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RT6224D-based step down circuit yields 0V - why?
Announcing the arrival of Valued Associate #679: Cesar Manara
Planned maintenance scheduled April 17/18, 2019 at 00:00UTC (8:00pm US/Eastern)Debugging a nonsynchronous step-down power supply problemSMPS regulator blows up, could it be a layout issue?Hacking Circuits Together Using Existing SchematicsTI TPS57160-Q1 step-down converter outputs sawtooth-like voltage at high input voltagesUnusual chemical reaction on PCB (SMPS circuit)Intermittent Power Selection with MosfetsBlown Capacitor and Bad Zener Diode in a Switching Power CircuitWhich regulator to use from 12v to 4.2/2.5A and to 3.3VTPS61169 LED driver not functioning properlyLM2577 5V Boost Circuit does not boost voltage
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$begingroup$
We received a set of prototype boards. They have a DC power supply input feeding into a step-down converter, which is built around an RT6224D. It is supposed to deliver 5.0V. The circuit is almost exactly straight from the datasheet, just that the designer chose a 3.3 uH inductivity.
Here is what we have:
This is the Typical Application Circuit from the datasheet:
The problem is, I get exactly 0V at the output. And I can not figure out why. Even on a quick breadboard reproduction of the same circuit, I still get 0 output. I have this feeling there must be something very obvious.
Do you have any idea what is going on here? I greatly appreciate your help!
Edit to answer SamGibson's questions:
(a) PCB layout:
(b) The populated PCB, sorry I don't have an unpopulated board:
(c) Someone else did the design and the layout, I am just trying to make it work. The boards came from a domestic manufacturer. I talked with the designer about the issue, he said U6 it must be a faulty chip. On all 5 boards. So I replaced it with a new one, same result.
(d) I don't know where the board manufacturer got the components initially, my replacement was from Digikey.
(e) I can't find any usable signal to scope, VIN and EN are at 12V, all other pins show a flat lines at 0V.
(f) The inductor is an ASPI-4030S-3R3M-T.
Thanks!
power-supply voltage-regulator switch-mode-power-supply
asked Apr 13 at 15:48
ChrisHChrisH
163
New contributor
ChrisH is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$
We received a set of prototype boards. They have a DC power supply input feeding into a step-down converter, which is built around an RT6224D. It is supposed to deliver 5.0V. The circuit is almost exactly straight from the datasheet, just that the designer chose a 3.3 uH inductivity.
Here is what we have:
This is the Typical Application Circuit from the datasheet:
The problem is, I get exactly 0V at the output. And I can not figure out why. Even on a quick breadboard reproduction of the same circuit, I still get 0 output. I have this feeling there must be something very obvious.
Do you have any idea what is going on here? I greatly appreciate your help!
Edit to answer SamGibson's questions:
(a) PCB layout:
(b) The populated PCB, sorry I don't have an unpopulated board:
(c) Someone else did the design and the layout, I am just trying to make it work. The boards came from a domestic manufacturer. I talked with the designer about the issue, he said U6 it must be a faulty chip. On all 5 boards. So I replaced it with a new one, same result.
(d) I don't know where the board manufacturer got the components initially, my replacement was from Digikey.
(e) I can't find any usable signal to scope, VIN and EN are at 12V, all other pins show a flat lines at 0V.
(f) The inductor is an ASPI-4030S-3R3M-T.
Thanks!
power-supply voltage-regulator switch-mode-power-supply
asked Apr 13 at 15:48
ChrisHChrisH
163
New contributor
ChrisH is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
$begingroup$
Welcome :-) Please edit your question to add: (a) the PCB layout from your EDA software; (b) a photo of this part of the PCB - preferably from an unpopulated PCB and a populated one, but add whatever variations you have; (c) explain the history of the design - did you make a working prototype first (if so, add a photo of that) or did you go from schematic straight to these PCBs? (d) where did you source the regulator ICs from e.g. known distributor, or AliExpress/Ebay etc.? (e) have you used an oscilloscope to see if there is any attempt for the IC to start? (f) link to inductor datasheet?
