Tektronix 2465B oscilloscope teardown

[james_s]

It's possible that it's a fake that is not even a real FRAM inside. It could even be something like a microcontroller paired with a serial EEPROM, you never know with random Chinese parts. I got several Dallas SRAM modules that were obvious fakes.

[Miti]

It's possible that it's a fake that is not even a real FRAM inside. It could even be something like a microcontroller paired with a serial EEPROM, you never know with random Chinese parts. I got several Dallas SRAM modules that were obvious fakes.

It is possible but I would think is too much trouble, does it even make economic sense? I'll give it an X-Ray one day to see how many dies are inside.

[BravoV]

It's possible that it's a fake that is not even a real FRAM inside. It could even be something like a microcontroller paired with a serial EEPROM, you never know with random Chinese parts. I got several Dallas SRAM modules that were obvious fakes.

It is possible but I would think is too much trouble, does it even make economic sense? I'll give it an X-Ray one day to see how many dies are inside.

I've read somewhere but forgot where, for those dodgy ones especially Maxim/Dallas BBSRAM products, actually they're genuine, but re-cycled and re-labelled.

[james_s]

I've read somewhere but forgot where, for those dodgy ones especially Maxim/Dallas BBSRAM products, actually they're genuine, but re-cycled and re-labelled.

I've seen both, old parts that have been relabeled, and counterfeit copies, confirmed by xray followed up by grinding into the thing. The copies had a completely different internal layout.

[usergen]

hi all and hope not to be OT, could anybody suggest how to remove the front panel knobs not having screws? I tried to pull them out with my fingers but they seem very tight and I'm afraid to break something if applying more force. thanks.

[usergen]

any feedback from you guys? 

[MarkL]

any feedback from you guys? 

They do just pull off, but maybe after being on there for so long they are stuck.

Maybe warm the knob up a little (like with hair dryer, not a heat gun) before pulling on it?

[usergen]

tnx a lot MarkL, even for the picture!!

[BravoV]

Also be warned, as sometimes not all knobs can flushed completely, like mine here. 

[usergen]

Hello BravoV, I haven't tried to remove any yet but I'm a bit confused now, does it mean your knobs can't be entirely pulled off or do they can't be pulled in further? thanks a lot.

[cheeseit]

Its the latter and the same on my scopes with about 1-2 mm distance from knob to face.

[usergen]

all the knobs safely removed, thanks again guys.

[gregariz]

any feedback from you guys? 

They do just pull off, but maybe after being on there for so long they are stuck.

Maybe warm the knob up a little (like with hair dryer, not a heat gun) before pulling on it?

My advice after learning the hard way is that Tektronix knobs are really not meant to be removed. Really they are a weak point in an otherwise classic cro. They clip onto that inner plastic sheath and with a bit of age the clips in the knobs become very brittle and can break. If that happens often the only thing to do is to apply some glue and glue them back on - hoping you never need to remove them again. Some years back a fellow on the net bought up the old Tektronix stock and was charging a fairly heavy price per knob, but once you've broken a few you know why he did it.

[james_s]

It's possible that the plastic shrinks slightly in addition to becoming brittle. That's a fairly common and rather annoying trait of plastic. It wouldn't take much shrinkage for a knob to get stuck on a shaft.

[BravoV]

Although I haven't tried on mine, just thinking out loud on the idea about applying some plastic friendly grease before putting back the knob, but not making it too loose that they falling out by it self during use. 

[Miti]

It's possible that it's a fake that is not even a real FRAM inside. It could even be something like a microcontroller paired with a serial EEPROM, you never know with random Chinese parts. I got several Dallas SRAM modules that were obvious fakes.

It is possible but I would think is too much trouble, does it even make economic sense? I'll give it an X-Ray one day to see how many dies are inside.

I've read somewhere but forgot where, for those dodgy ones especially Maxim/Dallas BBSRAM products, actually they're genuine, but re-cycled and re-labelled.

Ok, I have the X-Ray. It seems to be one die inside, no evidence of MCU and EEPROM. It's either a crappy part or 2445 cannot work with FRAM. I'm inclined towards the first.

[pquadrat]

Hi,

I've got another 2445B (with new style A5 board), defective, no trace or anything on the CRT, but otherwise it is working fine, all buttons/LEDs working, triggering on signals etc.

