Which deserves to live, 2445 or 2465?


Don N3DEB
 

I have restored and own a few tek 2465 scopes, now have a decision to make and looking for opinions. I have an otherwise good condition 2465 with U800 failure - power supply recapped a couple of years ago.

I just purchased a 2445 as a potential U800 donor, has power on symptoms of click, click (with corresponding blinking indicator lights). I assume it will prove to be a bad power supply. Externally in good condition, giving me second thoughts about ending her life.

1. Harvest the 2445 U800 for the 2465?
2. Rebuild the 2445?
3. Put the 2465 power supply into the 2445 and make the 2465 a donor?
4. Enter addiction rehab?


 

I wouldn't have any second thoughts about using the 2445 as a parts mule for the 2465. The 2465 is just the more capable instrument.

I'm still waiting on a new run of the RU800 (https://www.ebay.com/itm/154246923795) so that I can have a non-donor replacement U800 for my trusty 2465 DMS. If Ram ever manages to release a new batch then you could always rebuild the 2445 with one of those. Until then it is a good use to restore a 2465.

-- Jeff Dutky


DaveH52
 

I'd fix up the 2465A first. Put U800 on a socket if you have to replace it. It will make putting in an RU800 so much easier if necessary.
FWIW I installed the first generation RU800 in my 2465 and it works quite well.


 

My question is whether the RU800 would work better in the 2445 than in the 2465. I understand that there is some bandwidth limitation with the RU800, and that might not be a problem when the scope has half the bandwidth.

—Jeff Dutky


Don N3DEB
 

I have the 2465, not B by the way.

Is the power supply the same for the 2445 and 2465? I am wondering if I should first get the 2445 running to verify it's U800 is good.

It is hard for me to create donors - some sort of obsession.


 

It would be a lot easier just to swap the U800 into the otherwise working 2465 than to rehab the 2445 power supply, wouldn't it?

I completely understand your difficulty making parts donors. I have the same trouble: of five 475s I purchased as parts mules, only two have actually been relegated to that role, and they are both in sorry physical condition, either having been terribly mishandled, to the point of physical damage, or having already been scavenged by a previous owner. My new strategy for obtaining parts mules is to get them pre-scavenged or partly disassembled. This has worked well for my 7k scope, and my 2465. If it has a CRT that looks to be even half working, though, I find it really hard to resist fixing it.

-- Jeff Dutky


Don N3DEB
 

Any way to replace the U800 without pulling the board out? Some comments that I have seen said it was a PITA. I handled several power supply replacement without problems, but that is probably a lot easier than the U800. I may end up with two donors.

I have a great Hakko desolder station which has been amazing for this work, seems to be the only de-soldering tool that makes me appear to know what I am doing.


Ram
 

On Wed, Jan 12, 2022 at 05:08 PM, Jeff Dutky wrote:


I'm still waiting on a new run of the RU800 (
https://www.ebay.com/itm/154246923795 ) so that I can have a non-donor
replacement U800 for my trusty 2465 DMS. If Ram ever manages to release a new
batch then you could always rebuild the 2445 with one of those.
Jeff, thank you for referring to my item on eBay. You bet I am working quite hard on a redesigned and re-laid-out RU800 which I have had to do 3 revisions of, trying to find time for it amongst my other projects. I am definitely happier with how this version of it is turning out, but just when it appeared to be nearing completion I am thwarted by what seemed like noise or oscillation on the highest speeds, causing a little blurring of the trace, but what in fact turns out, after 2 weeks of digging, to be crosstalk that happens on the all-important channel switch LMH6574. I posted the issue on the TI forums as well -- if curious you can see it here
https://e2e.ti.com/support/amplifiers-group/amplifiers/f/amplifiers-forum/1068396/lmh6574-crosstalk-present-only-while-actively-switching-channels
I have ordered an AD8174 to see if it is the IC or something in my layout. Either way I believe I am not too far from releasing v2!
Cheers - Ram


 

Ram,

I can see the discussion on the TI support board. That is an interesting problem you are seeing with the 6574. I am currently reading along with both the TI support discussion, and the 6574 data sheet. If I can clear space on the bench it might be interesting to get a couple 6574s and see if I can replicate the issue.

It looks like there is some leakage (as you say, crosstalk) during the switching operation, but that leakage lasts MUCH longer than you would expect from the data sheet, which says only 8 ns channel switching time. If I'm reading your scope display correctly the crosstalk lasts for over 600 ns!

-- Jeff Dutky


Tom KJ6SVS
 

Before you try replacing U800, confirm part numbers. The 2465 shows two revisions of the Horiz. Output IC. The service manual I have shows two parts, but may not be the most recent, so there may be even more.

Serial Numbers
Part # Effective Discontinued
155-241-01 B010100 B011274
155-241-02 B011275

The changes may be minor, but support circuitry likely reflects the different U800 revisions. A check of the part numbers on the two scopes would be advisable.

-- Tom -- KJ6SVS --


victor.silva
 

Don,

I have seen it done, but definitely not something I would do.
Snip the pins off the bad U800 as close to the case as possible.
On the good U800 cut the ends of the pins off leaving the wider parts intact.
Put the new U800 in place and solder the pins together.

I have personally removed many 2465B mainboards, soldered a machine socket for U800 and recapped without any issues.
It is a time consuming process the first time you do it. Later I got it down to less than an hour, for removal, refurbish and install.

--Victor


victor.silva
 

Ram,

Put me on the list (if you have one) for interested people in your RU800.
I would love to have one or two for evaluation.

Thanks,
Victor


Don N3DEB
 

Upon checking my 2445 it has 155-0241-02 and my 2465 155-0241-01.
Deal killer?