$endgroup$
– SamGibson
Apr 13 at 16:08
$begingroup$
Thanks for the update. I didn't look further at the start, until that update was available, and the lack of evidence you have been given by the original designer for point (c) i.e the history, is especially revealing - there is no history that the design has ever worked! They seem to have gone straight from schematic to PCB, meaning we have to consider possible design problems, not just layout or manufacturing problems. Looking at it from that perspective, Randy has likely identified the problem. Good luck with a replacement chip, a resistor and a scalpel (X-Acto knife) to rework the PCB.
$endgroup$
– SamGibson
Apr 13 at 17:54
$begingroup$
That is true, I am not aware of any prototypes between the schematic and the pcb.
$endgroup$
– ChrisH
Apr 13 at 18:19
add a comment |
$begingroup$
We received a set of prototype boards. They have a DC power supply input feeding into a step-down converter, which is built around an RT6224D. It is supposed to deliver 5.0V. The circuit is almost exactly straight from the datasheet, just that the designer chose a 3.3 uH inductivity.
Here is what we have:
This is the Typical Application Circuit from the datasheet:
The problem is, I get exactly 0V at the output. And I can not figure out why. Even on a quick breadboard reproduction of the same circuit, I still get 0 output. I have this feeling there must be something very obvious.
Do you have any idea what is going on here? I greatly appreciate your help!
Edit to answer SamGibson's questions:
(a) PCB layout:
(b) The populated PCB, sorry I don't have an unpopulated board:
(c) Someone else did the design and the layout, I am just trying to make it work. The boards came from a domestic manufacturer. I talked with the designer about the issue, he said U6 it must be a faulty chip. On all 5 boards. So I replaced it with a new one, same result.
(d) I don't know where the board manufacturer got the components initially, my replacement was from Digikey.
(e) I can't find any usable signal to scope, VIN and EN are at 12V, all other pins show a flat lines at 0V.
(f) The inductor is an ASPI-4030S-3R3M-T.
Thanks!
power-supply voltage-regulator switch-mode-power-supply
asked Apr 13 at 15:48
ChrisHChrisH
163
New contributor
ChrisH is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
We received a set of prototype boards. They have a DC power supply input feeding into a step-down converter, which is built around an RT6224D. It is supposed to deliver 5.0V. The circuit is almost exactly straight from the datasheet, just that the designer chose a 3.3 uH inductivity.
Here is what we have:
This is the Typical Application Circuit from the datasheet:
The problem is, I get exactly 0V at the output. And I can not figure out why. Even on a quick breadboard reproduction of the same circuit, I still get 0 output. I have this feeling there must be something very obvious.
Do you have any idea what is going on here? I greatly appreciate your help!
Edit to answer SamGibson's questions:
(a) PCB layout:
(b) The populated PCB, sorry I don't have an unpopulated board:
(c) Someone else did the design and the layout, I am just trying to make it work. The boards came from a domestic manufacturer. I talked with the designer about the issue, he said U6 it must be a faulty chip. On all 5 boards. So I replaced it with a new one, same result.
(d) I don't know where the board manufacturer got the components initially, my replacement was from Digikey.
(e) I can't find any usable signal to scope, VIN and EN are at 12V, all other pins show a flat lines at 0V.
(f) The inductor is an ASPI-4030S-3R3M-T.
