Line 6 DL4 Mod gone wrong?

[effectsbay]

Hello All

My first post!

So I just picked up a cheap Line 6 DL4, and I thought I would do some mods. First, I checked if everything was working properly (BUT.. I checked with batteries - not powered externally), and it's working perfect. My mods would be simple.. replace the footswitches, and replace the LEDs.

After I completed the mods, everything works as expected (for the most part), except a continuous blink on Channel A, B and C if set. The blink happens once approximately every 1-2 seconds. I tried to a factory reset, and the problem persists.

I followed the footswitch mods from 2 YouTube tutorials, and my soft touch switches are Normal Open. Based on what I'm seeing, I feel like they need to be Normal Close switches. I doubt this has anything to do with the blink though.

Here is a video and further explanation:

After doing further debugging, the problem goes away with batteries.. only with the external power supply. I'm using the power supply from another DL4 I have and tested with that unit and works perfectly. The power supply is:

Line 6 Class 2 Power Supply
Model: SY-09200A
Part No: 11-32-0000
Input: 120V AC 60Hz
Output: 9v AC 2000mA

Let me know if you have any ideas? I just ordered a batch of the Normal Close switches.

Thanks!
hank

[g1]

Maybe try putting the stock LED's back in. Could have something to do with different current consumption LED's.
If the problem is gone, then you know your switches are fine.
Did you check the old switches to see if they are NO or NC ?

[effectsbay]

Maybe try putting the stock LED's back in. Could have something to do with different current consumption LED's.
If the problem is gone, then you know your switches are fine.
Did you check the old switches to see if they are NO or NC ?

Wouldn't that cause the same problem when it's run batteries? Right now, I'm leaning towards the capacitor at C40.

Talking with a friend that works on these.. he says the switches are NO, which doesn't make a lot of sense to me. So, if that's the case, these switches are correct.

hank

[MarkusBass]

I'm confused with your confusion about the switches. It seems to me that they should be NORMALLY OPEN. Now, if you want to change them to NORMALLY CLOSED, it is a good moment to stop and think a little bit. Typically, in circuits based on a microprocessor you have NO switches and when you press them (close), you send low level signal to the microprocessor. Usually, there is a pull-up resistor and by closing the switch, you change the voltage sent to the processor. So, the first advise is to measure the voltages on the switches. One pin should be on ground level (0V), and the other is what? In my opinion should be close to the supply voltage of the processor - close to 3.3V. If you have anything else, you should think why. For me, it looks like at least one of the switches is permanently shorted but maybe I'm wrong. Just measure the voltages.

If you have any doubts about the type of the switches, you can just check the old ones with a multimeter (I hope you have one). Also the one that you installed can be easily tested "in-circuit", assuming that you don't connect the batteries, nor the external power supply.

Regarding the problem with the power supply: this is also something that you can easily check. With batteries the effect is supplied with +6V (4x1.5V). With the external power supply it should be exactly the same. So when you plug in the external power supply, there should be +6V on the V+ wire to the batteries. If it is not +6V, either the power supply is bad (e.g. it does not have 9V, or there is something wrong with the circuit between the power supply jack and the rest of the circuit), or you implemented the mods incorrectly. Is it AC power supply, or DC?

PS: I assume you have a multimeter, don't you?

Mark

[Jazz P Bass]

Here is the power supply schematic & info.

DL4_ps.zip

[effectsbay]

If I measure from the capacitor on C40 or C39 to the + on the battery terminal.. I see 8.74v - 8.89v.. not 6v.

Thanks everyone for the help... still learning!

hank

[MarkusBass]

You haven't answer to most important questions:
- what are the voltages on the switches?
- is your power supply AC, or DC?

Edit: if the power supply is AC, can you measure the voltage (AC) directly on the power supply jack? If it is slightly higher than 9V and the input Zener diode is not shorted, voltage slightly above 8V are possible. I was wrong. But instead of fighting with the input voltage, you can just check U14 output voltage (on C58).
And I can only try to convince you that the voltages on switches may tell you a lot about the problems you have.

Mark

[effectsbay]

You haven't answer to most important questions:
- what are the voltages on the switches?
- is your power supply AC, or DC?

Voltages on the switches are reading 3.23v. I didn't think the switch would the issue since it works fine when battery powered. And I'm referring to the bigger problem of the blink. Talking with another individual who works on DL4 thinks something is goofy with the power from AC that is tricking the unit to think something is changed from preset.

Power Supply is proper Line 6 DL4 AC power supply. I tested with another DL4 and no problems. I think the power supply is in good working order.

Thanks!
hank

[MarkusBass]

In such cases I use lab power supply. You have about 2 components to be checked: the Zener diode and the diode in series. Isn't one of them shorted?
Another test that you can do is to use a 9V (DC) power supply. But in this case you have to be sure where is +9V when you connect the power supply. Otherwise, you may case serious damages to the effect. And see what happens.

[effectsbay]

In such cases I use lab power supply. You have about 2 components to be checked: the Zener diode and the diode in series. Isn't one of them shorted?
Another test that you can do is to use a 9V (DC) power supply. But in this case you have to be sure where is +9V when you connect the power supply. Otherwise, you may case serious damages to the effect. And see what happens.

What's the best way to check the diodes? Are you referring to D11, D12 and D16?

Thanks!
hank

[MarkusBass]

You can check them with diode tester in your multimeter. But the easiest way is to connect it to +9V (DC not AC) and measure voltage drop on each diode. On 3.6V Zener diode it should be 3.6V (surprise!) and on the other (series) diode it should be something between 0.55 to 0.65V. The third diode is just a protection diode and it is connected reversed. I don't think that there is anything wrong with it.