HP 1740A Oscilloscope - Repair HELP!!!

[Barry Fox]

Hi Eric,

I will give the USA spares unit a try. Some of their 2nd hand units work, and have photo's of the actual traces at work.

I am based in Randburg, Johannesburg. We attended the World cup soccer final last night. What a game and event.

 

[ericgibbs]

Hi Eric,

I will give the USA spares unit a try. Some of their 2nd hand units work, and have photo's of the actual traces at work.

I am based in Randburg, Johannesburg. We attended the World cup soccer final last night. What a game and event.

hi,
I have not seen the PSU specs for the 1704A, but I would expect the mains to be dual 110/230V 50/60Hz.?

I visit my Son in PE [via Jo'burg] for two months each year, around Xmas time.

 

[Barry Fox]

Good to know you are also a "local" South African

 

[JayBS]

Barry:
Barry:

Did you manage to source the HP hybrid (5081-3032)?

If not, I think this company is selling them for a not-unreasonable price.

**broken link removed**

John

 

[Barry Fox]

Hi John

No, I have not found the HP hybrid (5081-3032) What a find !

Thank you for the link. I will receive a HP-1740A bought on Ebay this week. With this unit I will be able to confirm if the Hybrid is faulty. If so, your link will enable me to purchase the hybrid, and repair my unit. I will then have a spare fully working unit.

Thank you.

Barry

 

[Jonas Karud]

Hello!

I'm new to this forum, stumbled upon it when searching fore an input hybrid
circuit for my beloved HP 1740 oscilloscope (I will never let it go!).

The circuit is situated on the input board and is called A3A1 here, and the HP part number is 5081-3030.

Barry, please dont scrap Your oscilloscope, I can pay what ever You want for this circuit!

regards, Jonas in Malmoe, Sweden

 

[tvtech]

Eric you are a man of knowledge.
Your wisdom knows no bounds.

Thank you for your input here on ETO

I am learning daily from your constructive and informative posts.

Kind regards

TV Tech

 

[jacobbal]

i have a hp1743a scope the screen flickered a couple of times then went out. checked the hv side and found the transister 939 4-433 gone. This is a motorola transister Any one know what the crossref could be?

 

[KeepItSimpleStupid]

I would join the yahho group for Agilent stuff and ask there. Someone or their archive should have a list of part numbers to OEM numbers. **broken link removed**

I ave been wanting to join, just for the info.

 

[HiTech]

As mentioned, those HP hybrid chips are known failure parts and difficult to come by. I have a working spare 1741A that I intended to sell online rather than have it lying around unused, taking up space. However after reading this thread, I'm wondering if I should keep it afterall. The 1741A is my favorite scope of them all, without a doubt. All of the HP 1700 series scopes are fetching amazingly high $$ online. Even the broken/parts-only scopes fetch $100 or more. I was fortunate to pick up two of them for well under $100, the one being in very nice condition and calibrated in 2011. That's a rareity.

 

[jacobbal]

berry
On the hv board a15a1 has a hv osc q1 transistor that is mounted to the case do you know what the part number is and it,s crossreferance is? I need to replace mine. checked votage going in and get 21v but get nothing out of the transistor when checking to ground. PM me.

 

[peterpan007]

Sorry, that I speak: here's the answer to your question.
**broken link removed**

 

[Saul Britto]

hi Barry,
If its your favourite scope, you could design and build on a added PCB, a Y amp driver and bypass the IC.

Eric Gibbs,how to bypass A5A1? I had a 1740A with the same problem,but i am a proteus user and i can do it. Have you a schematic for it?
Thank you.

 

[Saul Britto]

Good to know you are also a "local" South African

Barry,look at the resistors R1 and R5.Measure the resistors r1 and r5, although you're seeing 12 volts on the DMM, they can be changed, as it did to me, you will see 12,5 volts, but, there will be a current reduction.Remove and measure resistors disconnected from the PCB.Don't buy anything without to measure these resistors before!!! From Brasil Saul Britto.

Solved ?