Need help understanding a power circuit (caps and diodes)LM7805 and Zener DiodesPower origin and power planes placement on PCBLayout of decoupling capacitorsBulk Capacitance and Inrush Current Limiting Diodes burn for PSU first stageNeed help identifying replacement Magic Smoke ContainerNeed Help Understanding a Circuit (Atari 2600 XTAL Oscillator)Why do some capacitors not have vents?switch mode power supply diodesUnderstanding how an audio amplifying circuit worksDC Power Supply Output Caps: Electrical Advantage to using many smaller capacitors instead of few large?
What are these boxed doors outside store fronts in New York?
Accidentally leaked the solution to an assignment, what to do now? (I'm the prof)
A Journey Through Space and Time
Why Is Death Allowed In the Matrix?
What is the command to reset a PC without deleting any files
Copenhagen passport control - US citizen
How to report a triplet of septets in NMR tabulation?
Banach space and Hilbert space topology
Is it tax fraud for an individual to declare non-taxable revenue as taxable income? (US tax laws)
The magic money tree problem
How much RAM could one put in a typical 80386 setup?
Chess with symmetric move-square
Possibly bubble sort algorithm
Circuitry of TV splitters
Download, install and reboot computer at night if needed
I see my dog run
What is the offset in a seaplane's hull?
Modification to Chariots for Heavy Cavalry Analogue for 4-armed race
Extreme, but not acceptable situation and I can't start the work tomorrow morning
Why is this code 6.5x slower with optimizations enabled?
TGV timetables / schedules?
How can bays and straits be determined in a procedurally generated map?
DOS, create pipe for stdin/stdout of command.com(or 4dos.com) in C or Batch?
What typically incentivizes a professor to change jobs to a lower ranking university?
Need help understanding a power circuit (caps and diodes)
LM7805 and Zener DiodesPower origin and power planes placement on PCBLayout of decoupling capacitorsBulk Capacitance and Inrush Current Limiting Diodes burn for PSU first stageNeed help identifying replacement Magic Smoke ContainerNeed Help Understanding a Circuit (Atari 2600 XTAL Oscillator)Why do some capacitors not have vents?switch mode power supply diodesUnderstanding how an audio amplifying circuit worksDC Power Supply Output Caps: Electrical Advantage to using many smaller capacitors instead of few large?
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty margin-bottom:0;
$begingroup$
I'm trying to repair an old electric piano (Baldwin Piano Pro EP101) and I've gotten advice to check out the filter caps in the power circuit. I've metered out the voltages and I found power where I didn't expect it. Please see image:
Power from transformer coming in the top. Pins "I" and "J" are ground on the bottom. I've mirrored the board so the traces match up with the components on the top side.
- Why do I find voltage on the (-) side of the black capacitor?
- Why is the (+) of the black capacitor going to ground?
- I think both of these capacitors are in series, but why is there ground in the middle of the two caps?
- Does it mean I have power coming in through the "M" pin at that bottom that shouldn't be? Or maybe one of the diodes at D9 and D10 (2nd and 3rd from the left) are bad and letting the power go the wrong way?
Am I on the right track? Should I just start pulling parts and testing them out of circuit? If you're interested in the overall problem, see the short youtube video here: Baldwin Piano Pro - Very loud noises
Edit: Thanks for the feedback.Larger picture and my attempt of a diagram. Surprised to see AC and DC volts when I measured. Not sure what that is about.
simulate this circuit – Schematic created using CircuitLab
power capacitor diodes
asked Mar 30 at 18:39
lopazopylopazopy
436
$endgroup$
|
show 1 more comment
$begingroup$
I'm trying to repair an old electric piano (Baldwin Piano Pro EP101) and I've gotten advice to check out the filter caps in the power circuit. I've metered out the voltages and I found power where I didn't expect it. Please see image:
Power from transformer coming in the top. Pins "I" and "J" are ground on the bottom. I've mirrored the board so the traces match up with the components on the top side.
- Why do I find voltage on the (-) side of the black capacitor?
- Why is the (+) of the black capacitor going to ground?
- I think both of these capacitors are in series, but why is there ground in the middle of the two caps?
- Does it mean I have power coming in through the "M" pin at that bottom that shouldn't be? Or maybe one of the diodes at D9 and D10 (2nd and 3rd from the left) are bad and letting the power go the wrong way?
