HELP! Someone know the mainframe oscilloscope Tektronix 7000 series? I
have some 7704 with power supply broken,with same defect: don't start
the oscillator.
Some suggestion??

If you get some money send it in for repair and calibration. Cost on good
test equipment is out of site.

"giannibo" wrote in message
...
HELP! Someone know the mainframe oscilloscope Tektronix 7000 series? I
have some 7704 with power supply broken,with same defect: don't start
the oscillator.
Some suggestion??

"David Wright" wrote in message
...
If you get some money send it in for repair and calibration. Cost on good
test equipment is out of site.

"giannibo" wrote in message
...
HELP! Someone know the mainframe oscilloscope Tektronix 7000 series? I
have some 7704 with power supply broken,with same defect: don't start
the oscillator.
Some suggestion??



You can download the manual for the 7704 from
http://bama.edebris.com/manuals/tek/7704/. It should help you figure out the
problem.
The usual suspects are aging electrolytic capacitors.

--
Dave M
MasonDG44 at comcast dot net (Just substitute the appropriate characters in the
address)

"In theory, there isn't any difference between theory and practice. In
practice, there is." - Yogi Berra

"DaveM" wrote in
:

"David Wright" wrote in message
...
If you get some money send it in for repair and calibration. Cost on
good test equipment is out of site.

"giannibo" wrote in message

...
HELP! Someone know the mainframe oscilloscope Tektronix 7000 series?
I have some 7704 with power supply broken,with same defect: don't
start the oscillator.
Some suggestion??



You can download the manual for the 7704 from
http://bama.edebris.com/manuals/tek/7704/. It should help you figure
out the problem.
The usual suspects are aging electrolytic capacitors.

both in the power supply and the mainframe itself.



just make sure you have a 7704 and not a 7704A. There's a big difference.

although both have complex series-resonant switching power supplies.

usually,you hear a clicking or "chirping" from the PS;it's trying to
start,but something is loading a supply,or a diode is shorted.
Some failures blow a lot of parts....and then the line fuse afterwards.

--
Jim Yanik
jyanik
at
kua.net

On 29 Dic, 04:43, Jim Yanik wrote:
"DaveM" wrote :





"David Wright" wrote in message
...
If you get some money send it in for repair and calibration. *Cost on
good test equipment is out of site.

"giannibo" wrote in message

...
HELP! Someone know the mainframe oscilloscope Tektronix 7000 series?
I have some 7704 with power supply broken,with same defect: don't
start the oscillator.
Some suggestion??

You can download the manual for the 7704 from
http://bama.edebris.com/manuals/tek/7704/. *It should help you figure
out the problem.
The usual suspects are aging electrolytic capacitors.

both in the power supply and the mainframe itself.



just make sure you have a 7704 and not a 7704A. There's a big difference.

although both have complex series-resonant switching power supplies.

usually,you hear a clicking or "chirping" from the PS;it's trying to
start,but something is loading a supply,or a diode is shorted.
Some failures blow a lot of parts....and then the line fuse afterwards.

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks for answer.The model is 7704A. I replace the fast diode.The
defect remaining is that try to start the oscillator,but isn't
stable.After several test, I found that disconnecting the transistor
TO5 on parallel to base-emitter of power transistor, the oscillator
start, but isn't stabilized.May be is the small SCR. I checked all
components, only the SCR remain... Further the semiconductor indicated
on circuit as a element with 2 emitter, what is?This machine remain on
stock for several years, so some components are gone.Is a pity ,
because this instrument is made on beautifull mode, and I try to save.
Thanking for help!!
Gianni

On 29 Dic, 01:35, "DaveM" wrote:
"David Wright" wrote in message

...

If you get some money send it in for repair and calibration. *Cost on good
test equipment is out of site.

"giannibo" wrote in message
...
HELP! Someone know the mainframe oscilloscope Tektronix 7000 series? I
have some 7704 with power supply broken,with same defect: don't start
the oscillator.
Some suggestion??

