Dead component replacement
Hi EEEEs (Experts Exchange Electronics Engineers),
I just turned the house power off and back on and found that my answering machine won't go back on. It's an Audioline TAM838. I thought I'd see if I could spot any dead looking components, and sure enough, there's a burnt area on the circuit board. So if it's not too hard, I might try to fix it. (Probably not worth my time, but could be interesting.)
Attached are long-distance and close-up photos of the insides.
Correct me if I'm wrong, but it looks to me as if the big crimson component has exploded and leaked onto the 2 resistors (covering one completely and another partially).
You can't see it in the picture, but the crimson component has this written on the burnt side:
474K
250V
Q1. Would you agree that the crimson component is most likely dead?
Q2. Is it likely that any other components have died as a result? (Just trying to calculate funeral expenses, here.)
Q3. Can someone give me a description of that crimson component? (A web search shows me it's probably a polyester film capacitor, but how can I tell what the capacitance is, etc? Do I need a capacitance meter or should it be written on it somewhere?)
Q4. Do we have enough info for me to buy a replacement? If not, how can I get enough?
Q5. Can you see any likely replacement candidates, here:
http://newzealand.rs-online.com/web/c/passive-components/capacitors/polyester-film-capacitors/?sra=p
(The above link takes you directly to polyester film capacitors, in case that's what we need.)
Q6. Would you expect that the black & white 470uF 16V electrolytic(?) capacitor (top-right of close-up photo) is also dead? I see it has some brown stuff on top of it, and maybe on the white phone-line connector cover next to it.
My electronics experience is not very good, but I do have a basic multimeter (no capacitance mode), if that helps.
Thanks.
tel2
DSCF9301.jpg
DSCF9303.jpg
I just turned the house power off and back on and found that my answering machine won't go back on. It's an Audioline TAM838. I thought I'd see if I could spot any dead looking components, and sure enough, there's a burnt area on the circuit board. So if it's not too hard, I might try to fix it. (Probably not worth my time, but could be interesting.)
Attached are long-distance and close-up photos of the insides.
Correct me if I'm wrong, but it looks to me as if the big crimson component has exploded and leaked onto the 2 resistors (covering one completely and another partially).
You can't see it in the picture, but the crimson component has this written on the burnt side:
474K
250V
Q1. Would you agree that the crimson component is most likely dead?
Q2. Is it likely that any other components have died as a result? (Just trying to calculate funeral expenses, here.)
Q3. Can someone give me a description of that crimson component? (A web search shows me it's probably a polyester film capacitor, but how can I tell what the capacitance is, etc? Do I need a capacitance meter or should it be written on it somewhere?)
Q4. Do we have enough info for me to buy a replacement? If not, how can I get enough?
Q5. Can you see any likely replacement candidates, here:
http://newzealand.rs-online.com/web/c/passive-components/capacitors/polyester-film-capacitors/?sra=p
(The above link takes you directly to polyester film capacitors, in case that's what we need.)
Q6. Would you expect that the black & white 470uF 16V electrolytic(?) capacitor (top-right of close-up photo) is also dead? I see it has some brown stuff on top of it, and maybe on the white phone-line connector cover next to it.
My electronics experience is not very good, but I do have a basic multimeter (no capacitance mode), if that helps.
Thanks.
tel2
DSCF9301.jpg
DSCF9303.jpg
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i would assume it is a 470k = 0,470 microFarad for the orange one
i would expect a 250 V type to be much larger
i would expect a 250 V type to be much larger
474 = 470,000 picofarads / .47 microfarads.
ASKER
Thanks again guys.
Hi Dave,
a) Are you trying to imply that the "K" indicates thousands in this case, and is not about tolerance?
b) Why picofarads? Is that the default unit for all caps or just for polyester film, or what?
Thanks.
tel2
Hi Dave,
a) Are you trying to imply that the "K" indicates thousands in this case, and is not about tolerance?
b) Why picofarads? Is that the default unit for all caps or just for polyester film, or what?
