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Minnie....Hitachi TV fuses

 
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tvioland
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PostPosted: Sun Jul 22, 2007 9:16 pm    Post subject: Minnie....Hitachi TV fuses Reply with quote

I can't really see the number for that object but its red and looks like it has 3 bumps in which the hardened substance runs inbetween the bumps. hopefully this helps because i don't have the circuit board out yet. The substance is a dark yellowish
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minnie



Joined: 18 Aug 2005
Posts: 2877
Location: Hell

PostPosted: Sun Jul 22, 2007 9:47 pm    Post subject: Reply with quote

C707, a blue cap usually gets a pin hole in it and takes out E994. Take a meter and see if E994 is open. The next common is Q777 shorts. I looked at the print and I don't see a thing with 3 humps. When you get a location post it.
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minnie



Joined: 18 Aug 2005
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PostPosted: Sun Jul 22, 2007 9:50 pm    Post subject: Reply with quote

E994 is a 2 amp pico fuse.
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tvioland
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PostPosted: Mon Jul 23, 2007 3:17 am    Post subject: Reply with quote

Can you send me a link of the print that you are looking at of the fuses.
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minnie



Joined: 18 Aug 2005
Posts: 2877
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PostPosted: Tue Jul 24, 2007 11:39 pm    Post subject: Reply with quote

PM me your email and I'll forward the service manual/schematics. Include the model # again.
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dansmith



Joined: 13 Jan 2008
Posts: 3
Location: austin texas

PostPosted: Sun Jan 13, 2008 7:26 pm    Post subject: Hitachi Q777 shorted? Reply with quote

minnie wrote:
C707, a blue cap usually gets a pin hole in it and takes out E994. Take a meter and see if E994 is open. The next common is Q777 shorts. I looked at the print and I don't see a thing with 3 humps. When you get a location post it.


Hi Minnie,
I would appreciate any help you can give me.
Typical Hitachi problem: I replaced C707 and the fuse (both of which tested bad out of circuit). Still no B+. Q777 is shorted between base and emitter while in circuit. Should I remove Q777 to test out of circuit? Are there other components on the Q777 base drive that could cause the short? This is my second free set. The first one was fixed with the cap and fuse change (thanks!).
Thanks,
Dansmith
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minnie



Joined: 18 Aug 2005
Posts: 2877
Location: Hell

PostPosted: Sun Jan 13, 2008 7:37 pm    Post subject: Reply with quote

A short between the emitter and collector is normal, base to emitter indicates a shorted transistor. Remove the transistor and see if the set stays on.
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dansmith



Joined: 13 Jan 2008
Posts: 3
Location: austin texas

PostPosted: Sun Jan 13, 2008 8:15 pm    Post subject: Reply with quote

minnie wrote:
A short between the emitter and collector is normal, base to emitter indicates a shorted transistor. Remove the transistor and see if the set stays on.


Thanks, I'll give it a try. I found a replacement part at Newark, NTE2354 for $14.00. Again, I really appreciate your help! You must be an electronics guru!
dansmith
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dansmith



Joined: 13 Jan 2008
Posts: 3
Location: austin texas

PostPosted: Wed Jan 16, 2008 2:02 am    Post subject: Reply with quote

dansmith wrote:
minnie wrote:
A short between the emitter and collector is normal, base to emitter indicates a shorted transistor. Remove the transistor and see if the set stays on.


Thanks, I'll give it a try. I found a replacement part at Newark, NTE2354 for $14.00. Again, I really appreciate your help! You must be an electronics guru!
dansmith


Hi Minnie,
Well, I'm stumped. I unsoldered the base of Q777 from the board and the HOT tested OK. Must be something still on the board causing a short.
Any idea where I can find a schematic? Model 50SBX78B, chassis AP84.
Thanks,
Dan
[email protected]
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minnie



Joined: 18 Aug 2005
Posts: 2877
Location: Hell

PostPosted: Wed Jan 16, 2008 11:31 pm    Post subject: Reply with quote

Email error message came back.
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