Thanks!
power-supply voltage-regulator switch-mode-power-supply
power-supply voltage-regulator switch-mode-power-supply
asked Apr 13 at 15:48
ChrisHChrisH
163
New contributor
ChrisH is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked Apr 13 at 15:48
ChrisHChrisH
163
New contributor
ChrisH is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited Apr 13 at 16:42
ChrisH
asked Apr 13 at 15:48
ChrisHChrisH
163
New contributor
ChrisH is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked Apr 13 at 15:48
ChrisHChrisH
163
asked Apr 13 at 15:48
ChrisHChrisH
163
163
New contributor
ChrisH is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
ChrisH is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
ChrisH is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$begingroup$
Welcome :-) Please edit your question to add: (a) the PCB layout from your EDA software; (b) a photo of this part of the PCB - preferably from an unpopulated PCB and a populated one, but add whatever variations you have; (c) explain the history of the design - did you make a working prototype first (if so, add a photo of that) or did you go from schematic straight to these PCBs? (d) where did you source the regulator ICs from e.g. known distributor, or AliExpress/Ebay etc.? (e) have you used an oscilloscope to see if there is any attempt for the IC to start? (f) link to inductor datasheet?
$endgroup$
– SamGibson
Apr 13 at 16:08
$begingroup$
Thanks for the update. I didn't look further at the start, until that update was available, and the lack of evidence you have been given by the original designer for point (c) i.e the history, is especially revealing - there is no history that the design has ever worked! They seem to have gone straight from schematic to PCB, meaning we have to consider possible design problems, not just layout or manufacturing problems. Looking at it from that perspective, Randy has likely identified the problem. Good luck with a replacement chip, a resistor and a scalpel (X-Acto knife) to rework the PCB.
$endgroup$
– SamGibson
Apr 13 at 17:54
$begingroup$
That is true, I am not aware of any prototypes between the schematic and the pcb.
$endgroup$
– ChrisH
Apr 13 at 18:19
add a comment |
$begingroup$
Welcome :-) Please edit your question to add: (a) the PCB layout from your EDA software; (b) a photo of this part of the PCB - preferably from an unpopulated PCB and a populated one, but add whatever variations you have; (c) explain the history of the design - did you make a working prototype first (if so, add a photo of that) or did you go from schematic straight to these PCBs? (d) where did you source the regulator ICs from e.g. known distributor, or AliExpress/Ebay etc.? (e) have you used an oscilloscope to see if there is any attempt for the IC to start? (f) link to inductor datasheet?
$endgroup$
– SamGibson
Apr 13 at 16:08
$begingroup$
Thanks for the update. I didn't look further at the start, until that update was available, and the lack of evidence you have been given by the original designer for point (c) i.e the history, is especially revealing - there is no history that the design has ever worked! They seem to have gone straight from schematic to PCB, meaning we have to consider possible design problems, not just layout or manufacturing problems. Looking at it from that perspective, Randy has likely identified the problem. Good luck with a replacement chip, a resistor and a scalpel (X-Acto knife) to rework the PCB.
$endgroup$
– SamGibson
Apr 13 at 17:54
$begingroup$
That is true, I am not aware of any prototypes between the schematic and the pcb.
$endgroup$
– ChrisH
Apr 13 at 18:19
$begingroup$
Welcome :-) Please edit your question to add: (a) the PCB layout from your EDA software; (b) a photo of this part of the PCB - preferably from an unpopulated PCB and a populated one, but add whatever variations you have; (c) explain the history of the design - did you make a working prototype first (if so, add a photo of that) or did you go from schematic straight to these PCBs? (d) where did you source the regulator ICs from e.g. known distributor, or AliExpress/Ebay etc.? (e) have you used an oscilloscope to see if there is any attempt for the IC to start? (f) link to inductor datasheet?
$endgroup$
– SamGibson
Apr 13 at 16:08
$begingroup$
Welcome :-) Please edit your question to add: (a) the PCB layout from your EDA software; (b) a photo of this part of the PCB - preferably from an unpopulated PCB and a populated one, but add whatever variations you have; (c) explain the history of the design - did you make a working prototype first (if so, add a photo of that) or did you go from schematic straight to these PCBs? (d) where did you source the regulator ICs from e.g. known distributor, or AliExpress/Ebay etc.? (e) have you used an oscilloscope to see if there is any attempt for the IC to start? (f) link to inductor datasheet?