Thanks.
tel2
The K isn't part of the capacitor's value ... it's the symbol for tolerance -- in this case it means it's a 10% tolerance unit.
The 470 is a measure of capacitance.
As I noted before, it's likely a 470uF, 10% capacitor.
r.e. the comments that indicate that's too high a value for it's size -- I don't think so. Take a look at similar units: http://www.ebay.com/itm/Capacitor-470uf-250v-Electrolytic-Aluminum-85-C-4-pcs-/161100155327?pt=LH_DefaultDomain_0&hash=item25825149bf
The 470 is a measure of capacitance.
As I noted before, it's likely a 470uF, 10% capacitor.
r.e. the comments that indicate that's too high a value for it's size -- I don't think so. Take a look at similar units: http://www.ebay.com/itm/Capacitor-470uf-250v-Electrolytic-Aluminum-85-C-4-pcs-/161100155327?pt=LH_DefaultDomain_0&hash=item25825149bf
ASKER
Thanks Gary,
> r.e. the comments that indicate that's too high a value for it's size -- I don't think so.
What comments from whom are you refering to? I can't find any such comments from anyone above?
Thanks.
tel2
> r.e. the comments that indicate that's too high a value for it's size -- I don't think so.
What comments from whom are you refering to? I can't find any such comments from anyone above?
Thanks.
tel2
Both nobus and DaveBaldwin suggested it was 0.470 uF
I don't agree. It's fairly clear it's a 470uF, 250v, 10% capacitor :-)
Nevertheless, I wouldn't suggest trying to fix this board (as I noted earlier).
I don't agree. It's fairly clear it's a 470uF, 250v, 10% capacitor :-)
Nevertheless, I wouldn't suggest trying to fix this board (as I noted earlier).
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I had a brain lapse => I knew that, but was off by a factor of 10^3 !!
My "mental math" when I said "... K is the code for a 10% tolerance ... so that's a 470uF capacitor +/- 10% " was 47 x 10^4 = 470,000 ... but I was thinking the relationship between pf and uf was 10^3 when it's actually 10^6
... and when nobus said "... i would expect a 250 V type to be much larger ..." (which is, of course, not true) I simply focused on that instead of re-thinking my math :-)
My "mental math" when I said "... K is the code for a 10% tolerance ... so that's a 470uF capacitor +/- 10% " was 47 x 10^4 = 470,000 ... but I was thinking the relationship between pf and uf was 10^3 when it's actually 10^6
... and when nobus said "... i would expect a 250 V type to be much larger ..." (which is, of course, not true) I simply focused on that instead of re-thinking my math :-)
i agree a modern one "could " have the same size factor, but the older ones are bigger imo.
tx for the backing up, Dave
tx for the backing up, Dave
ASKER
Hi again guys,
Thanks for sorting out that wee point of contention. Good to have agreement on that now.
I unsoldered the capacitor, diode and resistor, and you can see them attached (after some cleaning), and the circuit board before and after I cleaned the gunk off it. All 3 components appear to be in tact...visually.
* The resistor tested OK at 2.18K ohms (approx as expected for 3 red bands).
* The diode reads infinite resistance in one direction (as expected), but in the other direction I get different ohms readings depending on the scale on my digital multimeter! I.e.:
- On the 200 ohm range it reads infinite. Fine so far - obviously more than 200 ohms.
- On the 2000 ohm range it reads 816.
- On the 200K ohm range it reads 3.57 (i.e. 3,570 ohms).
- On the 20K ohm range it reads 28.1 (i.e. 28,100 ohms).
- On the 20M ohm range it reads 2.07 (i.e. 2,070,000 ohms).
Q7. Is this normal? Why does this happen? Is the diode likely to be faulty? (No such thing happens when I test the resistor so I don't think it's my multimeter).
