Tektronix 2465B oscilloscope teardown

[Old ET]

HI,
I am a newby so bear with me, I have a 2467B and just got the Caps so I can begin that process. I have the machine disassembled, that was fun as I had no instructions. What I am interested in are replacements for RT1001 and RT1016 as well as the E1001 and E1002, have not had any luck in finding the parts but it sounds like from your post you were well on the way to getting that handled. I am aware that your post is old, but hoped I would be able to make contact and be able to get the info. My scope is over SN B05000 so I have the SMD's. I am going to replace all the can type tantalums as they are starting to leak around the base of the mounting. My scope was working fine and is extremely clean in side and out, but upon closer inspection I have found a few problems with the filter of the line voltage, couple of resistor blew up and I will replace all that as I get the parts. Also the alum can type tantalums are leaking at the base, don't want the pads to be eaten away so will take care of that as well. Any help would be greatly appreciated.

GR

[tekky]

Part way thru a recap of a later model 2465B, and have removed/reworked boards: Regulator_A2A1, Inverter_A2 & Control_A5. The next step is to remove Main_A1. Different writeups suggest the removal of boards: HV_A9, FrontPanel_A6, and some manipulation of the DL100 delay line on A1.

To be clear, do I need to remove the HV_A9 board to remove the Main_A1? It seems the one elect cap on A9 is easily dealt with from the component side without having to deal with fragile CRT connections.

I see discussion but no pics showing the DL100 delay line and what makes it an obstacle. From what I can see peering into the chassis, it connects at both ends to A1. Does it really need to be disconnected during removal of A1 or does it come out with the board?

[tekky]

It was far simpler to remove A1 than I expected, and no, I didn't need to remove A9 or mess with the delay line, which sits coiled in a plastic carrier (see pic). It all comes out together. The trickiest part of the operation is detaching two push pins from the CRT. I believe these are the vertical signals on W916,W917. They are a long reach with needlenose pliers and will need a light touch to reconnect. I possibly could have unsoldered the wires from the exposed ends of the two inline inductors instead and will do that if it proves hard to push the pins back on with A1 in the way. (Update: I was able to reattach the push pins using the same long needlenose pliers, although long tweezers might provide a more delicate touch. Also I had taken a prior pic of these connections to avoid confusing the two connections.)

Note: there are three elec caps whose leads are hidden under the delay line carrier tray. It was not difficult to lift the tray away from the board slightly and replace those caps without unsoldering the delay line.

[BravoV]

Thanks for sharing this details, hopefully this will help future owners that going to do the same task.   

[tekky]

Is there a preferred orientation to the clear implosion shield? I wasn't paying attention when I took it off and cleaned it, but then noticed it was a sandwich of two or three plastic layers. Does the thin mylar layer face in or out? Replacement bulbs from digikey/mouser will supposedly be in stock by Oct.   

[HAF_RIO]

Hi everybody,
Typically the DAC problem ( Serial B050000 and above ) cause a mess in all controls.
As everybody knows, the electrolytics leak contaminate the board and need to be cleaned very well.
I used this four step process ( don't be afraid! ).
1) With WD40 keeping the board with the product about 5 hours.
2) Rinse with neutral - detergent, repeat about 3 times.
3) Rinse again with only pure water ( destiled is better ).
4) Drying com hot air.

After the board cleaned, did rigorose inspection with power magnifying lens, better use stereo microscope ( mine case ).
Some corrosion could be remained, and with thin needle, do the job to remove incrustation.
Measure all resistors and capacitors around the area shown in attached -.
( I found the R2013 open ( measured in 20k scale ), replaced.
After that, the voltages 1.36V and 1.25V apears again!
After all, when power on the oscilloscope, the starting process in the LED panel was slow, found two bad potentiometers ( 5k ), replaced.
Start now is very fast! All controls working again!
Only normal error message due lost calibration.
NVRAM replaced too!

Best Regards,
Helcio

[SoundTech-LG]

I would NEVER use, and never RECOMMEND using WD-40 on any circuit board of value. 
You are changing the capacitance of the board forever. Particularly in any high frequency section.
Use 99% or higher IPA Isopropanol. It may leave some whitish film, but it will evaporate, and won't leach into the board and stay in there permanently in liquid form.