After swapping some boards with another 2554B, I could locate the fault on the A1 mainboard. Removing the horizontal and vertivcal deflection cables did not give an image, so my guess was, that the error could only be the Z (intensity) control. And it was U950, which is the Z axis control chip. With the U950 from the other 'scope, all works fine.

Does anyone here has a working U950 (155-0242-01) chip for sale? Preferred in Europe?

[tautech]

Does anyone here has a working U950 (155-0242-01) chip for sale? Preferred in Europe?

At the foot of this page there's a link to a 27 MB cross ref file of Tek parts.
http://www.sphere.bc.ca/test/tekequiv.html

It might be commonly available so check what it is. 

[pquadrat]

Does anyone here has a working U950 (155-0242-01) chip for sale? Preferred in Europe?

At the foot of this page there's a link to a 27 MB cross ref file of Tek parts.
http://www.sphere.bc.ca/test/tekequiv.html

It might be commonly available so check what it is. 

It is one of the custom Tek chips.

And I was able to get one here in Germany, so no longer looking for one.

[neo]

Anyone know what it means when a 2465B bleeps its front lights? Fan's running and it starts up like normal until it starts that, the blinking of it's front light i mean.

[med6753]

Anyone know what it means when a 2465B bleeps its front lights? Fan's running and it starts up like normal until it starts that, the blinking of it's front light i mean.

Start with the basics and work from there. Make absolutely certain all your supply voltages are within spec as far as voltage and ripple. J119 on the main board is a convenient location to check them. I don't have the manual in front of me at the moment so I can't tell you what page it's on. 

[neo]

Anyone know what it means when a 2465B bleeps its front lights? Fan's running and it starts up like normal until it starts that, the blinking of it's front light i mean.

Start with the basics and work from there. Make absolutely certain all your supply voltages are within spec as far as voltage and ripple. J119 on the main board is a convenient location to check them. I don't have the manual in front of me at the moment so I can't tell you what page it's on.

So then, the blinking points to nothing specific then, therefore the long way it is. Thank you that is exactly what i wanted to know, the 70s were easier to work on 

https://www.eevblog.com/forum/repair/tektronix-2465b-repair/

[andy2000]

I recently started working on my late model 2445B.  It had the usual leaking caps on the A5 board, plus some open traces.  I've taken care of those problems, and it's basically working, but there's one peculiarity. 

If I use auto scale, or any of the auto measurements, it momentarily blanks the trace (I assume this is normal), but when it's done, the trace is either very dim, or invisible.  I can get the trace back by turning up the intensity, but the same thing happens again if I repeat the auto operation.  After enough times, it needs to be near maximum to get a visible trace.  Reducing the intensity control to minimum, and turning it up restores its normal range.  I assume this isn't normal. 

[tggzzz]

I recently started working on my late model 2445B.  It had the usual leaking caps on the A5 board, plus some open traces.  I've taken care of those problems, and it's basically working, but there's one peculiarity. 

If I use auto scale, or any of the auto measurements, it momentarily blanks the trace (I assume this is normal), but when it's done, the trace is either very dim, or invisible.  I can get the trace back by turning up the intensity, but the same thing happens again if I repeat the auto operation.  After enough times, it needs to be near maximum to get a visible trace.  Reducing the intensity control to minimum, and turning it up restores its normal range.  I assume this isn't normal.

It happens on my 2445B. I have presumed it is because it doesn't "know" how bright to set the beam, and so adopts a conservative value.

[pquadrat]

I recently started working on my late model 2445B.  It had the usual leaking caps on the A5 board, plus some open traces.  I've taken care of those problems, and it's basically working, but there's one peculiarity. 

If I use auto scale, or any of the auto measurements, it momentarily blanks the trace (I assume this is normal), but when it's done, the trace is either very dim, or invisible.  I can get the trace back by turning up the intensity, but the same thing happens again if I repeat the auto operation.  After enough times, it needs to be near maximum to get a visible trace.  Reducing the intensity control to minimum, and turning it up restores its normal range.  I assume this isn't normal.

I tested it on a late 2465B and a late 2445B, both set the intensity to the same intensity as adjusting the intensity knob to the mid-position. On one this is fine, on the other it is to dark. But both are equal to the mid-position if adjustet by hand.

Re-adjusting grid bias and the other intensity adjustments (see the service manual) so that mid-position of the intensity pot gives a "normal" intensity will help.