Date   

CSA803A vs 11801C

santa0123456
 

Apart from the fact that the 11801C has 4 functional head slots
and may be expanded, what differences exist between these models?
I see that 7 chips are missing on the 11801C TimeBase/Controller
board compared to the CSA803A but I cannot find any obvious differences in the specs.

Regards


SC 503 HV

Jerry Massengale <jmassen418@...>
 

Hi
 
I have a high series SC 503 with no trace and Low voltages in the HV section. The HV Osc runs but the drivers get hot very quickly. The -2kv test point reads -1200V at turnon and quickly starts to fall off. Removing the crt does not relieve problem. I can see that the transformer is working with outputs on all windings. They are low in the same way as the   -2kv. An ohms check of the transformer does not arouse any suspicions.
 
I am in the process of ordering the electrolytics in the HV secondary from mouser but have not found a fault with any.
 
Advice is welcome.
 
jerry
 


Re: 7904 readout on the wrong place - vertical signal squeezed

Jerry Massengale <jmassen418@...>
 

Hi,
 
Sorry,
 
I have none in my stock. I have 7603s and a 7704. No 7904 stuff.
jerry


--- On Wed, 1/20/10, kupkagerhard wrote:

From: kupkagerhard
Subject: [TekScopes] Re: 7904 readout on the wrong place - vertical signal squeezed
To: TekScopes@...
Date: Wednesday, January 20, 2010, 1:48 PM

 


Hi Jerry,
sorry, I can't answer your question at the moment, because I destroyed the hybrid U685 on the vertical ampliefier board by a short circuit during checking the output signal.
Do you know, where I can get a U685 or a vertical ampliefier board?
Gerhard
--- In TekScopes@yahoogrou ps.com, Jerry Massengale wrote:
>
> Hi,
>  
> I forgot to ask if the signal on the vertical plates swing positive above zero.
>  
> jerry
>
> --- On Wed, 1/20/10, kupkagerhard wrote:
>
>
> From: kupkagerhard
> Subject: [TekScopes] 7904 readout on the wrong place - vertical signal squeezed
> To: TekScopes@yahoogrou ps.com
> Date: Wednesday, January 20, 2010, 7:07 AM
>
>
>  
>
>
>
> In my 7904 the readout is placed 1 division below the middle of the screen. Additionally the vertical signal can't be moved to upper half of the screen. When I move the vertical signal from bottom of the screen upwards, the signal will be squeezed vertically in the left part of the screen. The output signal of the vertical main amplifier doesn't show any queezing. The output of the horizontal main amplifier shows no distortion on the sawtooth signal
>


Re: A Tale Of Two Teks (454A CRT Swapout)

TomS <bullet@...>
 

Hi:

It was a bit of a chore because I had to tear it down a good bit further than I otherwise would have. This is because I needed to remove the rear casting on #2 to replace the damaged one on #1. Given all of the added complexity this resulted in, I suspect I will just find a way to leave the existing casting in place if at all possible. Also, I am finding so much evidence of damage from overheating that I am considering stripping it all the way down to the bare frame. It may be that (if I am lucky) the CRT might be one of only a few good part in the whole unit! Its pretty thoroughly trashed. No evidence that I dumped the vacuum on the tube, thought. Still hopeful on that front. Thanks for the feedback.

-Tom

--- In TekScopes@yahoogroups.com, "DEANE KIDD" <dektyr@...> wrote:

To Thomas:
You sure make sound like it was a chore to get this thing apart. It was just a few little things to take apart. That CRT has a socket that just plugs onto the base of the CRT and does not require cutting any wires. The HV power supply comes out as a module and should be saved for its' parts. This was the first high frequency scope and you boys make fun of the work of art that it intailed and I hope that you find a way to make the 2nd one work and I hope that the channel 2 amplifier does not require any repair.(Remove the CRT to get to the circuit board). The HV annode lead just plugs into the shield and I hope that you haven't broken the CRT vacuum because a replacement CRT will be almost impossible to find and this was a Tek made version. Good luck,
Deane, I am an old timer as I started in August of '49 and retired in June of '91.
----- Original Message -----
From: Thomas Simpson
To: TekScopes@yahoogroups.com
Sent: Tuesday, January 19, 2010 7:53 PM
Subject: Re: [TekScopes] A Tale Of Two Teks (454A CRT Swapout)



Oh, and I think I figured out what deadlined scope #2: looks like the
case fan siezed up, 'cause I see extensive discoloration on the
underside of both the LV regulator and sweep boards, and the plastic
covers over several of the HV caps have melted. Man, this thing lived a
hard life, and thats BEFORE the kids got ahold of it. :- )

Not sure to what extent these boards are fixable. Might be, might not.
Sweep board actually has a charred place on it. We'll have to see.

