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old tv, brightness drifting

 
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tgx
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PostPosted: Sat Mar 31, 2007 10:19 am    Post subject: old tv, brightness drifting Reply with quote

hello all, I have this very old tv ,I guess ~25 years old, but it wasn't used much. Model number is HITACHI CEP-286.
The picture is still very good and easily beats the modern cheap crap you can buy everywhere. There is a small but annoying problem with my tv, and that is after turning it on, the brightness level is very high and picture looks washed out, and after about 5 minutes the picture is perfect. I have measured many voltages (such as screen, voltage on brightness pot etc.) and none of them seems to be drifting. Do you think I can do anything to fix this, or is my tube going weak? I really don't feel like throwing this tv away, unless there is absolutely nothing I can do to fix it.
thanks!
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minnie



Joined: 18 Aug 2005
Posts: 2877
Location: Hell

PostPosted: Sat Mar 31, 2007 2:02 pm    Post subject: Reply with quote

Sounds like a weak tube. If the picture comes in after 5 minutes, run it till it pukes. Hitachi and Mitt's made the damn best CRT sets. 25 years gives you your answer. It was made to last, but the time has come.
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H3liax
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PostPosted: Sat Mar 31, 2007 2:43 pm    Post subject: Re: old tv, brightness drifting Reply with quote

tgx wrote:
hello all, I have this very old tv ,I guess ~25 years old, but it wasn't used much. Model number is HITACHI CEP-286.
The picture is still very good and easily beats the modern cheap crap you can buy everywhere. There is a small but annoying problem with my tv, and that is after turning it on, the brightness level is very high and picture looks washed out, and after about 5 minutes the picture is perfect. I have measured many voltages (such as screen, voltage on brightness pot etc.) and none of them seems to be drifting. Do you think I can do anything to fix this, or is my tube going weak? I really don't feel like throwing this tv away, unless there is absolutely nothing I can do to fix it.
thanks!



Hii...tgx..
I wondering if you have to check the dryjoint at the socket for TUBE/CRT,HOT,all capacitor/elco nearby the FTB ?
mybe u can do this weak things ( but some times work for me )....

Wink
e-mail : [email protected]
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tgx
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PostPosted: Sat Mar 31, 2007 3:15 pm    Post subject: Re: old tv, brightness drifting Reply with quote

H3liax wrote:

Hii...tgx..
I wondering if you have to check the dryjoint at the socket for TUBE/CRT,HOT,all capacitor/elco nearby the FTB ?
mybe u can do this weak things ( but some times work for me )....

Wink

Hi H3liax I resoldered all solder joints on the power/horizontal board before, I will also try resoldering the pins at the crt "neck" board, but I don't expect this will fix my problem.
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cory
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PostPosted: Sat Mar 31, 2007 5:29 pm    Post subject: Reply with quote

check pins on flyback for poor solder connections.if ok there will be a capacitor near flyback for 200 volt source to crt.it will be rated at 250 volts,try changing it.
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tgx
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PostPosted: Sat Mar 31, 2007 6:25 pm    Post subject: Reply with quote

cory wrote:
check pins on flyback for poor solder connections.if ok there will be a capacitor near flyback for 200 volt source to crt.it will be rated at 250 volts,try changing it.

I measured this voltage it is at 160Volts and does not drift. but thanks anyway Smile
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Frank
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PostPosted: Sat Mar 31, 2007 8:24 pm    Post subject: Reply with quote

You should replace most of the Electrolitic caps everywhere, get an ESR meter and check for dry caps ,
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cory
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PostPosted: Sat Mar 31, 2007 8:43 pm    Post subject: Reply with quote

160 volts right at capacitor is too low.should be 200.you can also measure this at crt neck board.right at connector.
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