Date   

2430A-2/2

Maxy Sac
 

Hello,


I’m back with new a issue.
First want to share what I did this time


I bought two 2430A on E-bay planning that if one had an issue, I could use the parts from the other to fix it.
The first one is older and, it has a separate battery on board for NV-RAM.
Second got DALAS NV-RAM.
The first had a couple issue and fixed, recap, calibrated, now it works fine.
Thanks you guys for the groups previous posts, it helped me a lot.


Second is in good condition inside and couple scratches outside.
Is there any sort of timer that tells me how long it has been running?


First change C706 and C816 (just in case because they were cracked)
With start, it showed a fail 4000, 6000, 7000, 8000, 9000.
The previous posts said that the most issued problem is that it is mostly
connected with NV-RAM chips, especially the 4722
and 4723 Low Battery on U350 and U664.
The original is DALAS DS1235ABW-120 (5 years on battery)
Found by Mouser DS1230AB-120 IND+
I de-soldered, then installed the IC socket, then I copied the chips, then I plugged it in.
Some of the previous fails disapeared, but some were still there.
After External calibration, the one that failed is 9000, even on tree time calibration.
9113 Slope for TRIGGER- A and 9300 REPET*
Ripple Voltages on regulator are in limits. Plan to recap later.
By Service manual, there were instructions for the fail 9000, so I followed ATG signal from U761 pin-2 to U370 by R368,
but signal does not show in manual for signal #99 on page 330.(MIL manual)
The normal mode is HIGH, in continues mode is series of TTL signal different length.
Sometimes if I exit continues mode , it shows pass on 9113. But after I restart it, it shows a fail on
9123 Slope TRIGGER-B and 9300 REPET*.
After another restart, it shows a fail to the previous 9113.
I checked on the first oscilloscope, ATG signal, and it was the same.
I tried to change U150 and U370 from first oscilloscope, there was the same output.



Now I need your help, thanks.


Re: Repaired a 7A13: thank you TekScopes people

 

A 7B80 will work fine in a 7603. It will even display more of the
leading edge because it triggers much more quickly.

When used in a slower mainframe like the 7603, the maximum accurate
sweep rate is limited by the mainframe's horizontal performance. For
the 7603, that is 50ns/div and 5ns/div with 10x magnification; I do
not remember any problems in the 7603 at the fastest unmagnified 7B80
sweep of 10ns/div; magnified sweeps of 2ns/div and 1ns/div were
inaccurate at the beginning of the sweep.

The 7B92A timebase has a jumper for fast and slow mainframes which
affects the minimum holdoff time but I do not think that is an issue
with the 7B80 because the 7B50A which is practically identical and has
the same holdoff timing also lacks the jumper and it is specified to
work in the 7603. I think this was a special design issue with the
7B92A which is older.

On 13 Feb 2017 16:30:05 +0000, you wrote:

Thank you David for your advice. I replaced the twin capacitor of the shorted one on the -15V supply line and the trace looks clean again. Before it looked like something was not right, even if a different plugin than the 7A13 was chosen.

Now I am left with a 7B80 plugin that triggers but shows no trace. It is full of "modern" electrolytics inside, so either a previous owner had replaced them, or it was already designed that way. I do have a working timebase, so it will probably rest few more years in a drawer with a visible note of a possible area to look for the failure. I am left with a doubt: I have a R7603 chassis, but 7B80 manual says it is for 7700, 7800, 7900 series. Could this be the cause of no trace showing up?!

Long live Tek instruments!
Paolo


Re: Repaired a 7A13: thank you TekScopes people

ik1zyw@...
 

Thank you David for your advice. I replaced the twin capacitor of the shorted one on the -15V supply line and the trace looks clean again. Before it looked like something was not right, even if a different plugin than the 7A13 was chosen.

Now I am left with a 7B80 plugin that triggers but shows no trace. It is full of "modern" electrolytics inside, so either a previous owner had replaced them, or it was already designed that way. I do have a working timebase, so it will probably rest few more years in a drawer with a visible note of a possible area to look for the failure. I am left with a doubt: I have a R7603 chassis, but 7B80 manual says it is for 7700, 7800, 7900 series. Could this be the cause of no trace showing up?!

