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Tektronix 555 problem

zerousair
 

The upper beam on this scope will only sweep unless set to trigger from the lower beam time base. I can only get a dot with the upper beam set to the (A) upper time base. Both time bases are set the same for recurrent. I have tested all the upper time base tubes and all good. The supply voltages checked as per the Tek schem. for the time base seem to be fine. There is a "sawtooth out" jack on the front of the upper time base and from what I'm seeing using the working trace, there is no sawtooth waveform there. I only have this scope to check that with. Before I dig into it further, thought I'd ask you fellows here if you've had any experience with this. Been many years since I've worked electronic problems. I do have a time base extender. Thank for any time and advice.

Garrett

Tektronix 2445B help

Albert Prat
 

I have a 2445B that stopped working and need a set of shematics, I have the 2445 service manual but it is very different and the only 2445B manual I could find on line does not have the schematics section. Can anybody help? Thank you.
Albert

Re: Tektronix 2445B help

ArtekManuals
 

Albert

We have it including the separate Options service manual

http://artekmanuals.com/manuals/tektronix-manuals/

Enter 2445B in the searcxh box

Not free but not insulting either, high quality scans

Dave
ArtekManuals.com

On 1/22/2016 7:06 PM, aprat@... [TekScopes] wrote:

I have a 2445B that stopped working and need a set of shematics, I
have the 2445 service manual but it is very different and the only
2445B manual I could find on line does not have the schematics
section. Can anybody help? Thank you.
Albert



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


--
Dave
Manuals@...
www.ArtekManuals.com

Re: Tektronix 2445B help

 

Based on the dates, the 2465B may be very similar if not mostly
identical.

On 22 Jan 2016 16:06:09 -0800, you wrote:

I have a 2445B that stopped working and need a set of shematics, I have the 2445 service manual but it is very different and the only 2445B manual I could find on line does not have the schematics section. Can anybody help? Thank you.
Albert

Re: Tek 555 service manual.

Tothwolf
 

On Fri, 22 Jan 2016, lbfulton@... [TekScopes] wrote:

Those are the same manual I already have, John. I've been told there is a much larger Tek manual for troubleshooting/repair down to component level for the 555. If it does exist that's the one I'm looking for.
There are a number of different manuals for the 555. Becky at manualsplus sent me an entire collection of 555 manuals shortly before they shut down. I'll have a look this weekend to see exactly which P/Ns I have (I do know they have schematics) but I won't be able to scan them right now as I do not own a suitable scanner.

Re: Tek 555 service manual.

Malcolm Hunter
 

For the odd schematic, a decent camera phone can serve extremely well
instead of scanning.

Malcolm


On 23 January 2016 02:18:50 "Tothwolf tothwolf@... [TekScopes]"
<TekScopes@...> wrote:

On Fri, 22 Jan 2016, lbfulton@... [TekScopes] wrote:

Those are the same manual I already have, John. I've been told there is
a much larger Tek manual for troubleshooting/repair down to component
level for the 555. If it does exist that's the one I'm looking for.
There are a number of different manuals for the 555. Becky at manualsplus
sent me an entire collection of 555 manuals shortly before they shut down.
I'll have a look this weekend to see exactly which P/Ns I have (I do know
they have schematics) but I won't be able to scan them right now as I do
not own a suitable scanner.

Re: Tek 555 service manual.

n4mf_sc
 

Or just a Digital Camera, and then to software.

Mitch
N4MF

Re: Tek 555 service manual.

zerousair
 

Thanks for your time, wolf.

Re: 7603 weirdo inverted Z axis

 

There are some ways you can narrow down the problem before tracing the
z-axis control circuits:

1. Does the readout intensity control also operate backwards?

Its signal goes directly to the readout board which then drives the
input to the z-axis amplifier in parallel with the normal intensity
signal so it bypasses all of the z-axis logic.

2. Plug-ins can also adjust the beam intensity. If you have a 7B92A
timebase, what does its intensity control do?

3. Is the leading edge unblanking working correctly when a fast pulse
edge is observed?

I checked my 7603 and with a 7B53A timebase, about 1/2 division at 50
ns/div (25 nanoseconds) is unblanked before a fast pulse edge. With a
faster timebase like a 7B92A, 1 full division at 50 ns/div (50
nanoseconds) is unblanked before a fast pulse edge. Oddly enough a
7B50A also unblanked 50 nanoseconds before the fast pulse edge so I
assume it shares more in common with the faster timebases than the
7B53A.

As far as tracing the circuit, the z-axis amplifier is straightforward
but the z-axis logic shown on schematic 2 gives me a headache. I will
have to break out Clipboard CAD to figure out exactly what is suppose
to be happening there. I do see one thing however:

The sweep gate rises at the base of U99B to redirect the current from
the intensity control through the emitter of U99B to the collector.
The intensity is controlled by this current. If the -15 volt
connection to the intensity potentiometer is open, then the current
would *increase* as it is turned counterclockwise lowering the
resistance between the wiper and ground reversing its operation. The
intensity control range would also be affected but this might not be
very noticeable if the grid bias was adjusted.