Am I on the right track? Should I just start pulling parts and testing them out of circuit? If you're interested in the overall problem, see the short youtube video here: Baldwin Piano Pro - Very loud noises
Edit: Thanks for the feedback.Larger picture and my attempt of a diagram. Surprised to see AC and DC volts when I measured. Not sure what that is about.
simulate this circuit – Schematic created using CircuitLab
power capacitor diodes
asked Mar 30 at 18:39
lopazopylopazopy
436
$endgroup$
1
$begingroup$
measure the voltage across the black capacitor ..... what do you get? .....Why is the (+) of the black capacitor going to ground?because the negative terminal of the black capacitor is connected to a voltage that is more negative than ground
$endgroup$
– jsotola
Mar 30 at 19:14
2
$begingroup$
I'm with @Transistor , Some details of that transformer are missing. Either those red & green transformer wires are connected somehow to the yellow transformer wires (perhaps inside the transformer), or there are other wires coming from the transformer not shown. You seem certain that I,J are ground...could there be a transformer connection to this point?
$endgroup$
– glen_geek
Mar 30 at 19:15
$begingroup$
The overall problem looks like keyboard trouble.
$endgroup$
– AltAir
Mar 30 at 19:34
$begingroup$
Measure Vdc across every part and Vac across the Caps. You should expect +Vdc across each cap and Vac<5%Vdc. Suspect any with 0V
$endgroup$
– Sunnyskyguy EE75
Mar 30 at 20:07
$begingroup$
@glen_geek You're right. There is a wire coming from the transformer that I labeled as 0 V. I think I am wrong to call that Ground.
$endgroup$
– lopazopy
Mar 30 at 22:22
|
show 1 more comment
$begingroup$
I'm trying to repair an old electric piano (Baldwin Piano Pro EP101) and I've gotten advice to check out the filter caps in the power circuit. I've metered out the voltages and I found power where I didn't expect it. Please see image:
Power from transformer coming in the top. Pins "I" and "J" are ground on the bottom. I've mirrored the board so the traces match up with the components on the top side.
- Why do I find voltage on the (-) side of the black capacitor?
- Why is the (+) of the black capacitor going to ground?
- I think both of these capacitors are in series, but why is there ground in the middle of the two caps?
- Does it mean I have power coming in through the "M" pin at that bottom that shouldn't be? Or maybe one of the diodes at D9 and D10 (2nd and 3rd from the left) are bad and letting the power go the wrong way?
Am I on the right track? Should I just start pulling parts and testing them out of circuit? If you're interested in the overall problem, see the short youtube video here: Baldwin Piano Pro - Very loud noises
Edit: Thanks for the feedback.Larger picture and my attempt of a diagram. Surprised to see AC and DC volts when I measured. Not sure what that is about.
simulate this circuit – Schematic created using CircuitLab
power capacitor diodes
asked Mar 30 at 18:39
lopazopylopazopy
436
$endgroup$
I'm trying to repair an old electric piano (Baldwin Piano Pro EP101) and I've gotten advice to check out the filter caps in the power circuit. I've metered out the voltages and I found power where I didn't expect it. Please see image:
Power from transformer coming in the top. Pins "I" and "J" are ground on the bottom. I've mirrored the board so the traces match up with the components on the top side.
- Why do I find voltage on the (-) side of the black capacitor?
- Why is the (+) of the black capacitor going to ground?
- I think both of these capacitors are in series, but why is there ground in the middle of the two caps?
- Does it mean I have power coming in through the "M" pin at that bottom that shouldn't be? Or maybe one of the diodes at D9 and D10 (2nd and 3rd from the left) are bad and letting the power go the wrong way?