Pictures to follow.

-Tom

Thomas Simpson wrote:
>
>
> Okay, I have the rear casting off and have removed a billion little
> screws and nuts of various descriptions. I almost have the front of the
> CRT free. At this point, I have two questions:
>
> 1) Regarding the anode wire that goes into the left side of the tube
> near the front...I have the rubber cover pried back, exposing what
> appears to be the inner core of a coaxial cable that is connected to a
> plug inserted into a recess in the side of the tube body. How do I
> separate the anode wire from the tube? Does that connector on the end of
> the lead simply pull out?
>
> 2) Regarding all of the wiring harness stuff that runs to the back of
> the CRT...wires from several harness run into the back of the CRT
> housing and dissapear under a flat white cap. The cap has two holes in
> it as if it were meant to be unscrewed using a spanner. Is that cap
> removable? If so, then how? Just what is the school solution for
> swapping out the wiring at the back of the CRT? Does it disconnect at
> the rear, or do I (shudder) have to cut and splice all that wiring? I
> would hope not the latter.
>
> But otherwise, things are going very well. The care that went into the
> design and execution of the 454A is a real credit to Textronix. Truly
> elegant.
>
> Thanks;
>
> -Tom
>






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Re: 7904 readout on the wrong place - vertical signal squeezed

kupkagerhard <ghm1@...>
 

Hi Jerry,
sorry, I can't answer your question at the moment, because I destroyed the hybrid U685 on the vertical ampliefier board by a short circuit during checking the output signal.
Do you know, where I can get a U685 or a vertical ampliefier board?
Gerhard

--- In TekScopes@yahoogroups.com, Jerry Massengale <jmassen418@...> wrote:

Hi,
 
I forgot to ask if the signal on the vertical plates swing positive above zero.
 
jerry

--- On Wed, 1/20/10, kupkagerhard <ghm1@...> wrote:


From: kupkagerhard <ghm1@...>
Subject: [TekScopes] 7904 readout on the wrong place - vertical signal squeezed
To: TekScopes@yahoogroups.com
Date: Wednesday, January 20, 2010, 7:07 AM


 



In my 7904 the readout is placed 1 division below the middle of the screen. Additionally the vertical signal can't be moved to upper half of the screen. When I move the vertical signal from bottom of the screen upwards, the signal will be squeezed vertically in the left part of the screen. The output signal of the vertical main amplifier doesn't show any queezing. The output of the horizontal main amplifier shows no distortion on the sawtooth signal


Re: NV ram in 2465B

Tom Miller <tmiller@...>
 

Hey guys,
 
I wonder if I could use an ECL one shot triggered from a HP 8656B signal generator to get the three pulses needed to finish the cal?
It could have a 5, 2, and 1 nS pulse and triggered from the sig gen at the proper frequency to make the correct markers.
 
Maybe put it in a small box and battery power it? Is there an ECL 1-shot chip available? Or could it be done with S-TTL?
 
That would get around the CG551 limits.
 
Regards,
Tom
 
 
 
 

----- Original Message -----
Sent: Wednesday, January 20, 2010 5:41 AM
Subject: [TekScopes] Re: NV ram in 2465B

 

Stan,

I perfectly understand slewed markers. I stand by what I said.
The CG551AP has never been called out in an 2465, 2465A or 2465B service manual. I have all three: TG501A, CG551AP and CG5011 in my possession, the CG5011 can perfectly replace the TG501(A). In my opinion the CG551AP cannot be used to calibrate a 2465(B) or if possible it will be very, very difficult and would possibly produce questionable results.

One possible error I did make was calling the horizontal CAL 01 steps 28, 30, 33, 34 a transient response adjustment. Although the 2465B service manual states, set the time marker to 2ns and ADJ TRANS RESP (R802). So I maybe you can define what Tek meant by this statement since you worked in their marketing department. Maybe when Tek says transient response, they mean something else here?

In any case applying slewed edges markers to steps 17 and above in the CAL 01 procedure will be completely confusing.

I begin to wonder if you have actually ever done a 2465B calibration from the statements you have made.

