Tektronix 2465B oscilloscope teardown

[JSC]

I like the 1502. In fact, I like it better than the "improved" 1503 with the LCD screen. The trace was sharper and quicker responding.

A coworker of mine flew RC controlled aircraft. He had a hi-tech Ni-Cad battery charger that could resurrect a bad TEK battery pak about 2/3s of the time by subjecting it repeated charge-discharge cycles. Took about a week each.

I never knew about the 1 ma drain. I always thought the main problem was the age of the batteries and the high temperature. The only places I ever used a 1502 were in Ft. Bliss, TX (gets sort of warmish), Saudi Arabia, and Bahrain (really warmish).

John

[tggzzz]

I like the 1502. In fact, I like it better than the "improved" 1503 with the LCD screen. The trace was sharper and quicker responding.

A coworker of mine flew RC controlled aircraft. He had a hi-tech Ni-Cad battery charger that could resurrect a bad TEK battery pak about 2/3s of the time by subjecting it repeated charge-discharge cycles. Took about a week each.

I never knew about the 1 ma drain. I always thought the main problem was the age of the batteries and the high temperature. The only places I ever used a 1502 were in Ft. Bliss, TX (gets sort of warmish), Saudi Arabia, and Bahrain (really warmish).

The manuals state "recharge every month", but don't explain why that is necessary

The chart recorder is permanently connected to the battery, and is responsible for a lot of the current drain. I can't remember what happens with the XY-output option or an empty slot, but the battery is not disconnected and there is still some drain.

[JSC]

Everyone always says, "RTFM.", but alas, hardly anybody does.

John

[AMR Labs]

I like the 1502. In fact, I like it better than the "improved" 1503 with the LCD screen. The trace was sharper and quicker responding.

A coworker of mine flew RC controlled aircraft. He had a hi-tech Ni-Cad battery charger that could resurrect a bad TEK battery pak about 2/3s of the time by subjecting it repeated charge-discharge cycles. Took about a week each.

I never knew about the 1 ma drain. I always thought the main problem was the age of the batteries and the high temperature. The only places I ever used a 1502 were in Ft. Bliss, TX (gets sort of warmish), Saudi Arabia, and Bahrain (really warmish).

The manuals state "recharge every month", but don't explain why that is necessary

The chart recorder is permanently connected to the battery, and is responsible for a lot of the current drain. I can't remember what happens with the XY-output option or an empty slot, but the battery is not disconnected and there is still some drain.

Guys, just a friendly suggestion for the benefit of everyone on this long and distinguished thread about Tek 2465 scopes, and try not to wander off too far to other unrelated things like the 1502 scope or RC controlled aircraft, etc. Suggest it would be best to open a separate new thread and move the discussion there of those other topics. Thank you.

[JSC]

Sorry. I have been a moderator. I should have known better. 

[jonpaul]

Please start a NEW thread eg "Tektronix 1502/1503 TDR".

j

[Scopetechniques]

[IIRC, that is one of a number of mods performed by well-known eBay vendor 2465b on all his "Refurbished/Guaranteed" 24xx scopes.]

I was searching online for images of a 2465B mainboard and saw this image, which I know to be my work.
My ebay ID is "scopetechniques" - same as EEVBLOG id.  The quoted posting attributed this work to ebay seller "2465B" and that is not true.

On the original question, I believe the black plastic piece stuck to the bottom of the scope was meant to protect the scope case when it was installed on a cart.

--Victor

[jonpaul]

risky to touch U800 HOR hybrid. Heatsink not needed and can short to case.

j

[AMR Labs]

Not worth the risk of messing with U800, besides no additional heatsink has ever been necessary.

[Scopetechniques]

No risk if you have the proper equipment, which I do.
Although I do agree with the limited value of the heatsink.
Unfortunately customers do research on the web and some want the heatsink.

In my research U800 runs at 112F (at 75F ambient), with the heatsink installed it runs at 102F.

Also, I have modified the attachment method for the heatsink. I install it below the U800 tab, so the high points of the whole assembly are the two studs.
So if there is a short to the case it will be on the studs not the heatsink.

--Victor

[AMR Labs]

The main risk, aside from a short (studs are not at ground potential) is physically damaging the chip legs where they come out of the package due to improper tightening of the two nuts. Very easy to do if not careful and failing to keep the proper hardware in the correct place. This topic has been explained many times here and on Tekscopes group, as it has been stated and explained why no heatsink is needed. Not to mention stick-on heatsinks falling off unexpectedly and possibly shorting other things inside the main board. Not worth trying to fix a problem that does really not exist.

[Scopetechniques]

The main risk, aside from a short (studs are not at ground potential) is physically damaging the chip legs where they come out of the package due to improper tightening of the two nuts. Very easy to do if not careful and failing to keep the proper hardware in the correct place. This topic has been explained many times here and on Tekscopes group, as it has been stated and explained why no heatsink is needed. Not to mention stick-on heatsinks falling off unexpectedly and possibly shorting other things inside the main board. Not worth trying to fix a problem that does really not exist.

I agree with what you say.  It does require care and some expertise to perform this work, along with a proper de-soldering workstation.
I have literally sold hundreds of 2465Bs and the U800 and A1 recap is only performed when the customer requests it.
I am not a fan of stick on heatsinks, only metal to metal and mechanically attached.

--Victor

[jonpaul]

See the many comments of Chuck Harris on Tekscopes2 and Tekscopes at groups.io, RE U800.

Note the earlier SN 2465B have original TEK ICs but later SN used to substute from Maxim, not  as good.

Jon

[Scopetechniques]

See the many comments of Chuck Harris on Tekscopes2 and Tekscopes at groups.io, RE U800.

Note the earlier SN 2465B have original TEK ICs but later SN used to substute from Maxim, not  as good.

Jon

Chuck and I communicate a lot.  He has sent me a lot of 2465B business my way since he retired.
Chuck and I do not agree on removing the A1 for complete recap and U800 socket install.
My opinion is that if a customer wants it I give to them. Worst case an A1 with a socketed U800 will allow a casual user to repair their beloved 2465B when a U800 failure occurs.

--Victor

[jorgino]

Hi all,

I'm also a "happy" owner of a 2465A CT. I was having issues with the display jumping all over the place:
https://youtu.be/g6iKEVwqY9M
So I took it apart to recap the boards, but then I decided to put it together so I could get the CAL constants before recaping the boards, however, now I get an error message and no traces and the LEDS above the display don't light up:
https://youtu.be/q4gS29u1FuY?si=lmVH3ULfq2Pwa76U
From your experience, did I re-connect something wrong, or did one of the boards go bad? I wasn't having any other issues before other than the display jumping. The manual says TEST 05 FAIL 24 is ADD Main Board - Positive Level is not Positive Enough. I didn't touch the High Voltage Power supply or the board that's underneath the O'scope, originally I only removed the 2 boards from inside and the one on the side with the NVRAM battery. Any help would be greatly appreciated!

Thanks,
George