14 on: February 13, 2018, 02:36:43 PM »
He has the battery connected for pos. ground.