Tektronix 2335 Oscilloscope Repair

I have a early 1980's era Tek 2335 here that is in need of repair. I
know this is a somewhat scarce ruggedized military model, but it may
be helpful if someone could tell me if there is a more standard model
that this may be a clone of.

I have many Tek service manuals, but not for this particular model.
It would be great if I could troubleshoot from the manual of a
slightly different model.

Even advice would be helpful. The symptoms it displays are:

Beam out of focus. Cannot sharpen, but does take some adjustment.
Vertical adjustment does not work.
Straight horizontal line, which does not change on Ch1 or CH2. No
visible channel seperation.
Does not respond to input of either AC or DC.
Brightness varies with sweep frequency.

I have another scope, so testing is not a difficulty.

 

[JW]

On 20 Nov 2008 02:13:05 -0600 kel@netcene.com wrote in Message id:
<tm3ai497vrtb2dqkuch00npf2532ii2djm@4ax.com>:

I have a early 1980's era Tek 2335 here that is in need of repair. I
know this is a somewhat scarce ruggedized military model, but it may
be helpful if someone could tell me if there is a more standard model
that this may be a clone of.

I have many Tek service manuals, but not for this particular model.
It would be great if I could troubleshoot from the manual of a
slightly different model.

Even advice would be helpful. The symptoms it displays are:

Beam out of focus. Cannot sharpen, but does take some adjustment.
Vertical adjustment does not work.
Straight horizontal line, which does not change on Ch1 or CH2. No
visible channel seperation.
Does not respond to input of either AC or DC.
Brightness varies with sweep frequency.

I have another scope, so testing is not a difficulty.

Download the 86MB service manual here:
http://www.ko4bb.com/cgi-bin/manuals.pl?dir=Tektronix/Tektronix_-_2235

There's even a txt file with a possible solution for your scopes focus
problem:

http://www.ko4bb.com/Manuals/Tektronix/Tektronix_-_2235/Tektronix_2235_Poor_Focus_Problem_and_Solution.txt
----- Original Message -----
From: Jay Sario
To: TekScopes@yahoogroups.com
Sent: Thursday, December 27, 2007 12:28 AM
Subject: [TekScopes] TEK 2235 no good focus

hi to all,

Would like to ask help from anybody. I recently got a used TEK-2235, I
cant get a clear focus on the screen even if I rotate the "focus"
knob, its always blurred. Hope anybody can share where I would check
or what part to check...thank you and merry xmas to all.

Having a 2235 myself, I had found and saved this note from another
newsgroup:

Between the hv multiplier (has CRT anode lead coming out of it) and the
focus pot are two 1/2w resistors,510k ohm.Then behind the focus pot are
four more 1/2w res,all lined up neatly in a row,also 510k ohms. These go bad frequently.
Use carbon COMPOSITION type as replacements. The old ones change
value,usually increasing in value.

Good luck! Adriano

 

[JW]

On Thu, 20 Nov 2008 05:26:24 -0500 JW <none@dev.null> wrote in Message id:
<fpeai4lc3tohrk1khes1e44dv8vbvm1bv1@4ax.com>:

On 20 Nov 2008 02:13:05 -0600 kel@netcene.com wrote in Message id:
tm3ai497vrtb2dqkuch00npf2532ii2djm@4ax.com>:



I have a early 1980's era Tek 2335 here that is in need of repair. I
know this is a somewhat scarce ruggedized military model, but it may
be helpful if someone could tell me if there is a more standard model
that this may be a clone of.

I have many Tek service manuals, but not for this particular model.
It would be great if I could troubleshoot from the manual of a
slightly different model.

Even advice would be helpful. The symptoms it displays are:

Beam out of focus. Cannot sharpen, but does take some adjustment.
Vertical adjustment does not work.
Straight horizontal line, which does not change on Ch1 or CH2. No
visible channel seperation.
Does not respond to input of either AC or DC.
Brightness varies with sweep frequency.

I have another scope, so testing is not a difficulty.

Download the 86MB service manual here:
http://www.ko4bb.com/cgi-bin/manuals.pl?dir=Tektronix/Tektronix_-_2235

Oops. I mis-read the model number. It's possible that the focus problem
may have the same solution, though...

 

[JW]

On Thu, 20 Nov 2008 05:35:26 -0500 JW <none@dev.null> wrote in Message id:
<creai4ho41b8i5dm3m5bhb3j33ck7kk4gr@4ax.com>:

Oops. I mis-read the model number. It's possible that the focus problem
may have the same solution, though...

And if you get desperate:
http://yourmanualsource.com/

90 bucks though. Ouch.

 

[Jim Yanik]

kel@netcene.com wrote in news:tm3ai497vrtb2dqkuch00npf2532ii2djm@4ax.com:

I have a early 1980's era Tek 2335 here that is in need of repair. I
know this is a somewhat scarce ruggedized military model, but it may
be helpful if someone could tell me if there is a more standard model
that this may be a clone of.

No.there's the 2335,2336,2337;all one family.
An unusual scope,uses a lot of TEK-made ICs(sole source,NLA!),and difficult
to work on. Not a big seller like 465 or 7000 series.

I checked BAMA and one other manuals site,and neither had any of the 2300
manuals.

I have many Tek service manuals, but not for this particular model.
It would be great if I could troubleshoot from the manual of a
slightly different model.

