Aion L5 Preamp (9VDC Version) Troubleshooting (voltage drop issue)

[Rob Strand]

'm getting 0,095A without the ICs in and 0.080A with the ICs in measuring between the circuit and L1
I'm measuring 62,8ohm for L1 and about 59ohm for both L2 and L3

That seems pretty low for the current no?

The inductor resistances are way too high for them to be 10uH. 
You should see less than 1 ohm.

The inductors are the problem.   Fairly sure you have 10mH and not 10uH.

FWIW, the radial inductors in the size you have should have an OK DC resistance
for the 10uH.   I think they are 8mm high and 6mm diameter.   The next size up
10mm high and 8mm diameter would also work.

The currents look OK but I haven't added up the currents on the schematic to see if the measurements are "correct".
I guess good enough to say there isn't some major fault.

However, in the documentation it mentions using:
   TEC 3-0923    100mA, 100mA
It mentions that the
   TEC 2-0923   67mA, 67mA
doesn't have enough power.

If the TEC 2-0923 was running at full we would expect to see 300mA from the 9V rail.
For the TEC 3-0923 we expect to see upto 450mA.

The documentation implies we expect should see at least 300mA.
Your currents are much lower than that.  That doesn't means there is a problem.
Maybe things will change with the correct inductors.

[noisegrrrl]

'm getting 0,095A without the ICs in and 0.080A with the ICs in measuring between the circuit and L1
I'm measuring 62,8ohm for L1 and about 59ohm for both L2 and L3

That seems pretty low for the current no?

The inductor resistances are way too high for them to be 10uH. 
You should see less than 1 ohm.

The inductors are the problem.  Fairly sure you have 10mH and not 10uH.

FWIW, the radial inductors in the size you have should have an OK DC resistance
for the 10uH.  I think they are 8mm high and 6mm diameter.  The next size up
10mm high and 8mm diameter would also work.

Well, guess I need to order new inductors then!

The currents look OK but I haven't added up the currents on the schematic to see if the measurements are "correct".
I guess good enough to say there isn't some major fault.

However, in the documentation it mentions using:
  TEC 3-0923 100mA, 100mA
It mentions that the
  TEC 2-0923 67mA, 67mA
doesn't have enough power.

If the TEC 2-0923 was running at full we would expect to see 300mA from the 9V rail.
For the TEC 3-0923 we expect to see upto 450mA.

The documentation implies we expect should see at least 300mA.
Your currents are much lower than that.  That doesn't means there is a problem.
Maybe things will change with the correct inductors.

I'm using a TEC3-0923, I have a spare just in case, if the inductors change doesnt work I'll try that.

Thanks a lot everybody for the help, I'll report back once I have the new inductors.

[noisegrrrl]

IT'S ALIVE!

I went to a local radio shop yesterday, got some 10µH inductances and it works perfectly now.

Except for one thing: I get a loud pop when switching the pedal on or off.
I took it out of the enclosure to check the value of RPD, it's the correct value.
I did a test again with the board out of the enclosure, I don't get the pop.
I haven't yet reassembled it, but I'm not sure what was causing the pop in the first place and how to prevent it if reassembling the pedal causes it to happen again.

[ElectricDruid]

IT'S ALIVE!

I went to a local radio shop yesterday, got some 10µH inductances and it works perfectly now.

Excellent news, and well done! 

You need to give Musikding a good kick up the backside for supplying the wrong inductors with the kit. It sounds like it's a fairly simple "parts number" mistake to make, but it's still an absolute pain in the backside for a builder if you build the kit with the parts provided and it doesn't work. *Of course* you're going to assume it's something you've done, and that's so frustrating if actually the problem is you've been given the wrong parts. Grrrr... 


 

[Rob Strand]

You need to give Musikding a good kick up the backside for supplying the wrong inductors with the kit. It sounds like it's a fairly simple "parts number" mistake to make, but it's still an absolute pain in the backside for a builder if you build the kit with the parts provided and it doesn't work. *Of course* you're going to assume it's something you've done, and that's so frustrating if actually the problem is you've been given the wrong parts. Grrrr...

An inductor error like that would be extremely hard to find for a newbie.  Many hours and IC replacements could go by before giving up and binning the whole build.  The circuit isn't small so that's going to limit debugging.

[Chillums]

I have some Coilcraft inductors that have a 104 (100mH) code on the top of them but they actually measure 100uH (which should read 101) so in there defense maybe something like this happened.  But your right, they should have tested the parts they supplied with the PCB to make sure they worked.

[Rob Strand]

have some Coilcraft inductors that have a 104 (100mH) code on the top of them but they actually measure 100uH (which should read 101) so in there defense maybe something like this happened.  But your right, they should have tested the parts they supplied with the PCB to make sure they worked.

For the Coilcraft inductor 104 does decode to 100uH.
https://www.coilcraft.com/getmedia/dede7c64-f55b-411f-b928-177457845965/rfc0807.pdf

So they have scaled everything to nH.    Very confusing!
(You can buy nH inductors these days so the normal uH scaling doesn't work for those.)

[Chillums]

For the Coilcraft inductor 104 does decode to 100uH.
https://www.coilcraft.com/getmedia/dede7c64-f55b-411f-b928-177457845965/rfc0807.pdf

So they have scaled everything to nH.    Very confusing!
(You can buy nH inductors these days so the normal uH scaling doesn't work for those.)

That makes sense... With the size of the enameled wire and the small size of them I just thought they screwed up the label.  Good to know, thanks Rob!!

[Rob Strand]

That makes sense... With the size of the enameled wire and the small size of them I just thought they screwed up the label.  Good to know, thanks Rob!!

Those things could easily get through as 100mH.  For me I'd see those thick wires and say no way that's 100mH - 100mH would have a heap of very fine wire turns.   However, put some heatshrink over it like some of those through-hole radial types and your only hope is the DC resistance - pretty much the key factor from this thread.   If you aren't expecting problems you aren't going to be measuring DC resistance!