* I can't test the capacitor properly (no proper capacitor test equipment), but on my multimeter I can see it charging, etc (then again when I swap the terminals), but I can see this only on the 20M resistance range.
Q8. Where do you think all that gunk could have come from? The right-hand leg of the capacitor, perhaps?
The other side of the circuit board looks fine to me.
Q9. Just out of interest, why do you think the manufacurer used a 250V capacitor for this application? The output of the (external) power adaptor (not shown in the photos, but its model "9VDC300"), takes 240V AC 50Hz input, but gives 9V DC 300mA output.
PS: Yes, I'm aware this is most likely not with fixing, but I'm learning stuff.
Thanks again.
tel2
DSCF9304.jpg
DSCF9308.jpg
DSCF9310.jpg
Thanks for sorting out that wee point of contention. Good to have agreement on that now.
I unsoldered the capacitor, diode and resistor, and you can see them attached (after some cleaning), and the circuit board before and after I cleaned the gunk off it. All 3 components appear to be in tact...visually.
* The resistor tested OK at 2.18K ohms (approx as expected for 3 red bands).
* The diode reads infinite resistance in one direction (as expected), but in the other direction I get different ohms readings depending on the scale on my digital multimeter! I.e.:
- On the 200 ohm range it reads infinite. Fine so far - obviously more than 200 ohms.
- On the 2000 ohm range it reads 816.
- On the 200K ohm range it reads 3.57 (i.e. 3,570 ohms).
- On the 20K ohm range it reads 28.1 (i.e. 28,100 ohms).
- On the 20M ohm range it reads 2.07 (i.e. 2,070,000 ohms).
Q7. Is this normal? Why does this happen? Is the diode likely to be faulty? (No such thing happens when I test the resistor so I don't think it's my multimeter).
* I can't test the capacitor properly (no proper capacitor test equipment), but on my multimeter I can see it charging, etc (then again when I swap the terminals), but I can see this only on the 20M resistance range.
Q8. Where do you think all that gunk could have come from? The right-hand leg of the capacitor, perhaps?
The other side of the circuit board looks fine to me.
Q9. Just out of interest, why do you think the manufacurer used a 250V capacitor for this application? The output of the (external) power adaptor (not shown in the photos, but its model "9VDC300"), takes 240V AC 50Hz input, but gives 9V DC 300mA output.
PS: Yes, I'm aware this is most likely not with fixing, but I'm learning stuff.
Thanks again.
tel2
DSCF9304.jpg
DSCF9308.jpg
DSCF9310.jpg
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ASKER
Thanks for the fast and helpful response, Dave!
Good spotting about the black & white cap! As mentioned in Q6, I had noticed the gunk on top of that cap, but I didn't notice the gunk on the circuit board before, so it seems your eyesight from a few thousand miles away is better than mine from a here.
I've now disconnected that cap, and the gunk trail goes from its top down to the circuit board (and the circuit board is lower than the components in this device), so I assume it's been leaking from the top.
It passed the basic resistance test I did for it before, but that doesn't mean much.
Apart from the 470uF & 16V, it also says "18 degrees C", "+/-20%" and "VENT" on the side, and the brand looks like "truth"??? I think. Would this suffice as a replacement:
http://www.ebay.com/itm/10-x-470uF-16V-105C-Radial-Electrolytic-Capacitor-8x11-/250851988762?pt=LH_DefaultDomain_0&hash=item3a67f1951a
(That would leave me with just 9 spares!)
I'd still probably need to replace the polyester film cap, of course.
Good spotting about the black & white cap! As mentioned in Q6, I had noticed the gunk on top of that cap, but I didn't notice the gunk on the circuit board before, so it seems your eyesight from a few thousand miles away is better than mine from a here.
I've now disconnected that cap, and the gunk trail goes from its top down to the circuit board (and the circuit board is lower than the components in this device), so I assume it's been leaking from the top.
