Slow control response on TDS724, was Re: TDS640A



I've got a similar problem with a TDS724 - it seems to be very slow to respond to the front panel controls.

Denis if you are still around, did you manage to solve your problem?

Meanwhile I'll check those caps.


- Guy.

--- In TekScopes@..., <denis.cobley@...> wrote:

I agree
Any TDS400/500/600/700 before about 1994 is highly suspect.
Even if it is currently working if any of you own one and would like to keep
it then please do yourself a favour and pull the case off to check for leaky
If you find ANY then replace all of them on the acquisition, processor and
front panel board.

You might need to buy a hundred caps but that's much cheaper then a new high
end TDS scope.

80% of all of these models fail just from these caps and I fully expect it
to be 100% within a few years.
If you are lucky either Tek or the previous owner has already done the cap
You can see the early signs by dull solder on surrounding components and
dust sticking to the leaking electrolyte.


-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...] On Behalf
Of John Miles
Sent: Friday, 9 December 2005 9:07 AM
To: TekScopes@...
Subject: RE: [TekScopes] TDS640A

I think the conventional wisdom on those is to open it up and inspect all
surface-mount electrolytics you can find for electrolyte leakage and/or high
ESR. Haven't had the pleasure, myself.

-- john

Hello All,

First message from a new member. I have a TDS 640A scope that
developed a problem. The only service manual I can get my hands on is
PN 070-8718-04. It's only useful to the board/assembly level.

Here are the symptoms:

The scope intermittently fails the following self tests:

- Acquisition
- Attn/Acq Interface

Even when it passes the tests, the front panel controls are very slow
to respond - the processor seems to be waiting for something, and
isn't paying attention to the front panel.

The displayed traces are more or less credible.

The error log yields the following message:

"240 Hardware error - bad acq. proc. diagnostic byte f8"

Can anyone shed some light on what I could try to repair this?



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