Am I on the right track? Should I just start pulling parts and testing them out of circuit? If you're interested in the overall problem, see the short youtube video here: Baldwin Piano Pro - Very loud noises
Edit: Thanks for the feedback.Larger picture and my attempt of a diagram. Surprised to see AC and DC volts when I measured. Not sure what that is about.
simulate this circuit – Schematic created using CircuitLab
power capacitor diodes
power capacitor diodes
asked Mar 30 at 18:39
lopazopylopazopy
436
asked Mar 30 at 18:39
lopazopylopazopy
436
edited Mar 30 at 21:40
lopazopy
asked Mar 30 at 18:39
lopazopylopazopy
436
asked Mar 30 at 18:39
lopazopylopazopy
436
asked Mar 30 at 18:39
lopazopylopazopy
436
436
1
$begingroup$
measure the voltage across the black capacitor ..... what do you get? .....Why is the (+) of the black capacitor going to ground?because the negative terminal of the black capacitor is connected to a voltage that is more negative than ground
$endgroup$
– jsotola
Mar 30 at 19:14
2
$begingroup$
I'm with @Transistor , Some details of that transformer are missing. Either those red & green transformer wires are connected somehow to the yellow transformer wires (perhaps inside the transformer), or there are other wires coming from the transformer not shown. You seem certain that I,J are ground...could there be a transformer connection to this point?
$endgroup$
– glen_geek
Mar 30 at 19:15
$begingroup$
The overall problem looks like keyboard trouble.
$endgroup$
– AltAir
Mar 30 at 19:34
$begingroup$
Measure Vdc across every part and Vac across the Caps. You should expect +Vdc across each cap and Vac<5%Vdc. Suspect any with 0V
$endgroup$
– Sunnyskyguy EE75
Mar 30 at 20:07
$begingroup$
@glen_geek You're right. There is a wire coming from the transformer that I labeled as 0 V. I think I am wrong to call that Ground.
$endgroup$
– lopazopy
Mar 30 at 22:22
|
show 1 more comment
1
$begingroup$
measure the voltage across the black capacitor ..... what do you get? .....Why is the (+) of the black capacitor going to ground?because the negative terminal of the black capacitor is connected to a voltage that is more negative than ground
$endgroup$
– jsotola
Mar 30 at 19:14
2
$begingroup$
I'm with @Transistor , Some details of that transformer are missing. Either those red & green transformer wires are connected somehow to the yellow transformer wires (perhaps inside the transformer), or there are other wires coming from the transformer not shown. You seem certain that I,J are ground...could there be a transformer connection to this point?
$endgroup$
– glen_geek
Mar 30 at 19:15
$begingroup$
The overall problem looks like keyboard trouble.
$endgroup$
– AltAir
Mar 30 at 19:34
$begingroup$
Measure Vdc across every part and Vac across the Caps. You should expect +Vdc across each cap and Vac<5%Vdc. Suspect any with 0V
$endgroup$
– Sunnyskyguy EE75
Mar 30 at 20:07
$begingroup$
@glen_geek You're right. There is a wire coming from the transformer that I labeled as 0 V. I think I am wrong to call that Ground.
$endgroup$
– lopazopy
Mar 30 at 22:22
1
1
$begingroup$
measure the voltage across the black capacitor ..... what do you get? .....
Why is the (+) of the black capacitor going to ground? because the negative terminal of the black capacitor is connected to a voltage that is more negative than ground$endgroup$
– jsotola
Mar 30 at 19:14
$begingroup$
measure the voltage across the black capacitor ..... what do you get? .....
Why is the (+) of the black capacitor going to ground? because the negative terminal of the black capacitor is connected to a voltage that is more negative than ground$endgroup$
– jsotola
Mar 30 at 19:14
2
2
$begingroup$
I'm with @Transistor , Some details of that transformer are missing. Either those red & green transformer wires are connected somehow to the yellow transformer wires (perhaps inside the transformer), or there are other wires coming from the transformer not shown. You seem certain that I,J are ground...could there be a transformer connection to this point?
$endgroup$
– glen_geek
Mar 30 at 19:15
$begingroup$
I'm with @Transistor , Some details of that transformer are missing. Either those red & green transformer wires are connected somehow to the yellow transformer wires (perhaps inside the transformer), or there are other wires coming from the transformer not shown. You seem certain that I,J are ground...could there be a transformer connection to this point?
$endgroup$
– glen_geek
Mar 30 at 19:15
$begingroup$
The overall problem looks like keyboard trouble.
$endgroup$
– AltAir
Mar 30 at 19:34
$begingroup$
The overall problem looks like keyboard trouble.