Even advice would be helpful. The symptoms it displays are:

Beam out of focus. Cannot sharpen, but does take some adjustment.
Vertical adjustment does not work.
Straight horizontal line, which does not change on Ch1 or CH2. No
visible channel seperation.
Does not respond to input of either AC or DC.
Brightness varies with sweep frequency.

I have another scope, so testing is not a difficulty.

--
Jim Yanik
jyanik
at
kua.net

 

I finally set aside time and got inside the HV section.

I found that the 2335 bears no simarity at all to the 2200 family as
far as schematics and design.

There are alot of specially made parts inside the HV section,
including a thick film resistor combo.

I may be able to bypass or jury rig something here, but I would need a
copy of the schematic for the HV section. Are there any links to one?

Many thanks in advance....


On 20 Nov 2008 14:24:31 GMT, Jim Yanik <jyanik@abuse.gov> wrote:

kel@netcene.com wrote in news:tm3ai497vrtb2dqkuch00npf2532ii2djm@4ax.com:



I have a early 1980's era Tek 2335 here that is in need of repair. I
know this is a somewhat scarce ruggedized military model, but it may
be helpful if someone could tell me if there is a more standard model
that this may be a clone of.

No.there's the 2335,2336,2337;all one family.
An unusual scope,uses a lot of TEK-made ICs(sole source,NLA!),and difficult
to work on. Not a big seller like 465 or 7000 series.

I checked BAMA and one other manuals site,and neither had any of the 2300
manuals.

I have many Tek service manuals, but not for this particular model.
It would be great if I could troubleshoot from the manual of a
slightly different model.

Even advice would be helpful. The symptoms it displays are:

Beam out of focus. Cannot sharpen, but does take some adjustment.
Vertical adjustment does not work.
Straight horizontal line, which does not change on Ch1 or CH2. No
visible channel seperation.
Does not respond to input of either AC or DC.
Brightness varies with sweep frequency.

I have another scope, so testing is not a difficulty.

 

[JW]

On 24 Nov 2008 23:30:01 -0600 kel@netcene.com wrote in Message id:
<l73ni410fqluctp7bunlu9ae2nl3989clp@4ax.com>:

I finally set aside time and got inside the HV section.

I found that the 2335 bears no simarity at all to the 2200 family as
far as schematics and design.

There are alot of specially made parts inside the HV section,
including a thick film resistor combo.

I may be able to bypass or jury rig something here, but I would need a
copy of the schematic for the HV section. Are there any links to one?

Well, as I said before, yes. Unfortunately, it doesn't come cheap:
http://yourmanualsource.com/

Just be sure to ask them if it contains schematics before you purchase it.
There's some manual companies who sell service manuals without diagrams...

 

[Jim Yanik]

kel@netcene.com wrote in
news:l73ni410fqluctp7bunlu9ae2nl3989clp@4ax.com:

I finally set aside time and got inside the HV section.

I found that the 2335 bears no simarity at all to the 2200 family as
far as schematics and design.

There are alot of specially made parts inside the HV section,
including a thick film resistor combo.

I may be able to bypass or jury rig something here, but I would need a
copy of the schematic for the HV section. Are there any links to one?

Many thanks in advance....


On 20 Nov 2008 14:24:31 GMT, Jim Yanik <jyanik@abuse.gov> wrote:

kel@netcene.com wrote in
news:tm3ai497vrtb2dqkuch00npf2532ii2djm@4ax.com:



I have a early 1980's era Tek 2335 here that is in need of repair. I
know this is a somewhat scarce ruggedized military model, but it may
be helpful if someone could tell me if there is a more standard
model that this may be a clone of.

No.there's the 2335,2336,2337;all one family.
An unusual scope,uses a lot of TEK-made ICs(sole source,NLA!),and
difficult to work on. Not a big seller like 465 or 7000 series.

I checked BAMA and one other manuals site,and neither had any of the
2300 manuals.

I have many Tek service manuals, but not for this particular model.
It would be great if I could troubleshoot from the manual of a
slightly different model.

Even advice would be helpful. The symptoms it displays are:

Beam out of focus. Cannot sharpen, but does take some adjustment.
Vertical adjustment does not work.
Straight horizontal line, which does not change on Ch1 or CH2. No
visible channel seperation.
Does not respond to input of either AC or DC.
Brightness varies with sweep frequency.

I have another scope, so testing is not a difficulty.

if you have no vertical deflection or positioning,why are you looking at
the HV section?

--
Jim Yanik
jyanik
at
kua.net

 

[msg]

JW wrote:

On 24 Nov 2008 23:30:01 -0600 kel@netcene.com wrote

<snip>

I would need a
copy of the schematic for the HV section. Are there any links to one?


Well, as I said before, yes. Unfortunately, it doesn't come cheap:
http://yourmanualsource.com/

Just be sure to ask them if it contains schematics before you purchase it.
There's some manual companies who sell service manuals without diagrams...

Posts like these continually appear and the answer is always the same, "buy
the manual"; if someone really does buy one, please consider scanning it and
posting the document somewhere for public download, perhaps the 'bama' site
or any other of your choosing -- help to mitigate the documentation problems
for older gear! Paper manuals will eventually become unavailable and businesses
selling copies may vanish as well; please help to make tech documentation a public
access resource.

Michael