[HAF_RIO]

Hi,
WD40 is better than the alcohol to remove acid action from the electrolytics! WD40 don't cause any problem in the board with fiberglass epoxy clad. The A5 board don't suffer this problem wits "HF", don't have enough to capacitance to act in low frequebcy pulses.
The microprocessor clock is 20MHz, and working very well after all!

[SoundTech-LG]

Have fun. Maybe WD will hire you!

[Dave_CA]

I do not care for the fumes (VOCs) given off by WD40.  Plus WD leaves a residue.  That is its purpose... to leave oil behind.  YMMV.

[tggzzz]

Hi,
WD40 is better than the alcohol to remove acid action from the electrolytics! WD40 don't cause any problem in the board with fiberglass epoxy clad. The A5 board don't suffer this problem wits "HF", don't have enough to capacitance to act in low frequebcy pulses.
The microprocessor clock is 20MHz, and working very well after all!

That's wrong, simple Fourier Transform theory.

For an introduction with measurements, see https://entertaininghacks.wordpress.com/2018/05/08/digital-signal-integrity-and-bandwidth-signals-risetime-is-important-period-is-irrelevant/

I wouldn't use Water Displacement 40 on a digital PCB. The nearest I use is Craig DeOxit, and I'm careful to use that only on contacts.

[AMR Labs]

Hi,
WD40 is better than the alcohol to remove acid action from the electrolytics! WD40 don't cause any problem in the board with fiberglass epoxy clad. The A5 board don't suffer this problem wits "HF", don't have enough to capacitance to act in low frequebcy pulses.
The microprocessor clock is 20MHz, and working very well after all!

NO-NO-NO-NOOOOO!!!

ONLY use dishwasher soap and a soft (tooth) brush to remove any cap leakage in the affected areas.
Then rinse off all soap from the board with water and let dry for a couple of hours before testing.
And BTW, IPO will not remove the acidic leakage residue at all, it will only help spread it further.
As for using WD40.... congratulations, you're basically be looking for a replacement A5 board very soon.

[Mark Krass]

Hi,

Has anybody come across this issue - readout display is shifted too far to the right, see photo. The problem is that if you look at the display not directly but from an angle, some characters covered by CRT frame and not visible.

Service manual offers no adjustment to shift readout display horizontally. But must be something in readout schematic to tweak it?

Mark

[AMR Labs]

Best if you could provide some history/context of the fault, and on the instrument itself. Is this a scope new to you, or did the fault suddenly appear in a scope you had for some time? if so was the scope in regular use? etc, etc. Are the traces also affected and/or the regular readout displays? What is the exact model you have, plain 2465, A, or B? Anything else that might be relevant to the fault?

If this is a scope that you just purchased, and assuming this is not a plain 2465, and you have a SMD version A5 board I would venture that first thing to check would be for the usual corrosion problems. Or perhaps something going on in the horizontal deflection circuit. Difficult to say what else without more information. I am sure once you provide more details other people here might be able to provide additional useful suggestions.

[Mark Krass]

Scope 2465B fully re-capped and cleaned.

This is not a fault, I'd say it is a feature relevant to all 2465 models that needs to be tweaked due to the issue I described above.

Somebody who familiar with readout I/O circuitry and horizontal DAC that generates the voltages used to horizontally position dots of the readout display.

[jonpaul]

Check A5 for leaking SMD lytics, PCB damage must be corrected,before any other troubleshoot.

Are only the readout characters displace left,or also the scope,traces?
CAL HOR can,adj if both RO and scope traces affected.
RO position cal also in full CAL

Référence to service manual

Jon

[med6753]

Hi,

Has anybody come across this issue - readout display is shifted too far to the right, see photo. The problem is that if you look at the display not directly but from an angle, some characters covered by CRT frame and not visible.

Service manual offers no adjustment to shift readout display horizontally. But must be something in readout schematic to tweak it?

Mark

Yes it does. Section 5-13 of the 2465B Service Manual. Read the entire section carefully. It adjusts the horizontal centering which should fix the readout offset.

[Zenith]

I wouldn't use Water Displacement 40 on a digital PCB. The nearest I use is Craig DeOxit, and I'm careful to use that only on contacts.

