Help for Aion FX Nucleus (Colorsound Power Boost)

[Wizard69]

I just finished my build of the Nucleus (this is about my 15th pedal or so, about five now from Aion). Never had issues except for this one: I just cannot get it to work, no signal when it's switched on...
- bypass mode works (HW wiring seems OK)
- voltage 9V is ok, LED is on when switched on
- charge pump is working, VA is 17,76V
- triple checked components and soldering joints, all seem OK
- I took some photos of the dissembled pedal
- I took some voltage measurements and put them in the schematics
Hopefully one of you guys can spot a hint what else to check or look for...
Cheers

 

[eh là bas ma]

are you sure the transistors are correctly oriented ?

On schematics, the arrow in the transistor symbol is the Emitter, you can do a continuity test to check if your Emitters are going to the right component, according to schematics.

An other way to debugg this, would be to follow the signal path with an audio probe, that's probably the fastest way too.

Misc > Audio Probe : DIY Fever – Building my own guitars, amps and pedals

[DIY Fever] Audio Probe - very simple contraption that helps with debugging audio circuits

diy-fever.com

 

[Wizard69]

are you sure the transistors are correctly oriented ?

On schematics, the arrow in the transistor symbol is the Emitter, you can do a continuity test to check if your Emitters are going to the right component, according to schematics.

An other way to debugg this, would be to follow the signal path with an audio probe, that's probably the fastest way too.

Misc > Audio Probe : DIY Fever – Building my own guitars, amps and pedals

[DIY Fever] Audio Probe - very simple contraption that helps with debugging audio circuits

diy-fever.com

Hi, Thanks for your quick reply. I struggled there, too. I checked for NPN transistors (as 2N5088): the arrow in the schematic as you mentioned should be the emittor, the input coming from above the collector. I compared this with the spec sheet of the manufacturer (Central Semiconductor) and others (Motorola), should be correct. The Central Semi lead code is:
1) Emitter, 2) Base, 3) Collector

Hope I'm not mistaken (actually I do, this would solve the issue ;-)
I will build the probe tonight and check. I'll share the findings...

 

[eh là bas ma]

Hi, Thanks for your quick reply. I struggled there, too. I checked for NPN transistors (as 2N5088): the arrow in the schematic as you mentioned should be the emittor, the input coming from above the collector. I compared this with the spec sheet of the manufacturer (Central Semiconductor) and others (Motorola), should be correct. The Central Semi lead code is:
1) Emitter, 2) Base, 3) Collector

Hope I'm not mistaken (actually I do, this would solve the issue ;-)
I will build the probe tonight and check. I'll share the findings...

that's the standard pinout for 5088

 

[eh là bas ma]

If you need to audioprobe the circuit to narrow down the issue's location, here is the signal path. In red is the main path, in green are alternate paths to check if the signal goes in and comes out of the Drive and Treble controls.

If the signal stops somewhere, keep probing to find the exact location where it stops, following the schematics. Once you find that location, check the connections with your multimeter on continuity mode, reflow the soldering pads, etc.

Edit : use a cheap amp with your audioprobe, there can be some loud popping sounds.

 

[Wizard69]

I built the probe and checked the signal path: Q1-base has signal, the rest is dead: no signal on Q1-collector, Q2-base or C3. So it's pointless checking the rest at this stage.
Weird, as you can see, the positions of all 5088 on the PCB seem correct. Do you have another guess?
Could it be, that while soldering the 5088 were damaged?

 

[Wizard69]

I just checked the Nucleus documentation again. Kevin from Aion FX mentioned there:
"Be careful of the pinout. For TO-92 transistors, the USA “2N” types are typically 180 degrees rotated
from the European “BC” types. Always check the datasheet to confirm, and line them up to the pads
marked “B”, “C”, and “E” on the PCB. "
Anyone had issues with this?
However, I re-chcked the transistors: is says 2N5088 on the front (flat) side...

 

[eh là bas ma]

I built the probe and checked the signal path: Q1-base has signal, the rest is dead: no signal on Q1-collector, Q2-base or C3. So it's pointless checking the rest at this stage.
Weird, as you can see, the positions of all 5088 on the PCB seem correct. Do you have another guess?
Could it be, that while soldering the 5088 were damaged?

View attachment 90840

If you're sure about the pinout, it could be a bad soldering joint on Q1 or one of the components connected to it. Did you try to reflow the soldering pads in the aera ?
You can also do some continuity tests, touching the transistors legs and the leg of the next component in the circuit according to schematics, see if the parts are correctly connected. If you just touch the soldering pads it could give you wrong results because the pads are connected by the pcb traces.

i'd suggest to socket your transistors, they are heat sensitive, so if you applied heat for too long on their legs, they could be damaged, but if you quickly soldered them, applying heat for 2 or 3 seconds, they should be fine.

If you need to desolder them, do it slowly, let them cool off between each attempts.

At least now you know where the signal stops, you can focus on this zone, that's progress.

From what i can see, it looks like you used lots of solder on your pads... C11 for example, it can lead to bad connections.

Can you post a few pictures of the soldering side ?

Edit: if you have doubts on your transistors pinout, you can try them in another circuit with NPN transistors (unless you never socket your transistors in your builds).
Alternatively, if your multimeter has an hFe reading mode, you can use it to figure out the pinout.

 

[Feral Feline]

Sometimes you can get a dud board, or a dud transistor/resistor/capacitor/whatever...

More likely, the Q1 was damaged during soldering, but still that may not be the case.

Nonetheless, I'm thinking Q1 was/is the culprit, as you say you're not getting any signal past its base.

So, that's first to address. If there are any other issues, they can wait, they'll still be there.



You can try to REFLOW Q1's Collector and Emitter, but given that you've got nothing beyond them (you checked where they meet with R1, R2, and R3 right?) I think just replace Q1 with a SOCKET so you can use a known good 5088 or 5089 etc.

If it were a cold solder joint, then it would likely be just one transistor leg and you'd have signal beyond Q1 somewhere off the good leg.
It is possible to have cold joints on both the collector and emitter legs, though.
Given that you've got NADA at C3, I'm guessing Q1's Collector is the problem.


What's puzzling is you're getting juice throughout Q1. I don't know what the voltages should be for a good transistor there, but I imagine if Q1 is toast you'd be getting some grossly abnormal voltage readings on it (and for all I know the Emitter voltage is grossly off ).

 

[Wizard69]

I took some additional photos from both side of the PCB. My soldering skills are ok I guess, at least I managed 2 working amps and a dozen working pedals. However, I agree that a few solder point are far from perfect ;-)
I re-soldered all that looked suspicious (incl. all transistors) but same effect: NO signal past Q1 base. I agree the 5088 in Q1 seems bad. I'll follow the proposal to use a transistor socket, hope I can squeeze it in since there's very little space between the caps. Already ordered some metal can BC169 as replacements for the socktets. I'll give an update in a few days.
Thanks so far guys!

 

[Wizard69]

Some slight progress: I improvised transistor sockets by using single SIL sockets and probed. Same as before. Then I turned the transistors 180°, now I got signal on Q1-collector as well as Q2-base. Q2-collector still not working. Seems like the pin out of my transistors was NOT the same as on the data sheets...Weird...
So next step is to use the new transistors and try again. Should arrive tomorrow, will report after checking...