Caesar Chorus rate light on but not strobing

[Olde Kraken]

having huge issues with this build. I got my rate light to finally come on but it will not strobe. swapped out all leds to make sure anode is where it should be. I get sound and no sound when turning blend, but this thing doesn't sound like its working correctly. Any ideas floating around out there cause i'm at my wits end. i attached a few pics of unit. Thanks

 

[Stickman393]

The rate LED is tied in parallel with the LFO. If it's not pulsing, it means your LFO is stalled out.

I'd look around the circled components. Keep the trimpot at 50% until you find the problem. Sometimes it's as simple as a bad solder joint, or a tiny solder bridge.

 

[Locrian99]

First thing i would do is reflow all your solder joints. Just take your tip and push it into the blob, hold it there for 3-5 seconds, go to the next.

Solder follows two things heat and gravity. The thru holes should literally pull the solder thru.

I hate being the solder guy, but id eliminate the easiest to find first.

 

[Olde Kraken]

Well, I have gone through all the components in the suggested circuit and here are the results. I had replaced the 10u in C103 position and the 47k in position R15. I also replaced the Zener Diode 9V1 in position D101 and still have no flash and it sounds like the pedal really is not changing anything tone wise. Bypass works and I get sound with the pedal on. Scratching my head still, any other suggestions guys?

 

[Olde Kraken]

I have also reflowed all solder joints and inspected under a magnifying lense and found no solder bridges or components touching.

 

[Stickman393]

I take it those resistance measurements were taken in circuit, across each component?

R15 is showing up as a dead short, 0 ohms?

Your problem is somewhere around that component.

 

[Olde Kraken]

i will double check around that area, it may be a bit before i can get to it things got crazy around here. Thanks

 

[Olde Kraken]

went through the system again today, found the 250k pot shot, replaced C1,R1, and C3. I now have 44.6K on R15, but still no strobing rate light. One other question with the switch off should I still have ! led light up as long as there is power to the board? with everything disconnected and the stomp button off I still have 1 Red LED on until I unplug the power source. These Puzzles for grown ups sure give a guy a brain work out. Any other ideas guys, they are greatly appreciated.
Thanks

 

[Stickman393]

The rate LED will pulse regardless of if the pedal is engaged or bypassed. The behavior you describe here is normal, except that the LED should be pulsing, not steadily on.

The rate LED is driven by the Low Frequency Oscillator: the portion of the circuit that I circled in the schematic. If the LED is staying on, that means your LFO is stalled in the "on" state.

Something is causing this to be the case. Maybe a cap that's the wrong value. Double check that you've got the right value in C3, C7, and C11.

Double check the value of R4 and R7.

I'd caution against randomly changing components unless you know that something is incorrect. You run the risk of lifting a trace and making troubleshooting much more difficult.

Keep looking: something isn't right there, and it's keeping your LFO from operating.

 

[Olde Kraken]

I'm running through the testing and found on the schematic D FLO beside a Diode. Which Diode is it , on one side I have R11 and the other side goes to GROUND. So far everything seems to fall in spec, i have even swapped out the IC1 and IC2 chips as I have brand new spares and still no change in function. I am starting to lose faith in my troubleshooting skills. I really appreciate the help as this is my first pedal build and so far its not going to well.

Thanks Again.

 

[eh là bas ma]

A chorus is a bit ambitious as a first build. You should probably start with smaller circuits like a Rat or a SHO booster.

Looking at your pics, i guess i would try to work on these soldering pads. Lots of them are looking suspicious.

Iron set around 400°C.

Remove the excess of solder when necessary with a desoldering pump, re-heat and reflow when they aren't looking perfect. Bend the legs to vertical position when needed.

Once everything looks perfect, hunt for shorts with a multimeter on continuity mode. The slightest piece of hair can bridge two pads and create an issue in the circuit. Clean the space between pads with your iron. If two pads are connected together and you have a doubt about it, check the schematics to see if they should be.

ICs and transistors are heat-sensitive, remove them before using your iron.

 

[Olde Kraken]

does anyone have any technical information as to how the LFO circuit works and what values should be were? I'm getting nowhere with this board and am very frustrated at this point as all individual components are correct and functional as far as i can tell. I could really use some guidance in this situation.
Thanks.

 

[Bio77]

What ICs do you have in IC1 and IC2?

 

[PJS]

I just finished one of these. When it was first built it did the same thing - with the rate light on continuously. Then I remembered to put all the ICs into the sockets and it worked perfectly. I have even changed R11 to a higher value because I am using high brightness LEDs and it works fine. Realistically as long as everything up to the Ic1/R11/R12 junction is correct it should be oscillating.

 

[Stickman393]

does anyone have any technical information as to how the LFO circuit works and what values should be were? I'm getting nowhere with this board and am very frustrated at this point as all individual components are correct and functional as far as i can tell. I could really use some guidance in this situation.
Thanks.

ElectroSmash - Boss CE-2 Analysis

Chorus Effect,Architecture,Circuit, Achematic,Layout,Components Part List,JFET Bypass Switch, Power Supply,Boss ACA vs. PSA Power Supply Adapters,Input Buffer,Input Impedance,Pre-De Emphasis Filters,Shelving Filters with Operational Amplifiers,Inverting O

www.electrosmash.com

The Julia is based off a modified, later version of the Boss CE-2. The early CE-2s use an MN3007 BBD. IIRC, later CE-2s switched to a MN3207 and changed the circuit to accommodate. The MN3007 absolutely does not work in the Julia without significant modification.

The Caesar is based off the Julia, which as a few extra controls, like the switch for the triangle wave LFO.

The D LFO diode is your Rate LED (light emitting DIODE). I can guarantee that diode is not the problem, as you've described that it is always ON. If that LED lights, it is working as it should. The LFO that drives the LED on and off is what isn't working.

Here's another thing: don't assume that you're interpreting the value codes on your components correctly. Double check. That 47n cap could be marked as 47n, 473, 0.047u, 47,000p. Those all mean the same thing.

Double check resistor values using this calculator too: https://www.digikey.com/en/resource...ors/conversion-calculator-resistor-color-code

 

[Olde Kraken]

What ICs do you have in IC1 and IC2?

TL022 IN IC#1 AND RC4558 IN IC#2.

 

[Olde Kraken]

I'm going to take a break from this thing, I cannot figure it out. I'll try in a few weeks again when im not so frustrated. I appreciate the help from you guys and will talk to you soon, when I pick this project up again.
Thank you very much, i'll chat in a few weeks.

 

[Stickman393]

I'm going to take a break from this thing, I cannot figure it out. I'll try in a few weeks again when im not so frustrated. I appreciate the help from you guys and will talk to you soon, when I pick this project up again.
Thank you very much, i'll chat in a few weeks.

Ya know, I endorse this approach as well.

Get a few more builds under your belt. Do some reading, learn more about how these work. Knowledge is cumulative, and you may find a eureka moment when you get back to it.

 

[PJS]

Yep. I know from experience that if I try to troubleshoot when I am frustrated I can do more harm than good. It can be an idea to leave it for a bit and come back calmer.

When you checked all you components did you check the markings, or did you measure them (Measure resistance and capacitance)? The reason I ask is that I have had batches of mis-labelled components before, so they are marked with a value but measure a wildly different value. If a whole batch is bad then of course replacing the component doesn't help. If you checked markings maybe try and measure them.