I have a Panasonic model PV-V4522 that has power supply damage -- screen indicates there's some AC in the unit where there should be DC. A power supply 82Mfd/200V capacitor has a swelled end and I suspect that part but before I disassemble the unit to possibly replace that I'd like to look for other possible problems by checking some voltages if I knew what they should be and where to measure. Help would be appreciated. Tnx Jim
If a capacitor has swelled then it's bad. When was the unit made? There was a huge batch of defective capacitors made back around 2000-2003 that found their way into all sorts of stuff over the next few years. They often fail like this for no apparent reason.
Tnx James. I'm thinking made about 2002 -- I bought it late 2002. I KNOW when the unit was subject to a power surge and that's when it failed. However there might be other parts damaged as well and that's why I like to know correct voltages and where to look for them.
Failed electrolytics are common in Panasonic VCR power supplies. There are capacitor kits to replace them all and they aren't expensive. That's the first thing to do. Just replacing that one cap may fix it but doing them all isn't that much work and others are probably going to fail soon.
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Was it a surge, or was it a sag? Momentary losses and brownouts often trigger an apparent failure once capacitors get worn out like this. The power supply can run, barely, but then if the voltage dips down to the point it shuts down, it can't start up again.
If you don't know where to measure, and what voltages to expect in a switch mode power supply such as this, then I honestly don't recommend that you try. I don't say this out of any desire to berate your skills or experience, but trust me when I tell you that this type of power supply is EXTREMELY dangerous to people not very experienced in how they work, and very savvy as to what goes wrong with them. Apart from the fact that it has the ability to kill you - literally - one slip of the meter probe can spell instant death to many components on the primary side of the supply. The cap that is bulging is likely, by its value and voltage rating, to be on the primary side of the supply, and any voltage measurements here have to be taken with the negative side of the line power rectifier bridge, as the 'ground' reference for your meter, so you're on dangerous territory right from the off. To begin to be anything like safe when working on switchers, you need at least a bench isolation transformer.
As James said, if the cap is bulging, it's bad, and it was likely a sag rather than a surge that led to the supply stopping for exactly the reasons given. The advice to just change this cap is well given, and will most likely result in a fix. As Sam suggested also, a repair kit is a good route to go down, but if you do finish up changing multiple caps from a kit, do them one at a time, and double check the value and polarity of each replacement before soldering it in. The slightest error will at best result in the supply just not working, and at worst, a cascade failure with fireworks that Disney would be proud of ... !!
Tnx all. The surge was a overvoltage surge (I had several wall transformers burn-out on other equipment). Tnx for the warnings -- I do have a bench isolation transformer. I may just try replacing the 82 ufd capacitor and see if that fixes it. If not it can be added to the pile of defective VCRs (I've never had one that lasted even with limited use! ) and I'll try to find a like-new replacement (I'd really like to advoid the combination units). Jim H.
"jimhigh66" wrote in news: snipped-for-privacy@localhost.talkaboutelectronicequipmen t.com:
The power company should pay for replacements or your homeowner's insurance.
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bz
please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.
bz+spr@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap
Power company possibly, if they were at fault (i.e. not lightning, act of god, car crashing into a pole, etc.) Homeowner's insurance is useless because of deductables.
PeterD wrote in news: snipped-for-privacy@4ax.com:
If it came in on the power line, the power companies insurance may still cover it.
Check the policy. The deductable may not apply to Personal property damaged by lightning or a power surge. You need to read your policy carefully.
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bz 73 de N5BZ k
please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.
bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap
The damage was my fault when, as a result of an ice storm, I connected a
240V generator to the house system and the unequal 120V loads see-sawed one side low and the other side high (live and learn) + the damage never equaled my insurance deductable.
"jimhigh66" wrote in news: snipped-for-privacy@localhost.talkaboutelectronicequipmen t.com:
Thanks. That will serve to remind me of what NOT to do next time our power is out. Hurrican Andrew had me without power for a week and Katrina ... well the power was out at our house for over a week but we were out of town.
If you have checked your policy carefully or with your agent, then you have my sympathy.
If you are just assuming that the deductable would apply in this case, it won't cost you a thing to check and you might be pleasantly surprised.
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bz 73 de N5BZ k
please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.
bz+ser@ch100-5.chem.lsu.edu remove ch100-5 to avoid spam trap
The neutral WAS connected. Some generators will work fine -- mine didn't. (As a precaution I first did a test with a high-wattage bulb on one 120 and low-wattage on the other an it appeared to be OK. The test wasn't adequate.) Now I strap both 120V circuits together. I can't use anything
240V of course, but I can do without that for the limited time required. Regards Jim H.
That sounds like something is screwy in the generator itself, are you sure the neutral didn't break off internally from the 240V socket? I've only dealt with a few of them, but every 240V generator I've used works just fine powering both sides of the panel.
Why do you think other sections of the VCR are blown? It's usually hard for a surge to get past a switchmode power supply. I had one where someone plugged it into 230 VAC by mistake somehow and the only problem was a blown fuse.
One also shouldn't discount the possibility that despite the fact that it seemed to happen due to a problem with the Neutral, that the real reason was that it had power off for awhile and was on the verge of dying from bad caps. Seen that. Works fine until power is removed for a short time.
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Nothing against him personally, but I don't recall Jerry *ever* saying anything besides "take it to a tech", or "throw it away and buy a new one" in the years that I've been on here.
My own experience coincides with yours, power surges very rarely get past the first or second stage of the power supply in any piece of equipment. Unless it took a lightning strike, it's usually pretty simple to fix.
I repair many switchers in the course of my working life, and I would also concur. The 'failure to restart after a power outage' syndrome is in my experience, most often caused by either the small cap which decouples the supply to the switch mode controller IC, or the high value startup resistor(s). The one place where I have had a faulty switcher cause additional damage, is in el cheapo supermarket DVD players, where failure of under-rated secondary side filter electrolytics, can lead to the supply being unable to regulate itself. This can result in the 5v or 12v rails doubling, with the inevitable consequences to the LSIs dotted around on the main board. This is a 'just out of interest' comment, and not to do with power surges finding their way through switchers, of course ...
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