You can download the manual for the 7704 fromhttp://bama.edebris.com/manuals/tek/7704/. *It should help you figure out the
problem.
The usual suspects are aging electrolytic capacitors.

--
Dave M
MasonDG44 at comcast dot net *(Just substitute the appropriate characters in the
address)

"In theory, there isn't any difference between theory and practice. *In
practice, there is." *- Yogi Berra

Thanks for suggestions. The items I found aren't good, are the diodes
on low voltage circuit.
I checked also the capacitor on main frame, but are ok. The defect is
that oscillator is on and off continously. Now I take out the TO5 on
parallel of base-emitter of power transitor, and remain on firmly, but
isn't stabilized.
I follow to work on, I want resume this beautifull instrument!!
Thanks a lot!!
Gianni

On 29 Dic, 00:15, "David Wright" wrote:
If you get some money send it in for repair and calibration. *Cost on good
test equipment is out of site.

"giannibo" wrote in message

...



HELP! Someone know the mainframe oscilloscope Tektronix 7000 series? I
have some 7704 with power supply broken,with same defect: don't start
the oscillator.
Some suggestion??- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks, but transport cost, custom, etc.., are out of budget. Further
I like repair my self....
HI! Gianni

giannibo wrote in
:

On 29 Dic, 04:43, Jim Yanik wrote:
"DaveM" wrote
innews:gcOdnekazMCkC-janZ2dnUVZ_
:





"David Wright" wrote in message
...
If you get some money send it in for repair and calibration. *Cost
on

good test equipment is out of site.

"giannibo" wrote in message

om
...
HELP! Someone know the mainframe oscilloscope Tektronix 7000
series? I have some 7704 with power supply broken,with same
defect: don't start the oscillator.
Some suggestion??

You can download the manual for the 7704 from
http://bama.edebris.com/manuals/tek/7704/. *It should help you
figure
out the problem.
The usual suspects are aging electrolytic capacitors.

both in the power supply and the mainframe itself.



just make sure you have a 7704 and not a 7704A. There's a big
difference.

although both have complex series-resonant switching power supplies.

usually,you hear a clicking or "chirping" from the PS;it's trying to
start,but something is loading a supply,or a diode is shorted.
Some failures blow a lot of parts....and then the line fuse
afterwards.

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks for answer.The model is 7704A. I replace the fast diode.The
defect remaining is that try to start the oscillator,but isn't
stable.After several test, I found that disconnecting the transistor
TO5 on parallel to base-emitter of power transistor, the oscillator
start, but isn't stabilized.May be is the small SCR. I checked all
components, only the SCR remain... Further the semiconductor indicated
on circuit as a element with 2 emitter, what is?

A Diac;it triggers at ~33V IIRC.

This machine remain on
stock for several years, so some components are gone.Is a pity ,
because this instrument is made on beautifull mode, and I try to save.
Thanking for help!!
Gianni




--
Jim Yanik
jyanik
at
kua.net

On 31 Dic 2007, 23:35, Jim Yanik wrote:
giannibo wrote :





On 29 Dic, 04:43, Jim Yanik wrote:
"DaveM" wrote
innews:gcOdnekazMCkC-janZ2dnUVZ_
:

"David Wright" wrote in message
...
If you get some money send it in for repair and calibration. *Cost
on

good test equipment is out of site.

"giannibo" wrote in message

om
...
HELP! Someone know the mainframe oscilloscope Tektronix 7000
series? I have some 7704 with power supply broken,with same
defect: don't start the oscillator.
Some suggestion??

You can download the manual for the 7704 from
http://bama.edebris.com/manuals/tek/7704/. *It should help you
figure
out the problem.
The usual suspects are aging electrolytic capacitors.

both in the power supply and the mainframe itself.

just make sure you have a 7704 and not a 7704A. There's a big
difference.

although both have complex series-resonant switching power supplies.

usually,you hear a clicking or "chirping" from the PS;it's trying to
start,but something is loading a supply,or a diode is shorted.
Some failures blow a lot of parts....and then the line fuse
afterwards.

