Fun with my 2467 today

[Ground_Loop]

I must admit I was terrified to tear into this thing, but its a miserable day out so no yard work.  I dove in and the following was repaired:

1.  Found a broken trace affecting CH3 position.  This thing had been worked on before and the controls ADC multiplexing section was a mess.
2.  Replace the B Sweep actuator.
3.  Replaced all the RIFA caps in the power supply plus a couple suspicious electrolytics.
4.  The Big One, replaced and socketed U800.  The replacement is Dr. Ram's version of U800.
5.  tweaked horizontal gain for the new U800.

I couldn't find a YooToob video showing how to get the main board out, so lots of very careful deliberate motions to get it out.

The 2467B lives.  Now I just need a set of screen control knob caps.

[bdunham7]

Very nice!  I'll look in my junk pile and see about knobs.  Both my 2465 parts mules are missing those knobs, but some of the others may interchange.

A couple of questions.

How did Dr. Rams U800 work out and how did you 'tweak' the horizontal gain for the replacement?  He mentioned some possible limitations--do any of those show up in normal operation?

On my 2465B, I don't see how to get that frequency measurement on the screen like that and when I do a frequency measurement, I get 4 digits not 7.  Does yours have an option, is the 2467B different or is this just a difference between the early and later 246xB models?

[Ground_Loop]

Very nice!  I'll look in my junk pile and see about knobs.  Both my 2465 parts mules are missing those knobs, but some of the others may interchange.

A couple of questions.

How did Dr. Rams U800 work out and how did you 'tweak' the horizontal gain for the replacement?  He mentioned some possible limitations--do any of those show up in normal operation?

On my 2465B, I don't see how to get that frequency measurement on the screen like that and when I do a frequency measurement, I get 4 digits not 7.  Does yours have an option, is the 2467B different or is this just a difference between the early and later 246xB models?

The RU800 worked out well.  It's been many months since I bought it and just now getting around to doing the work.  Nonetheless,  I ran a bunch of tests and independently noted each of the issues he identifies in his product description having completely forgotten about it.

Horizontal gain begins to roll off at highest  sweep rates.  DR says that can be adjusted out.
B intensified display is fuzzy at the transitions.
X-Y mode is noisy in the horizontal, about 1-2 minor divisions.
parameter display has horizontal jitters in 10X mode.  This may be fixable as well.
Some of the issues may be attributable to installing a socket for the chip.

None of this is severe and this is not my primary scope so I'm good with the limitations.  When I installed the RU800 the horizontal trace only spanned 8 divisions, so I applied a known good square wave--100KHz I think--and calibrated the horizontal gain against it.  I also ran it up to 400MHz (max sweep rate and 10X) and my frequency cursors were reading about 403MHz at the zero crossings.  So the displayed trace was getting shorter.

I have the counter option on mine, I think it's either 8 or 6, and that is where I get the 7 digits from.  It is activated through the measurement menu.

[Caliaxy]

On my 2465B, I don't see how to get that frequency measurement on the screen like that and when I do a frequency measurement, I get 4 digits not 7.  Does yours have an option, is the 2467B different or is this just a difference between the early and later 246xB models?

I have the counter option on mine, I think it's either 8 or 6, and that is where I get the 7 digits from.  It is activated through the measurement menu.

Not sure about your 2465B, but on my 2247A, there are two ways of measuring frequency: through the "Counter" menu (which uses the internal counter and displays a 7 digit value regardless of what exactly is shown on the screen) and through the "Time" menu, which shows the two (adjustable) vertical cursors and displays the time between them (or the inverse of the time, with 4 digits).

[Tantratron]

4.  The Big One, replaced and socketed U800.  The replacement is Dr. Ram's version of U800.

Hello, I live in France so I'm curious to know about this replacement from Dr. Ram's U800... any link, reference

Does the replacment can be installed on 2465 and 2445 oscilloscope as well ?

Thanks, Albert

[bdunham7]

https://www.ebay.com/itm/The-RU800-Ver-1-0-A-Drop-In-Replacement-for-the-Tektronix-U800-155-0241-XX/154246923795?hash=item23e9d54613:g:BDoAAOSwS9Jf2KzP

Appears sold out right now?

This was designed and made by EEVBlog member Dr_Ram and he appears in several threads.  This should work in the earlier 2465 and 2445 as well since they used the same p/n 155-0241-01/02 U800 custom IC. 

[med6753]

I don't understand why you would want to change out U800 if it's working properly for a device that's clearly inferior to the original. Yes, U800 can be troublesome especially the Maxim built dies. But if you follow the simple rules of keeping the cooling system in good order and don't stack the scope on other hot equipment U800 will continue to work just fine as it has for the past 30 years or so.

Someone please educate me. I'm listening. 

[bdunham7]

Someone please educate me. I'm listening. 

His was broken.

[med6753]

Someone please educate me. I'm listening. 

His was broken.

OK, fair enough. But with patient and careful searching you can find junker 2465's with the Tek die for under $125 USD. That would give you the U800 plus a mother lode of valuable parts such as hybrids, etc. Exactly why I have a junk 2465 sitting in my closet to support my two functioning 2465's.
     

[Ground_Loop]

As BD7 said my U800 was crapped out. I was curious about RU800 and grabbed one. It's really an impressive piece of work.

On getting a junker unit, maybe next time. However, I don't want parts mules laying around. I don't run a junk business. Everything I have works or it's gone.  The end of my driveway is a popular spot for the local community. There is a single exception to that rule. I have a parts mule for my 555 that I bought in 1989 only because it was nearly free.