$endgroup$
– AltAir
Mar 30 at 19:34
$begingroup$
Measure Vdc across every part and Vac across the Caps. You should expect +Vdc across each cap and Vac<5%Vdc. Suspect any with 0V
$endgroup$
– Sunnyskyguy EE75
Mar 30 at 20:07
$begingroup$
Measure Vdc across every part and Vac across the Caps. You should expect +Vdc across each cap and Vac<5%Vdc. Suspect any with 0V
$endgroup$
– Sunnyskyguy EE75
Mar 30 at 20:07
$begingroup$
@glen_geek You're right. There is a wire coming from the transformer that I labeled as 0 V. I think I am wrong to call that Ground.
$endgroup$
– lopazopy
Mar 30 at 22:22
$begingroup$
@glen_geek You're right. There is a wire coming from the transformer that I labeled as 0 V. I think I am wrong to call that Ground.
$endgroup$
– lopazopy
Mar 30 at 22:22
|
show 1 more comment
2 Answers
2
active
oldest
votes
$begingroup$
I can only guess what those clever Japanese designers had in mind with these diodes.
Large E-caps must have a Dissipation Factor of << 1% where DF=ESR/Xc(120Hz) with 120Hz ripple current thus with the same current means Vac/Vdc =DF= <1%
Thus C1 is bad , C2 seems OK C3,C4,C5 are all bad.
I would replace all 5 Caps and consider replacing any other E-caps found on other circuit boards from Digikey or Mouser. Consult with tech support for equivalent or better in similar sizes.
simulate this circuit – Schematic created using CircuitLab
answered Mar 31 at 1:21
Sunnyskyguy EE75Sunnyskyguy EE75
70.9k227103
$endgroup$
add a comment |
$begingroup$
+1 for mirroring the underside of the board. Best practice is to draw the schematic and mark up the measured voltages. You can add one in using the CircuitLab button on the editor toolbar. Double-click a component to edit its properties. 'R' = rotate, 'H' = horizontal flip. 'V' = vertical flip. I suspect that there's a transformer centre-tap connected somewhere other than the top of the board so try to draw that too.
Why do I find voltage on the (-) side of the black capacitor?
The circuits must require both positive and negative supplies with respect to ground. This is common in audio circuits.
Why is the (+) of the black capacitor going to ground?
So that correct polarity is maintained.
I think both of these capacitors are in series, but why is there ground in the middle of the two caps?
Time for a schematic.
simulate this circuit – Schematic created using CircuitLab
Figure 1. (a) A single-rail supply. (b) A split-rail supply giving both positive and voltage power outputs.
Does it mean I have power coming in through the "M" pin at that bottom that shouldn't be?
Or maybe one of the diodes at D9 and D10 (2nd and 3rd from the left) are bad and letting the power go the wrong way?
No. All is well in that regard.
Post a schematic as best you can and we'll update the answer.
answered Mar 30 at 19:16
TransistorTransistor
88.4k785190
$endgroup$
$begingroup$
Sorry but your schematic here looks nothing like the board as all inputs go only to Anodes while an AC bridge input connects to one Anode and one Cathode on each input. But the caps are correct and there is no obvious 0V reference except may I,J which are paired.
$endgroup$
– Sunnyskyguy EE75
Mar 30 at 20:11
1
$begingroup$
My Figure 1 isn't meant to be a board schematic. All the inputs go to anodes only. That's why I requested more details.
$endgroup$
– Transistor
Mar 30 at 20:21
add a comment |
Your Answer
StackExchange.ifUsing("editor", function ()
return StackExchange.using("mathjaxEditing", function ()
StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix)
StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["\$", "\$"]]);
);
);
, "mathjax-editing");
StackExchange.ifUsing("editor", function ()
return StackExchange.using("schematics", function ()
StackExchange.schematics.init();
);
, "cicuitlab");
StackExchange.ready(function()
var channelOptions =
tags: "".split(" "),
id: "135"
;
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function()
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled)
StackExchange.using("snippets", function()
createEditor();
);
else
createEditor();
);
function createEditor()
StackExchange.prepareEditor(
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: false,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: null,
bindNavPrevention: true,
postfix: "",
imageUploader:
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
,
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
);
);
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2felectronics.stackexchange.com%2fquestions%2f429857%2fneed-help-understanding-a-power-circuit-caps-and-diodes%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
I can only guess what those clever Japanese designers had in mind with these diodes.