There is a WD40 branded contact cleaner which is probably much the same as any other contact cleaner, Servisol etc. That may be the source of confusion here. As for classic WD40, used for cars and lawnmowers etc, it's absolutely the wrong thing thing to use on electronics.

I agree about not spraying contact cleaner about willy nilly, but carefully applying it to contacts only.

IPA used for electronics should be the proper pure grade.

[tggzzz]

I wouldn't use Water Displacement 40 on a digital PCB. The nearest I use is Craig DeOxit, and I'm careful to use that only on contacts.

There is a WD40 branded contact cleaner which is probably much the same as any other contact cleaner, Servisol etc. That may be the source of confusion here. As for classic WD40, used for cars and lawnmowers etc, it's absolutely the wrong thing thing to use on electronics.

I'm vaguely aware that the WD40 product has been "diluted" by marketeers -- to the point it is so useless that I don't even consider using it.

"Caig DeOxit" - without specifying which DeOxit - is pretty much the same.

[Mark Krass]

Yes it does. Section 5-13 of the 2465B Service Manual. Read the entire section carefully. It adjusts the horizontal centering which should fix the readout offset.

That's it! This is what I was needed. Thank you. It's a R801 if somebody will be looking for it.

[med6753]

Yes it does. Section 5-13 of the 2465B Service Manual. Read the entire section carefully. It adjusts the horizontal centering which should fix the readout offset.

That's it! This is what I was needed. Thank you. It's a R801 if somebody will be looking for it.

Good deal. Glad I could help. 

[DavidAlfa]

TL; DR, sorry!

About the DS1225Y NVRAM, do we know what else is stored there?
I know cal data is @ 0x1FE00 - 0x1FFFF, but the scope displays a lot of interrogation signs when not programmed properly.

First attempt of preventive maintenance (Adding the battery before it's too late) ended losing the data, although I'm 100% sure I didn't short anything out.

The battery read 3.2V, but just touching the DMM tips with the fingers dropped to 2.7V, so go figure if only the capacitive kick when touching the + terminal with the earthed iron (Battery not earthed though) was enough to kill the data.

From now I'll use the EXER 02 procedure to manually extract the cal data on still working scopes, before touching anything, hand-copying 512bytes will take 10 minutes, but way less than running a full calibration!

But some 2465B have extra boards on them (I.E. GPIB, TV(?) modules), I have no idea if they're recognized automatically or they need to me added manually in the diagnostic menu?

Cheers!

[AMR Labs]

The battery read 3.2V, but just touching the DMM with the fingers dropped to 2.7V, so go figure if only the capacitive kick when touching the + terminal with the earthed iron (Battery not earthed though) was enough to kill the data.

The discharge curve of those batteries is pretty steady, so if you are getting 3.2V (and assuming an accurate reading) battery looks to be still quite good. Anything above 3.0 is to be considered OK. Touching the probe is probably upsetting your DMM reading, not the battery voltage.

[DavidAlfa]

Why? I would be acting like a parallel resistor.
I later tried soldering a 470K resistor and definitely, the battery dropped quite a lot, while drawing only 6uA, I'm pretty sure the battery was already weak (Dated '88).
My theory is the heat from the desoldering process affected it, batteries don't like heat, while device quiescent and leakage currents increase, sum it all... bang!

Not sure what a brand-new battery should measure, if it's the same chemistry as the LTC-7P modules (3.5V), then 3.2V is already in the dead zone, these batteries seem to die suddenly with little warning.

[MarkL]

...
About the DS1225Y NVRAM, do we know what else is stored there?
I know cal data is @ 0x1FE00 - 0x1FFFF, but the scope displays a lot of interrogation signs when not programmed properly.

At a minimum, the last operating configuration at power down (knob positions, etc.) and user presets are in there.

From now I'll use the EXER 02 procedure to manually extract the cal data on still working scopes, before touching anything, hand-copying 512bytes will take 10 minutes, but way less than running a full calibration!

You can also just take a video of flipping through the locations and transcribe it later when, or if, you need it (this also avoids transcribing errors).  If you have a GPIB interface, you can dump the NVRAM data directly to a computer (and reload it too).

But some 2465B have extra boards on them (I.E. GPIB, TV(?) modules), I have no idea if they're recognized automatically or they need to me added manually in the diagnostic menu?

They are recognized automatically.