It passed the basic resistance test I did for it before, but that doesn't mean much.
Apart from the 470uF & 16V, it also says "18 degrees C", "+/-20%" and "VENT" on the side, and the brand looks like "truth"??? I think. Would this suffice as a replacement:
http://www.ebay.com/itm/10-x-470uF-16V-105C-Radial-Electrolytic-Capacitor-8x11-/250851988762?pt=LH_DefaultDomain_0&hash=item3a67f1951a
(That would leave me with just 9 spares!)
I'd still probably need to replace the polyester film cap, of course.
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ASKER
Thanks Dave,
The dimensions look the same (8x11mm).
Regarding the crimson cap:
- How do we know whether it's polyester film or ceramic or other?
- If polyester film, are there cheaper alternatives for this application?
The dimensions look the same (8x11mm).
Regarding the crimson cap:
- How do we know whether it's polyester film or ceramic or other?
- If polyester film, are there cheaper alternatives for this application?
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ASKER
Well, I don't see how (or why) there would be high voltage, considering the output voltage of the (external) power supply is 9V DC, Dave. That being the case, do I just have to allow for 9V max or could it be higher?
Also, is "plastic polyester" the same as "polyester film"? Google's not helping much...yet.
Thanks again.
Also, is "plastic polyester" the same as "polyester film"? Google's not helping much...yet.
Thanks again.
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All you need to know: http://en.wikipedia.org/wiki/Film_capacitor And polyester is also know as Mylar which is trademarked by DuPont.
ASKER
Great!
Thanks Dave.
Feel free to take the rest of the day (or is it night?) off. You deserve it.
Thanks Dave.
Feel free to take the rest of the day (or is it night?) off. You deserve it.
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ASKER
OK, nobus. Thanks.
Would it be reasonable to guess that if 2 caps have already leaked, others are likely to do the same in the reasonably near future? This device is probably 10 years old.
Would it be reasonable to guess that if 2 caps have already leaked, others are likely to do the same in the reasonably near future? This device is probably 10 years old.
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ASKER
Thanks Dave.
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ASKER
Thanks nobus.
> in most cases, the leaking is caused either by high temperature,
Either by high temperature or what?
Thanks.
tel2
> in most cases, the leaking is caused either by high temperature,
Either by high temperature or what?
Thanks.
tel2
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ASKER
Thanks to all of you for your input with this.
I hope the points work out reasonably fair. Sorry, nobus, I think I should have increased the default points for your "accepted solution". However, your last 2 posts were probably only worth 30 points total, so hopefully that compensates somewhat. I marked that post as the "accepted solution" because it was the most comprehensive single post which worked through all my questions.
Anyway, if I find time I might try to fix this someday, armed with the education you've given me.
BTW, can anyone recommend a cheap device for properly testing capacitors? Something on ebay, perhaps? Hopefully under US$30. Or do proper capacitance test devices cost more than that? I've seen some multimeters there that claim to test capacitors, like this one:
www.ebay.com/itm/20mA-20A-AC-Current-Capacitor-Voltmeter-Ohmmeter-HFE-Multitester-Yellow-Black-/290952661495?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item43be2149f7
And here's a dedicated capacitance testor:
www.ebay.com/itm/A6013L-LCD-Capacitance-Capacitor-Meter-Tester-Multimeter-20mF-To-200pF-/161083029896?pt=LH_DefaultDomain_0&hash=item25814bf988
Any comments about the cheap ones above, and do you expect the dedicated one somehow do a more thorough test than the multimeter one? Obviously it has more ranges.
Thanks again.
tel2
I hope the points work out reasonably fair. Sorry, nobus, I think I should have increased the default points for your "accepted solution". However, your last 2 posts were probably only worth 30 points total, so hopefully that compensates somewhat. I marked that post as the "accepted solution" because it was the most comprehensive single post which worked through all my questions.
