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Re: 2440 CCD Gain channel 2-1 fail

bc
 

Found more useful data!

The "FORCE DAC" command on the soft button extended menus was interesting. I switched it to "GN21" which apparently is GAIN21 and it looks like it was able to change that voltage on the fly using the intensity knob!

Also finally got a useful trace on my 2465, was very dicey to trigger on these very scratchy waveforms on the output of the gain cell boards (GCX/GCY). With the 2440 hooked up to its probe cal output, I can finally see a semblance of the cal waveform, the sickly 5MHz square wave that sort of looks like a sine wave. Though very spotty and jittery I can see them on the outputs of the gain cell boards (GCX - pin 18 and GCY - pin 19)... all except for the A32 GCX pin 18 gain cell board! Adjusting GN21 I can make the waveform a little bigger but self cal already was able to make it as big as it could at setting 4095. However, when the 2440 is switched slower than 100ns/div, the waveforms appear just fine! Still a mystery here.

The CCD outputs feeding into the board look identical but I can't discern the input waveform in the output of the CCDs. Seems there's a large precharge phase and then the data out phase,which I'll need to find an external trigger or something... and more x10 probes... and read more theory...

-Ben

---In TekScopes@yahoogroups.com, <laser92awd@...> wrote :

BTW, it's been *really* tough trying to get a useful waveform from my 2465. Ouch. All the waveforms in the service manual seems to be made from...another 2440. Sigh.

Comparison between ch1 (OK) vs ch2 (bad) at 20ns/div:
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Apparently this is an intermittent problem but haven't been able to get it to flip by touching the board, however, I would need to do a self cal after every experiment making it tough to use this method of debug... If I could force the DAC output for the A32 gain board to be 0V like the other gain boards, that would make it a bit easier to debug...


Re: 453 with no trace, meets willing novice troubleshooter with DMM !

bc
 

Crap, must have accidentally omitted: The copy of the service manual is on BAMA, and can take a look at sheet 17 which is the low voltage power supply. Keep in mind that 150VDC is considered "low voltage" but this too is lethal if not handled properly. Check fuses! F1204, F1172, etc.


Re: 453 with no trace, meets willing novice troubleshooter with DMM !

bc
 

Curious, did the trace disappear while you were using it? Did it slowly go away, suddenly go away, or didn't notice it before it disappeared? Did you accidentally set the trigger to external or 1-shot perhaps? These are just clues and checks and make sure there's any simple issues.

I guess when one doesn't know how it failed (like when someone buys a defective one of unknown condition), first start with testing the power supplies, starting with the low voltage. You should compare all the voltages with what's listed in the manual, usually they vary from 5 to 150 volts DC. On the schematic you can sometimes see a number near a wire or a testpoint, that's a general voltage that you should see at that particular node in the real circuit if things are working correctly.

Then you should move on to the high voltage - though not to explicitly test high voltage, but see of the heater is on, check the fuse F937, etc. If you have a meter that can measure multi kilovolts, then you can see if the cathode voltage is good, but if the CRT heater is working, you're likely good to go.

After the power supplies are good, then you have to go look at the signal path. A scope would indeed be helpful, but the older scopes they were somewhat made to keep in mind having more than one scope is a luxury... Again voltages are printed on many nodes on the schematic that you can check with a multimeter to see if they're close, and you can start debugging from there.


Re: 453 with no trace, meets willing novice troubleshooter with DMM !

Rg P
 

Thanks Göran,
I pulled a lead and checked the resistor, it's good, I posted a picture of parts of the A Sweep/A Trigger board with a reply to Dale. Seems to indicate prior work/ replacements done on the unit in these sections.
Specific points for checking the low voltages and sweeps on this unit?
ric.


Re: 453 with no trace, meets willing novice troubleshooter with DMM !

Rg P
 

Thank you for the pointers Dale, If I get another scope (i.e. a inexpensive digital scope...Rigol?), this might not get fixed, since the use is still occasional.
I did pull a lead of the resistor, and read it. It reads proper value.
I see that some diodes on parts of the A trigger/ sweep generator board have been worked on, and /or upgraded.
Tek453ric061516.jpg https://www.dropbox.com/s/k7havqzvr1770kh/Tek453ric061516.jpg?dl=0



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I am still hoping there is a set of steps in a process to solving the problem of having no trace, on this Model scope, and that someone there has worked on enough of them to have the format down.
Then I could snip and check particular components.
ric


Re: Tektronix 224 question

Mark Pilant
 

Hi Jon.

if you find probes that will work (expect modifying ) please, please let
us know !!
I did find this article on the web:

<http://www.worldphaco.com/uploads/USING_STANDARD_x1_and_x10_OSCILLOSCOPE_PROBES_WITH_THE_TEKTRONIX_222PS_OSCILLOSCOPE.pdf>;

It is about using standard probes and another type of battery conversion.

