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Magnavox - no power

Sparky85

Dec 21, 2015
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Hi - I have a Magnavox, model 55ME314V/F7 s/n DS3A1438112657. The set will not power up, and the power board is an A4GRDMPW. This is a different board than I have see on other sites.
F602 - 1 2.5A 250V fuse appears to be blown, as well as diodes D601, D1707, and D613 (i.e. diodes read 0, vs others that read .5 or .6 on simple multimeter) . All other diodes, capacitors, and resistors give good readings.

I found diodes at Fry's, so no issue there.

I have found multiple similar fuses at littlefuse.com : TE7 - 804 series, TE5 - 392 series, TE5 - 400 series. How do I know which one is correct, or doe is not matter? (I can't seen to upload an image of the fuse ...)



Thanks!
 

dorke

Jun 20, 2015
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What is written on the Fuse (all of it)?
 

Sparky85

Dec 21, 2015
2
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Dec 21, 2015
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an inverted triangle with sTa , T2.5A250V
cRJ (RJ are printed backwards) Registration symbol over US , triangle with Y3E , oval with CQC , diamond w T/5 E with JET below the diamond
 

73's de Edd

Aug 21, 2015
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Sir Sparky . . . . . . . . . . . .aka " the Sparkster "


Initially confirm if your submitted PS part # of A4GRDMPW is not actually being being A4GR1MPW.
With your then comparison and further confirmation of component agreement, with the submitted board info below.

There are 4 separate supplies on the board , you have found fault in the main power supply source as well as a part in each of two of its separate power supplies.

You zeroed in on top right corner areas D601 which is one only one unit of set of 4 of a discrete Full Wave Bridge rectifier circuit with D604 being its mate.

Best to change out all 4 . . . .D601-2-3 and 4 with the equivalent substitution that "Fly's" is going to have in its NTE product line.

That avoids a mismatched imbalanced junction of that ONE replaced unit against the other 3 units.
The good units can be used in the future as individual units or a like set of 2 in a lesser full wave rectifier circuits application.

The other found D1707 and D613 diodes certainly reek of also having a breakdown in their circuits POWER FET's being used ( they're mounted to their alum plate heat sinks.)

When you get to the point where you think that you have found ALL defects , don't just plug in and HOPE.

Instead, rig up a series 40 to 60 watt incandescent lamp, so that it will be in series with one wire of your incoming AC power.

THEN, when you turn on, if the lamp comes on bright, you STILL have troubles right there in River City.

If having a subtle initial glow and decline, that is indicative of the initial surge of power supply filter charge up and then a load down and decline of produced voltage, since the lamp is restricting the sets FULL current consumption demands.

Then . . . . you might be safe to eliminate the series test lamp and proceed to full AC input . . .with all fingers and toes TIGHTLY crossed.

BOARD REFERENCING:
(With the suspect components, being RED starred and YELLOW boxed)


lfDOw3V.jpg


.


Thasssit . . . . .

73's de Edd


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