Long live Tek instruments!
Paolo


Re: Tek 2465 timebase issue - FIXED

Mark
 

Well,

Having broken a component during removal I can state that the problem was
EITHER C72 0.47uF (as suggested by Craig - thanks) or R724 (the replacement
for which I have had to make using 2 resistors).

Both have been replaced and the sweep times on all settings are close to the
money - I need to re-calibrate now :-(

So I think it's time to do the PSU cap replacement and fix the rattling fan,
but it looks like I'm back in business with this 'scope.

Thanks to all who offered suggestions.

Mark

-----Original Message-----
From: Mark, G0MGX [mailto:@G0MGX]
Sent: 11 February 2017 17:25
To: TekScopes@...
Subject: RE: [TekScopes] Tek 2465 timebase issue

Yes, it should have been a "B" - eyesight not what it used to be!

Can we age this from the serial number?

Mark

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: 11 February 2017 16:10
To: TekScopes@...
Subject: Re: [TekScopes] Tek 2465 timebase issue

I suspect that is really B025365 (not 8025365)

Anyway the later USA versions did change "officially" to 1.78B/5.36K at
serial B028680


Dave

manuals@...


On 2/11/2017 10:56 AM, 'Mark, G0MGX' @G0MGX [TekScopes] wrote:

8025365

-----Original Message-----
From: TekScopes@... [mailto:TekScopes@...]
Sent: 11 February 2017 15:56
To: TekScopes@...
Subject: Re: [TekScopes] Tek 2465 timebase issue

R736/R737 were changed to 1.78K/5.36K in the 2465A (or possibly in
later models of the 2465)

What is the serial number of your 2465?

Dave

---
This email has been checked for viruses by AVG.
http://www.avg.com

--
Dave
Manuals@...
www.ArtekManuals.com


Re: X10 probe in series with X20 attenuator question

Albert Otten
 

(continued) Note that my calculations were for the DC attenuation. The input capacitance of the attenuator is not specified and could very well mismatch the capacitance expected by the probe. It's also not specified which 'scope input capacitance is expected by the attenuator. The effect on total attenuation at higher frequencies AC can be quite large.
Albert


Re: X10 probe in series with X20 attenuator question

Albert Otten
 

So the specs of the attenuator are
Specifications:
Attenuation: 20:1
Bandwidth: 10MHz
Input Resistance: 1.053M
Most likely it's internally a divider 1M : 53R (theoretically 1M : 52.63R). The 1M input of the 'scope will disturb the 20X attenuation very slightly to 20.87X. The official 10X probe attenuation will be very slightly disturbed as well in the opposite direction. It depends on the internals of your probe, but it will be somewhere between 10X and 9.55X. The product will always be between 200X and 208.7X. You will hardly notice that max 5% error in your 'scope display.

Albert


Re: X10 probe in series with X20 attenuator question

Craig Sawyers <c.sawyers@...>
 

Whilst it's actually a Picoscope one it looks the same and has the same specs as this
Hantek one.
They are probably re-badged from the same Chinese source. Im usually use it for automotive work,
but want to look at some spikes on the drains of FETs in push pull in a Class D 136kHz 1 kW RF
amp.

The Picoscope one is long obsolete, and was part of the obsolete automotive kit (2004-6). The
archived manual for this on the picoscope site is silent on the question of specification of the
20:1 attenuator. And the Hantek one is likewise unspecified other than "10MHz bandwidth" on Hantek's
site, and again no manual, schematic etc.

Both the Picoscope and Hantek were intended for 1Mohm probes/input Z, and were probably a simple L
or pi pad of high value resistors appropriate for the high impedance environment. Which would
explain the low bandwidth.

If you intend looking for spikes on drains you might well need more bandwidth than a poorly
specified 10MHz. I'd consider a fixed 100x probe; although I would normally not suggest a Chinese
alternative to Tek, Hantek seem to do one. T3100, 100MHz bandwidth and 2.5kV input maximum for
between �10 and �15 on eBay UK. Personally I'd go for a second hand Tektronix one*, but horses for
courses and all that.