Anyway, if I find time I might try to fix this someday, armed with the education you've given me.
BTW, can anyone recommend a cheap device for properly testing capacitors? Something on ebay, perhaps? Hopefully under US$30. Or do proper capacitance test devices cost more than that? I've seen some multimeters there that claim to test capacitors, like this one:
www.ebay.com/itm/20mA-20A-AC-Current-Capacitor-Voltmeter-Ohmmeter-HFE-Multitester-Yellow-Black-/290952661495?pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item43be2149f7
And here's a dedicated capacitance testor:
www.ebay.com/itm/A6013L-LCD-Capacitance-Capacitor-Meter-Tester-Multimeter-20mF-To-200pF-/161083029896?pt=LH_DefaultDomain_0&hash=item25814bf988
Any comments about the cheap ones above, and do you expect the dedicated one somehow do a more thorough test than the multimeter one? Obviously it has more ranges.
Thanks again.
tel2
I have a BK 815 Component Tester that I have used for years that I like. Looks like the price hasn't changed much, http://www.ebay.com/itm/BK-Precision-815-Component-Tester-/190895827392?pt=LH_DefaultDomain_0&hash=item2c724729c0
if yourrefer with "your last 2 posts were probably only worth 30 points total" then i must say i'll never get many points, since i keep my answers as short as possible (ASAP) since i'm spending now each day already 3 Hours at least helping here
have fun...
regarding the capacitor tester, you should know that there is no really good, complete tester, since in order to be able to measure them properly, it should be tested at the working voltage - which varies from less than 1 V to maybe over 1000 V
so what they do is do a basic measurement of the capacitance only
you can also test the internal resistance of a capaciitor http://shop.anatekcorp.com/products/component-analyzers/blue-ring-tester-assembly/?back=products
have fun...
regarding the capacitor tester, you should know that there is no really good, complete tester, since in order to be able to measure them properly, it should be tested at the working voltage - which varies from less than 1 V to maybe over 1000 V
so what they do is do a basic measurement of the capacitance only
you can also test the internal resistance of a capaciitor http://shop.anatekcorp.com/products/component-analyzers/blue-ring-tester-assembly/?back=products
ASKER
Hi nobus,
Thanks for that extra info.
> if yourrefer with "your last 2 posts were probably only worth 30 points total" then i must say i'll never get many points, since i keep my answers as short as possible (ASAP) since i'm spending now each day already 3 Hours at least helping here
True, but I'm talking about relative to other posts, including some of yours. There are only 500 points to go around a lot of posts, and I think you got a reasonable proportion of the total.
BTW, when I asked this:
>> in most cases, the leaking is caused either by high temperature,
>Either by high temperature or what?
I was trying to get you to give me the other part of the either/or sentence. I'm not sure you understood that, coz I still don't know whether there was one.
Anyway, thanks for all your advice.
tel2
Thanks for that extra info.
> if yourrefer with "your last 2 posts were probably only worth 30 points total" then i must say i'll never get many points, since i keep my answers as short as possible (ASAP) since i'm spending now each day already 3 Hours at least helping here
True, but I'm talking about relative to other posts, including some of yours. There are only 500 points to go around a lot of posts, and I think you got a reasonable proportion of the total.
BTW, when I asked this:
>> in most cases, the leaking is caused either by high temperature,
>Either by high temperature or what?
I was trying to get you to give me the other part of the either/or sentence. I'm not sure you understood that, coz I still don't know whether there was one.
Anyway, thanks for all your advice.
tel2
could be anything really (so i left that off, leaving the either) : manufacturing faults, voltage spikes etc... not really something that gives you a clear indication - so i deleted that part
ASKER
OK.
tel2
tel2
ASKER
Re my Q3, what is this "474K" a measure of? Capacitance? Surely it could not be 474KF, so what is it?
If 474K about capacitance, then how can I tell the capacitance value?
Thanks.
tel2