Build Your Own Clone Message Board

I have an analogue chorus I built a few years ago. It worked great for a long time. I moved, it went into storage, and I recently tried it again but there’s no effect. The LED blinks and does change with the rate knob. There’s also a “ticking” in time with the rate changes. I’ve tried to reflow the solder with no success. I appreciate any suggestions.

Which version of the AC do you have? It's printed on the top of the PCB.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

It’s version 3.1

Do you have access to a multimeter and know how to measure DC voltage with one? If so, please get a set of pin voltages on the MN3102 and MN3207 IC's. Pin numbering is as shown below.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

I’ll check it ASAP and let you know. Thanks for the help.

Here’s what I found:

MN3102
1 . Varies
2 .038
3 .065
4 .032
5 .029
6 varies
7 .158
8 varies

MN3207
1 .054
2 .033
3 0
4 varies
5 varies
6 .037
7 0
8 0

Thanks, but those values aren't remotely close to what they should be. Are you certain that you took the readings correctly? Here's the method that should be used:

Set the multimeter to the DC voltage mode, indicated by a solid line above a dotted one. Use the 20VDC range setting if it's not an auto-ranging meter. Your power source needs to be connected and there must be a cable in the input jack. If the pedal is assembled into the metal enclosure, put the black probe into one of the corner screw bosses of the enclosure--this is your ground connection. If the "guts" are out of the enclosure, use the sleeve tab of the input jack for the ground connection. Then touch the red probe to each test point that you want to measure.

While you're at it, please also measure & report the pin voltages for the 4558 op amp.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

User error, here are the readings:

MN3102
8.4
4.05
.1
4.07
varies, around 300mV
8
2.7
7.84

MN3207
.1mV
4.04
1.64
7.84
8.4
4.05
0
0

4558
2.26
2.28
2.26
.1mV
2.26
2.26
2.26
8.67

OK, those readings make a lot more sense, but not all of them look good. The 3102 voltages appear to be fine....the 3207, not so much. Pin 3 should be around 4V, and pins 7 & 8 in my fully functional AC are at ~6.75V. I suspect a failed 3207, but your readings on the 4558 are also concerning. Pins 1 - 3 and 5 - 7 are all biased by that trimpot and should be up in the 4 - 5V range, not the 2.26 value you are reporting. So we need to get a few more voltage readings to pin this down.

First, measure the DC voltage level on the middle leg of the trimpot, down adjacent to the bottom edge of the PCB. Next, remove the 3207 from its socket (pull gently straight up to avoid bending/breaking any of the legs). Then take a set of DC voltage readings on the 8 sockets themselves using the same method as previously. Also, take another reading on the middle leg of the trimpot while the 3207 is out of the circuit. Report all the results here.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Here’s the latest:

Middle Leg Voltage
2.29, when I turn all the way up it maxes out at 8.66

3207 with IC removed
.4 mV
4.1
3.32
7.85
8.42
4.06
0
0

Middle Leg with 3207 Removed
Same as above, now set to 4

I would recommend replacing the MN3207 IC and then see where you're at. Contact sales@buildyourownclone.com.

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2

Quick update on this. After replacing the IC everything works beautifully. Wouldn’t have expected to have a faulty one but it happens. Thanks so much for the help, I’m really glad to have this back on my board.

Actually, though nowhere near as common as soldering-related issues, IC failures are probably the next most common source of problems we see here. I believe their degree of complexity and the tiny internal clearances within them are big contributors to premature failures. Then again, I'm a chemist by training, not an electrical engineer, so take my opinions with a big ol' grain of salt!

In any case, glad to hear that the new IC got your pedal running again!

_________________
“My favorite programming language is SOLDER” - Bob Pease (RIP)

My Website * My Musical Gear * My DIY Pedals: Pg.1 - Pg.2