So instead of checking to see if the intensity potentiometer is
connected backwards, check to see if the -15 volt supply is present at
the intensity potentiometer and that the wiper actually moves between
0 and -15 volts as the control is turned through its full travel
range. Note that -15 volts is suppose to produce the highest
intensity and 0 volts is suppose to produce the lowest intensity.

On Fri, 22 Jan 2016 20:18:20 +0100, you wrote:

Among other issues with this 7603 were the Z axis operation, it seemed
like a blanking issue (beam is not blanked correctly), but on closer
inspection it is a bit more involved:

The intensity control works reversed (fully CCW is maximum intens, fully
CW blanks the beam). This is not a cabling issue.

Blanking signals are correctly processed by the Z axis logic, and the Z
axis amplifier produces the correct voltages on pin B (about 20 V with
P1171 open for a blanked beam, and about 90 V with maximum input current
for maximum intensity). I also cross checked this against a working 7623
just to be sure that I analyzed the circuitry correctly and understood
the circuit description.

So the inversion must happen somewhere else. I previously replaced all
HV caps in the HV unit, including the DC restorers. Now I also replaced
all diodes in the grid DC bias restorer. No change in behaviour.

The focus amplifier, preset and front panel control all work correctly.

I don't know what else I could check or what else could cause this.
Maybe someone here has another idea?

Cheers,
Marian

Re: Test 04 Fail 02

Christoph
 

I turned to a new attempt repeating the CAL cycles to get rid of that
Test 04 fail 02 condition when powering up the scope.

Just went through CAL01 and still have this error. Do I have to go through all the cycles in ordered sequence or may I possibly skip one cycle and enter one that is more likely responsible for the fail condition?

Maybe I should mention that I obtained a preprogrammed Dallas NVRAM chip from that greek firm (QService) which contains calibration data for a 2465B (mine is a 2445B).

Not that some preprogrammed data now conflicts with my entered data so far.

I also have an empty "new" empty Dallas DS1225. Should I rather start with that to rule out any conflict with pre-existing data?

--
Christoph

TEKTRONIX 260-1421-00 Switch, Beam Finder

Chris Pierce
 

Hello everyone, I'm not sure if I am posting this in the right place. If I am in the wrong place please correct me. But I need a beam Finder switch for a 2445 scope the part number is TEKTRONIX " 260-1421-00 " I think any beam finder switch for any 2400 scope would work. Please someone Email me at piercec99@... or message me here. Thank you all !!!

Re: TEKTRONIX 260-1421-00 Switch, Beam Finder

Malcolm Hunter
 

On 23 January 2016 at 15:18, piercec99@... [TekScopes] <
TekScopes@...> wrote:

Hello everyone, I'm not sure if I am posting this in the right place. If I
am in the wrong place please correct me. But I need a beam Finder switch
for a 2445 scope the part number is TEKTRONIX " 260-1421-00 " I think any
beam finder switch for any 2400 scope would work. Please someone Email me
at piercec99@... or message me here. Thank you all !!!
​Have you tried ebay or Qservice? I can see the switch is available on both
sites.

Malcolm​


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

Re: Tektronix 2445B help

Albert Prat
 

Thank you for the reply, I managed to get a service manual with schematics.

Best regards





From: TekScopes@... [mailto:TekScopes@...]
Sent: Friday, January 22, 2016 4:23 PM
To: TekScopes@...
Subject: Re: [TekScopes] Tektronix 2445B help





Based on the dates, the 2465B may be very similar if not mostly
identical.

On 22 Jan 2016 16:06:09 -0800, you wrote:

I have a 2445B that stopped working and need a set of shematics, I have the
2445 service manual but it is very different and the only 2445B manual I
could find on line does not have the schematics section. Can anybody help?
Thank you.
Albert

Re: Tektronix 2445B help

Albert Prat
 

Dave,

Thank you for the reply, I finally got a manual with the schematics section yesterday.

Best regards

Albert





From: TekScopes@... [mailto:TekScopes@...]
Sent: Friday, January 22, 2016 4:09 PM
To: TekScopes@...
Subject: Re: [TekScopes] Tektronix 2445B help





Albert

We have it including the separate Options service manual

http://artekmanuals.com/manuals/tektronix-manuals/

Enter 2445B in the searcxh box

Not free but not insulting either, high quality scans

Dave
ArtekManuals.com

On 1/22/2016 7:06 PM, aprat@... [TekScopes] wrote:

I have a 2445B that stopped working and need a set of shematics, I
have the 2445 service manual but it is very different and the only
2445B manual I could find on line does not have the schematics
section. Can anybody help? Thank you.
Albert



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

--
Dave
Manuals@...
www.ArtekManuals.com

Re: 7603 weirdo inverted Z axis

Albert Otten
 

Hi David,

The sweep gate rises at the base of U99B to redirect the current from
the intensity control through the emitter of U99B to the collector.
The intensity is controlled by this current. If the -15 volt
connection to the intensity potentiometer is open, then the current
would *increase* as it is turned counterclockwise lowering the
resistance between the wiper and ground reversing its operation. The
intensity control range would also be affected but this might not be
very noticeable if the grid bias was adjusted.

