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Magnavox 51MP392H/17 RPTV only squeaks   Goto page 1, 2  Next  
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Coltonhursey



Joined: 28 Sep 2011
Posts: 9
Location: Cave city, ky

PostPosted: Wed Sep 28, 2011 2:14 am    Post subject: Magnavox 51MP392H/17 RPTV only squeaks Reply with quote

Let me start by saying that I'm new to working on TV's.
I am electrically inclined. Have had circuits courses, have experience with audio equipment scratch building and repair, and can solder, and use a meter.
I have a feeling that this is going to be more than a simple repair.
Just got the TV stated in title, if you need anymore specific details, please feel free to ask.
Lady said that she left the TV unplugged while she was on vacation for a week. When she returned, she plugged the TV in, and ever since, it hasn't worked.
When the power button is pressed, ELECTRICAL components make a strange squeak/chirp noise about twice per second.
No noise coming from speakers, nothing on the screen, not even a flash.
I am pretty good at figuring things out, but I have no idea where to start on something like this.
Any guidance is greatly appreciated.
And if feel free to ask any questions.
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kuhurdler



Joined: 28 Dec 2006
Posts: 2862
Location: Overland Park, KS

PostPosted: Wed Sep 28, 2011 7:20 am    Post subject: Reply with quote

I would first test the horizontal output transistor.
JTS1957



Joined: 21 Jan 2009
Posts: 2340
Location: Far, Far Away

PostPosted: Wed Sep 28, 2011 8:16 am    Post subject: Reply with quote

If it doesn't start when plug 1516 is disconnected, I would highly suspect the High Voltage Generator.

If set starts when plug 1516 is disconnected, probably bad convergence.
Coltonhursey



Joined: 28 Sep 2011
Posts: 9
Location: Cave city, ky

PostPosted: Wed Sep 28, 2011 2:15 pm    Post subject: Reply with quote

okay, more information and questions.
found source of squeaking.

in picture, yellow component in center towards the top.
if fuse a little to the right of it is pulled, no noise is made.

pulled plug 1516, and squeak is gone.
now, the screen will turn on, and slowly increase in brightness until it becomes completely white. then screen shuts off, and just sits there and makes a normal tv idling noise (very low quiet hum)
Coltonhursey



Joined: 28 Sep 2011
Posts: 9
Location: Cave city, ky

PostPosted: Sat Oct 01, 2011 5:34 am    Post subject: Reply with quote

Any help here?
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kuhurdler



Joined: 28 Dec 2006
Posts: 2862
Location: Overland Park, KS

PostPosted: Sat Oct 01, 2011 9:01 am    Post subject: Reply with quote

if I'm following James correctly, he's stating that it's a convergence problem. Replace the two STK392-120 convergence chips, and check the resistors surrounding them. I like to buy my convergence ICs from MCM Electronics.

This is a fairly easy job for an experienced solder-er. just make sure you don't bridge any solder pads to each other.
JTS1957



Joined: 21 Jan 2009
Posts: 2340
Location: Far, Far Away

PostPosted: Sat Oct 01, 2011 10:50 am    Post subject: Reply with quote

It's "John." "James" is my younger brother.

Correct, I thought I was clear enough, although I should have mentioned you only had to observe the set trying to turn on - you didn't need to wait for a lit screen, etc.

Don't create any shorts, don't use too hot an iron, don't stay on any one pad too long, don't use acid core solder.

DO use fresh thermal paste on back of those ICs/heatsinks.
Coltonhursey



Joined: 28 Sep 2011
Posts: 9
Location: Cave city, ky

PostPosted: Sat Oct 01, 2011 2:30 pm    Post subject: Reply with quote

Okay, sounds easy enough.
And thanks so much for giving me a site to look for the convergence ICs.
I'm guessing that the convergence ICs are the 2 largest ICs on the largest heatsink?
If so, I just checked the solder points, and one looks to need to be resoldered, and if that doesn't work, I'll order the ICs
Coltonhursey



Joined: 28 Sep 2011
Posts: 9
Location: Cave city, ky

PostPosted: Mon Oct 03, 2011 1:49 pm    Post subject: Reply with quote

i have noticed that the convergence chips are sanyo STK394-160.
would you still recommend that i use the STK392-120?
i would imagine that they are different ic's, and would not be compatible.
JTS1957



Joined: 21 Jan 2009
Posts: 2340
Location: Far, Far Away

PostPosted: Mon Oct 03, 2011 4:36 pm    Post subject: Reply with quote

Service literature says:

7044 IC, STK392-120 . . . . . . . . . . . 9322 123 44682
7045 IC, STK392-120 . . . . . . . . . . . 9322 123 44682
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