Large E-caps must have a Dissipation Factor of << 1% where DF=ESR/Xc(120Hz) with 120Hz ripple current thus with the same current means Vac/Vdc =DF= <1%
Thus C1 is bad , C2 seems OK C3,C4,C5 are all bad.
I would replace all 5 Caps and consider replacing any other E-caps found on other circuit boards from Digikey or Mouser. Consult with tech support for equivalent or better in similar sizes.
simulate this circuit – Schematic created using CircuitLab
answered Mar 31 at 1:21
Sunnyskyguy EE75Sunnyskyguy EE75
70.9k227103
$endgroup$
add a comment |
$begingroup$
I can only guess what those clever Japanese designers had in mind with these diodes.
Large E-caps must have a Dissipation Factor of << 1% where DF=ESR/Xc(120Hz) with 120Hz ripple current thus with the same current means Vac/Vdc =DF= <1%
Thus C1 is bad , C2 seems OK C3,C4,C5 are all bad.
I would replace all 5 Caps and consider replacing any other E-caps found on other circuit boards from Digikey or Mouser. Consult with tech support for equivalent or better in similar sizes.
simulate this circuit – Schematic created using CircuitLab
answered Mar 31 at 1:21
Sunnyskyguy EE75Sunnyskyguy EE75
70.9k227103
$endgroup$
add a comment |
$begingroup$
I can only guess what those clever Japanese designers had in mind with these diodes.
Large E-caps must have a Dissipation Factor of << 1% where DF=ESR/Xc(120Hz) with 120Hz ripple current thus with the same current means Vac/Vdc =DF= <1%
Thus C1 is bad , C2 seems OK C3,C4,C5 are all bad.
I would replace all 5 Caps and consider replacing any other E-caps found on other circuit boards from Digikey or Mouser. Consult with tech support for equivalent or better in similar sizes.
simulate this circuit – Schematic created using CircuitLab
answered Mar 31 at 1:21
Sunnyskyguy EE75Sunnyskyguy EE75
70.9k227103
$endgroup$
I can only guess what those clever Japanese designers had in mind with these diodes.
Large E-caps must have a Dissipation Factor of << 1% where DF=ESR/Xc(120Hz) with 120Hz ripple current thus with the same current means Vac/Vdc =DF= <1%
Thus C1 is bad , C2 seems OK C3,C4,C5 are all bad.
I would replace all 5 Caps and consider replacing any other E-caps found on other circuit boards from Digikey or Mouser. Consult with tech support for equivalent or better in similar sizes.
simulate this circuit – Schematic created using CircuitLab
answered Mar 31 at 1:21
Sunnyskyguy EE75Sunnyskyguy EE75
70.9k227103
edited Mar 31 at 1:39
answered Mar 31 at 1:21
Sunnyskyguy EE75Sunnyskyguy EE75
70.9k227103
answered Mar 31 at 1:21
Sunnyskyguy EE75Sunnyskyguy EE75
70.9k227103
answered Mar 31 at 1:21
Sunnyskyguy EE75Sunnyskyguy EE75
70.9k227103
70.9k227103
add a comment |
add a comment |
$begingroup$
+1 for mirroring the underside of the board. Best practice is to draw the schematic and mark up the measured voltages. You can add one in using the CircuitLab button on the editor toolbar. Double-click a component to edit its properties. 'R' = rotate, 'H' = horizontal flip. 'V' = vertical flip. I suspect that there's a transformer centre-tap connected somewhere other than the top of the board so try to draw that too.
Why do I find voltage on the (-) side of the black capacitor?
The circuits must require both positive and negative supplies with respect to ground. This is common in audio circuits.
Why is the (+) of the black capacitor going to ground?
So that correct polarity is maintained.
I think both of these capacitors are in series, but why is there ground in the middle of the two caps?
Time for a schematic.
simulate this circuit – Schematic created using CircuitLab
Figure 1. (a) A single-rail supply. (b) A split-rail supply giving both positive and voltage power outputs.
Does it mean I have power coming in through the "M" pin at that bottom that shouldn't be?
Or maybe one of the diodes at D9 and D10 (2nd and 3rd from the left) are bad and letting the power go the wrong way?
No. All is well in that regard.