Regards,
Victor Silva

--- In TekScopes@yahoogroups.com, "Stan & Patricia Griffiths" wrote:
>
> I don't know why you think you can't use a CG551AP to do the timing
> adjustments and checks on a 2465. I think that is exactly what it was made
> for.
>
>
>
> It sounds like maybe you don't really understand the "slewed edge", how it
> works, and what it is used for. I will try to explain it here. The slewed
> edge is used for timing checks and adjustments on the fastest sweep speeds.
> It is not used for adjusting the high frequency transient response of the
> vertical amplifier. The slewed edge consists of a series of very accurately
> spaced "edges", space accurately "in time" from the CG551AP Trigger Output
> pulse. A scope display of it will consist of 10 or 12 accurately spaced
> transitions. The BIG advantage of the slewed edge is that you can get a
> display that allows you to check very fast sweep speeds (as fast as 0.4ns
> per division) without having to have a vertical amplifier with a bandwidth
> higher than about 100 MHz. This is really important in a large company
> calibration lab where you may be calibrating a 7104 with a 7B92A (as fast as
> 10ns per division) in the horizontal and have only a 7A18 (75 MHz) vertical
> plugin available.
>
>
>
> For checking vertical transient response, you must have the Pulse Head
> (015-0311-01) which is a standard accessory included with the CG551AP.
> (CG551AP Option 02 DELETED the Pulse Head.) Since the Pulse Head is a
> plug-in accessory, it can easily get separated from the CG551AP, never to be
> found again. I suspect you do not have the Pulse Head for your CG551AP and
> you will need to get one if you are going to use the CG551AP to check and
> adjust vertical amplifier transient response.
>
>
>
> I hope this clears up some of the confusion. I worked in TM500 Marketing at
> Tek when the CG551AP was introduced and it was my project to introduce it to
> the world. It was a LONG time ago but I remember it well.
>
>
>
> If you still have some questions about how to use it, please ask and I will
> try to help.
>
>
>
> Stan Griffiths
>
>
>
>
>
>
>
> _____
>
> From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] On Behalf
> Of David C. Partridge
> Sent: Monday, January 18, 2010 5:22 AM
> To: TekScopes@yahoogroups.com
> Subject: RE: [TekScopes] Re: NV ram in 2465B
>
>
>
>
>
> Victor,
>
> I've not had to do a 2465 cal before now. If one can't use a CG551AP to
> calibrate the timing, what is the weapon of choice? I don't really want to
> have to buy a CG5011 and TM5000 frame to put it in (not that I wouldn't
> *like* to have them, just a money shortage).
>
> Thanks
> Dave
>
> -----Original Message-----
> From: TekScopes@yahoogrou 40yahoogroups.com> ps.com
> [mailto:TekScopes@yahoogrou 40yahoogroups.com> ps.com] On
> Behalf
> Of victor.silva
> Sent: 18 January 2010 08:29
> To: TekScopes@yahoogrou 40yahoogroups.com> ps.com
> Subject: [TekScopes] Re: NV ram in 2465B
>
> I don't see how a CG551AP can be used. The slewed markers at the high
> frequencies will make it very difficult to tell which marker is the correct
> one for the high frequency adjustment.
>
> To get rid of a 04 02 error you should be able to blow through the tests in
> about 15 minutes. Remember you're not really calibrating it, you just want
> to get through the steps. If finishing all the CAL steps (in 15 min.) gets
> rid of the 04 02 error then you can redo the Cal more carefully.
>
> --Victor
>


Re: Crazy question regarding 2445A...

amstel78 <amstel78@...>
 

Thanks for the reply Victor.

Ok then, any way to center the focus knob? Seems both my 2430 and 2445A come into focus right about 2 o'clock on the potentiometer.

Just curious if this was possible.

Thanks,
James

--- In TekScopes@yahoogroups.com, "victor.silva" <daejon1@...> wrote:

It's a different shaped base that the knob cap snaps onto. It has the a longer neck and I see no reason for that base. It can't be for re-centering because when you pull it out; the shaft on pot is still in the D-slot. Besides all the pots under the CRT are one turn only, I could see it if they were free turning pots.

I think some Cal house or tech just randomly threw whatever they had in their parts bin onto those shafts. I've seen those white caps before but they were mounted on the free turning pots (two stacked pots). But even in these cases if the pot's D-shaft is locked in the D-slot no matter how much you pull it out I see no purpose to those type of knob bases.