Craig

* Old generation Tek 100x probes
P6002/P6005, 30MHz BW
P6007 50MHz
P6009 180MHz

All these are physically larger than modern probes, but are built to last and the manuals are a work
of art


Re: TEKTRONIX 2430A DIAGNOSTIC TEST FAIL

Joe
 

As a first step clean and deox the attenuator relay contacts for Ch 1. Do
Ch.2 also as long as you're in there. The relays are delicate so be gentle.

Joe

On Mon, Feb 13, 2017 at 4:49 AM, NIgel Pritchard nigel-pritchard@...
[TekScopes] <TekScopes@...> wrote:



Not necessarily either CCD or PA :). See my very recent post on Saga of
three 2430A; there may be some clues in there. Also, read the service
manual in detail and you might find clues in there.

I think Trigs (9000) might fail simply because of a prior issue in the PA.

In the 7000 range they should read CH1-1 and CH1-3 (not CH3 FAIL), so both
in CH1. The modes are CH1-1, CH1-3, CH2-1, CH2-3.

Iterative SELF CAL and EXT CAL might resolve to no-failure like mine did
on one scope.

Hope this helps.

Regards

Nigel





[Non-text portions of this message have been removed]


Re: X10 probe in series with X20 attenuator question

 

I do not know that this will work with a standard oscilloscope probe
the way that you hope. This attenuator is intended for signals
connected directly to the oscilloscope without a probe. Beware that
the attenuator does *not* raise the maximum voltage capability of the
probe which has its own voltage rating independent of the oscilloscope
input.

Attenuation factors add if they are logarithms (dB) and otherwise
multiply, so:

10x probe and 20x attenuator = 200x

or

20dB (10x probe) and 26dB (20x attenuator) = 46dB (200x)

dB = 20*log10(attenuation factor)

3dB x1.414
6dB x2
8dB x2.5
14dB x5
20dB x10
26dB x20

On Mon, 13 Feb 2017 10:41:57 +0000, you wrote:

Whilst it's actually a Picoscope one it looks the same and has the
same specs as this Hantek one. They are probably re-badged from the
same Chinese source. Im usually use it for automotive work, but want
to look at some spikes on the drains of FETs in push pull in a Class D
136kHz 1 kW RF amp.

http://www.ebay.co.uk/itm/Hantek-HT201-20-1-Signal-Attenuator-10MHz-Bandwidth-BF-/252603580201?hash=item3ad058bf29:g:GmwAAOSwal5YDxBs

I haven't yet, but will, look at a known DC voltage source with and
without the X20 attenuator. It's a X20 one, not a -20 dB one

The probe is a cheap Chinese 20 MHz one with 1meg impedance.

Thanks for the replies.


Re: TEKTRONIX 2430A DIAGNOSTIC TEST FAIL

NigelP
 

Not necessarily either CCD or PA :). See my very recent post on Saga of three 2430A; there may be some clues in there. Also, read the service manual in detail and you might find clues in there.

I think Trigs (9000) might fail simply because of a prior issue in the PA.

In the 7000 range they should read CH1-1 and CH1-3 (not CH3 FAIL), so both in CH1. The modes are CH1-1, CH1-3, CH2-1, CH2-3.

Iterative SELF CAL and EXT CAL might resolve to no-failure like mine did on one scope.

Hope this helps.

Regards

Nigel


Re: X10 probe in series with X20 attenuator question

Chris Wilson
 

Whilst it's actually a Picoscope one it looks the same and has the
same specs as this Hantek one. They are probably re-badged from the
same Chinese source. Im usually use it for automotive work, but want
to look at some spikes on the drains of FETs in push pull in a Class D
136kHz 1 kW RF amp.


http://www.ebay.co.uk/itm/Hantek-HT201-20-1-Signal-Attenuator-10MHz-Bandwidth-BF-/252603580201?hash=item3ad058bf29:g:GmwAAOSwal5YDxBs



I haven't yet, but will, look at a known DC voltage source with and
without the X20 attenuator. It's a X20 one, not a -20 dB one

The probe is a cheap Chinese 20 MHz one with 1meg impedance.

