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Toshiba 50A60 no video    
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kuhurdler



Joined: 28 Dec 2006
Posts: 2879
Location: Overland Park, KS

PostPosted: Thu Jul 24, 2008 5:16 am    Post subject: Toshiba 50A60 no video Reply with quote

Toshiba 50A60, chassis TAC 0050

This set had no video.

Fuse F851 was open. Replaced

Now, video comes on, but flickers and set buzzes

while poking around R241, R242, R244 (all 33k Resistors) and get hot and blackened. I didn't really have time to test much else before they roasted.

Flyback rang good, removed the lead to the HV splitter anyway but it still made the buzzing sound.

Any advice is much appreciated.
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Jesse Mack



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

PostPosted: Thu Jul 24, 2008 11:26 am    Post subject: Reply with quote

This is interesting, F851 is in the -15 Volt supply. R241 and R242, according the the schematic, are 10K resistors in the ABL circuit. R244 is not even listed in the parts list and I could not find it in the schematic.
Is the buzz in the audio or mechanical or arcing?
Have you tried tapping lightly on the CRT neck?
You might disconnect the Second Anode (Protected of course) and fire the set up to see if it still buzz's

Jesse
kuhurdler



Joined: 28 Dec 2006
Posts: 2879
Location: Overland Park, KS

PostPosted: Thu Jul 24, 2008 2:16 pm    Post subject: Reply with quote

The history of this TV is unknown. However, I saw no solder marks on the circuit board like it had been worked on previously.

It is quite odd that those resistor values are so significantly different. I know it was red-red-something on the resistor that I took out. I'll try the ones from the manual.

I took out the anode that fed the splitter, I assumed that eliminated the case that the buzz was coming from CRTs. perhaps I was mistaken?

It's not from the audio, I disconnected that. I also disconnected the Degauss. I'll keep looking, and thinking about this one.

Thanks for the help.
Jesse Mack



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

PostPosted: Thu Jul 24, 2008 7:34 pm    Post subject: Reply with quote

Are you sure of the schematic location of the burned resistor's?? It does not make much sense since the fuse was in the convergence circuit and the flashing could be from a failing convergence chip and the buzzing may be coming from the yokes. I do not know if the next procedure will work on this model but I have done it on other makes and models. If you disconnect the sub deflection connectors to the yokes you should get an uncorrected picture. (all messed up) however it should remove the current drain from the output IC's. Before I would try that however I think I would carefully check the soldering on the stk's and or replace them since the fuse was blown. The no picture condition with the open convergence circuit is a pretty normal reaction on many brands.

Jesse
kuhurdler



Joined: 28 Dec 2006
Posts: 2879
Location: Overland Park, KS

PostPosted: Thu Jul 24, 2008 9:32 pm    Post subject: Reply with quote

Thanks for doublechecking, I just checked again... and the numbers I gave before were correct. at least the designators were, who knows if the Ohm-values were off.



Link to Larger Picture

I will check out that schematic and as soon as I get a chance and try to narrow some things down. Thanks again.
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