I just looked at the pictures. Where did you get the 234-0408-20 from?
David
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--- In TekScopes@..., David <davidwhess@...> wrote:
Beware that there are two versions of the 2230 storage channel switch
and while they use the same circuit board, there are some discrete
parts changes which need to be made if you replace one with the other.
When I swapped a 234-0408-20, the one with popcorn noise that I posted
about some time ago, with a 155-0022-00 I got uncontrolled
oscillation. I managed to procure a replacement 234-0408-20 instead
of making the changes.
If you measure at pin 21 of the A/D converter, the voltage should be
between about 0.25 and -2.25 volts as you adjust the vertical position
control. If it adjusts within that range and you have no displayed
trace, then the problem is not before this point. I suppose you could
remove R2293 and apply about 1.0 volts directly to the A/D converter
which should generate a vertically centered trace to verify everything
past this point.
On Wed, 25 Jan 2012 17:12:53 -0000, "david_s5y" <david_s5@...>
wrote:
I am trying to trouble shoot the missing storage traces. Does anyone have the DC voltage levels for Pin 6 and 11 of a working U2101 (MO36E). I am seeing +5.6 Volts which seems intuitively wrong give the 511 Ohm to -5 Volts.
I measured -2.1 volts in store mode and -1.25 volts in non-store mode
for the 155-0022-00.
I measured -1.62 volts in store mode and -1.11 volts in non-store mode
for the 234-0408-20.
In store mode the voltage changes a bit depending on the channel
selection and alt/chop selection.
+5.6 volts does sound high. Schematic 11 shows the power connections
for the chip on pins 3 and 5 which are not shows on schematic 16. They
should be about 7.4 volts and 1.8 volts although I think it depends a
little bit on which version you have.
For that matter with a 1Khz 1V sin wave applied to chan 1 set to .5 V per. What should I see on 2 and 15 and 12 and 13?
I measured about 0.02 volts peak-to-peak to ground at pins 2 or 15
which may seem low but is expected since the impedance is about 50
ohms.
Pins 12 and 13 are the transconductance amplifier outputs into a
cascode so the voltage change there is too small to bother measuring.
I measured about 0.4 volts peak-to-peak at the collector of Q2101.
--- In TekScopes@..., David <davidwhess@> wrote:
The "storage channel switch" is a multiplexor and amplifier IC just
before the digitizer. It is not the storage mode button on the front
of the oscilloscope. I doubt the storage channel switch is the
problem but the vertical signal chain that goes through it should be
checked if the vertical position controls are not the problem.
There are two 4 pin flat cables which carry the channel 1 and channel
2 analog signals to the storage channel switch and if one falls off it
can cause the problem you describe but that would also cause the
readout to be displaced vertically so I do not think that is the
problem.
I never found a 2230 service manual to download. I ended up buying
the Artek Media PDF on CD and it was definately worth the price.
The 2230 that I repaired is pretty much my main oscilloscope.
On Thu, 19 Jan 2012 16:01:46 -0000, "david_s5y" <david_s5@>
wrote:
The trace if off screen in a vertical direction. But it is a flat line and will disappear when moved.
I think you may be onto something with the switch. The scope sat for a long time in high humidity and dust. The traces disappear when I begin to press the switch.
Do you know where I can download the service manual?
David
--- In TekScopes@..., David <davidwhess@> wrote:
I asked about this some time ago and as far as I know, the battery
only backs up the waveform storage which is part of either optional
interface board. None of the various settings persist across power
cycles. You might expect that with the optional battery backed up
memory, the oscilloscope would store its settings there but it does
not.
Is it possible that the trace if off screen in a vertical direction?
That could be a problem with the vertical signal chain through the
storage channel switch or the analog and digital registration
calibration. The vertical position controls are a little weird in
this design since they work in both the analog and digital domains
simultaneously. The oscilloscope reads them to adjust the digital
display to match up with future samples.
If the service manual procedure "Adjust Acquisition Position Offset"
on page 5-11 checks out, then I think the problem will be in the
vertical signal chain leading up to the digitizer.
On Thu, 19 Jan 2012 03:30:04 -0000, "david_s5y" <david_s5@>
wrote:
Sorry to be unclear: By the Acc table I ment the ACQ_MODE_SETUP_TABLE/SELECT_MODE table.
So it is not supposed to persist across power cycles?
The big issues is the missing traces once I press Store. Some times I can move the V positions for the channel and see the trace, but it is a flat line, that soon disappear again.
--- In TekScopes@..., David <davidwhess@> wrote:
Acc Table?
As far as I know, none of the settings are retained when powered down.
There is no calibration data to save either.
You changed the battery on the option card, right? I believe that
only backs up the waveform storage.
On Thu, 19 Jan 2012 03:13:08 -0000, "david_s5y" <david_s5@>
wrote:
I have an Tektronix 2230 Storage scope. Everything appears to work except for the storage.
The unit passes diagnostics. I replaced the NV battery, but it does not remember the Acc Table setting and when switched to Store the traces all disappear (but the display Delta V, time base etc are all there).
Anyone had a similar problem? Any guidance would be appreciated.
David