$endgroup$
– SamGibson
Apr 13 at 16:08
$begingroup$
Thanks for the update. I didn't look further at the start, until that update was available, and the lack of evidence you have been given by the original designer for point (c) i.e the history, is especially revealing - there is no history that the design has ever worked! They seem to have gone straight from schematic to PCB, meaning we have to consider possible design problems, not just layout or manufacturing problems. Looking at it from that perspective, Randy has likely identified the problem. Good luck with a replacement chip, a resistor and a scalpel (X-Acto knife) to rework the PCB.
$endgroup$
– SamGibson
Apr 13 at 17:54
$begingroup$
Thanks for the update. I didn't look further at the start, until that update was available, and the lack of evidence you have been given by the original designer for point (c) i.e the history, is especially revealing - there is no history that the design has ever worked! They seem to have gone straight from schematic to PCB, meaning we have to consider possible design problems, not just layout or manufacturing problems. Looking at it from that perspective, Randy has likely identified the problem. Good luck with a replacement chip, a resistor and a scalpel (X-Acto knife) to rework the PCB.
$endgroup$
– SamGibson
Apr 13 at 17:54
$begingroup$
That is true, I am not aware of any prototypes between the schematic and the pcb.
$endgroup$
– ChrisH
Apr 13 at 18:19
$begingroup$
That is true, I am not aware of any prototypes between the schematic and the pcb.
$endgroup$
– ChrisH
Apr 13 at 18:19
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
I'm fairly certain you're blowing up the chip by applying 12V to the EN pin. According to the data sheet the ABS MAX rating on that pin is 6V. Typically one would use a voltage divider to attenuate the input voltage to a value that would yield around 3V on the EN pin with 12V applied.
answered Apr 13 at 16:45
Randy NussRandy Nuss
1945
$endgroup$
4
$begingroup$
Looks right. I think OP can simply connect it to Vin through 100K. "For automatic start-up the EN pin can be connected to VIN, through a 100kΩ resistor. "
$endgroup$
– Spehro Pefhany
Apr 13 at 16:58
1
$begingroup$
Good catch Spehro! I missed that. Adding only one resistor will make the rework much easier.
$endgroup$
– Randy Nuss
Apr 13 at 17:20
2
$begingroup$
Thanks, Randy and Sphero, that is a great point. I had tried this with the very first board I got, lifted pin 4 up, air-wired a 100k to 12V, did not help. But then again, that chip might have been dead from our first attempt to start it up. Will cut some traces, put the 100k on the board, and report back.
$endgroup$
– ChrisH
Apr 13 at 18:18
3
$begingroup$
The chip will be dead. Try bending the lead up before soldering the new one down and bridge 4 to 5 on top of the chip with a 100K 0402 resistor for your "field enhancement".
$endgroup$
– Spehro Pefhany
Apr 13 at 19:16
add a comment |
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1 Answer
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1 Answer
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$begingroup$
I'm fairly certain you're blowing up the chip by applying 12V to the EN pin. According to the data sheet the ABS MAX rating on that pin is 6V. Typically one would use a voltage divider to attenuate the input voltage to a value that would yield around 3V on the EN pin with 12V applied.
answered Apr 13 at 16:45
Randy NussRandy Nuss
1945
$endgroup$
4
$begingroup$
Looks right. I think OP can simply connect it to Vin through 100K. "For automatic start-up the EN pin can be connected to VIN, through a 100kΩ resistor. "
$endgroup$
– Spehro Pefhany
Apr 13 at 16:58
1
$begingroup$
Good catch Spehro! I missed that. Adding only one resistor will make the rework much easier.
$endgroup$
– Randy Nuss
Apr 13 at 17:20
2
$begingroup$
Thanks, Randy and Sphero, that is a great point. I had tried this with the very first board I got, lifted pin 4 up, air-wired a 100k to 12V, did not help. But then again, that chip might have been dead from our first attempt to start it up. Will cut some traces, put the 100k on the board, and report back.