- Mark


Re: Tektronix 224 question

Jon Batters
 

Hi Mark ,

I want to add that I installed a Power Sonic PS-832 “brick” battery in my 222 because I could and there’s no wasted space from round batteries.

I did have to take my Dremel with a grinding bit to the case interior to grind down all the ribs and square-out the case interior. They were designed for the original battery and not needed now. The battery fills 95% of the interior and the lid slides on , fitting perfectly. I do have to wiggle/jiggle the lid a small bit to center the battery in the space so the lid lips will fit into their notchs.

The only detriment I can see is that there is zero gap for battery swell. But, if there’s swelling, there is a problem and once I get the battery out ( ! ) I can just drop in a new PS-832.

And, if you find probes that will work (expect modifying ) please, please let us know !!

Jon Batters, Grants Pass, Or.

Sent from Mail for Windows 10



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


Re: Tektronix 224 question

Mark Pilant
 

Hi John.

I think both the 222 and 224 have 10 million samples/sec as their maximum
ADC sample rate.
Yep. That is what the manuals say.

To get the 60MHz bandwidth on the 224, it uses "equivalent time" sampling
to get intermediate samples from multiple captures offset in trigger time.
That is sort of what I figured, because I couldn't see it explicitly stated
in the manual. Given the block diagrams of moth show the input signal going
into an ADC, I figured there wasn't an "alternate" analog mode available. I
believe some "digital" scopes had both an analog mode as well as digital mode
for capturing waveforms, etc.

Neat little scopes.

The only thing I have to do with the 222 is undo the Power Sonic battery mod.
The battery "mostly" fits, but it is quite tight and distorts the case a bit.
Using the Cyclon 2V SLA batteries is a much nicer fit. My 224 has the 4
Cyclon batteries.

Now all I need to do is find an appropriate probe. Which I'm sure will not
be easy.

- Mark


Re: Tektronix 224 question

John Gord
 

Mark, I think both the 222 and 224 have 10 million samples/sec as their maximum ADC sample rate. To get the 60MHz bandwidth on the 224, it uses "equivalent time" sampling to get intermediate samples from multiple captures offset in trigger time. At some sweep time (and slower) I assume they both work similarly (ie, without the multiple captures).
--John Gord


---In TekScopes@yahoogroups.com, <mark@...> wrote :

I recently picked up a Tektronix 224, and it appears to work well. The
question I have is about how the waveform is displayed.

When I hook up the probe to a 5 MHz square wave source, it takes several
"sweeps" to completely fill in the wave form. Is this just an artifact
of the digital sampling, or have I managed to confuse myself and not set
it up properly. (I did get the manuals from Qservice, so I'm not working
completely blind :-)

I tried using my Tektronix 222 with the same source and it did not seem
to do the same thing.

Thanks in advance.

- Mark


Tektronix 224 question

Mark Pilant
 

I recently picked up a Tektronix 224, and it appears to work well. The
question I have is about how the waveform is displayed.

When I hook up the probe to a 5 MHz square wave source, it takes several
"sweeps" to completely fill in the wave form. Is this just an artifact
of the digital sampling, or have I managed to confuse myself and not set
it up properly. (I did get the manuals from Qservice, so I'm not working
completely blind :-)

I tried using my Tektronix 222 with the same source and it did not seem
to do the same thing.

Thanks in advance.

- Mark


Re: Semi-OT: Orphaned instruments group?

n4buq
 

There is test-equipment@mailman.qth.net. That might help.

Regards,
Barry - N4BUQ

----- Original Message -----
From: "Brad Thompson brad.thompson@valley.net [TekScopes]" <TekScopes@yahoogroups.com>
To: TekScopes@yahoogroups.com, "hp agilent equipment" <hp_agilent_equipment@yahoogroups.com>
Sent: Thursday, June 16, 2016 4:12:02 PM
Subject: [TekScopes] Semi-OT: Orphaned instruments group?

Hello--

Does anyone know whether there's a Yahoo group that's dedicated to
sharing knowledge
about orphaned or obscure test instruments which are no longer supported
by their
manufacturers or whose manufacturers have long since disappeared?

Thanks, and 73--

Brad AA1IP


------------------------------------

------------------------------------


------------------------------------

Yahoo Groups Links




Semi-OT: Orphaned instruments group?

Brad Thompson <brad.thompson@...>
 

Hello--

Does anyone know whether there's a Yahoo group that's dedicated to sharing knowledge
about orphaned or obscure test instruments which are no longer supported by their
manufacturers or whose manufacturers have long since disappeared?

