Long shot on scope parts

[Dr Bob]

Ok mate, thanks for that, I have sent him a message, let's see what he says.

Did you ask Dad to have a look on the HP usergroup to see if anyone is selling any spares? I tried to register again this morning by entering a phone number from my wifes contacts list, an old company phone number. it accepted it then said it would send me the logon code, I won't receive it so I'm still stuffed, Bar Stewards :-( they can't demand that everyone gives them a phone number or even has a mobile phone, what the hell has happened to data protection and all that :-(
Bob

 

[large_ghostman]

sorry for getting his ID wrong! sometimes i try and stuff too much info into my brain and it gets a bit muddled!

 

[Dr Bob]

I know that feeling mate, no worries. Still waiting to hear from him :-( Did you read my question in the post above yours?

 

[Dr Bob]

Well the Watronics guy just answered me and said he doesn't do any trading on this model :-(

 

[Dr Bob]

suddenly gone very quiet, was it something I said?

 

[large_ghostman]

hi sorry to hear that! i havnt been in much last two days, i will try and get dad to post on yahoo group frday as we are not at home tomorrow

 

[Dr Bob]

Oh Hi Ghostie, Ok mate much appreciated

 

[Dr Bob]

I have got another guy I am , well, trying to talk to on the bay, He seems to be open to the idea of breaking it for me, but trying to get him to answer my messages is like pulling teeth and the other day he said ok I will take the add down then, I replied no please don't do that as I won't deal outside of the bay and that I would click the offer button and describe my offer as soon as he was happy for me to do so.
Haven't heard from him since so is he yet another con man who saw an opportunity to rip me off? I thought all the criminals went to Australia? they seem to have all moved to America!

 

[tunedwolf]

I tripped over this, dunno if it may be able to help you repair your own modules: http://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1988-06.pdf

 

[Dr Bob]

Got that thanks mate, no unfortunately the modules cannot be repaired because the faults are in the Hybrid chips that were designed by HP just for this scope and make some of the parts replace only. I know the FET has failed in the input of the attenuator, I even got my dremmel and cut off the top of the hybrid in the hope I could replace the fet with a modern one, but it's like looking at the insides of an I/C but about an inch square.

The ADC board has three of the hybrids on a big square sub board, and is the sample and hold and ADC all in the hybrid, there is only five other TTL chips on the board and I changed them.

The scope is beautifully easy to diagnose as both channels are identical, the boards are all plug in and you just swap them.

 

[Dr Bob]

Is there anyone else who could have a look on the Yahoo group for me to see if there are any parts for sale for the HP54111D please
The group is called, HP/Agilen Test Equipment

 

[Dr Bob]

Hmmmm obviously not, thanks for your help guys.
Well I finally got it sorted, I had and idea that maybe there was a test equipment rental company that had one out the back they had been using for spares, so I found a few on the net and emailed them and I got lucky and managed to pick up one with just one of the input attenuators missing, well that's what they told me. When I got it I found someone had taken the remaining input attenuator appart and there was parts missing from it, they are very fiddly and unless you know what you are doing it is very easy to lose a very tiny gold spring which connects the front passive attenuators to the fet and amp board, and of course that was missing. So although they thought they had got lucky and passed me off a pile of junk with no useful attenuators, I transplanted the pcb into my attenuator and it worked perfectly, I then tried all the plug in boards one at a time and found them all to be good as well, so I have some spares now too.
So the HP5411D now fires up with all self tests passed and is fully working. This thing was about eight thousand new so it's worth doing, it may be 30 years old but it's well ahead of it's time, even has colour and full signal analysis and measurement and auto-ranging.
Right! what can I fix next.......

 

[JimB]

Good to hear a success story. Well done!

JimB

 

[Dr Bob]

Thanks Jim.

 

[tunedwolf]

Way to go Bob. It's the same old story, there's no Iron, like old Iron

 

[Dr Bob]

That's right mate, they don't make em like they used to, and I reckon this one will see me out.

 

[tomizett]

I do love a happy ending!