DEFX Pompei JFET question

[duck_arse]

about those 2 3 position switches Dino - it might be advisable to add to the build docs a note about orienting them - checking the datasheet will/should indicate a direction marking of some sort, like the bushing keyway slot tab hole thing. because as we all know, they are not symmetric.

[digi2t]

about those 2 position switches Dino - it might be advisable to add to the build docs a note about orienting them - checking the datasheet will/should indicate a direction marking of some sort, like the bushing keyway slot tab hole thing. because as we all know, they are not symmetric.

You talking about the rotary switches duck?

[Zoot]

OK, gentlemen, amazing. Thank you so much.
I'll go through it calmly now that I got back from work.
Soon I'll post back here, hopefully with good news.
Let me reassure you that I did check all parts, twice. I printed the 3 board pages and all the BOM pages and went piece by piece, checking every color for the resistors. You can trust me on that. The first time I did I find a mistaken OPAMP (got a LM386 with the LM741 ones) and an inverted diode (4001) in the power input of the bottom board. Resistors and caps were all right (I'm pretty anal with that as well). BTW, I use this amazing App called EEToolkit PRO on my iPad. It's just the most amazing App I ever had for this use and many other.

All that said, I have a question about the GROWL switch. In the instructions, it's said that all DPDT on-on-on switches should be Type-1, but GROWL is an on-off-on DPDT switch, and is definitely not a Type 1 on-on-on on my build. Should I change??
Thanks.
Cheers,
Zoot

[digi2t]

All that said, I have a question about the GROWL switch. In the instructions, it's said that all DPDT on-on-on switches should be Type-1, but GROWL is an on-off-on DPDT switch, and is definitely not a Type 1 on-on-on on my build. Should I change??
Thanks.
Cheers,
Zoot

No. The message pertaining to the Type 1 on-on-on switches is only to ensure that the correct switch configuration is used in this case. The GROWL switch is effectively an on-off-on, so you're good there.

As you can see in the BOM listing for switches, the "Type 1" designation is only applied to the on-on-on units.

[Govmnt_Lacky]

All that said, I have a question about the GROWL switch. In the instructions, it's said that all DPDT on-on-on switches should be Type-1, but GROWL is an on-off-on DPDT switch, and is definitely not a Type 1 on-on-on on my build. Should I change??

No. The message pertaining to the Type 1 on-on-on switches is only to ensure that the correct switch configuration is used in this case. The GROWL switch is effectively an on-off-on, so you're good there.

As you can see in the BOM listing for switches, the "Type 1" designation is only applied to the on-on-on units.

Sorry... might be my bad. I didn't clarify. As Digi2t said... it was only for you to verify you had the proper switch in the GROWL position. If I said it was a Type 1 then I was mistaken. I'm going on an old man's memory here. 

[Zoot]

Gentlemen, my latest observations

Question: When you observe the LEDs on the front panel, do they alternate/strobe at all? Meaning, does one of them get brighter as the other is dim and vice-versa? You mentioned something about the depth pot and the LEDs however, the Depth pot should only make the LEDs get brighter or dimmer. Not strobe back and forth as I recall. Remember that you need to give the unit about a good 30 seconds for the LFO to kick in and start.

Unfortunately not, I doesn't strobe.

Where the LFO LED's are concerned (from memory) in either PHASE mode, with FREQUENCY SHIFT at the center position;

- The DEPTH should increase/decrease the amount of alternating strobing depth of the LED's. That's to say, at zero, both LED's should be on steady. As you dial up the DEPTH, the LED's will begin to strobe, in an alternating fashion.

DEPTH SWITCHES FROM UP TO DOWN IN LIGHT INTENSITY BUT NO STROBBING.

- The RATE will alter the speed of the alternating pattern.

NOTHING HAPPENING.

- Also keep in mind that the FREQUENCY SHIFT control is a center zero control. In the center position, with the DEPTH control NOT at zero (say noon) the LED's should alternate equally in brightness and pattern. As you shift the FREQUENCY SHIFT control in one direction or the other, this will also translate to the LED's, changing the bias of the brightness of the alternating pattern towards one LED or the other.

THIS HAPPENS WITH NO STROBE

It seems the LFO is not oscillating.
When I run a signal through it, sound comes back in the other side, and it changes if I change the MODE and TREATMENT. It doesn't have a oscillation feel nevertheless. The Preamp pot doesn't seem to have any effect (?)
How do I test the LFO?
Thank you!
Zoot

[duck_arse]

about those 2 position switches Dino - it might be advisable to add to the build docs a note about orienting them - checking the datasheet will/should indicate a direction marking of some sort, like the bushing keyway slot tab hole thing. because as we all know, they are not symmetric.

You talking about the rotary switches duck?

sorry, no, there's many a mickle muckle twixt dick and duckle, I meant the 3 position on-on-on SP3T toggle switches. they need to all be oriented as per their manufacturors datasheet, or the throws won't sync with the circuit. I did look at the circuit, but got a little lost.

[digi2t]

Oh, OK. Orientation is irrelevant. Whether you install them right side up, or upside down, the contact pattern remains the same.

