Total recall power wiring help

[zachlovescoffee]

Okay I know I'm probably missing something obvious. I've looked at every single photo I could find and read the instructions and searched on here and read everything I can find.

I just can't figure out what's wrong. I wired my jack like the photo but I was only get 13V on the regulator. Using an EHX 24v + center.

So I figured that wasn't right and switched the negative lead to the other nib on the DC jack and fried the 240R resistor. So I switched it back (as pictured). What am I missing?

[jimilee]

Is c42 backwards? I don't see the negative stripe.


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[zachlovescoffee]

Yep the 470uf cap appears to be wired correctly

[jimilee]

Yep the 470uf cap appears to be wired correctly

Ah, gotcha.


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[zachlovescoffee]

Weird thought but is there any chance that the 240pf (C40) cap is the wrong kind? I noticed in this build (https://www.madbeanpedals.com/forum/index.php?topic=28533.msg276786#msg276786, midway down the page) that his cap is MASSIVE and I just have a small little yellow MLCC.

[jimilee]

Weird thought but is there any chance that the 240pf (C40) cap is the wrong kind? I noticed in this build (https://www.madbeanpedals.com/forum/index.php?topic=28533.msg276786#msg276786, midway down the page) that his cap is MASSIVE and I just have a small little yellow MLCC.

Nope. May we have clearer, close up photos of both sides of the board along with voltages please sir?

[zachlovescoffee]

Absolutely. Here you go. Before I soldered in the pots I triple checks all of the welds in that area of the board.

The only voltages I can get at this point are from the EHX powersupply and from the DC jack. The power supply is providing 34vdc. As wired in the original picture, the jack was providing no voltage. So, I moved the black wire (-24v) to the other lug of jack. The white wire (+24v) stayed on the ground lug. Now, I can verify that I am getting 34vdc to the jack. And that is +34vdc at the center.

However, when I plug it into the board it immediately starts to toast R57 (240R). I got no readings at the voltage regulator.

[jimilee]

Absolutely. Here you go. Before I soldered in the pots I triple checks all of the welds in that area of the board.

The only voltages I can get at this point are from the EHX powersupply and from the DC jack. The power supply is providing 34vdc. As wired in the original picture, the jack was providing no voltage. So, I moved the black wire (-24v) to the other lug of jack. The white wire (+24v) stayed on the ground lug. Now, I can verify that I am getting 34vdc to the jack. And that is +34vdc at the center.

However, when I plug it into the board it immediately starts to toast R57 (240R). I got no readings at the voltage regulator.

Your diode next to the regulator is backwards.


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[zachlovescoffee]

<face fuqqin' palm>

[jimilee]

<face fuqqin' palm>

After 10 years, I still do it from time to time.


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[zachlovescoffee]

We'll I thought that would solve it and to a certain degree it did but still no dice. At least I'm not popping the R57 resistor now but I have little to no juice flowing to the regulator.

I have +34vdc from the EHX to the jack and to the board. But at the regulator I'm getting the following (no idea on correction measuring approach here):

Pin 1 (closet to top of board): -.05vdc
Pin 2: -1vdc
Pin 3: 0vdc

This ^ is with the board powered on and in bypass or on mode. LED is operational.

I'm measuring with the positive probe on the pin and the negative probable on a grounding point on my bench. Is that right?

Any ideas what I'm missing?

I verified continuity along the entire power path from looking at the circuit Trace/ I have confirmed continuity between power to the board and r57. I'm getting about -2.6vdc there across the resistor (-1vdc on a single side). At D1 diode I'm getting about -29vdc. At r60 I'm getting 0vdc.

[Zerro]

I don't know if I have proper schematic, but if D1 was sat backwards, it is probably damaged - that would explain, why at stabil is not power. BTW, 34V is almost top of what you can put at this stabil input. But now, if everything is ok, there must be at input of stabil cca -30V, at ground 0V and at output -15V. Plus minus. See picture. Those caps are different in this schema but it is not important now - it is only mooster. Power value recomended is -24V - this is what that input resistor 240 Ohm is calibrated on. Otherwise, for -34V put here something around 360 Ohm.

[zachlovescoffee]

I replaced the diode and now the voltages are even lower. I'm reordering my pins based on the graphic you shared. I measured all of these from the pin to ground.

Pin 3 (closet to top of the board): .8vdc
Pin 2 (middle): .45vdc
Pin 1 (bottom): 0vdc

When I measure across pin 3 to pin 2 I'm getting 25vdc.

Any thoughts on next steps?

[Zerro]

At middle (pin2) there must be power input from outer power source. Those -30V or so... Separated from input only by resistor. At output (pin3) must be -15V. I am affraid that or this resistor or even stabil are damaged.

Here is stil one thing: caps at power input are calibrated for 25V in list of details, so if you put here 35V, they are very probably damaged, shooting power from source at zero. And "duting" power source to shortage.

[zachlovescoffee]

Is stabil another word for voltage regulator (3 pin component)? All of the caps I'm using are rated for 35v or higher.

I am now reading -15vdc (black probe on pin 3, red probe on pin 2) across pin 3 and pin 2. Is that good?