madbeanpedals::forum

Projects => How Do I? Beginner's Paradise. => Topic started by: spilla on December 02, 2020, 10:33:06 AM

Title: Multiplex Jr (1776) modulation rate led not blinking?
Post by: spilla on December 02, 2020, 10:33:06 AM
Just finished up the multiplex Jr from 1776 but the rate led isn't blinking. It just stays lit the whole time.

Pedal sounds great. Modulation is working and the epth/speed knobs are working too. What should I be looking for to get the rate light blinking. I've jumpered the switch (having modulation always on) could that be why?

Thanks!
Title: Re: Multiplex Jr (1776) modulation rate led not blinking?
Post by: matmosphere on December 02, 2020, 11:38:41 AM
It's one of the best delays out there imo.

Need some more info if you want help. Pictures would go a really long way. Have you rested another led to see if the one you used is just bad? Is everything hooked up correctly? Did you make sure to include a clr?
Title: Re: Multiplex Jr (1776) modulation rate led not blinking?
Post by: spilla on December 02, 2020, 11:12:44 PM
I have to agree. Sounds wicked.

That clr you mention, that's for the modulation correct? I used the xvive vtl5c3 instead of a ldr/led for that. As you can see ive jumpered the switch that controls the mod (always on). The only thing that looks suspect (to me) is D2, see the shorter leg is on the anode side, pretty sure i just clipped the anode but not the cathode after install (trimming the leads with wire cutters). Surely, the led wouldnt work if it was in the wrong way?


Title: Re: Multiplex Jr (1776) modulation rate led not blinking?
Post by: spilla on December 02, 2020, 11:17:44 PM
Here are some pics (forgot to add them to the last post)

(https://i.imgur.com/iC6B4r8.jpg)
(https://i.imgur.com/luHlO8W.jpg)
(https://i.imgur.com/3GKBi0M.jpg)
(https://i.imgur.com/r0hL6sD.jpg)
Title: Re: Multiplex Jr (1776) modulation rate led not blinking?
Post by: matmosphere on December 03, 2020, 01:05:38 AM
Clr is a current limiting resistor, sorry I should have been more specific.

The led won't work if it's the wrong way. You can check it though. One side of the led base of flat and the other is rounded.
Title: Multiplex Jr (1776) modulation rate led not blinking?
Post by: jimilee on December 03, 2020, 01:35:50 AM
Look at the schematic around R19, see if you have a short to ground somewhere between the TL072 Pins 1, 2 and your LED.


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Title: Re: Multiplex Jr (1776) modulation rate led not blinking?
Post by: spilla on December 03, 2020, 05:50:59 AM
Thanks lads got it working. Replaced R19, IC2 and teh speed pot. Then reflowed that area. Also installed a switch for the mod (regretted not doing so the first time). I've changed the value of R19, that will only effect the brightness of that led right?  Not audio?

Cheers!
Title: Re: Multiplex Jr (1776) modulation rate led not blinking?
Post by: gtr2 on December 03, 2020, 02:24:46 PM
R19 is a current limiting resistor that will affect both the modulation indicator LED brightness and the LDR brightness.  So it will change the modulation depending on your value selection.
Josh
Title: Re: Multiplex Jr (1776) modulation rate led not blinking?
Post by: spilla on December 04, 2020, 03:26:34 AM
Ok, thanks! Ive put the 1k back in R19.