I'd be interested in knowing the answer myself.

--Victor


Re: 7904 readout on the wrong place - vertical signal squeezed

Jerry Massengale <jmassen418@...>
 

Hi,
 
I forgot to ask if the signal on the vertical plates swing positive above zero.
 
jerry


--- On Wed, 1/20/10, kupkagerhard wrote:

From: kupkagerhard
Subject: [TekScopes] 7904 readout on the wrong place - vertical signal squeezed
To: TekScopes@...
Date: Wednesday, January 20, 2010, 7:07 AM

 
In my 7904 the readout is placed 1 division below the middle of the screen. Additionally the vertical signal can't be moved to upper half of the screen. When I move the vertical signal from bottom of the screen upwards, the signal will be squeezed vertically in the left part of the screen. The output signal of the vertical main amplifier doesn't show any queezing. The output of the horizontal main amplifier shows no distortion on the sawtooth signal


Re: 7904 readout on the wrong place - vertical signal squeezed

Jerry Massengale <jmassen418@...>
 

Hi,
 
You might check continuity of the lead. If the lead is good, I would suspect the CRT itself. You can often inspect the internal leads through the glass. Sometimes the internal glass rods that support the elements are damaged. If you shake the tube you can hear glass rattles inside. Otherwise I do not know what to do. Good luck.
 
jerry


--- On Wed, 1/20/10, kupkagerhard wrote:

From: kupkagerhard
Subject: [TekScopes] Re: 7904 readout on the wrong place - vertical signal squeezed
To: TekScopes@...
Date: Wednesday, January 20, 2010, 8:13 AM

 


But the + wire from the horizontal main amplifier is plugged on the contact on the CRT neck, or do you think inside the crt?

--- In TekScopes@yahoogrou ps.com, Jerry Massengale wrote:
>
> Hi,
>  
> Sounds like the horizontal + pin on the neck of the crt is open.
>  
> jerry
> --- On Wed, 1/20/10, kupkagerhard wrote:
>
>
> From: kupkagerhard
> Subject: [TekScopes] 7904 readout on the wrong place - vertical signal squeezed
> To: TekScopes@yahoogrou ps.com
> Date: Wednesday, January 20, 2010, 7:07 AM
>
>
>  
>
>
>
> In my 7904 the readout is placed 1 division below the middle of the screen. Additionally the vertical signal can't be moved to upper half of the screen. When I move the vertical signal from bottom of the screen upwards, the signal will be squeezed vertically in the left part of the screen. The output signal of the vertical main amplifier doesn't show any queezing. The output of the horizontal main amplifier shows no distortion on the sawtooth signal
>


Re: Tek 2432 failing self test

victor.silva
 

Tek has the 2440 SM on its site:

http://www2.tek.com/cmswpt/madetails.lotr?ct=MA&;cs=msv&ci=15047&lc=EN

You really need the SM for the 2432, it's very different from the 2440 and even the 2432A.

If the CCDs are gone the 2432 may not be worth saving. Just my opinion.

--Victor

--- In TekScopes@yahoogroups.com, "David C. Partridge" <david.partridge@...> wrote:

The CCDs are the crucial Fast In Slow Out portion of the main sampling
circuit and yes CCD does stand for charge coupled device.

The PA failure points to the Pre-Amp, but is often a secondary result of CCD
failure.

I had to scrap a 2430A not long back with both CCDs failed :-(. Luckily, I
only lost about $120 on that deal. I have *all* PCBs available for it
*except* the main acquisition board (I do have the attenuators) if anyone
needs them. I also have the tube, which ISTR also fits 2465, 2465A, and
2465B.

If it still fails self test after sitting at a comfortable room temperature
(say 20C to 25C) for 24 hours, then I think you have a problem (though it
may just be the CCD driver circuits if you are *really* lucky). Are both
CCDs failing (dig down in the diagnostics) or just one?

I don't recollect seeing downloadable service manuals for either the 2432 or
the 2440.

Dave

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] On Behalf
Of Ryan Scott
Sent: 20 January 2010 14:45
To: TekScopes@yahoogroups.com
Subject: Re: [TekScopes] Re: Tek 2432 failing self test



Hi Jayw,

Thanks for your response.. I know tek used hybrids in alot of scopes, what
part of the ckt are these CCD's used in, and what does the CCD stand for,
charge coupled device?