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks for answer.The model is 7704A. I replace the fast diode.The
defect remaining is that try to start the oscillator,but isn't
stable.After several test, I *found that disconnecting the transistor
TO5 on parallel to base-emitter of power transistor, the oscillator
start, but isn't stabilized.May be is the small SCR. I checked all
components, only the SCR remain... Further the semiconductor indicated
on circuit as a element with 2 emitter, what is?

A Diac;it triggers at ~33V IIRC.

This machine remain on
stock for several years, so some components are gone.Is a pity ,
because this instrument is made on beautifull mode, and I try to save.
Thanking for help!!
Gianni

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks! I will replace it! In the meantime I foun that R120 and R122
( 1,8 Kohm) of Z axis board A41 are burning, with smoke. Many defect
all togheter!! Tomorrow i will check why these resistor are
smoking.Anyway I am bidding on ebay a 7704 so I can compare some
situations.
Thanks. I wil post when I found all defect!
Gianni
IK4EWH

On 1 Jan., 17:09, giannibo wrote:
On 31 Dic 2007, 23:35, Jim Yanik wrote:





giannibo wrote :

On 29 Dic, 04:43, Jim Yanik wrote:
"DaveM" wrote
innews:gcOdnekazMCkC-janZ2dnUVZ_
:

"David Wright" wrote in message
...
If you get some money send it in for repair and calibration. *Cost
on

good test equipment is out of site.

"giannibo" wrote in message

om
...
HELP! Someone know the mainframe oscilloscopeTektronix7000
series? I have some 7704 with power supply broken,with same
defect: don't start the oscillator.
Some suggestion??

You can download the manual for the 7704 from
http://bama.edebris.com/manuals/tek/7704/. *It should help you
figure
out the problem.
The usual suspects are aging electrolytic capacitors.

both in the power supply and the mainframe itself.

just make sure you have a 7704 and not a 7704A. There's a big
difference.

although both have complex series-resonant switching power supplies.

usually,you hear a clicking or "chirping" from the PS;it's trying to
start,but something is loading a supply,or a diode is shorted.
Some failures blow a lot of parts....and then the line fuse
afterwards.

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks for answer.The model is 7704A. I replace the fast diode.The
defect remaining is that try to start the oscillator,but isn't
stable.After several test, I *found that disconnecting the transistor
TO5 on parallel to base-emitter of power transistor, the oscillator
start, but isn't stabilized.May be is the small SCR. I checked all
components, only the SCR remain... Further the semiconductor indicated
on circuit as a element with 2 emitter, what is?

A Diac;it triggers at ~33V IIRC.

This machine remain on
stock for several years, so some components are gone.Is a pity ,
because this instrument is made on beautifull mode, and I try to save.
Thanking for help!!
Gianni

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks! I will replace it! In the meantime I foun that R120 and *R122
( 1,8 Kohm) *of Z axis board A41 are burning, with smoke. Many defect
all togheter!! Tomorrow i will check why these resistor are
smoking.Anyway I am bidding on *ebay a 7704 so I can compare some
situations.
Thanks. I wil post when I found all defect!
Gianni
IK4EWH- Zitierten Text ausblenden -

- Zitierten Text anzeigen -

Remember what Jim already said about 7704 and 7704A: Both models are a
lot different.

So if you plan to compare circuits and repair faults, go for the same
models at least.


hth,
Andreas

Andreas Tekman wrote in
:

On 1 Jan., 17:09, giannibo wrote:
On 31 Dic 2007, 23:35, Jim Yanik wrote:





giannibo wrote
innews:dca6ef88-f731-49ca-9
:

On 29 Dic, 04:43, Jim Yanik wrote:
"DaveM" wrote
innews:gcOdnekazMCkC-janZ2dnUVZ_
:

"David Wright" wrote in message
...
If you get some money send it in for repair and calibration.
*Co
st
on

good test equipment is out of site.