[Zoot]

When using any of the envelope controlled modes (RISE, FALL, UP, DOWN), the LED's will modulate according to the amount of signal input, RATE, DEPTH, SHIFT, and MODULATION RAMP setting. That's to say, with no signal input, both LED's might be on or off (I can't remember which), but when the envelope is triggered by an input signal, the LED's will strobe/alternate during the duration of the signal output. When the signal drops below a certain threshold (the effect stops) the LED's will return to their original state.

This is working as per your description, with signal input there is flickering and it variates with signal, rate, depth, shift, etc.
It seems my issue is only on the phaser side of the build.
Will keep checking, and any hint is welcome.
Thanks,
Zoot

[duck_arse]

Oh, OK. Orientation is irrelevant. Whether you install them right side up, or upside down, the contact pattern remains the same.

may I beg to differ? I have no experience with them in hand, just from digging into the datasheets, but if one side flings before the other in the middle position, and you then rotate the switch 180, then the down-flung is now up-flung, but on the other side of the switch. there's a good chance I will never fully understand these switches - but - the cross-commoned connection will be in the unexpected position if the switch is rotated. if you see what I mean.

from the t80-t datasheet, last page ....
http://www.fk-industrie.de/downloads/T80Ts.pdf

[digi2t]

I see.

I do believe what you're looking at there are example connections. That's to say, the black lines between switch lugs 3 and 5 (in the image above) represent a jumper. If you jumper the lugs as illustrated, then the result is what is described.

In reality, this jumper doesn't exist within the switches themselves. This is the typical contact convention for ON-ON-ON switches;



As you can see, whether it's a Type 1 or Type 2, orientation would make no difference (flip your monitor/laptop/tablet/phone around if you don't believe me). Same applies to the image you posted, as long as the jumper(s) are place as they are illustrated.

If we take it a step further, we can see in the picture you posted that the switch they are using is a Type 2. The black diagonal line between lugs 3 and 5 is user imposed. As such, you have a switch that will give you a different output path for each position. Path (as long as the jumper stays put) does not change if you change the switch orientation.

Also, the fact that they wrote "KEYWAY" above the switch image, at least in this case, is a red herring. Or, perhaps it's only to ensure that the lug numbering will match the illustration when you look at the lug end of the switch itself. Regardless, makes no difference.

On the Pompei, since the jumper is already provided for on the PCB, switch orientation is a non-issue. Just use the correct type switch, and stuff it in any which way.

[duck_arse]

excellent. you answer my next question as well, what being types 1 and 2. I was unaware of the user link business, but it is explicit in the C&K docs. why would you look anywhere else? [at least next time the 3 position toggle comes up in conversation, we have a comprehensive discussion to fall-back on.]

https://www.ckswitches.com/media/2226/ck_techdata.pdf

[Zoot]

Gentlemen,
I guess I found where the issue is.
Following the LFO tracks, the oscillation stops on IC 29. The part is good, I think the issue is related to a scratch I've done when I was assembling, and had completely forgotten. It's been a while... At the time I remember to have measured continuity around it and thought it wasn't going to be a problem, and moved on. I was wrong.
This is something I never fixed. Not sure how to do it...
Any experience on this?
Thanks
Zoot

[Govmnt_Lacky]

That scratch does look suspect. Might want to perform some continuity checks between points to make sure nothing got joined or disconnected.

Also, looks like the trace from the square pad at the bottom got broken (might be camera angle or flux issues though)

[digi2t]

As G_L stated, check continuity from point to point before proceeding. It might just be the masking that is scratched off, but the trace copper might be OK. If the trace is indeed broken, I've gone two different routes with equal success;
Either a short wire jumper between points to restore the continuity (easy), or, carefully scratch back the masking on the trace on either side of the break to reveal copper, and apply a small solder blob to bridge the gap (hard). Your call.

[Zoot]

Hello gentlemen,
I have given it a little break, just to refresh my mind...
Now... the scratch on the board (picture some posts above) has no influence, continuity show all is fine with the board.

What I did was to take the document that was on the thread when you (digi2t) was building it (named HIFLI circuits and test notes)
I checked the circuit points where I could follow some of the tests around the LFO shown in it.



So, in the pictures you can see what I measured, and what I got.
All tests were done with the trim 1/2 biasing parameters (?) I didn't identify what they should have been in the document.

IC28 pin13 shows the square wave, oscillating between +/-130mV. Seems right, although frequency is extremely low, often <2Hz



IC28 pin03 shows the triangle wave, between from +/- 50mV. Seems right too, frequency shows <2Hz most of the time



IC29 pin05 shows a triangle/sine wave, oscillating between +/- 50mV. This is wrong from what I understand. It should be a sine between +/-120mV. Frequency is often <2Hz



IC29 pin06 shows a straight line at -6V. That seems strange, unless the parameters should be changed here.

If you guys see anything I could try from this, and what other things I should be testing to advance I would really appreciate.
Cheers,
Zoot

[digi2t]

Is the GROWL switch in the center position (off)?

[Zoot]

 Yes sir, definitely.

[digi2t]

What kind of switch did you use for the Growl, on-off-on, or on-on-on?

[Zoot]

I have a on-off-on, these tests were done with it in the middle position.