Thanks,
Ryan


--- On Wed, 1/20/10, jayw_comark <jayw_comark@...> wrote:



From: jayw_comark <jayw_comark@...>
Subject: [TekScopes] Re: Tek 2432 failing self test
To: TekScopes@yahoogroups.com
Date: Wednesday, January 20, 2010, 3:51 AM



Hi Ryan,

These scopes had a high failure rate in the CCD hybrids. It is
likely that on or both are defective. You can determine which using the
extended service diagnostics. (Or looking at their output with a working
scope.)

--- In TekScopes@yahoogrou ps.com
<http://us.mc1125.mail.yahoo.com/mc/compose?to=TekScopes%40yahoogroups.com>;
, Ryan Scott <tweeker42000@ ...> wrote:
>
>
> Hi all,
>
> I have acquired a Tek 2432 scope that fails self test upon power
up. I'm warming it up in hopes it will pass then but so far it has failures
on the 7000 CCD, 8000 PA, 9000 Trig.
>
> I have not been able to find a manual online from the usual free
places... Anyone got any quick ideas how to resolve these self test errors?
>
> Thanks,
> Ryan
>


Re: Tek 2432 failing self test

David C. Partridge <david.partridge@...>
 

The CCDs are the crucial Fast In Slow Out portion of the main sampling
circuit and yes CCD does stand for charge coupled device.

The PA failure points to the Pre-Amp, but is often a secondary result of CCD
failure.

I had to scrap a 2430A not long back with both CCDs failed :-(. Luckily, I
only lost about $120 on that deal. I have *all* PCBs available for it
*except* the main acquisition board (I do have the attenuators) if anyone
needs them. I also have the tube, which ISTR also fits 2465, 2465A, and
2465B.

If it still fails self test after sitting at a comfortable room temperature
(say 20C to 25C) for 24 hours, then I think you have a problem (though it
may just be the CCD driver circuits if you are *really* lucky). Are both
CCDs failing (dig down in the diagnostics) or just one?

I don't recollect seeing downloadable service manuals for either the 2432 or
the 2440.

Dave

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] On Behalf
Of Ryan Scott
Sent: 20 January 2010 14:45
To: TekScopes@yahoogroups.com
Subject: Re: [TekScopes] Re: Tek 2432 failing self test



Hi Jayw,

Thanks for your response.. I know tek used hybrids in alot of scopes, what
part of the ckt are these CCD's used in, and what does the CCD stand for,
charge coupled device?

Thanks,
Ryan


--- On Wed, 1/20/10, jayw_comark <jayw_comark@yahoo.com> wrote:



From: jayw_comark <jayw_comark@yahoo.com>
Subject: [TekScopes] Re: Tek 2432 failing self test
To: TekScopes@yahoogroups.com
Date: Wednesday, January 20, 2010, 3:51 AM



Hi Ryan,

These scopes had a high failure rate in the CCD hybrids. It is
likely that on or both are defective. You can determine which using the
extended service diagnostics. (Or looking at their output with a working
scope.)

--- In TekScopes@yahoogrou ps.com
<http://us.mc1125.mail.yahoo.com/mc/compose?to=TekScopes%40yahoogroups.com>;
, Ryan Scott <tweeker42000@ ...> wrote:
>
>
> Hi all,
>
> I have acquired a Tek 2432 scope that fails self test upon power
up. I'm warming it up in hopes it will pass then but so far it has failures
on the 7000 CCD, 8000 PA, 9000 Trig.
>
> I have not been able to find a manual online from the usual free
places... Anyone got any quick ideas how to resolve these self test errors?
>
> Thanks,
> Ryan
>


Re: Tek 2432 failing self test

Ryan Scott
 

Hi Jayw,
 
Thanks for your response..  I know tek used hybrids in alot of scopes, what part of the ckt are these CCD's used in, and what does the CCD stand for, charge coupled device?
 
Thanks,
Ryan


--- On Wed, 1/20/10, jayw_comark wrote:

From: jayw_comark
Subject: [TekScopes] Re: Tek 2432 failing self test
To: TekScopes@...
Date: Wednesday, January 20, 2010, 3:51 AM

 
Hi Ryan,

These scopes had a high failure rate in the CCD hybrids. It is likely that on or both are defective. You can determine which using the extended service diagnostics. (Or looking at their output with a working scope.)