"giannibo" wrote in message

ups.
c
om
...
HELP! Someone know the mainframe oscilloscopeTektronix7000
series? I have some 7704 with power supply broken,with same
defect: don't start the oscillator.
Some suggestion??

You can download the manual for the 7704 from
http://bama.edebris.com/manuals/tek/7704/. *It should help you
figure
out the problem.
The usual suspects are aging electrolytic capacitors.

both in the power supply and the mainframe itself.

just make sure you have a 7704 and not a 7704A. There's a big
difference.

although both have complex series-resonant switching power
supplies.

usually,you hear a clicking or "chirping" from the PS;it's
trying to start,but something is loading a supply,or a diode is
shorted. Some failures blow a lot of parts....and then the line
fuse afterwards.

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks for answer.The model is 7704A. I replace the fast
diode.The defect remaining is that try to start the
oscillator,but isn't stable.After several test, I *found that
disconnecting the transisto
r
TO5 on parallel to base-emitter of power transistor, the
oscillator start, but isn't stabilized.May be is the small SCR. I
checked all components, only the SCR remain... Further the
semiconductor indicated

on circuit as a element with 2 emitter, what is?

A Diac;it triggers at ~33V IIRC.

This machine remain on
stock for several years, so some components are gone.Is a pity ,
because this instrument is made on beautifull mode, and I try to
save.

Thanking for help!!
Gianni

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks! I will replace it! In the meantime I foun that R120 and *R122
( 1,8 Kohm) *of Z axis board A41 are burning, with smoke. Many defect
all togheter!! Tomorrow i will check why these resistor are
smoking.Anyway I am bidding on *ebay a 7704 so I can compare some
situations.
Thanks. I wil post when I found all defect!
Gianni
IK4EWH- Zitierten Text ausblenden -

- Zitierten Text anzeigen -

Remember what Jim already said about 7704 and 7704A: Both models are a
lot different.

So if you plan to compare circuits and repair faults, go for the same
models at least.


hth,
Andreas


7704A uses a TEK-made IC for it's PS control,while the older 7704 non-
A uses discrete circuitry.
The A model has more control loops.


--
Jim Yanik
jyanik
at
kua.net

On 4 Gen, 11:51, Andreas Tekman wrote:
On 1 Jan., 17:09, giannibo wrote:





On 31 Dic 2007, 23:35, Jim Yanik wrote:

giannibo wrote :

On 29 Dic, 04:43, Jim Yanik wrote:
"DaveM" wrote
innews:gcOdnekazMCkC-janZ2dnUVZ_
:

"David Wright" wrote in message
...
If you get some money send it in for repair and calibration. *Cost
on

good test equipment is out of site.

"giannibo" wrote in message

om
...
HELP! Someone know the mainframe oscilloscopeTektronix7000
series? I have some 7704 with power supply broken,with same
defect: don't start the oscillator.
Some suggestion??

You can download the manual for the 7704 from
http://bama.edebris.com/manuals/tek/7704/. *It should help you
figure
out the problem.
The usual suspects are aging electrolytic capacitors.

both in the power supply and the mainframe itself.

just make sure you have a 7704 and not a 7704A. There's a big
difference.

although both have complex series-resonant switching power supplies..

usually,you hear a clicking or "chirping" from the PS;it's trying to
start,but something is loading a supply,or a diode is shorted.
Some failures blow a lot of parts....and then the line fuse
afterwards.

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks for answer.The model is 7704A. I replace the fast diode.The
defect remaining is that try to start the oscillator,but isn't
stable.After several test, I *found that disconnecting the transistor
TO5 on parallel to base-emitter of power transistor, the oscillator
start, but isn't stabilized.May be is the small SCR. I checked all
components, only the SCR remain... Further the semiconductor indicated
on circuit as a element with 2 emitter, what is?

