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Toshiba 56H80 convergence problem    
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cyberdave



Joined: 02 Aug 2008
Posts: 4
Location: Tucson AZ

PostPosted: Sat Aug 02, 2008 4:17 pm    Post subject: Toshiba 56H80 convergence problem Reply with quote

My son has a Toshiba 56H80 with blown convergence at least one IC. It is not possible to bring this TV to town as it is at least a ten mile bad dirt road and no tech will come out. So I am trying to help out. I located an old Avionics tech friend to do the soldering and another that knows how to do the convergence etc. I have the service manual and located the IC's (will replace both with the 372-150 series) but I was told that it is best to replace the feedback resistors also. I know how to recognize an obvious blown resistor but Tony would like to replace all the feedback resistors so it is done on one trip.
Any and all help would be appreciated.
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cyberdave



Joined: 02 Aug 2008
Posts: 4
Location: Tucson AZ

PostPosted: Tue Aug 05, 2008 2:17 pm    Post subject: Reply with quote

Sorry, I meant to type STK 392-110 can anyone help please?
Jesse Mack



Joined: 22 May 2008
Posts: 600
Location: The Last Frontier

PostPosted: Tue Aug 05, 2008 7:51 pm    Post subject: Reply with quote

The resistors are a low value and are standing up on the board usually about 1/4 of an inch above the board. Be aware that many times the resistors only have a tiny popoff spot and unless you look closely, or measure them, they are not so easy to tell if they are blown. It is best to measure them as they can all be measured in circuit. Unless they are overheated, and this is easy to see, replacing all of them simply is not necessary. The Values are 150 Ohm & 220 Ohm at 2 Watts and 2.2 Ohm, 1.5 Ohm, 3.3Ohm and 1.8 Ohm's at 1 Watt. Just have him bring 2 or 3 of each value.

Hope this Helps

Jesse
cyberdave



Joined: 02 Aug 2008
Posts: 4
Location: Tucson AZ

PostPosted: Tue Aug 05, 2008 10:18 pm    Post subject: Reply with quote

It does and I thank you for the help.
cyberdave



Joined: 02 Aug 2008
Posts: 4
Location: Tucson AZ

PostPosted: Thu Aug 07, 2008 3:56 pm    Post subject: IC's are replaced Reply with quote

We got the IC's replaced and checked every resistor for obvious defects and ohmed them all out but found none blown. In the service menu, the blue lines are bowed exactly in the middle of the screen top bowed down, bottom bowed up. We are unsure of what to do next....
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Jesse Mack



Joined: 22 May 2008
Posts: 600
Location: The Last Frontier

PostPosted: Fri Aug 08, 2008 10:00 am    Post subject: Reply with quote

You most likely have a blown fuse or open resistor in the + - power supply.
Check R7765 and R7750 .33 and .22 2 watt resistors close to the convergence chips. Look between the convergence IC's and the edge of the board close to some electrolytic capacitors.
If their ok check the fuses F851 and F850 on the Deflection Power board. They are 6.3 amp fuses. I cannot remember if they are glass or the pico type fuses. They are located on the edge of the circuit board on the edge opposite the High voltage transformer about 20% into the larger Half. They are right on the edge of the board.

Hope this helps

Jesse
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