On Mon, 10 Sep 2007 00:58:31 -0700 "
wrote in Message id:
. com:

[Sorry for the repost, but I just noticed that sci.electronics.repair
is not in the groupline - I've taken the liberty of adding it.]

We got some problems with HP/Agilent 4194A Impedance/gain-phase
analyzer.

It get stuck when the equipment starts up.
The error message shows "CPU_A RAM R/W error. 40000H".

Please advice us how to fix the problem. Is there any third party
repairing these instrument? We have called Agilent, it is sad to know
that they have stopped support for this instrument since 2005.

kristo

I work as a tech for a company that salvages and repairs test equipment:
https://www.techrecovery.com/
We don't normally do repairs for third parties, though...

We have called Agilent, it is sad to know
that they have stopped support for this instrument since 2005.

I haven't worked on this particular piece of equipment (yet) but start
with the service manual:
http://www.home.agilent.com/agilent/...2489.536879058
If that link doesn't work go here and navigate to the manuals section:
http://www.home.agilent.com/agilent/...eng&cmpid=4533

This would be a tough one, as the schematic of the A6 and A7 boards is
unreadable (Why did they even bother?) There appears to be two banks of
DRAM on each board, each bank is 256KB. Given this, it appears that the
upper bank of memory is defective on either the A6 or A7 board. Start by
probing the WE, RAS and CAS lines on each bank of A6 and A7. If they
appear OK, look at each DRAM's data line for a bit that may appear to be
tied or faulty. If you had a signature analyzer, that would be a plus!

hi,
Thanks for your earlier replies. i tried to solve theis problem.
Before taking any step further, first what i did was just shook the
instrument gently and opened it. I took out the A6 and A7 boards and
inserted them back in again.upon turning on the power supply now the
error message has changed to "B: ROM check sum err 004". Please
suggest how to get it fixed.
thanks.
kristo

On Tue, 16 Oct 2007 22:59:17 -0700 "
wrote in Message id:
.com:

[restored non-quoted text]

On Mon, 10 Sep 2007 00:58:31 -0700 "
wrote in Message id:
s.com:

[Sorry for the repost, but I just noticed that sci.electronics.repair
is not in the groupline - I've taken the liberty of adding it.]

We got some problems with HP/Agilent 4194A Impedance/gain-phase
analyzer.

It get stuck when the equipment starts up.
The error message shows "CPU_A RAM R/W error. 40000H".

Please advice us how to fix the problem. Is there any third party
repairing these instrument? We have called Agilent, it is sad to know
that they have stopped support for this instrument since 2005.

kristo

I work as a tech for a company that salvages and repairs test equipment:
https://www.techrecovery.com/
We don't normally do repairs for third parties, though...

We have called Agilent, it is sad to know
that they have stopped support for this instrument since 2005.

I haven't worked on this particular piece of equipment (yet) but start
with the service manual:
http://www.home.agilent.com/agilent/...2489.536879058
If that link doesn't work go here and navigate to the manuals section:
http://www.home.agilent.com/agilent/...eng&cmpid=4533

This would be a tough one, as the schematic of the A6 and A7 boards is
unreadable (Why did they even bother?) There appears to be two banks of
DRAM on each board, each bank is 256KB. Given this, it appears that the
upper bank of memory is defective on either the A6 or A7 board. Start by
probing the WE, RAS and CAS lines on each bank of A6 and A7. If they
appear OK, look at each DRAM's data line for a bit that may appear to be
tied or faulty. If you had a signature analyzer, that would be a plus!

hi,
Thanks for your earlier replies. i tried to solve theis problem.
Before taking any step further, first what i did was just shook the
instrument gently and opened it. I took out the A6 and A7 boards and
inserted them back in again.upon turning on the power supply now the
error message has changed to "B: ROM check sum err 004". Please
suggest how to get it fixed.
thanks.

This error is indicating that the problem is now in the A8 board's ROM
located at U4. Is the problem consistent over multiple power ups - do you
get the *exact* same message each time you cycle the power? If so, you
could try re-seating that board as well checking the gold fingers for
contamination/dirt. If that doesn't solve the problem, I would begin by
getting the pinout for U4 and probing it's chip select and output enable
pins. Also, have you checked the voltages on all the power supply outputs
as well as checking them for ripple?

Unfortunately, the schematic of this board is just as bad as the A6 and A7
boards.

Thanks.
Yes the problem is consistent now, all the time showing same message.
I have not tested the power supplies..i am going to do the things you
have suggested..thanks.