A Diac;it triggers at ~33V IIRC.

This machine remain on
stock for several years, so some components are gone.Is a pity ,
because this instrument is made on beautifull mode, and I try to save.
Thanking for help!!
Gianni

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks! I will replace it! In the meantime I foun that R120 and *R122
( 1,8 Kohm) *of Z axis board A41 are burning, with smoke. Many defect
all togheter!! Tomorrow i will check why these resistor are
smoking.Anyway I am bidding on *ebay a 7704 so I can compare some
situations.
Thanks. I wil post when I found all defect!
Gianni
IK4EWH- Zitierten Text ausblenden -

- Zitierten Text anzeigen -

Remember what Jim already said about 7704 and 7704A: Both models are a
lot different.

So if you plan to compare circuits and repair faults, go for the same
models at least.

hth,
Andreas- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

The model is 7704A and I got diagram. Now is working but isn't active
the automatic control. I must replace the DIAC. But rhey are others
defects... very hard competition!

On 4 Gen, 15:48, Jim Yanik wrote:
Andreas Tekman wrote :





On 1 Jan., 17:09, giannibo wrote:
On 31 Dic 2007, 23:35, Jim Yanik wrote:

giannibo wrote
innews:dca6ef88-f731-49ca-9
:

On 29 Dic, 04:43, Jim Yanik wrote:
"DaveM" wrote
innews:gcOdnekazMCkC-janZ2dnUVZ_
:

"David Wright" wrote in message
...
If you get some money send it in for repair and calibration.
*Co
st
on

good test equipment is out of site.

"giannibo" wrote in message

ups.
c
om
...
HELP! Someone know the mainframe oscilloscopeTektronix7000
series? I have some 7704 with power supply broken,with same
defect: don't start the oscillator.
Some suggestion??

You can download the manual for the 7704 from
http://bama.edebris.com/manuals/tek/7704/. *It should help you
figure
out the problem.
The usual suspects are aging electrolytic capacitors.

both in the power supply and the mainframe itself.

just make sure you have a 7704 and not a 7704A. There's a big
difference.

although both have complex series-resonant switching power
supplies.

usually,you hear a clicking or "chirping" from the PS;it's
trying to start,but something is loading a supply,or a diode is
shorted. Some failures blow a lot of parts....and then the line
fuse afterwards.

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks for answer.The model is 7704A. I replace the fast
diode.The defect remaining is that try to start the
oscillator,but isn't stable.After several test, I *found that
disconnecting the transisto
r
TO5 on parallel to base-emitter of power transistor, the
oscillator start, but isn't stabilized.May be is the small SCR. I
checked all components, only the SCR remain... Further the
semiconductor indicated

on circuit as a element with 2 emitter, what is?

A Diac;it triggers at ~33V IIRC.

This machine remain on
stock for several years, so some components are gone.Is a pity ,
because this instrument is made on beautifull mode, and I try to
save.

Thanking for help!!
Gianni

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks! I will replace it! In the meantime I foun that R120 and *R122
( 1,8 Kohm) *of Z axis board A41 are burning, with smoke. Many defect
all togheter!! Tomorrow i will check why these resistor are
smoking.Anyway I am bidding on *ebay a 7704 so I can compare some
situations.
Thanks. I wil post when I found all defect!
Gianni
IK4EWH- Zitierten Text ausblenden -

- Zitierten Text anzeigen -

Remember what Jim already said about 7704 and 7704A: Both models are a
lot different.

So if you plan to compare circuits and repair faults, go for the same
models at least.

hth,
Andreas

7704A uses a TEK-made IC for it's PS control,while the older 7704 non-
A uses discrete circuitry.
The A model has more control loops.