Post a schematic as best you can and we'll update the answer.
answered Mar 30 at 19:16
TransistorTransistor
88.4k785190
$endgroup$
$begingroup$
Sorry but your schematic here looks nothing like the board as all inputs go only to Anodes while an AC bridge input connects to one Anode and one Cathode on each input. But the caps are correct and there is no obvious 0V reference except may I,J which are paired.
$endgroup$
– Sunnyskyguy EE75
Mar 30 at 20:11
1
$begingroup$
My Figure 1 isn't meant to be a board schematic. All the inputs go to anodes only. That's why I requested more details.
$endgroup$
– Transistor
Mar 30 at 20:21
add a comment |
$begingroup$
+1 for mirroring the underside of the board. Best practice is to draw the schematic and mark up the measured voltages. You can add one in using the CircuitLab button on the editor toolbar. Double-click a component to edit its properties. 'R' = rotate, 'H' = horizontal flip. 'V' = vertical flip. I suspect that there's a transformer centre-tap connected somewhere other than the top of the board so try to draw that too.
Why do I find voltage on the (-) side of the black capacitor?
The circuits must require both positive and negative supplies with respect to ground. This is common in audio circuits.
Why is the (+) of the black capacitor going to ground?
So that correct polarity is maintained.
I think both of these capacitors are in series, but why is there ground in the middle of the two caps?
Time for a schematic.
simulate this circuit – Schematic created using CircuitLab
Figure 1. (a) A single-rail supply. (b) A split-rail supply giving both positive and voltage power outputs.
Does it mean I have power coming in through the "M" pin at that bottom that shouldn't be?
Or maybe one of the diodes at D9 and D10 (2nd and 3rd from the left) are bad and letting the power go the wrong way?
No. All is well in that regard.
Post a schematic as best you can and we'll update the answer.
answered Mar 30 at 19:16
TransistorTransistor
88.4k785190
$endgroup$
$begingroup$
Sorry but your schematic here looks nothing like the board as all inputs go only to Anodes while an AC bridge input connects to one Anode and one Cathode on each input. But the caps are correct and there is no obvious 0V reference except may I,J which are paired.
$endgroup$
– Sunnyskyguy EE75
Mar 30 at 20:11
1
$begingroup$
My Figure 1 isn't meant to be a board schematic. All the inputs go to anodes only. That's why I requested more details.
$endgroup$
– Transistor
Mar 30 at 20:21
add a comment |
$begingroup$
+1 for mirroring the underside of the board. Best practice is to draw the schematic and mark up the measured voltages. You can add one in using the CircuitLab button on the editor toolbar. Double-click a component to edit its properties. 'R' = rotate, 'H' = horizontal flip. 'V' = vertical flip. I suspect that there's a transformer centre-tap connected somewhere other than the top of the board so try to draw that too.
Why do I find voltage on the (-) side of the black capacitor?
The circuits must require both positive and negative supplies with respect to ground. This is common in audio circuits.
Why is the (+) of the black capacitor going to ground?
So that correct polarity is maintained.
I think both of these capacitors are in series, but why is there ground in the middle of the two caps?
Time for a schematic.
simulate this circuit – Schematic created using CircuitLab
Figure 1. (a) A single-rail supply. (b) A split-rail supply giving both positive and voltage power outputs.
Does it mean I have power coming in through the "M" pin at that bottom that shouldn't be?
Or maybe one of the diodes at D9 and D10 (2nd and 3rd from the left) are bad and letting the power go the wrong way?
No. All is well in that regard.
Post a schematic as best you can and we'll update the answer.
answered Mar 30 at 19:16
TransistorTransistor
88.4k785190
$endgroup$
+1 for mirroring the underside of the board. Best practice is to draw the schematic and mark up the measured voltages. You can add one in using the CircuitLab button on the editor toolbar. Double-click a component to edit its properties. 'R' = rotate, 'H' = horizontal flip. 'V' = vertical flip. I suspect that there's a transformer centre-tap connected somewhere other than the top of the board so try to draw that too.
Why do I find voltage on the (-) side of the black capacitor?
The circuits must require both positive and negative supplies with respect to ground. This is common in audio circuits.
Why is the (+) of the black capacitor going to ground?
So that correct polarity is maintained.
I think both of these capacitors are in series, but why is there ground in the middle of the two caps?
Time for a schematic.
simulate this circuit – Schematic created using CircuitLab
Figure 1. (a) A single-rail supply. (b) A split-rail supply giving both positive and voltage power outputs.
