Author Topic: Tremulus Lune - LEDs won't flash  (Read 1949 times)

Joe_Shroe

Tremulus Lune - LEDs won't flash
« on: February 01, 2018, 07:57:59 PM »
Here's the exact schematic I'm using which is this Tremulus Lune schematic with minor changes. Here's the vero board layout I whipped up on paint. (This circuit currently works as intended on my breadboard and the LEDs both flash as they should, so I know the design is fine.)

The problem I have is the 2 LEDs simply turn on and don't flash. Actually, the LED tied to the photocell stays on but the rate LED turns off sometimes when I'm probing it with the multimeter. More specifically when I'm measuring voltages on IC2 (bottom IC), the rate LED will sometimes turn off when I touch pin 3. The LED turns on again if I touch pin 3 and pin 4 together with a multimeter probe. Here's the voltage measurements I got from IC2:

VCC = 9.3 v
pin 1 (OUT) = 6.70 v
pin 2 (IN -) = 6.70 v
pin 3 (IN +) = 6.05 v
pin 4 (GND) = 0
pin 5 (IN +) = 6.20 v
*pin 6 (IN -) = 4.32 v
pin 7 (OUT) = 8.65 v
pin 8 (VCC) = 9.3 v

*When I try to measure pin 6, the voltage starts from around 2-5v then either steadily goes up or down at 0.02v every second. I've seen it start at 4.5v and steadily go down in voltage, another time it was at 0.9v steadily going up in voltage. Maybe an issue with the RC4558? I don't know how I'm supposed to measure this one

I've already checked the connections on the board and confirmed that they all connect to the right pin/wire/component, so my guess is that one of the parts must be the culprit. What's the next step I should take here?
« Last Edit: February 02, 2018, 09:23:49 PM by Joe_Shroe »

highwater

Re: Tremulus Lune - LEDs won't flash
« Reply #1 on: February 01, 2018, 08:52:00 PM »
What voltages are you getting on the breadboard? The same?
"I had an unfortunate combination of a very high-end medium-size system, with a "low price" phono preamp (external; this was the decade when phono was obsolete)."
 - PRR

Joe_Shroe

Re: Tremulus Lune - LEDs won't flash
« Reply #2 on: February 01, 2018, 11:45:00 PM »
Sorry should've put that in the original post.

From the breadboard circuit I'm taking measurements when the LEDs are flashing at about 4 Hz and the speed pot is set to 500 ohms (no "Fine" pot but I still included the 100 ohm resistor between the speed pot and 100 uF cap).

VCC = 9.3 v
pin 1 (OUT) = 5.05 v
pin 2 (IN -) = 5.05 v
pin 3 (IN +) = 5.05 v
pin 4 (GND) = 0
pin 5 (IN +) = 4.1-4.5 v (continually goes up and down, one cycle is about 2 sec)
pin 6 (IN -) = 5.05-7.00 v (also goes up and down, one cycle is about 3.5-4 sec)
pin 7 (OUT) = 5.05 v
pin 8 (VCC) = 9.3 v

Kipper4

Re: Tremulus Lune - LEDs won't flash
« Reply #3 on: February 02, 2018, 12:41:55 AM »
Your Lfo output should be wobbling. It don't look like it is.
I'd check around that.
"Duck_Arse
otherwise, you might end-up with SOIC or gullwings, for surface mounts."


Smoke me a Kipper. I'll be back for breakfast.

Grey Paper.
http://www.aronnelson.com/DIYFiles/up/

Joe_Shroe

Re: Tremulus Lune - LEDs won't flash
« Reply #4 on: February 02, 2018, 01:00:52 AM »
I measured the voltages again. For some reason when I had it at that setting on the speed pot, pins 1 2 3 7 were constant, but when I adjusted the speed a tiny bit (now it's at 460 ohms) the pins are all varying their voltages (except 4 and 8 of course).

pin 1 (OUT) = 4.8-5.2 v
pin 2 (IN -) = 4.8-5.2 v
pin 3 (IN +) = 4.8-5.2 v
pin 4 (GND) = 0
pin 5 (IN +) = 4.0-4.6 v
pin 6 (IN -) = 5.1-6.7 v
pin 7 (OUT) = 4.5-5.6 v
pin 8 (VCC) = 9.3 v

So if the voltage isn't changing on the RC4558 on my circuit, what would I do to fix or test it? I have 4 RC4558's in total and swapping them out don't seem to do anything different.

