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Magnavox HDTV Monitor 32MF605W/17   Goto page 1, 2  Next  
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law565



Joined: 22 Apr 2010
Posts: 4

PostPosted: Thu Apr 22, 2010 7:32 pm    Post subject: Magnavox HDTV Monitor 32MF605W/17 Reply with quote

When i turn this tv on i get a quick flash and then it goes dark. The power light stays green but i get nothing. Ive taken it apart to check for bad capacitors and all are ok. There is 1 ceramic fuse in it but i dont know how to tell if they are bad. I would just replace it to rule that out but my local radio shacks do not have the one i need. So is it maybe the fuse, or something else obvious that i can try? Thanks



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JTS1957



Joined: 21 Jan 2009
Posts: 1698
Location: Far, Far Away

PostPosted: Thu Apr 22, 2010 8:58 pm    Post subject: Reply with quote

Isn't that a tuner in the upper right corner of the Main board? So much for unit being a "monitor."

A fuse is a fuse is a fuse - all test alike = very low resistance (aka has "continuity").

Capacitors can be bad and NOT have a puffed top or oily bottom - I presume this is what you checked for "bad capacitors."
kuhurdler



Joined: 28 Dec 2006
Posts: 2662
Location: Overland Park, KS

PostPosted: Thu Apr 22, 2010 9:09 pm    Post subject: Reply with quote

that cap in the 2nd picture next to the opto-isolator looks bad to me.
JTS1957



Joined: 21 Jan 2009
Posts: 1698
Location: Far, Far Away

PostPosted: Thu Apr 22, 2010 9:22 pm    Post subject: Reply with quote

Which opto? Upper or lower (near sticker)?
law565



Joined: 22 Apr 2010
Posts: 4

PostPosted: Thu Apr 22, 2010 10:11 pm    Post subject: Reply with quote

i have only identified bad capacitors by the puffy tops. Ive never noticed the bad ones to have oily bottoms. Is there a way to test them if they look "normal". And yes that is a tuner on the mainboard. Its a tv first but can be used as a monitor.

JTS1957 wrote:
Isn't that a tuner in the upper right corner of the Main board? So much for unit being a "monitor."

A fuse is a fuse is a fuse - all test alike = very low resistance (aka has "continuity").

Capacitors can be bad and NOT have a puffed top or oily bottom - I presume this is what you checked for "bad capacitors."
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JTS1957



Joined: 21 Jan 2009
Posts: 1698
Location: Far, Far Away

PostPosted: Fri Apr 23, 2010 1:34 am    Post subject: Reply with quote

All kinds/prices of meters. Make sure it tests (at least) "value" and "ESR" ("leakage" & "DA" Dielectric absorption are two other tests).


In the "Good old days," Electrolytic capacitors (in no particular order) sometimes exploded, the electrolyte dried out, ESR rose too high or on occasion they shorted. (Drying out and ESR rising will affect capacitor's value).
Today the most common failure is the puffed top lytic.
Within the last decade, IMO, due to greed by the capacitor manufacturers, capacitors were made using substandard materials and quality control inspectors knowingly "passed" as O.K. caps that weren't even meeting their design specs.

Can anyone remember the tainted pet and baby formula stories of the recent past?

End of rant. I'll now fall off my soapbox.
law565



Joined: 22 Apr 2010
Posts: 4

PostPosted: Thu Apr 29, 2010 8:32 am    Post subject: Reply with quote

Ok well i still haven't fixed this tv. The fuse is good, so maybe a bad capacitor, just not noticable. Im not sure. On another note when changing out capacitors i Know i can go up slightly on the voltage for example change a 16v cap with a 25v. Now can that work the same with the uF capacity? Can i use maybe a 1000 uF capcitor in place of an 820uF
kuhurdler



Joined: 28 Dec 2006
Posts: 2662
Location: Overland Park, KS

PostPosted: Thu Apr 29, 2010 10:23 am    Post subject: Reply with quote

I wouldn't. That's a ~20% change.
JTS1957



Joined: 21 Jan 2009
Posts: 1698
Location: Far, Far Away

PostPosted: Thu Apr 29, 2010 11:20 am    Post subject: Reply with quote

Depends on the function of the circuit that the capacitor is being used in. In case of power supply 20% is the limit that I'd go.
If you plan on doing this work as more than a hobby, I'd try to stock a good assortment for the items/circuits you'lll be seeing. The more serious you are, the closer you should come to carrying ALL standard values at ALL standard voltages. Cool
law565



Joined: 22 Apr 2010
Posts: 4

PostPosted: Thu Apr 29, 2010 1:07 pm    Post subject: Reply with quote

I do have a very wide veriety of capacitors including the correct uF and voltage, The problem is, These new ones are alot fatter that the ones removed from the board and i cant fit them in unless i extend the leads. But then i would have to extend 1 of them about 3", is that acceptable?
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