--- In TekScopes@yahoogrou ps.com, Ryan Scott wrote:
>
>
> Hi all,
>  
> I have acquired a Tek 2432 scope that fails self test upon power up.  I'm warming it up in hopes it will pass then but so far it has failures on the 7000 CCD, 8000 PA, 9000 Trig.
>  
> I have not been able to find a manual online from the usual free places...  Anyone got any quick ideas how to resolve these self test errors?
>  
> Thanks,
> Ryan
>


Re: 7904 readout on the wrong place - vertical signal squeezed

David C. Partridge <david.partridge@...>
 

Checking the vertical plates are connected inside the CRT is easy - check
ohms from vertical plate input pin on CRT to the corresponding pin for the
terminator. Also of course check that the terminator is correctly
connected.

Dave

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] On Behalf
Of David C. Partridge
Sent: 20 January 2010 14:32
To: TekScopes@yahoogroups.com
Subject: RE: [TekScopes] 7904 readout on the wrong place - vertical signal
squeezed

Before you condemn the CRT (or the vertical output amp) check the values on
the large emitter resistors R724, R725. They should be 500 ohms (early
7904) or 332R in the later (post B260000) version. These tend to run
*very* hot, and are often WAY off nominal value.

Certainly I would agree it is a good idea to check the connections to the
vertical plates.

If they are out of specification, I typically replace each of them (in an
early 7904) with two 1K0 2W resistors in parallel and make sure they are
mounted well off the board.

HtH
Dave

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] On Behalf
Of Jerry Massengale
Sent: 20 January 2010 13:32
To: TekScopes@yahoogroups.com
Subject: Re: [TekScopes] 7904 readout on the wrong place - vertical signal
squeezed



Hi,

Sounds like the horizontal + pin on the neck of the crt is open.

jerry
--- On Wed, 1/20/10, kupkagerhard <ghm1@gmx.de> wrote:



From: kupkagerhard <ghm1@gmx.de>
Subject: [TekScopes] 7904 readout on the wrong place - vertical
signal squeezed
To: TekScopes@yahoogroups.com
Date: Wednesday, January 20, 2010, 7:07 AM



In my 7904 the readout is placed 1 division below the middle of the
screen. Additionally the vertical signal can't be moved to upper half of the
screen. When I move the vertical signal from bottom of the screen upwards,
the signal will be squeezed vertically in the left part of the screen. The
output signal of the vertical main amplifier doesn't show any queezing. The
output of the horizontal main amplifier shows no distortion on the sawtooth
signal









------------------------------------

Yahoo! Groups Links


Re: 7904 readout on the wrong place - vertical signal squeezed

Glenn Butzlaff <gbutzlaff@...>
 

This sounds like the same issue I have with my 7704A. Just curious; can you move the trace above the center line when you activate the beam finder button?

Glenn

----- Original Message -----
From: "kupkagerhard" <ghm1@gmx.de>
To: <TekScopes@yahoogroups.com>
Sent: Wednesday, January 20, 2010 8:13 AM
Subject: [TekScopes] Re: 7904 readout on the wrong place - vertical signal squeezed







But the + wire from the horizontal main amplifier is plugged on the contact on the CRT neck, or do you think inside the crt?

--- In TekScopes@yahoogroups.com, Jerry Massengale <jmassen418@...> wrote:

Hi,
�
Sounds like the horizontal + pin on the neck of the crt is open.
�
jerry
--- On Wed, 1/20/10, kupkagerhard <ghm1@...> wrote:


From: kupkagerhard <ghm1@...>
Subject: [TekScopes] 7904 readout on the wrong place - vertical signal squeezed
To: TekScopes@yahoogroups.com
Date: Wednesday, January 20, 2010, 7:07 AM


�



In my 7904 the readout is placed 1 division below the middle of the screen. Additionally the vertical signal can't be moved to upper half of the screen. When I move the vertical signal from bottom of the screen upwards, the signal will be squeezed vertically in the left part of the screen. The output signal of the vertical main amplifier doesn't show any queezing. The output of the horizontal main amplifier shows no distortion on the sawtooth signal



------------------------------------

Yahoo! Groups Links


Re: 7904 readout on the wrong place - vertical signal squeezed

David C. Partridge <david.partridge@...>
 

Before you condemn the CRT (or the vertical output amp) check the values on
the large emitter resistors R724, R725. They should be 500 ohms (early
7904) or 332R in the later (post B260000) version. These tend to run
*very* hot, and are often WAY off nominal value.