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Infact: all IC are custom, with various models.Now I am arrived to
have: trace very weak, but seem trigger and vertical work.There is a
problem: the trace is only present on central zone of tube. I never
seen a wiew like this. I fund another mainframe so I can replace step
by step the circuit, so I can see which one is defected.
But really this is on very bad conditions. I repaired a lot of
465-475-7704-7603 and others , but this is very hard!!

giannibo wrote in
:

On 4 Gen, 11:51, Andreas Tekman wrote:
On 1 Jan., 17:09, giannibo wrote:





On 31 Dic 2007, 23:35, Jim Yanik wrote:

giannibo wrote
innews:dca6ef88-f731-49ca
:

On 29 Dic, 04:43, Jim Yanik wrote:
"DaveM" wrote
innews:gcOdnekazMCkC-janZ2dnUVZ_
:

"David Wright" wrote in message
...
If you get some money send it in for repair and
calibration. *
Cost
on

good test equipment is out of site.

"giannibo" wrote in message

roup
s.c
om
...
HELP! Someone know the mainframe oscilloscopeTektronix7000
series? I have some 7704 with power supply broken,with
same defect: don't start the oscillator.
Some suggestion??

You can download the manual for the 7704 from
http://bama.edebris.com/manuals/tek/7704/. *It should help
you figure
out the problem.
The usual suspects are aging electrolytic capacitors.

both in the power supply and the mainframe itself.

just make sure you have a 7704 and not a 7704A. There's a big
difference.

although both have complex series-resonant switching power
supplies
.

usually,you hear a clicking or "chirping" from the PS;it's
trying t
o
start,but something is loading a supply,or a diode is shorted.
Some failures blow a lot of parts....and then the line fuse
afterwards.

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks for answer.The model is 7704A. I replace the fast
diode.The defect remaining is that try to start the
oscillator,but isn't stable.After several test, I *found that
disconnecting the transis
tor
TO5 on parallel to base-emitter of power transistor, the
oscillator start, but isn't stabilized.May be is the small SCR.
I checked all components, only the SCR remain... Further the
semiconductor indicat
ed
on circuit as a element with 2 emitter, what is?

A Diac;it triggers at ~33V IIRC.

This machine remain on
stock for several years, so some components are gone.Is a pity
, because this instrument is made on beautifull mode, and I try
to sav
e.
Thanking for help!!
Gianni

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks! I will replace it! In the meantime I foun that R120 and
*R122 ( 1,8 Kohm) *of Z axis board A41 are burning, with smoke.
Many defect all togheter!! Tomorrow i will check why these resistor
are smoking.Anyway I am bidding on *ebay a 7704 so I can compare
some situations.
Thanks. I wil post when I found all defect!
Gianni
IK4EWH- Zitierten Text ausblenden -

- Zitierten Text anzeigen -

Remember what Jim already said about 7704 and 7704A: Both models are
a lot different.

So if you plan to compare circuits and repair faults, go for the same
models at least.

hth,
Andreas- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

The model is 7704A and I got diagram. Now is working but isn't active
the automatic control. I must replace the DIAC. But rhey are others
defects... very hard competition!


read the service manual's circuit description;
it's VERY valuable in understanding how the PS works.
Make notes on a printout of the schematic.

--
Jim Yanik
jyanik
at
kua.net

giannibo wrote in
:



Infact: all IC are custom, with various models.Now I am arrived to
have: trace very weak, but seem trigger and vertical work.There is a
problem: the trace is only present on central zone of tube. I never
seen a wiew like this.

It could be a HV problem like loss of anode supply(usually bad HV
multiplier),or a loss of a power supply rail that supplies the deflection
output amps.(much less likely)


I fund another mainframe so I can replace step
by step the circuit, so I can see which one is defected.
But really this is on very bad conditions. I repaired a lot of
465-475-7704-7603 and others , but this is very hard!!


TEK series-resonant power supplies used in the 7704A,7904,7104,485 are very
complex and hard to repair.Many TEK service techs had hard times with
them,often just put in new PS assemblies.(not possible anymore...)

the manual's circuit description is VERY valuable in understanding them.