Though it looks like this, I think that the CRT will simply remain dark. With the wiper at 0 V the CRT should definitively be dark. An extra resistance to 0 V will decrease the current to U99B and reduce the intensity which was already at dark. IIRC there are other scopes in which the wiper actively pulls a voltage or current higher and lower (and the current to the wiper changes direction). In that case the effect of an open connection can be different.

So instead of checking to see if the intensity potentiometer is
connected backwards, check to see if the -15 volt supply is present at
the intensity potentiometer and that the wiper actually moves between
0 and -15 volts as the control is turned through its full travel
range. Note that -15 volts is suppose to produce the highest
intensity and 0 volts is suppose to produce the lowest intensity.

Sure that's the first thing to check anyway. I thought this would have been done already as part of checking for a cabling faults.

Albert

Re: TDS754A printer compatibiliy

Ed Breya
 

Thanks Tothwolf, I found one of my printers is an HL-2070N, and it worked right off the bat with the output printer type set to Laserjet. This may be the only one that takes PCL and has a Centronix port, so I'll have to take good care of it. I'm hoping I have another one of these buried somewhere.

I thought you mentioned in your other post that you had some maintenance info on these. If so, I'd sure appreciate anything you can send me.

Ed

Re: TDS544A status

Ed Breya
 

I managed to get a pretty good setup going. I happened to have an old rack-mount, slide-out LCD VGA station on hand that I got for free a while back. When opened up, it perches perfectly on top of the 544A. The native 640x480 VGA is also a perfect fit and gives a nice big-screen scope look that can be seen from across the room. It's a little awkward working the menu buttons since the display isn't physically associated with the button locations, but I can get used to it. The built-in laptop style keyboard isn't needed of course, but the deck makes a nice tray for paperwork or small items.

Ed

Re: TDS754A printer compatibiliy

Torch Fireman
 

Or you could connect a newer USB printer to your legacy equipment with one of these:

http://www.ipcas.com/products/centronics-parallel-to-usb-printer.html

On 23/01/2016 3:54 PM, edbreya@... [TekScopes] wrote:

Thanks Tothwolf, I found one of my printers is an HL-2070N, and it worked right off the bat with the output printer type set to Laserjet. This may be the only one that takes PCL and has a Centronix port, so I'll have to take good care of it. I'm hoping I have another one of these buried somewhere.

Re: TDS754A printer compatibiliy

Torch Fireman
 

Here's another interesting approach, but you have to make your own cable:

http://www.printcapture.com

On 23/01/2016 3:54 PM, edbreya@... [TekScopes] wrote:

Thanks Tothwolf, I found one of my printers is an HL-2070N, and it worked right off the bat with the output printer type set to Laserjet. This may be the only one that takes PCL and has a Centronix port, so I'll have to take good care of it. I'm hoping I have another one of these buried somewhere.

Re: Tektronix 555 problem

Morris Odell
 

I assume you have a type 21 timebase in the upper beam slot and you can't
get it to sweep at all. Have you tried adjusting the stability screwdriver
pot? What is the "ready" light and the other neons in the timebase doing? If
you try to trigger it from the line, are there pulses coming out of the
"gate" jack? Let us have some more info.


Coincidentally I have just had to repair my 555 and, as ever, am amazed at
what a great performer it is - lovely sharp traces and easy & flexible
triggering in a nearly 60 year old scope. In my case the symptom was extreme
trigger jitter in both time bases. Checking the power supplies I found right
voltages but enormous ripple on the +500 supply. The fault was C760, a dual
40 mfd 450 volt electrolytic that filters the +150 that's stacked on top of
the +350 to make +500. I had a dual 50 mfd 350 volt cap to replace it and
now it's a good as new. Waiting for the relay to pull in the first time
after replacing a cap in a high energy circuit is not for the faint hearted!

Morris

----------------
The upper beam on this scope will only sweep unless set to trigger from
the lower beam time base. I can only get a dot with the upper beam set to
the (A) upper time base. Both time bases are set the same for recurrent. I
have tested all the upper time base tubes and all good. The supply voltages
checked as per the Tek schem. for the time base seem to be fine. There is a
"sawtooth out" jack on the front of the upper time base and from what I'm
seeing using the working trace, there is no sawtooth waveform there. I only
have this scope to check that with. Before I dig into it further, thought
I'd ask you fellows here if you've had any experience with this. Been many
years since I've worked electronic problems. I do have a time base extender.
Thank for any time and advice.

Garrett