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?
Is c42 backwards? I don't see the negative stripe.
Sent from my iPhone using Tapatalk
Yep the 470uf cap appears to be wired correctly
Quote from: zachlovescoffee on December 19, 2021, 12:58:45 PM
Yep the 470uf cap appears to be wired correctly
Ah, gotcha.
Sent from my iPhone using Tapatalk
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.
Quote from: zachlovescoffee on December 19, 2021, 03:06:15 PM
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?
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.
Quote from: zachlovescoffee on December 19, 2021, 07:38:18 PM
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.
Sent from my iPhone using Tapatalk
<face fuqqin' palm>
Quote from: zachlovescoffee on December 19, 2021, 10:25:15 PM
<face fuqqin' palm>
After 10 years, I still do it from time to time.
Sent from my iPhone using Tapatalk
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.
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.
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?
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.
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?
Stabil or stabilizator - yes it is another word for your regulator, thouhg it doesn't regulate any values, only makes one value firm, independently at input values. I am sorry for this confusing you. The "butt" of stabil is here pin 1, sitting at ground. Against this pin you will read all values. So, at input pin 2 you will have some voltage from power supply - you said that you use cca 34V. So here you will have cca 30V (after input resistor). At pin 3 will be output, against ground. So, here 15V. All according picture I attached. BTW, if you use somewhere 34V, filtering caps must have by cca 25% voltage values higher. Here for 34V at input you may need use caps for 40V or higher.
I just took the readings as followings:
Pin 3 across pin 1: -15.09vdc
Pin 3 across pin 2: -29.08vdc
I think that looks right. Do you think I should still increase the size of R57 in this case? Shall I move on to taking IC readings bows?
Quote from: zachlovescoffee on December 21, 2021, 01:41:52 AM
I just took the readings as followings:
Pin 3 across pin 1: -15.09vdc
Pin 3 across pin 2: -29.08vdc
I think that looks right. Do you think I should still increase the size of R57 in this case? Shall I move on to taking IC readings bows?
What wattage is your 240R resistor?
1/4 watt
Unhapilly I don't know what is comperhensive current consumtion of all vehement. So, I don't know what power is lost at this R57. Maybe Madbean will know. If your power has 34V, and after this resistor you have 29V, at this resistor is lost 5V with some current, I just don't know. This will give power lost in heat (current x voltage) Let's say that 100mA is proper value. With 5V lost at R57 it will give 500mW lost in heat. R57 must have mimimally 2x higher calibration - so here it is 1W. But if you will change polarity (by mistake), that protecting diode D1 will make shortage of this at ground, to protect circuit from bad polarity. Not to be D1 damaged, this resistor must lower current thru this diode at safe value. If you will use 34V, and diode can withstand 200mA (catalogue value), you will need 160 Ohm minimal value. But better raise this value for some safety at cca 270 Ohm. (Simplyfied, power lost at this resistor 160 Ohm when shortage, is 34V x 200mA= 7W! When resistor is 270 Ohm, lost power is cca 4W. For a moment it can protect your system. Dependig at max. current that power source can really give, and it's anti-shortage protection, of course!
I hope I didn't bore you with my article :@) I recommend to use 270 Ohm, 4W.
I got a 270 ohm @ 2 watt resistor. But, can someone confirm that the voltages I posted most recently appear to be correct?
I'd like to keep moving forward with the build if I am within the margin of safe operation.
According to the build doc, the 10r is supposed to be 1/2 watt and the 240r is supposed to be 1watt. 2 is plenty good. I'll dig out my power supply, can you clarify what to voltages you are referring? There are a lot listed.
Sent from my iPhone using Tapatalk
Thanks! My resistors should be in spec. Readings from the regulator:
Pin 3 across pin 1: -15.09vdc
Pin 3 across pin 2: -29.08vdc
Output is desired 15V. It is ok.
It's been a long time but the total recall consumes areound 50-75ma depending on how the delay pot is set. It is DEFINITELY under 100ma consumption.
Quote from: danfrank on December 26, 2021, 01:35:40 AM
It's been a long time but the total recall consumes areound 50-75ma depending on how the delay pot is set. It is DEFINITELY under 100ma consumption.
Thank you, so resistors I recommended are sufficient.