--
Jim Yanik
jyanik
at
kua.net

giannibo wrote:
On 4 Gen, 15:48, Jim Yanik wrote:
Andreas Tekman wrote :





On 1 Jan., 17:09, giannibo wrote:
On 31 Dic 2007, 23:35, Jim Yanik wrote:
giannibo wrote
innews:dca6ef88-f731-49ca-9
:
On 29 Dic, 04:43, Jim Yanik wrote:
"DaveM" wrote
innews:gcOdnekazMCkC-janZ2dnUVZ_
:
"David Wright" wrote in message
...
If you get some money send it in for repair and calibration.
Co
st
on
good test equipment is out of site.
"giannibo" wrote in message

ups.
c
om
...
HELP! Someone know the mainframe oscilloscopeTektronix7000
series? I have some 7704 with power supply broken,with same
defect: don't start the oscillator.
Some suggestion??
You can download the manual for the 7704 from
http://bama.edebris.com/manuals/tek/7704/. It should help you
figure
out the problem.
The usual suspects are aging electrolytic capacitors.
both in the power supply and the mainframe itself.
just make sure you have a 7704 and not a 7704A. There's a big
difference.
although both have complex series-resonant switching power
supplies.
usually,you hear a clicking or "chirping" from the PS;it's
trying to start,but something is loading a supply,or a diode is
shorted. Some failures blow a lot of parts....and then the line
fuse afterwards.
--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -
- Mostra testo tra virgolette -
Thanks for answer.The model is 7704A. I replace the fast
diode.The defect remaining is that try to start the
oscillator,but isn't stable.After several test, I found that
disconnecting the transisto
r
TO5 on parallel to base-emitter of power transistor, the
oscillator start, but isn't stabilized.May be is the small SCR. I
checked all components, only the SCR remain... Further the
semiconductor indicated
on circuit as a element with 2 emitter, what is?
A Diac;it triggers at ~33V IIRC.
This machine remain on
stock for several years, so some components are gone.Is a pity ,
because this instrument is made on beautifull mode, and I try to
save.
Thanking for help!!
Gianni
--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -
- Mostra testo tra virgolette -
Thanks! I will replace it! In the meantime I foun that R120 and R122
( 1,8 Kohm) of Z axis board A41 are burning, with smoke. Many defect
all togheter!! Tomorrow i will check why these resistor are
smoking.Anyway I am bidding on ebay a 7704 so I can compare some
situations.
Thanks. I wil post when I found all defect!
Gianni
IK4EWH- Zitierten Text ausblenden -
- Zitierten Text anzeigen -
Remember what Jim already said about 7704 and 7704A: Both models are a
lot different.
So if you plan to compare circuits and repair faults, go for the same
models at least.
hth,
Andreas
7704A uses a TEK-made IC for it's PS control,while the older 7704 non-
A uses discrete circuitry.
The A model has more control loops.

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Infact: all IC are custom, with various models.Now I am arrived to
have: trace very weak, but seem trigger and vertical work.There is a
problem: the trace is only present on central zone of tube. I never
seen a wiew like this. I fund another mainframe so I can replace step
by step the circuit, so I can see which one is defected.
But really this is on very bad conditions. I repaired a lot of
465-475-7704-7603 and others , but this is very hard!!

Depending on which version you have, there's a bleeder resistor on the
HV board...actually a bunch of 'em in series. They go open, the high
voltage goes up, the trace shrinks.

Mine had four of about 7 open resistors in series. I found that
improbable...
The explanation given was that they're carbon and they crack. Then
the first one arcs to keep the current flowing until the second one
cracks and opens...which arcs...until finally there are enough of them
open that it can't sustain all those series arcs at once and the string
starts acting like it's open.

--
Return address is VALID!