Thanks for the replies.



Best Regards,
Chris Wilson. 2E0ILY (UK)

A few questions.

Do you have a part number for the attenuator?
Is it a standard 10Mohm probe, rather than a "low" impedance Z0 resistive
divider probe?
What are the actual measurements?
Have you tried them with a DC signal and a multimeter?
What are the results with the probe and the attenuator only, and then with the
two in series?
Is it a *20 or a 20dB attenuator?

A 20dB attenuator will be for a specific input/output impedance, 50ohms or
75ohms for RF, or 600ohms for audio. Mixing impedances will give unexpected
results. A standard *10 probe will expect a load impedance of 1Mohm, not
50/75/600ohms. A 20dB attenuator with correct source/load impedances reduces the
voltage by a factor of 10.


Re: 7B92A No Sweep

Albert Otten
 

Just try a diode check with a simple 220R resistor (value of R433) and you will probably find the same reading.
Albert


Re: X10 probe in series with X20 attenuator question

Tom Gardner
 

On 13/02/17 08:33, Chris Wilson chris@... [TekScopes] wrote:

I have my probe set to X10. That then feeds through a x20 attenuator
on the normal high impedance scope input. Let's say I have a 100V
signal at the probe. Is the scope seeing 100V divided by 10 (10V),
then 10V divided by 20 (0.5V)? or is it seeing 100V divided by 30
(3.33V)? Thanks, I am having a mental block about this! I have been
told it's actually a X200 attenuation, but results seem to show THAT
is definitely wrong... Sorry for the rather naive question. So what
is the combined attenuation please?
A few questions.

Do you have a part number for the attenuator?
Is it a standard 10Mohm probe, rather than a "low" impedance Z0 resistive divider probe?
What are the actual measurements?
Have you tried them with a DC signal and a multimeter?
What are the results with the probe and the attenuator only, and then with the two in series?
Is it a *20 or a 20dB attenuator?

A 20dB attenuator will be for a specific input/output impedance, 50ohms or 75ohms for RF, or 600ohms for audio. Mixing impedances will give unexpected results. A standard *10 probe will expect a load impedance of 1Mohm, not 50/75/600ohms. A 20dB attenuator with correct source/load impedances reduces the voltage by a factor of 10.


Re: X10 probe in series with X20 attenuator question

Craig Sawyers <c.sawyers@...>
 

I have my probe set to X10. That then feeds through a x20 attenuator on the normal high impedance
scope input. Let's say I have a 100V signal at the probe. Is the scope seeing 100V divided by 10
(10V),
then 10V divided by 20 (0.5V)? or is it seeing 100V divided by 30 (3.33V)? Thanks, I am having
a
mental block about this! I have been told it's actually a X200 attenuation, but results seem to
show
THAT is definitely wrong... Sorry for the rather naive question. So what is the combined
attenuation
please?
I suspect that the x20 attenuator is intended for use in a 50 ohm environment. So it will not give
the intended attenuation.

Also I suspect that your probe is a regular probe intended to look into 1M input. So again feeding
it into a 50 ohm attenuator will do something distinctly odd.

Craig


X10 probe in series with X20 attenuator question

Chris Wilson
 

13/02/2017 08:30

I have my probe set to X10. That then feeds through a x20 attenuator
on the normal high impedance scope input. Let's say I have a 100V
signal at the probe. Is the scope seeing 100V divided by 10 (10V),
then 10V divided by 20 (0.5V)? or is it seeing 100V divided by 30
(3.33V)? Thanks, I am having a mental block about this! I have been
told it's actually a X200 attenuation, but results seem to show THAT
is definitely wrong... Sorry for the rather naive question. So what
is the combined attenuation please?


--
Best Regards,
Chris Wilson.
mailto: chris@...


Re: CRT noise (sound) and low +15V rail

Tomas Alori
 

BTW, fixing the +15V rail also fixed the display shift seen on my first post and also fixed my horizontal sweep which had stopped completely.