Certainly I would agree it is a good idea to check the connections to the
vertical plates.

If they are out of specification, I typically replace each of them (in an
early 7904) with two 1K0 2W resistors in parallel and make sure they are
mounted well off the board.

HtH
Dave

-----Original Message-----
From: TekScopes@yahoogroups.com [mailto:TekScopes@yahoogroups.com] On Behalf
Of Jerry Massengale
Sent: 20 January 2010 13:32
To: TekScopes@yahoogroups.com
Subject: Re: [TekScopes] 7904 readout on the wrong place - vertical signal
squeezed



Hi,

Sounds like the horizontal + pin on the neck of the crt is open.

jerry
--- On Wed, 1/20/10, kupkagerhard <ghm1@gmx.de> wrote:



From: kupkagerhard <ghm1@gmx.de>
Subject: [TekScopes] 7904 readout on the wrong place - vertical
signal squeezed
To: TekScopes@yahoogroups.com
Date: Wednesday, January 20, 2010, 7:07 AM



In my 7904 the readout is placed 1 division below the middle of the
screen. Additionally the vertical signal can't be moved to upper half of the
screen. When I move the vertical signal from bottom of the screen upwards,
the signal will be squeezed vertically in the left part of the screen. The
output signal of the vertical main amplifier doesn't show any queezing. The
output of the horizontal main amplifier shows no distortion on the sawtooth
signal


Re: 7904 readout on the wrong place - vertical signal squeezed

kupkagerhard <ghm1@...>
 

But the + wire from the horizontal main amplifier is plugged on the contact on the CRT neck, or do you think inside the crt?

--- In TekScopes@yahoogroups.com, Jerry Massengale <jmassen418@...> wrote:

Hi,
 
Sounds like the horizontal + pin on the neck of the crt is open.
 
jerry
--- On Wed, 1/20/10, kupkagerhard <ghm1@...> wrote:


From: kupkagerhard <ghm1@...>
Subject: [TekScopes] 7904 readout on the wrong place - vertical signal squeezed
To: TekScopes@yahoogroups.com
Date: Wednesday, January 20, 2010, 7:07 AM


 



In my 7904 the readout is placed 1 division below the middle of the screen. Additionally the vertical signal can't be moved to upper half of the screen. When I move the vertical signal from bottom of the screen upwards, the signal will be squeezed vertically in the left part of the screen. The output signal of the vertical main amplifier doesn't show any queezing. The output of the horizontal main amplifier shows no distortion on the sawtooth signal


Re: test 05 fail 24

tom jobe <tomjobe@...>
 

Hi Gerald,
Whenever problems of this sort appear on Tekscopes, I search the archives
for additional information about the problems if they are of interest to me.
A search of the archives for "test 05 fail 04" turns up a post by you on May
4th 2009 stating that you fixed your test 05 fail 04 problem by replacing a
TL074.
Are you just having some fun with us, or is there more to your story?
Below is your May 2009 post about the successful repair.
tom jobe...

Hi All,
Some feedback to all those with 2465/2467.
During powerup test my 2465B showed fail 05 test 04, Negative voltage to
negative. I assumed it was a power supply fault.
The fault exhibited no intensity and focus control, with random trace
movement
all over the screen.
It ended up being a fault on the analog control schematic 2 "partial A5
control/readout/buffer" section circuit.
The issue was a faulty TL074 U2420, ref voltages +1.36 and -1.25 was
missing.
These are voltages present across a number of control POTS, e.g. intensity,
focus.
Replaced TL074 and it came up like new.
Regards
Gerald<<<



----- Original Message -----
From: "Gerald" <vk3gjm@commtelns.com>
To: <TekScopes@yahoogroups.com>
Sent: Wednesday, January 20, 2010 2:06 AM
Subject: [TekScopes] Re: test 05 fail 24


Hi Tom,

My appologies, typo. Actually my error is test 05 fail 04. Yes it's been
quite a while May 2009.

The unit has been under the bench covered for a while and decided last
year that one of resolutions is to fix it in the 1st QTR 2010.

Sometimes you need a break, recharge the batteries and hopefully you get a
new perspective on the problem at hand.

After another solid week trying to find any issue, I have come to the
conclusion that an instrument of it's age needs some TLC in the power supply
region, so out with the old Caps and get some fresh low ESR parts in.

The search continues.

Thanks for the fedback.

