The Ebay HP scope repair and teardown thread

[Iceclaw]

Hi everyone,

I'm new around here, as evidenced by my post count, so if this is the wrong place for this thread tell me and I'll move it. That aside, let's move on to the topic of this thread. I recently picked up a HP 1744A off of Ebay. The plan is to update this thread if it work or if it doesn't, fix it. I might do a few videos on my youtube channel, but I might not. One thing I will do, however, is write up every time I make significant progress with the repair of the scope. I'll attach photos of the scope when it seems necessary. Until then, I'll look through the manual. (Which is available here) It's expected to be here August 4th, so that'll be the next update from me.

Until next time,
RM


Edit: Forgot to close an <a> tag properly.

[TerraHertz]

$2.75 !! Cool, I hope it's easy to fix. Maybe it even works right away, you never know.

I have a HP 1743A, serving well as a 'simple stuff' scope.

I like the ebay listing "comes with everything shown" and some of the photos are of an 8743B Transmission reflection test unit.
Mistake? What mistake?

[Wuerstchenhund]

"The Ebay HP scope repair and teardown thread"

Deja vu? There was already a a repair and teardown thread for the 1744A, with pictures:

https://www.eevblog.com/forum/repair/hp-1744a-analog-storage-oscilloscope-repair-thread/msg377336/#msg377336

Maybe it makes sense adding yours to that thread instead, so that all information can be found in one place instead?

[Iceclaw]

Maybe it makes sense adding yours to that thread instead, so that all information can be found in one place instead?

Should i go ahead and add to it before i start posting anything major?

[Wuerstchenhund]

Maybe it makes sense adding yours to that thread instead, so that all information can be found in one place instead?

Should i go ahead and add to it before i start posting anything major?

Perhaps once you get the scope you could post some infos plus a few pictures there, and then document your findings.

[Iceclaw]

Update:
Scope is here, and without spoilers, video and pictures will be up tomorrow.

[Iceclaw]

Update:
Scope is here, and without spoilers, video and pictures will be up tomorrow.

Sorry for the wait, the video is taking longer than I thought, so I'll get to posting it at a later date. But onto the scope.

The first thought I had when I saw this thing was how yellowed it was, so after a quick clean and some retrobrite it cleaned up nicely. While I still need to clean out and check the internals, I want to wait until I check the calibration a bit more. I suspect that there would be nothing more than a bit of dust due to something on the front that took me a bit to notice. Can you spot it in the pictures? No? Well, the label on the top right says it all. "Hughes aircraft company".

Enough with cleaning, let's see if this thing works. Now, I don't have probes and just want to check if I can get a trace. A small amount of wire later and, I'm seeing a nice cal wave. Now, I still haven't checked ext triggering or the big delay dial up in the corner. I'll leave serious calibration until I get some probes. But, I can still check timings and Volts per division. They seem fine, but I wont trust what I see until I get actual probes.

Anyway, here's the photos for this post. The video is still being edited and will be up within the next few days.

[Vgkid]

Looks to be working(we will wait to see how well), I will await any updates.

[tautech]

Anyway, here's the photos for this post.

Good starting CRO untill you can afford a DSO.

If you quote this post you will see how the syntax is used to attach pics. 
Use Insert Image button. 

[helius]

It's a nice scope but has such a small screen.
Bonus points to those who know why they made such small screens on scopes like these.

[Iceclaw]

It's a nice scope but has such a small screen.
Bonus points to those who know why they made such small screens on scopes like these.

I'm going to guess because of storage mesh in the crt, but I dont know for sure.

[helius]

Well you're on the right track.
This is an almost identical unit to the 1741A, also a storage scope, which has a larger screen (and an additional switch to act as a non-storage scope). By putting both specs side by side you will see something very interesting:

	1741A	1744A
Storage speed	100 cm/µs	1800 cm/µs

[Iceclaw]

Update: Probes are here, and the scope is completely within cal. Triggering and delay works 100%. Not bad for $2.

[e_sousa]

Well you're on the right track.
This is an almost identical unit to the 1741A, also a storage scope, which has a larger screen (and an additional switch to act as a non-storage scope). By putting both specs side by side you will see something very interesting:

	1741A	1744A
Storage speed	100 cm/µs	1800 cm/µs

Looks like the tek 466 normal scan 150div/µs versus reduced scan 3000div/µs specs.
It has a secondary graticule in the center with 0,45cm divisions for the reduced scan mode.

[rf-loop]

Well you're on the right track.
This is an almost identical unit to the 1741A, also a storage scope, which has a larger screen (and an additional switch to act as a non-storage scope). By putting both specs side by side you will see something very interesting:

	1741A	1744A
Storage speed	100 cm/µs	1800 cm/µs

Looks like the tek 466 normal scan 150div/µs versus reduced scan 3000div/µs specs.
It has a secondary graticule in the center with 0,45cm divisions for the reduced scan mode.

just for fun one sidenote (and not so seriously )

HP 1800cm/µs
TEK 1350cm/µs 

Of course HP can do 4000div/µs  if we insert 0.45cm/div grid.
This is because also in Tektronix, as in every company,  marketing peoples co work with peoples who write specs.
After then Tek sales can write 7000 div/µs.. and tell that div is now...  now it is very amazing speed  what looks much better than HP's only 1800cm/µs
And more, HP speed is full screen and including also variable persistence mode.

Reading specifications is...

[e_sousa]

Interesting stuff...
I figured the different unit for writing speed was for that reason but after the conversion is done the difference is quite significant.
Kudos to HP for having been more clear on these specs.