Products > Test Equipment

HP 1741A oscilloscope - restoration project

<< < (28/33) > >>

tautech:

--- Quote from: techie1234 on July 09, 2016, 12:47:28 pm ---Keeping this thread alive...I'm working on a 1743A and am having problems with TIME/DIV controls.  The main control won't rotate more than a couple of positions CW or CCW - sounds like it might be a bent contact in the rotary switch or perhaps some hardened grease.  Also the delay TIME/DIV knob cracked off, but at least the shaft rotates easily by hand.  And those grub screws in the knobs are a pain - wish they would have milled some flat surfaces into the shaft so the set screws could mate flush.  Seems like this is a weak point on these scopes.  Will be having a closer look inside...

My main question is: is there a version of the 1743A manual that has as much detailed repair information as the 1740A one?  The 1743A manual on the Agilent site:

http://cp.literature.agilent.com/litweb/pdf/01743-90905.pdf

has a BoM and exploded diagrams but not a schematic, repair procedures, etc.

Also, are there any recommendations on who sells various parts (like the aforementioned cracked delay TIME/DIV knob) for the 174x series?

--- End quote ---
IIRC a 1740 I had at one time did the same and I'm pretty sure it's a result of incorrect reassembly, at least it was in mine....I'd had it apart.  :palm:
The timebase shaft goes through a # of selector wafers on a # of plugin PCB's and if the wafers aren't in the correct positions you end up "hamstrung" as you describe. Some careful fiddling should sort it out. One wafer might be 180 out.
Thinking back.....the timebase shaft is withdrawn from the front panel, knob and all after the shaft retaining collars are loosened on the shaft, each retaining collar hex grub screw retained IIRC.

tggzzz:

--- Quote from: tautech on July 09, 2016, 09:15:25 pm ---IIRC a 1740 I had at one time did the same and I'm pretty sure it's a result of incorrect reassembly, at least it was in mine....I'd had it apart.  :palm:

--- End quote ---

I'll second that, having had similar experiences on my hp1740.

It is surprisingly difficult to get both knobs, both shafts and both rotors in the right position. It is even worse if, like me, you had also moved the knobs on the shaft in order to add a more visible legend to the timebase control.

techie1234:

--- Quote from: tggzzz on July 09, 2016, 10:52:03 pm ---
--- Quote from: tautech on July 09, 2016, 09:15:25 pm ---IIRC a 1740 I had at one time did the same and I'm pretty sure it's a result of incorrect reassembly, at least it was in mine....I'd had it apart.  :palm:

--- End quote ---
I'll second that, having had similar experiences on my hp1740.
It is surprisingly difficult to get both knobs, both shafts and both rotors in the right position. It is even worse if, like me, you had also moved the knobs on the shaft in order to add a more visible legend to the timebase control.

--- End quote ---
Turned out you both were pretty close - the boards appear to have been knocked around a bit at some point.  The side of the boards closest to the case were all about 10 degrees flexed towards the back of the case, relative to the side of the chassis. As such, the middle board (for the main TIME/DEV) was askew relative to where it mated with the shaft.  A careful bit of forward pressure and "pop" - all three boards returned to perpendicular, unjamming the main TIME/DIV shaft.  All is now good. They should really have had slots on the case side for each board to slip into so they weren't just held in place by the one edge connector.  Now to find those knobs...

tggzzz:

--- Quote from: techie1234 on July 10, 2016, 12:55:06 pm ---
--- Quote from: tggzzz on July 09, 2016, 10:52:03 pm ---
--- Quote from: tautech on July 09, 2016, 09:15:25 pm ---IIRC a 1740 I had at one time did the same and I'm pretty sure it's a result of incorrect reassembly, at least it was in mine....I'd had it apart.  :palm:

--- End quote ---
I'll second that, having had similar experiences on my hp1740.
It is surprisingly difficult to get both knobs, both shafts and both rotors in the right position. It is even worse if, like me, you had also moved the knobs on the shaft in order to add a more visible legend to the timebase control.

--- End quote ---
Turned out you both were pretty close - the boards appear to have been knocked around a bit at some point.  The side of the boards closest to the case were all about 10 degrees flexed towards the back of the case, relative to the side of the chassis. As such, the middle board (for the main TIME/DEV) was askew relative to where it mated with the shaft.  A careful bit of forward pressure and "pop" - all three boards returned to perpendicular, unjamming the main TIME/DIV shaft.  All is now good. They should really have had slots on the case side for each board to slip into so they weren't just held in place by the one edge connector.  Now to find those knobs...

--- End quote ---

Good stuff!

For future reference, my A timebase was faulty and I traced it to two problems. A faulty 100uF electrolytic was easy, but some PCB tracks had been abraded and needed replacing.

The tracks in question are inside the rotary PCB switch. To access them, remove the board, slide off the spring clip so the two black switch halves can be removed from the PCB, but don't drop the internal spring contacts!. The edges of those black halves rub against the PCB at their periphery, and eventually sever the PCB track. The track(s) can be replaced with fine wire and careful soldering - try to avoid getting solder on the gold contacts.

atlacamani:
Hello guys :).
sorry for my english, i use the google translator to communicate with you.
A friend gave me a disassembled oscilloscope hp1741a. I want to collect it
but I do not know where to connect some wires. Help please. Look at the photo please.

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod