Tektronix 2465B oscilloscope teardown

[JSC]

Any way to manually read the contents of the NV RAM before unsoldering it?

John

[tggzzz]

Any way to manually read the contents of the NV RAM before unsoldering it?

John

One of the tests dumps the 256 bytes to the crt.   RTFSM for details

[Homer J Simpson]

2465B SN's

Greetings,

I am interested in finding out what the latest serial numbers were for Beaverton produced 2465B's

My latest unit is BO64879

I think once a saw a listing for a BO7xxx something.

Does any one now how far these got and what was the actual last year of production ?

-K

[calibrationfixture]

I think once a saw a listing for a BO7xxx something.

Hi,

Maybe you saw a H70xxxx (Heerenveen) listing. My latest production 24xxB Scope is a 2455B (J301046) with parts dated 9434 (year 1994, week 34) etc. Last (?) Product Catalogs in which only the 2465B and 2467B are listed are 1995 and 1996. The 1994 Product Catalog lists the 2445B, 2465B. 2467B and 2467BHD. Nothing about the 2455B, 2456BHD (listed recently on eBay) and 2466BHD.

Calibrationfixture

[JSC]

2465B SN's

Greetings,
I am interested in finding out what the latest serial numbers were for Beaverton produced 2465B's
My latest unit is BO64879

I have SN B067580.

John

[JSC]

Any way to manually read the contents of the NV RAM before unsoldering it?

John

One of the tests dumps the 256 bytes to the crt.   RTFSM for details

Found it. Page 6-10. I have copied the 256 bytes onto paper. The next question: Where in the DS1225 address space is the starting address? I don't want to risk clearing the RAM when I unsolder the chip.

John

[calibrationfixture]

Hi Homer J Simpson again,

Looking for some information on TekScopes I noticed this in a Thread:

" On Wed, Apr 22, 2020 at 03:31 AM, victor.silva wrote:

Yes, after around serial number B066xxx (guesstimate) Tek started conformal
coating their A5 assemblies.
The latest serial number on a 2465B, that I have seen, is B079xxx, from 1996.
The early B051xxx A5s had already started leaking, so the conformal coating
was their solution. "

Calibrationfixture

[ninja_zx11]

Hi all,

Last night , I turned my 2445A (assuming 2465B shares the same board) after long time and within 10 mins, saw smoke coming out from the rear but it was still functioning. So I turned it off and opened it. Found 2 caps (.068) and 1 resistor(68) smoked. Could any one please give me the part no. so that I can order and replace. Around 10 years ago, I swapped the complete power supply board with recapped one. But it looks like they never replaced these caps. I am attaching the pics. Thanks.

[AMR Labs]

Very common scenario, specially if scope is operated in a 240V country, but environment humidity also becomes a big factor once those caps start developing the fine cracks.
It happened to me even tough I am on 120V.

Just replace both RIFA caps with non-RIFA branded same spec film caps 0.068uF but ideally higher voltage, say 350-400VAC (instead of just 250V as where the original caps), and make sure to only use X2 line safety rated caps.

You also have a burned resistor R1016, replace with 68-ohm 1/2w, to the left of the top RIFA cap in your picture. Thanks to it things stopped there with it sacrificing itself. Make sure to also check R1019 (I think it is) which is the other series resistor of the other cap, seems like 30-ohms (your pic of the schematic is a bit difficult to read), as this other resistor may have also gone open circuit.

[tggzzz]

Common indeed

Condoraudio has a pdf describing recapping, and sells recapping kits on fleabay.

Also check the A5 board for SMD electrolytics; IIRC they are 24x5B only.

Watch out for the battery backed RAM failing and losing the cal constants.

[ninja_zx11]

@AMR Labs:  Many thanks for the reply. I am also on 120V 60Hz supply.  Caps i found https://www.mouser.ca/ProductDetail/594-222233810683
Regarding 68ohm  and 30 ohm 1/2 watt resistors, is there any special kind of resister needed or just generic 1/2 watt would do.

@tggzzz: I believe I bought the refurbished A2 board from him 10~11 years ago.  Yes I did all other recommended caps , battery and also installed heat sink on some rare IC at that time IIRC.

[tggzzz]

Good stuff

Any correct wattage or bigger resistor will do; it is principally used to limit inrush current.

[ninja_zx11]

Thanks!! I am gonna order.

[calibrationfixture]

Hi,

I use these 1W Resistor Replacements (Mouser PN's):

660-MO1CT52R150J and

660-MOS1CT528R680J

I should also replace both 15R 1/2 Watt Resistors (R1352 and R1353) around Q1351. On half of the A2A1 Boards I came across these look very stressed (to the limit of their dissipation).

Calibrationfixture

[ninja_zx11]

I will order these resistors as well. Thanks.

[factory]

Hi,

I use these 1W Resistor Replacements (Mouser PN's):

660-MO1CT52R150J and

660-MOS1CT528R680J

I should also replace both 15R 1/2 Watt Resistors (R1352 and R1353) around Q1351. On half of the A2A1 Boards I came across these look very stressed (to the limit of their dissipation).

Calibrationfixture

I used 1/2W flameproof resistors, for obvious reasons. Can't understand why you would want to increase the wattage, unless you prefer extra crispy PCB in a fault condition.

David

[tggzzz]

Hi,

I use these 1W Resistor Replacements (Mouser PN's):

660-MO1CT52R150J and

660-MOS1CT528R680J

I should also replace both 15R 1/2 Watt Resistors (R1352 and R1353) around Q1351. On half of the A2A1 Boards I came across these look very stressed (to the limit of their dissipation).

Calibrationfixture

I used 1/2W flameproof resistors, for obvious reasons. Can't understand why you would want to increase the wattage, unless you prefer extra crispy PCB in a fault condition.

David

One of mine also removed a 1cm diameter bit of prepreg.

I can't remember whether there is a fuse between the RIFA and the mains socket, but one school of thought is that the capacitor going short circuit causes the fuse to blow.

[i386]

First post here.

I bought a Tek 2465 about 10 years ago but never learned how to use it. Recently I dragged it out of storage. After a few minutes of being powered on it let the smoke out.

I decided to have a go at fixing it. With the help of this forum I managed to disassemble it without destroying the fan. It is not obvious that the collet is back there! Mine came out perfectly and runs whisper quiet. I only replaced the Rifa caps. There was no swelling or leakage on the electrolytics. The Rifa cap that blew also took out the carbon comp resistor that was adjacent to it. After replacing the caps and resistor, I carefully reassembled everything and timidly powered it on. All good, no errors. It came with 4 10x probes. One is bad (would not compensate).

While I was researching the fix and waiting for parts I found tons of videos that were not available back when I bought the scope. I have the operator and service manuals too.

I'll be using this for audio (guitar tube amp) work so the 300Mhz bandwidth is way overkill for what I need.


I'm going to poke around in here and read some before I start asking questions. Just wanted to say thanks for helping me get this far.