Does it mean I have power coming in through the "M" pin at that bottom that shouldn't be?
Or maybe one of the diodes at D9 and D10 (2nd and 3rd from the left) are bad and letting the power go the wrong way?
No. All is well in that regard.
Post a schematic as best you can and we'll update the answer.
answered Mar 30 at 19:16
TransistorTransistor
88.4k785190
answered Mar 30 at 19:16
TransistorTransistor
88.4k785190
answered Mar 30 at 19:16
TransistorTransistor
88.4k785190
answered Mar 30 at 19:16
TransistorTransistor
88.4k785190
88.4k785190
$begingroup$
Sorry but your schematic here looks nothing like the board as all inputs go only to Anodes while an AC bridge input connects to one Anode and one Cathode on each input. But the caps are correct and there is no obvious 0V reference except may I,J which are paired.
$endgroup$
– Sunnyskyguy EE75
Mar 30 at 20:11
1
$begingroup$
My Figure 1 isn't meant to be a board schematic. All the inputs go to anodes only. That's why I requested more details.
$endgroup$
– Transistor
Mar 30 at 20:21
add a comment |
$begingroup$
Sorry but your schematic here looks nothing like the board as all inputs go only to Anodes while an AC bridge input connects to one Anode and one Cathode on each input. But the caps are correct and there is no obvious 0V reference except may I,J which are paired.
$endgroup$
– Sunnyskyguy EE75
Mar 30 at 20:11
1
$begingroup$
My Figure 1 isn't meant to be a board schematic. All the inputs go to anodes only. That's why I requested more details.
$endgroup$
– Transistor
Mar 30 at 20:21
$begingroup$
Sorry but your schematic here looks nothing like the board as all inputs go only to Anodes while an AC bridge input connects to one Anode and one Cathode on each input. But the caps are correct and there is no obvious 0V reference except may I,J which are paired.
$endgroup$
– Sunnyskyguy EE75
Mar 30 at 20:11
$begingroup$
Sorry but your schematic here looks nothing like the board as all inputs go only to Anodes while an AC bridge input connects to one Anode and one Cathode on each input. But the caps are correct and there is no obvious 0V reference except may I,J which are paired.
$endgroup$
– Sunnyskyguy EE75
Mar 30 at 20:11
1
1
$begingroup$
My Figure 1 isn't meant to be a board schematic. All the inputs go to anodes only. That's why I requested more details.
$endgroup$
– Transistor
Mar 30 at 20:21
$begingroup$
My Figure 1 isn't meant to be a board schematic. All the inputs go to anodes only. That's why I requested more details.
$endgroup$
– Transistor
Mar 30 at 20:21
add a comment |
Thanks for contributing an answer to Electrical Engineering Stack Exchange!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
Use MathJax to format equations. MathJax reference.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function ()
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2felectronics.stackexchange.com%2fquestions%2f429857%2fneed-help-understanding-a-power-circuit-caps-and-diodes%23new-answer', 'question_page');
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function ()
StackExchange.helpers.onClickDraftSave('#login-link');
);
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
1
$begingroup$
measure the voltage across the black capacitor ..... what do you get? .....
Why is the (+) of the black capacitor going to ground?because the negative terminal of the black capacitor is connected to a voltage that is more negative than ground$endgroup$
– jsotola
Mar 30 at 19:14
2
$begingroup$
I'm with @Transistor , Some details of that transformer are missing. Either those red & green transformer wires are connected somehow to the yellow transformer wires (perhaps inside the transformer), or there are other wires coming from the transformer not shown. You seem certain that I,J are ground...could there be a transformer connection to this point?
$endgroup$
– glen_geek
Mar 30 at 19:15
$begingroup$
The overall problem looks like keyboard trouble.
$endgroup$
– AltAir
Mar 30 at 19:34
$begingroup$
Measure Vdc across every part and Vac across the Caps. You should expect +Vdc across each cap and Vac<5%Vdc. Suspect any with 0V
$endgroup$
– Sunnyskyguy EE75
Mar 30 at 20:07
$begingroup$
@glen_geek You're right. There is a wire coming from the transformer that I labeled as 0 V. I think I am wrong to call that Ground.
$endgroup$
– lopazopy
Mar 30 at 22:22