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#1
04-11-2011, 04:10 AM
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Panasonics VHS Issues
Ok, Now I've got alot of my Panasonic VHS VCRS up and running with new Electrolytics.. I've got a few decks that burns out the 1.6 amp fuse, even after replacing all the electrolytics.. I've did some searches and read something about that it's got something to do with zeners and regulators also.. Anyone know? I'm guessing previous owners used them to the point the electrolytics got really bad, causing other components to fail..
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#2
04-11-2011, 08:16 AM
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They usually have a Zener diode on one of the power supply outputs to short and blow the fuse in case the PS puts out too much voltage. Look for a Zener across the 12V output to ground, something like a 1W 15V Zener, or maybe a little higher voltage rated.
Do you have an ESR meter for capacitor checking? I can't work on these with all the bad caps without one.
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#3
04-11-2011, 08:39 AM
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I haven't gotten to that level yet, I think reading a meter requires math, etc.. Plus names and components I don't know fully yet.. I just got familiar with Electrolytics a few years ago, And just know common problems with Caps in certain electronics, and just know what to replace for certain problems..
Last edited by tvcollector; 04-11-2011 at 08:44 AM.
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#4
04-11-2011, 08:51 AM
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Quote:
I would tackle my AG-1830's bad caps but Panasonic for some reason decided to apply hot glue to all the adjustment pots and all over the capacitors and other board components, plus it's modular with the smaller boards packed in close together and soldered to the main board. Truely a mess to try and work on. Not technician-friendly!
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#5
04-11-2011, 09:03 AM
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Hum, I heard walmart has one pretty cheap.. I also heard ESR meters can't read caps below 1uf.
I also don't know about other types of caps, alot of them have no info on value and voltage.. I also have a few VCRS that only work on channel 4, when it's selected to 3 it doesn't come in... I'm still trying to figure that out.. Last edited by tvcollector; 04-11-2011 at 09:11 AM.
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#6
04-11-2011, 09:20 AM
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Quote:
What I am talking about is testing the electrolytics. Others types (ceramic, etc) are pretty stable over time, rarely ever a problem. Not that many electrolytics below 1 ufd. Some maybe .1, .22, .33, .47 ufd sizes which ESR will read still high if they are bad. You are not measuring the capacitance, just the ESR. If ESR is high the cap is bad.
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#7
04-11-2011, 09:39 AM
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I guess I will have to buy an ESR meter
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#8
05-05-2011, 04:05 PM
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I opened up the chassis of one of the VCRS I have that blow the fuse... I looked at all the diodes, and not one of them say any thing about the voltage or wattage some of them have numbers and letters but none that say the voltage with a "V" after numbers or wattage with "W" after any numbers. Some diodes are color coded and look like resistors, and one or two of them are black/grey and brown shaped like a resistor and pretty big in size, and others look like a chip... How would i find out the voltage and wattage on these things, if they don't say?
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#9
05-06-2011, 03:09 AM
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The best ways I know to figure out diodes is to look up the numbers you find in an NTE or other part-substitution book, then check the details for the NTE replacement listed, if there is one. You can also try a Google search, but I have found most part search results to be heavily polluted with mass-part-list sites of no value.
Diodes never have any voltage or power ratings on their cases. Older U.S.-made devices could have diodes with part numbers such as 1N914, 1N4004, 1N34 or others, but I have not seen Japanese diodes being as easy to read.
__________________
Chris Quote from another forum: "(Antique TV collecting) always seemed to me to be a fringe hobby that only weirdos did."
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#10
05-06-2011, 07:39 AM
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Quote:
Last edited by Ed in Tx; 05-06-2011 at 07:42 AM.
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