highwater

Re: Tremulus Lune - LEDs won't flash
« Reply #5 on: February 02, 2018, 02:59:03 AM »
I measured the voltages again. For some reason when I had it at that setting on the speed pot, pins 1 2 3 7 were constant, but when I adjusted the speed a tiny bit (now it's at 460 ohms) the pins are all varying their voltages (except 4 and 8 of course).
I presume that you're measuring the breadboard again. If so, don't worry about that -- digital meters can be misleading when it comes to LFOs. Chances are, the "500ohm" setting just happened to oscillate at the same rate as the sampling-rate of the DMM. Many people keep an old-school moving-needle meter around entirely for that reason.

Quote
So if the voltage isn't changing on the RC4558 on my circuit, what would I do to fix or test it?
You've demonstrated that the non-working build has substantially higher voltages on pins 5-7 than the working breadboard. This suggests that you either (a) have a poor connection between pin 5 and ground (check/re-do the soldering on both of those 1Meg resistors), or (b) there is a short to 9v somewhere around pin 5.

Without pictures of your build, it's hard to say, but from your layout I suspect that the upper lead of the 100ohm resistor might be brushing against the 200k resistor from pin-5 to pin-7. If not, check that your track-cuts are complete, and that there are no solder-bridges between traces; specifically around pins 5, 6, and 7.
"I had an unfortunate combination of a very high-end medium-size system, with a "low price" phono preamp (external; this was the decade when phono was obsolete)."
 - PRR

duck_arse

Re: Tremulus Lune - LEDs won't flash
« Reply #6 on: February 02, 2018, 09:19:46 AM »
welcome to the forum, Joe_Shroe.

looking at the circuit you posted, and the lune circuit, I can see you have the smoothness pot connecting to the 200k and pin 6 of the IC, whereas the lune shows one end of the smooth goes to the (+) pin, pin 5 in your case. what does your board show?

also, did you change the osc timing cap from 10uF to 100uF for extra long slow rate?
Now battery powered. Remove plug when not in use, please.

Joe_Shroe

Re: Tremulus Lune - LEDs won't flash
« Reply #7 on: February 02, 2018, 01:57:46 PM »
Quote
Without pictures of your build, it's hard to say, but from your layout I suspect that the upper lead of the 100ohm resistor might be brushing against the 200k resistor from pin-5 to pin-7. If not, check that your track-cuts are complete, and that there are no solder-bridges between traces; specifically around pins 5, 6, and 7.
Could be, I'll check this when I get home.

Quote
looking at the circuit you posted, and the lune circuit, I can see you have the smoothness pot connecting to the 200k and pin 6 of the IC, whereas the lune shows one end of the smooth goes to the (+) pin, pin 5 in your case. what does your board show?
Oops, I actually drew that wrong on the schematic. Lug 1 of the smoothness pot is connected to pin 5 like it shows in the original Tremulus Lune. I'll have to update that drawing in a bit.

Quote
also, did you change the osc timing cap from 10uF to 100uF for extra long slow rate?
You mean the 100 uF cap that's connected to lug 3 of the smoothness pot? I didn't change the value, it should be 100 uF on the original design as well. Where does it say it should be 10 uF?

Kipper4

Re: Tremulus Lune - LEDs won't flash
« Reply #8 on: February 02, 2018, 04:32:00 PM »

fuzzcentral.ssguitar.com/tremulus/tremulusschematic.gif
"Duck_Arse
otherwise, you might end-up with SOIC or gullwings, for surface mounts."


Smoke me a Kipper. I'll be back for breakfast.

Grey Paper.
http://www.aronnelson.com/DIYFiles/up/

Joe_Shroe

Re: Tremulus Lune - LEDs won't flash
« Reply #9 on: February 03, 2018, 04:48:54 AM »
The 100 uF timing cap actually is pretty slow for me and makes it harder to adjust the faster rates. I might just swap that out with a 10 uF instead, if I get this working right.

I've checked that there's no accidental shorts between copper tracks or pins, and I've spaced out the resistors/caps so they shouldn't be shorting each other. I keep looking over at my breadboard circuit and scratching my head over why that circuit is working but my veroboard one isn't. It must be that I made a mistake with the construction somewhere along the line but I just can't find it (all the wires and components seem to pass the continuity test pretty easily).

Here's some pictures of the top and bottom of my circuit if it helps.