$endgroup$
– ChrisH
Apr 13 at 18:18
3
$begingroup$
The chip will be dead. Try bending the lead up before soldering the new one down and bridge 4 to 5 on top of the chip with a 100K 0402 resistor for your "field enhancement".
$endgroup$
– Spehro Pefhany
Apr 13 at 19:16
add a comment |
$begingroup$
I'm fairly certain you're blowing up the chip by applying 12V to the EN pin. According to the data sheet the ABS MAX rating on that pin is 6V. Typically one would use a voltage divider to attenuate the input voltage to a value that would yield around 3V on the EN pin with 12V applied.
answered Apr 13 at 16:45
Randy NussRandy Nuss
1945
$endgroup$
4
$begingroup$
Looks right. I think OP can simply connect it to Vin through 100K. "For automatic start-up the EN pin can be connected to VIN, through a 100kΩ resistor. "
$endgroup$
– Spehro Pefhany
Apr 13 at 16:58
1
$begingroup$
Good catch Spehro! I missed that. Adding only one resistor will make the rework much easier.
$endgroup$
– Randy Nuss
Apr 13 at 17:20
2
$begingroup$
Thanks, Randy and Sphero, that is a great point. I had tried this with the very first board I got, lifted pin 4 up, air-wired a 100k to 12V, did not help. But then again, that chip might have been dead from our first attempt to start it up. Will cut some traces, put the 100k on the board, and report back.
$endgroup$
– ChrisH
Apr 13 at 18:18
3
$begingroup$
The chip will be dead. Try bending the lead up before soldering the new one down and bridge 4 to 5 on top of the chip with a 100K 0402 resistor for your "field enhancement".
$endgroup$
– Spehro Pefhany
Apr 13 at 19:16
add a comment |
$begingroup$
I'm fairly certain you're blowing up the chip by applying 12V to the EN pin. According to the data sheet the ABS MAX rating on that pin is 6V. Typically one would use a voltage divider to attenuate the input voltage to a value that would yield around 3V on the EN pin with 12V applied.
answered Apr 13 at 16:45
Randy NussRandy Nuss
1945
$endgroup$
I'm fairly certain you're blowing up the chip by applying 12V to the EN pin. According to the data sheet the ABS MAX rating on that pin is 6V. Typically one would use a voltage divider to attenuate the input voltage to a value that would yield around 3V on the EN pin with 12V applied.
answered Apr 13 at 16:45
Randy NussRandy Nuss
1945
answered Apr 13 at 16:45
Randy NussRandy Nuss
1945
answered Apr 13 at 16:45
Randy NussRandy Nuss
1945
answered Apr 13 at 16:45
Randy NussRandy Nuss
1945
1945
4
$begingroup$
Looks right. I think OP can simply connect it to Vin through 100K. "For automatic start-up the EN pin can be connected to VIN, through a 100kΩ resistor. "
$endgroup$
– Spehro Pefhany
Apr 13 at 16:58
1
$begingroup$
Good catch Spehro! I missed that. Adding only one resistor will make the rework much easier.
$endgroup$
– Randy Nuss
Apr 13 at 17:20
2
$begingroup$
Thanks, Randy and Sphero, that is a great point. I had tried this with the very first board I got, lifted pin 4 up, air-wired a 100k to 12V, did not help. But then again, that chip might have been dead from our first attempt to start it up. Will cut some traces, put the 100k on the board, and report back.
$endgroup$
– ChrisH
Apr 13 at 18:18
3
$begingroup$
The chip will be dead. Try bending the lead up before soldering the new one down and bridge 4 to 5 on top of the chip with a 100K 0402 resistor for your "field enhancement".
$endgroup$
– Spehro Pefhany
Apr 13 at 19:16
add a comment |
4
$begingroup$
Looks right. I think OP can simply connect it to Vin through 100K. "For automatic start-up the EN pin can be connected to VIN, through a 100kΩ resistor. "
$endgroup$
– Spehro Pefhany
Apr 13 at 16:58
1
$begingroup$
Good catch Spehro! I missed that. Adding only one resistor will make the rework much easier.
