smd cap identity

I have an old DesignTech car keyless entry remote that has started acting up and appears to have a burnt cap. Can anyone tell what value it might be based on basic wirless circuits that might be in a similar frequency range (which I don't happen to know yet)? The capacitor in question is the one tied to the bottom leg of the transistor. Thanks in advance for any insight here.

Hmmm, Can you check the capacitance of the other capacitor (above the cap) and replace it with that value? That would be the safest bet.

aabeuge said:

I have an old DesignTech car keyless entry remote that has started acting up and appears to have a burnt cap. Can anyone tell what value it might be based on basic wirless circuits that might be in a similar frequency range (which I don't happen to know yet)? The capacitor in question is the one tied to the bottom leg of the transistor. Thanks in advance for any insight here.

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The one marked 682 is a 6k8 resistor , I believe. Mostly these caps on the final driver transistor would be .01 uF SMD

you can get them from any faulty cellphone chargers -- salvage and use them

Thanks for the quick response. I don't have access to any test equipment other than a digital multimeter but I'll see what I can do to try to find that out.

Thanks Sarma, I think I may have an old cell phone charger that I can tear apart.

aabeuge said:

Thanks Sarma, I think I may have an old cell phone charger that I can tear apart.

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In fact if you have a capacitor range in the DMM, you can remove the one above and measure its value.
what if if you can use a multilayer caps with leads instead of chip cap.
there is enough space. I mean the ones we use for digital power supply decoupling -- 0.1 or 0.01.

it may be easier

Are you sure it is actually burned out? From the picture, it looks like it could just be covered with flux.
Check with an ohm meter if it is connected across the battery terminals. If it is, replace it with a 0.01 or 0.1uF cap. If not, it could be any value. Also check if it is shorted.

In most cases you'll need to remove the capacitor from the circuit to test it. If there's a lot of parallel resistance, then it will make the capacitor read a much higher value than it really is.

Okay, well, I'm not sure it's burned out. I removed it and replaced it with one from an old isa sound card of same thickness and size. The remote lit up but would not unlock the car. I put the old one back on and the car unlocks but the remote still acts up. The buttons all look good but the light sometimes stays lit after I press the button. It looks like the negative battery terminal (the longer one) might somehow be shorting to the positive but I don't see how it would cause the light to stay lit. Thanks for all the replies. I'll keep this info in mind if I ever have a similar problem.