Re: CRT noise (sound) and low +15V rail

 

Hi Tomas,
Two things come to mind: 1) it looks like a beat frequency from something is
modulating the Z-Axis intensity. By varying the sweep speed with the
variable knob I bet you can get it to slow down and go in the opposite
direction of that is what it is; or 2) it is being caused by the on-screen
readout which blanks the beam. I don't know what scope this is or how its
on-screen readout works but sometimes when conditions are just right (or
wrong actually) you can get interference from the on-screen readout blanking
the main traces while it writes information on the screen. On some scopes
even with the on-screen readout intensity turned way down or off you still
have this signal being gated onto the CRT. In the 7000 scopes there was
actually a way to disable it internally in some of the mainframes.

I would take a look at the Z-Axis theory of operation in the service manual
to learn where to look in the Z-Axis amplifier signal chain. I bet you find
a ripple or noise or some signal in that amplifier chain that correlates
with the signal on the screen.

I never saw the rest of this thread so I don't know if your -15V problem was
solved, but there is always a possibility that is causing the CRT brightness
ripples. Judging from the speed of the ripples I don't think these are 60Hz
related but other noise on the power supply rails could be the cause.

Dennis Tillman W7PF

-----Original Message-----
Sent: Sunday, February 12, 2017 9:04 PM
Subject: [TekScopes] Re: CRT noise (sound) and low +15V rail

David thanks for your advice! Checked the things you mentioned and was able
to fix the 15V rail! It was R3236 that was reading 49K instead of 40K. It
was in perpetual regulating mode. Replaced it and now its back at 15V.

I have another problem that maybe you can help me with:

Lately the display has been acting weird. My traces have these variations
in intensity that seem to "run" the right. Its difficult to explain so I
recorded a video where you can see the problem clearly:
https://goo.gl/photos/hRhytUWXHuTjATvY7
https://goo.gl/photos/hRhytUWXHuTjATvY7. The readout is also all wobbly. The
problem is getting worse with time. I used to get solid and static traces.
Any idea what could be causing this?

Thanks again!
------------------------------------
Posted by: tomas.alori@...
------------------------------------


Re: CRT noise (sound) and low +15V rail

Tomas Alori
 

David thanks for your advice! Checked the things you mentioned and was able to fix the 15V rail! It was R3236 that was reading 49K instead of 40K. It was in perpetual regulating mode. Replaced it and now its back at 15V.


I have another problem that maybe you can help me with:


Lately the display has been acting weird. My traces have these variations in intensity that seem to "run" the right. Its difficult to explain so I recorded a video where you can see the problem clearly: https://goo.gl/photos/hRhytUWXHuTjATvY7 https://goo.gl/photos/hRhytUWXHuTjATvY7. The readout is also all wobbly. The problem is getting worse with time. I used to get solid and static traces. Any idea what could be causing this?


Thanks again!


Re: Luck with an SC501

Jerry Massengale <jmassen418@...>
 

yes, i took a laser cut tab and coated with rubber spray


On Sun, Feb 12, 2017 at 2:44 PM, szigszabolcs@... [TekScopes] <
TekScopes@...> wrote:



Hi,

This one has a non original pull tab, looks like laser cut from thin black
plastic.


Szabolcs



[Non-text portions of this message have been removed]



[Non-text portions of this message have been removed]


Re: Trace thickness and edge variation by probe

Michael A. Terrell
 

You forgot the part about using it on your sky hooks to keep them from rusting. ;-)

-----Original Message-----
From: "'Dennis Tillman' @Dennis_Tillman_W7pF [TekScopes]" <TekScopes@...>
Sent: Feb 12, 2017 2:32 PM
To: TekScopes@...
Subject: RE: [TekScopes] Trace thickness and edge variation by probe

Antenna Wax is made up. It is based on the wax used for snow skis. Antenna Wax doesn't exist but it sounds like there should be something like it that you can use to make your antenna perform better.

I was referring to a tradition of fooling people on April 1 each year. This is called April's Fool's Day. Antenna Wax is the kind of joke that is just plausible enough to make you think about whether the person was telling you the truth or not.
Michael A. Terrell