$endgroup$
– Randy Nuss
Apr 13 at 17:20
2
$begingroup$
Thanks, Randy and Sphero, that is a great point. I had tried this with the very first board I got, lifted pin 4 up, air-wired a 100k to 12V, did not help. But then again, that chip might have been dead from our first attempt to start it up. Will cut some traces, put the 100k on the board, and report back.
$endgroup$
– ChrisH
Apr 13 at 18:18
3
$begingroup$
The chip will be dead. Try bending the lead up before soldering the new one down and bridge 4 to 5 on top of the chip with a 100K 0402 resistor for your "field enhancement".
$endgroup$
– Spehro Pefhany
Apr 13 at 19:16
4
4
$begingroup$
Looks right. I think OP can simply connect it to Vin through 100K. "For automatic start-up the EN pin can be connected to VIN, through a 100kΩ resistor. "
$endgroup$
– Spehro Pefhany
Apr 13 at 16:58
$begingroup$
Looks right. I think OP can simply connect it to Vin through 100K. "For automatic start-up the EN pin can be connected to VIN, through a 100kΩ resistor. "
$endgroup$
– Spehro Pefhany
Apr 13 at 16:58
1
1
$begingroup$
Good catch Spehro! I missed that. Adding only one resistor will make the rework much easier.
$endgroup$
– Randy Nuss
Apr 13 at 17:20
$begingroup$
Good catch Spehro! I missed that. Adding only one resistor will make the rework much easier.
$endgroup$
– Randy Nuss
Apr 13 at 17:20
2
2
$begingroup$
Thanks, Randy and Sphero, that is a great point. I had tried this with the very first board I got, lifted pin 4 up, air-wired a 100k to 12V, did not help. But then again, that chip might have been dead from our first attempt to start it up. Will cut some traces, put the 100k on the board, and report back.
$endgroup$
– ChrisH
Apr 13 at 18:18
$begingroup$
Thanks, Randy and Sphero, that is a great point. I had tried this with the very first board I got, lifted pin 4 up, air-wired a 100k to 12V, did not help. But then again, that chip might have been dead from our first attempt to start it up. Will cut some traces, put the 100k on the board, and report back.
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– ChrisH
Apr 13 at 18:18
3
3
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The chip will be dead. Try bending the lead up before soldering the new one down and bridge 4 to 5 on top of the chip with a 100K 0402 resistor for your "field enhancement".
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– Spehro Pefhany
Apr 13 at 19:16
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The chip will be dead. Try bending the lead up before soldering the new one down and bridge 4 to 5 on top of the chip with a 100K 0402 resistor for your "field enhancement".
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– Spehro Pefhany
Apr 13 at 19:16
add a comment |
ChrisH is a new contributor. Be nice, and check out our Code of Conduct.
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Welcome :-) Please edit your question to add: (a) the PCB layout from your EDA software; (b) a photo of this part of the PCB - preferably from an unpopulated PCB and a populated one, but add whatever variations you have; (c) explain the history of the design - did you make a working prototype first (if so, add a photo of that) or did you go from schematic straight to these PCBs? (d) where did you source the regulator ICs from e.g. known distributor, or AliExpress/Ebay etc.? (e) have you used an oscilloscope to see if there is any attempt for the IC to start? (f) link to inductor datasheet?
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– SamGibson
Apr 13 at 16:08
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Thanks for the update. I didn't look further at the start, until that update was available, and the lack of evidence you have been given by the original designer for point (c) i.e the history, is especially revealing - there is no history that the design has ever worked! They seem to have gone straight from schematic to PCB, meaning we have to consider possible design problems, not just layout or manufacturing problems. Looking at it from that perspective, Randy has likely identified the problem. Good luck with a replacement chip, a resistor and a scalpel (X-Acto knife) to rework the PCB.
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– SamGibson
Apr 13 at 17:54
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That is true, I am not aware of any prototypes between the schematic and the pcb.
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– ChrisH
Apr 13 at 18:19