Help / advise on HP 8714ET network analyser repair

[matthieu.e]

Hello,

I have an opportunity to buy a HP8714ET network analyser with 1 error on self test : Main DRAM tests failed.

I attached the screenshoot. I need one but don't know if I should buy this one.

Is it something fixable or should I avoid this unit ? Do you think I can still use it with this problem ?

Thank you

[Stray Electron]

  I'm not familiar with the 8714 so I can't advise you but did you look to see if there is a service manual for it?  IMO, the availability of those is one of the good things about HP equipment.  Also since it's DRAM, I wonder if there is a memory backup battery in the unit that has died?

[matthieu.e]

Hello, yes I am checking the service manual right now.
I think I will buy this unit and see 1 if it is usable with the problem and 2 if it is fixable.

I will post more picture when I got it

Here is the service manual :
https://keysight-docs.s3-us-west-2.amazonaws.com/keysight-pdfs/8712ES/8712ET+ES+and+8714ET+ES+RF+Network+Analyzers+Se.pdf

[matthieu.e]

From what I see in the service manual I will need to check the CPU board.

I will need to check this part :
"DRAM control circuitry U412-U414, DL401
DRAM data interface chips U406-U409, U421-U424 DRAM address MUX U427-U432
DRAM SIMM (J401)"

[jwet]

Older equipment has actual component level, service manuals with full schematics, etc. What you posted is kind of module level but this is what they did around 2000, even HP stopped publishing all that detail and adopted a Depot Level Module Repair Model.  I would generally rather have a bit older box with good docs than the later model.  I have an HP4195 Network and Spectrum Analyzer that is old school and fully documented and an HP4396B that is an equivalent newer model that has the module only repair.  Its never broken but it will be a tough repair when it does.  For old equipment that is popular, modules are sometimes available, especially for higher failure rate times.  An ebay search will usually give you a hint.

Having said all that, a DRAM failure doesn't sound like a real tough thing to run down RAW DOG without component level docs.  Hopefully, the built in test didn't just stop on the first fault and after you get your DRAM fixed, you'll have more.

Good Luck.

[Tubes]

I think the DRAM module is failed. That is 32MB SIMM 72pins module. You can get it from an old computer or ebay.