Capacitor Question

Thread Starter

k5 blazer

Joined Dec 1, 2019
26
I suspect that this cap is bad. There is no sign from visual inspection that this is bad but based on some testing this is my belief. That said I have two questions:

1. Is there anything special about getting a correct replacement to match. I am having a hard time finding one where the leads come out of each end. I understand it is 470uf 25v...... but what about different tolerances etc.

2. From a diagnosis stand point, If I were to remove this cap, in theory would I be about the power up the circuit and see if my issue is fixed that this is causing? Meaning that the cap only stores energy for when it is needed and if the circuit is not taxed would it potential work intermittently or temporary to prove me point.

The cap rings to ground and also rings to 12v positive. Down line of the circuit board I am expecting ground on pin9 on darling transistor array, however I am reading 10+ volts at that pin.
 

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Ylli

Joined Nov 13, 2015
1,089
This is likely just a power bus bypass cap, so the circuit would probably work without it. On the other hand, the chance that this cap is bad and is causing your problem is next to zero.
 

MisterBill2

Joined Jan 23, 2018
19,042
FIRST, the "test" makes no sense at all, and next, you give no statement as to what the problem is. If you used some sort of continuity tester on the capacitor, I can tell you that your results are meaningless.
How much electrical knowledge do you have??? And how much do you understand the system that the capacitor is part of?? AND please tell us what the failure is that you see that makes you believe something has failed.
 

Thread Starter

k5 blazer

Joined Dec 1, 2019
26
FIRST, the "test" makes no sense at all, and next, you give no statement as to what the problem is. If you used some sort of continuity tester on the capacitor, I can tell you that your results are meaningless.
How much electrical knowledge do you have??? And how much do you understand the system that the capacitor is part of?? AND please tell us what the failure is that you see that makes you believe something has failed.
So to sum up a lot of things for you I am a newbie and a bit over my head. I have repaired most, but the last part I can not figure out is the displays. I have 5v power and ground to the display driver. End result is that I believe there is something holding it back from working like the clock data signal is no good or something else that I am overlooking. I am getting above my knowledge base at this point.

And the cap I was referencing is not bad.
 

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MisterBill2

Joined Jan 23, 2018
19,042
If you see +10 volts on a pin that you think should be "ground" , the first step I suggest is an examination of the PCB traces, to verify that it should actually be tied to ground. It might be that you are counting pin locations incorrectly, or that the meter negative connection point is incorrect.
The capacitor mentioned in post #1 has the negative side tied to that ground plain it is mounted on so the negative from a single ended cap could conveniently be tied to ground anywhere.
 
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