On 5 Gen, 17:27, mike wrote:
giannibo wrote:
On 4 Gen, 15:48, Jim Yanik wrote:
Andreas Tekman wrote :

On 1 Jan., 17:09, giannibo wrote:
On 31 Dic 2007, 23:35, Jim Yanik wrote:
giannibo wrote
innews:dca6ef88-f731-49ca-9
:
On 29 Dic, 04:43, Jim Yanik wrote:
"DaveM" wrote
innews:gcOdnekazMCkC-janZ2dnUVZ_
:
"David Wright" wrote in message
. ..
If you get some money send it in for repair and calibration.
*Co
st
on
good test equipment is out of site.
"giannibo" wrote in message

ups.
c
om
...
HELP! Someone know the mainframe oscilloscopeTektronix7000
series? I have some 7704 with power supply broken,with same
defect: don't start the oscillator.
Some suggestion??
You can download the manual for the 7704 from
http://bama.edebris.com/manuals/tek/7704/. *It should help you
figure
out the problem.
The usual suspects are aging electrolytic capacitors.
both in the power supply and the mainframe itself.
just make sure you have a 7704 and not a 7704A. There's a big
difference.
although both have complex series-resonant switching power
supplies.
usually,you hear a clicking or "chirping" from the PS;it's
trying to start,but something is loading a supply,or a diode is
shorted. Some failures blow a lot of parts....and then the line
fuse afterwards.
--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -
- Mostra testo tra virgolette -
Thanks for answer.The model is 7704A. I replace the fast
diode.The defect remaining is that try to start the
oscillator,but isn't stable.After several test, I *found that
disconnecting the transisto
r
TO5 on parallel to base-emitter of power transistor, the
oscillator start, but isn't stabilized.May be is the small SCR. I
checked all components, only the SCR remain... Further the
semiconductor indicated
on circuit as a element with 2 emitter, what is?
A Diac;it triggers at ~33V IIRC.
This machine remain on
stock for several years, so some components are gone.Is a pity ,
because this instrument is made on beautifull mode, and I try to
save.
Thanking for help!!
Gianni
--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -
- Mostra testo tra virgolette -
Thanks! I will replace it! In the meantime I foun that R120 and *R122
( 1,8 Kohm) *of Z axis board A41 are burning, with smoke. Many defect
all togheter!! Tomorrow i will check why these resistor are
smoking.Anyway I am bidding on *ebay a 7704 so I can compare some
situations.
Thanks. I wil post when I found all defect!
Gianni
IK4EWH- Zitierten Text ausblenden -
- Zitierten Text anzeigen -
Remember what Jim already said about 7704 and 7704A: Both models are a
lot different.
So if you plan to compare circuits and repair faults, go for the same
models at least.
hth,
Andreas
7704A uses a TEK-made IC for it's PS control,while the older 7704 non-
A uses discrete circuitry.
The A model has more control loops.

--
Jim Yanik
jyanik
at
kua.net- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Infact: all IC are custom, with various models.Now I am arrived to
have: trace very weak, but seem trigger and vertical work.There is a
problem: the trace is only present on central zone of tube. I never
seen a wiew like this. I fund another mainframe so I can replace step
by step the circuit, so I can see which one is defected.
But really this is on very bad conditions. I repaired a lot of
465-475-7704-7603 and others , but this is very hard!!

Depending on which version you have, there's a bleeder resistor on the
HV board...actually a bunch of 'em in series. *They go open, the high
voltage goes up, the trace shrinks.

Mine had four of about 7 open resistors in series. *I found that
improbable...
The explanation given was that they're carbon and they crack. *Then
the first one arcs to keep the current flowing until the second one
cracks and opens...which arcs...until finally there are enough of them
open that it can't sustain all those series arcs at once and the string
starts acting like it's open.

--
Return address is VALID!- Nascondi testo tra virgolette -

- Mostra testo tra virgolette -

Thanks for help! Actually the PS work at 80 %. I must replace the
diac.I replaced all diodes fast use on PS. Before I used the normal
diodes, so doesn't work!! Anyway the mainframe suffered a lot because
was stored on wet place. Now I found several mainframe, so I try to
replace the whole circuit.
I will post the final results. Thanks again. Gianni