Thanks, and 73--

Brad AA1IP


Re: 475 knobs smashed in shipping

keantoken
 

I think I've found part of the problem. The board next to the CRT behind the attenuators seems to have been pushed back about 1-2mm. The binding posts and attenuator knob bushings are all skewed slightly. When the scope was hit, the feet of the standoffs on that board are the weak point. The aluminum panel supporting the standoffs has warped.


Re: 7k-series extender 067-0589-00

Albert Otten
 

Hi Colin,

First of all, the contact usage for each specific 7k 'scope is always shown in the Diagram (usually one of the first) of the Main Interface Board, connectors J1-J3 (and J4 for 4-bay).
Next be careful to number the contacts in the proper direction. The highest numbers 29-38 are used for the Readout, not the lowest numbers you mention. Also look at all connectors since some contacts are used only in horizontal slots and some only in vertical slots.
I would not take the risk to use this extender.

Albert


---In TekScopes@yahoogroups.com, <colingherbert@...> wrote :

Hi,
I purchased one of these rigid extenders and found it to be less-than-perfect. The edge connectors which the plug-in DUT mates with are not always making contact and some are missing. Both #1 and #2 on both "A" and "B" sides are missing, although there is evidence of something being soldered to the pcb track. Also, due I think to some small distortions, contacts #6 to #11 and #38 on the "A" side and #7 on the "B" side don't connect to the DUT properly, if at all. Does anyone know if there should be contact for the #1 and #2 "A" and "B" and has anyone succeeded in adjusting the contacts to make properly? If so, could any help be passed on to me?
I might add that I am (slowly) assembling one of John's flexible extenders and I can see that contacts "A1", "A2", "B1" and "B2" are labelled as Channels #1 and #2 "Row" and "Column". Is this related to the readout?


TIA, Colin.


Re: 475 knobs smashed in shipping

keantoken
 

I just took the attenuator cover off and have been inspecting the switch contacts. The "big roller thing" seems to be pushed towards the back of the scope, so that it hits only one side of the white plastic parts on the contacts. This causes one contact to not touch. It's not immediately clear from the mechanical diagrams what could have shifted when the knobs got bashed. Hopefully I can just loosen a setscrew somewhere.


When the 20MHz filter is engaged, this scope has a nice crisp trace, almost as good as my 561B.


7k-series extender 067-0589-00

Colin Herbert
 

Hi,
I purchased one of these rigid extenders and found it to be less-than-perfect. The edge connectors which the plug-in DUT mates with are not always making contact and some are missing. Both #1 and #2 on both "A" and "B" sides are missing, although there is evidence of something being soldered to the pcb track. Also, due I think to some small distortions, contacts #6 to #11 and #38 on the "A" side and #7 on the "B" side don't connect to the DUT properly, if at all. Does anyone know if there should be contact for the #1 and #2 "A" and "B" and has anyone succeeded in adjusting the contacts to make properly? If so, could any help be passed on to me?
I might add that I am (slowly) assembling one of John's flexible extenders and I can see that contacts "A1", "A2", "B1" and "B2" are labelled as Channels #1 and #2 "Row" and "Column". Is this related to the readout?


TIA, Colin.


Re: TEK 607 Storage Monitor woes

kshuff@...
 

Got it, thanks Vince. Yes there are schematics at the end of the manual. Coincidentally that picture of the 607 on the page is mine, don't remember when I submitted it though


Re: 475 knobs smashed in shipping

keantoken
 

Channel 1 doesn't show a trace, if I hold the knob just right it will show up, but other wise it's just noise from the case being removed.


I found C825 has one pin broken out. I can't find it in the schematics to see what it goes to though.


Tek Gray Paint

 

Has anyone had a reason to identify or find a source for the gray paint used on the front frame of the 492 spectrum analyzers and possibly other Tek instruments?

Bruce, KG6OJI


Re: TEK 607 Storage Monitor woes

Vince Vielhaber
 

The manual is available on TekWiki http://w140.com/tekwiki/wiki/607
Dunno if the schematic is in it.

Vince.

On Thu, June 16, 2016 10:11 am, kshuff@verizon.net [TekScopes] wrote:
Hello all, I have a 607 storage monitor that hasn't been used in years and
decided to dust it off and put it to use. It operated for a few weeks and
I left it on overnight the other day and when I remembered it was on went
to check and now I have no display. Doesn't look like there is power to
the filament of the crt. Anybody know where I can get a schematic or have
any poonters on fixing it?
--
Michigan VHF Corp. http://www.nobucks.net/ http://www.CDupe.com/
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