Regards


Gerald

VK3GJM


--- In TekScopes@yahoogroups.com, "tom jobe" <tomjobe@...> wrote:

Hi Gerald,
A search of the Tekscopes message archive for "test 05 fail 24" shows
that
you have been struggling with this problem for nearly a year.
Did you read the solution in the message archive for this "test 05 fail
24"
problem that was posted on June 6, 2006?
I have no idea how you would find out what the Tektronix capacitor spec
was,
but it seems that it is not a problem to buy good electrolytic
capacitors
from any of the major suppliers around the world. I've had very good
results
with capacitors from Digikey on some 24x5's in the last year.
tom jobe..




----- Original Message -----
From: "Gerald" <vk3gjm@...>
To: <TekScopes@yahoogroups.com>
Sent: Tuesday, January 19, 2010 10:01 PM
Subject: [TekScopes] test 05 fail 24


Hi All,

HNY everyone.

This year I want to tackle the restoration of my trusty 2465B. It has
been
indicated to me that the symptom test 05 fail 24 is a result of
excessive
noise on the supply, fair enough.

Has anybody recently ( past 12 months ) replaced most/all power supply
low
ESR caps and managed to resolve most issues?

I am looking for help for a supplier that provides good quality caps
that
meets the value, voltage and ESR rating as per Tek spec.

I look forward to some feedback.

Regards

Gerald

VK3GJM



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Re: 7904 readout on the wrong place - vertical signal squeezed

Jerry Massengale <jmassen418@...>
 

Hi,
 
Sounds like the horizontal + pin on the neck of the crt is open.
 
jerry

--- On Wed, 1/20/10, kupkagerhard wrote:

From: kupkagerhard
Subject: [TekScopes] 7904 readout on the wrong place - vertical signal squeezed
To: TekScopes@...
Date: Wednesday, January 20, 2010, 7:07 AM

 
In my 7904 the readout is placed 1 division below the middle of the screen. Additionally the vertical signal can't be moved to upper half of the screen. When I move the vertical signal from bottom of the screen upwards, the signal will be squeezed vertically in the left part of the screen. The output signal of the vertical main amplifier doesn't show any queezing. The output of the horizontal main amplifier shows no distortion on the sawtooth signal


Re: test 05 fail 24

 

Hi Gerald

I've done a couple of 2465B rebuilds.
The best capacitors (IMHO) for this application are Panasonic EB's. They are my first choice for about 90% of the replacement caps on the 2465B. Digikey or Mouser....

All caps (1uF, 4.7uF, 47uF, 100uF) to be replaced by same values (higher voltage permitted eg. 35V --> 50V), except for the following:

The 250uF/20V and 180uF/40V can all be replaced by a common 330uF/50V (quantity discounts)

The 10uF/100V and 10uF/160V can all be replaced by 10uF/160V - Nichicon PW.

The 2 big 290uF/200V power cans can be replaced by Panasonic TSHA 330uF/200V or 250V. You need to run extension wires from the PCB to the caps' terminals.

The only 85-degree cap is the 3.3uF/350V Nichicon - I forget which one.

There are 3 1uF/50V BiPolar caps - generally these are OK, and do not require replacement, but check the ESR to be sure.

There is 4.7uF/35V tantalum under the big power cans - if the ESR is less than 1.5, leave it alone.

Couple of pointers for failure-prone components on these PCB's (based on my experience):
On the Primary side - where the AC comes in:
1. You've got 2 5-ohm resistors - replace them with huge 3W or 5W ceramic units.
2. You've got 2 thermistors next to those resistors - a 5-ohm and a 7.5-ohm. I don't remember if they're NTC or PTC types - check on that.
3. Under the power cans, in the corner is a 270K resistor - fails over time - replace with huge 3W or 5W unit.

That should get you up and running to the point of being able to isolate other small problems.

I also recap the A1 PCB (all EB caps)- fantastic improvement in trace clarity.
If you want pics, send me your email.

Regards
Menahem Yachad
Israel


7904 readout on the wrong place - vertical signal squeezed

kupkagerhard <ghm1@...>
 

In my 7904 the readout is placed 1 division below the middle of the screen. Additionally the vertical signal can't be moved to upper half of the screen. When I move the vertical signal from bottom of the screen upwards, the signal will be squeezed vertically in the left part of the screen. The output signal of the vertical main amplifier doesn't show any queezing. The output of the horizontal main amplifier shows no distortion on the sawtooth signal

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