Re: 468 with no -2450

Samuel Rocha <py1dkw@...>
 

Dear Group,
I had changed the MC1458 and both supplies are now good.
But still no -2450 v!
Regards to ALL,
Sam Rocha






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--------------------------------------------
Em qui, 18/5/17, Samuel Rocha py1dkw@... [TekScopes] <TekScopes@...> escreveu:

Assunto: Re: [TekScopes] 468 with no -2459 v
Para: "David" <@DWH>, "TekScopes@..." <TekScopes@...>
Data: Quinta-feira, 18 de Maio de 2017, 11:50


 









Dear Group,

Sorry, completing the message:



Well, meanwhile I could repair the 55V supply. The VR725
diode, 9,1 v was open, replaced by a 9.1v/1W. This repaired
the +55v, the +15v is ok.Now, the  +5 v  supply is +7.0v
and the -8 v supply is -12v.

I checked the Q401,Q402,Q402, Q617 onboard and Q718 out of
board, they seems to be good with an analog Simpson7
multimeter,

Just for checking the influence of one suplly in tho the
other, I disconnected CR304 in collector of Q402 and
connected it to a +5v supply, still the -8v gives -12v.

I suspect the U506 is faulty. The measures in U506 are:Pin
1= +9,7Pin 2=+17

Pin 3=+5

Pin 4= -12,4Pin 5 =-3,8Pin 6 =0Pin 7 =+2,3Pin8 =+15Is it
possible to remove the  U506 without taking the interface
board out? I think I will have to destroy it cutting all ic
legs and soldering a 8 pin socket.Any ideas about these two
power supplies repair?

many thanks, nice weekend for all And Keep your world blue
as TEKTRONIX !!Sam Rocha 



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Em Quinta-feira, 18 de Maio de 2017 11:40, Samuel Rocha
<py1dkw@...> escreveu:





Dear Group

Well, meanwhile I could repair the 55V supply. The VR725
diode, 9,1 v was open, replaced by a 9.1v/1W. This repaired
the +55v, the +15v is ok.Now, the  +5 v  supply is +7.0v
and the -8 v supply is -12v.

I checked the Q401,Q402,Q402, Q617 onboard and Q718 out of
board, they seems to be good with an analog Simpson7
multimeter,

Just for checking the influence of one suplly in tho the
other, I disconnected CR304 in collector of Q402 and
connected it to a +5v supply, still the -8v gives -12v.

I suspect the U506 is faulty. The measures in U506
are:Pin Pin 

Pin 

 



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Em Terça-feira, 16 de Maio de 2017 3:42, David
<@DWH> escreveu:





On Fri, 12 May 2017 01:30:57 +0000 (UTC), you wrote:





>Dear David ,

>Thank you very much for your attention and answer.

>Confirming the tested voltages:-2450 => zero Volts

>+110 => +110,8 Volts

>-8 did not test

>

>+15v= +15v5v gives 6.75 Volts (higher voltage)



What?  So the +5 volt supply is actually +6.75 volts?  If
so that

needs to be fixed before all else.  A high voltage could
damage the

logic circuits.



[Non-text portions of this message have been removed]













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