开云体育

The original posting refers to the signal as RGBHV. All five components are already separated. As much as I like the LM1881, there is no need for it (i.e. sync separator) in this application.

To trigger on sync event number 270 or any other event, I recommend triggering the timebase after Delay-by-Events. If you can borrow a 7D10 or 7D11, you can either run after or trigger after the 270th event is counted. The DD501 can also provide the event delay function.

You might be able to use a standard delaying timebase, but the delay jitter might make it difficult to select the event to trigger the delayed timebase.

Evan,

Thanks. I have never seen a 7704 so I don't know if a 7704 cover would fit
on a 78xx or 79xx 'scope. I imagine that the only characteristics that
matter would be the outside dimensions of the 'scope bezel and the depth of
the front panel controls.

I'll wait to see what the dimensions of your cover are; at that point I
will be able to decide for myself.

I don't generally have a concern about damaging the front panel controls
but I do wish I had something other than random large plastic bags to keep
dust off of those controls. The same goes for my 547 and 76xx 'scopes.

And, no, I was not expecting you to print covers for me. I can probably
join a local maker shop and print them there.

Thanks.

DaveD
KC0WJN


On Mon, Jan 13, 2025 at 22:13 evan foss via groups.io <evanfoss=
gmail.com@groups.io> wrote:

Hi Dave,

The 79xx scopes have different geometry on the front panel. The
display is lower down (smart), the power switch is in a slightly less
obvious place, I think the controls might be taller, among many
changes. The 7000 series had a common design style but the geometry of
the front panel and it's layout wasn't very uniform.

It would take a number of thin printouts of the outline to test fit to
make this work or you taking very careful and precise measurements of
some things. Or a 3D scan.

Keep in mind I am not trying to make a business out of this. I just
wanted to share the files and hopefully stop more innocent knobs from
being crunched by accident.

-Evan

On Sun, Jan 12, 2025 at 4:26?AM Dave Daniel via groups.io
<kc0wjn@...> wrote:

Will your 7704A cover fit on 79xx 'scopes? If so, I'd be interested in
having several (4 or 5) of them.

DaveD
KC0WJN


On Sun, Jan 12, 2025 at 00:40 evan foss via groups.io <evanfoss=
gmail.com@groups.io> wrote:

Hi Folks,

I made a 3D printed cover for the front of my Tek 7704A. I was worried
about accidentally harming the switches while I move it off/on the
shelf. I could clean it up and share it but that would mean a large
reprint to test it and I wanted to gauge interest before wasting that
much plastic and electricity.

PS: I am planning to do one for the 11801 as well. Though I will
probably have to line that with copper tape or something.

Evan

Hi Dave,

The 79xx scopes have different geometry on the front panel. The
display is lower down (smart), the power switch is in a slightly less
obvious place, I think the controls might be taller, among many
changes. The 7000 series had a common design style but the geometry of
the front panel and it's layout wasn't very uniform.

It would take a number of thin printouts of the outline to test fit to
make this work or you taking very careful and precise measurements of
some things. Or a 3D scan.

Keep in mind I am not trying to make a business out of this. I just
wanted to share the files and hopefully stop more innocent knobs from
being crunched by accident.

-Evan

On Sun, Jan 12, 2025 at 4:26?AM Dave Daniel via groups.io
<kc0wjn@...> wrote:

Will your 7704A cover fit on 79xx 'scopes? If so, I'd be interested in
having several (4 or 5) of them.

DaveD
KC0WJN


On Sun, Jan 12, 2025 at 00:40 evan foss via groups.io <evanfoss=
gmail.com@groups.io> wrote:

Hi Folks,

I made a 3D printed cover for the front of my Tek 7704A. I was worried
about accidentally harming the switches while I move it off/on the
shelf. I could clean it up and share it but that would mean a large
reprint to test it and I wanted to gauge interest before wasting that
much plastic and electricity.

PS: I am planning to do one for the 11801 as well. Though I will
probably have to line that with copper tape or something.

Evan

I guess I should have said proto-bord or air circuit.

John Williams <books4you4@...> added the photo album LM1881 built into type L plugin ( /g/TekScopes/album?id=300050 ) : Small addition to type L for NTSC sync seperation

Here is the data sheet for the LM1881.



I will post a photo of how I built this.

/g/TekScopes/album?id=300050

It me again..I just took with a scope on the suppose 32 volts unreg.. it show 56 volts with praticaly NO ripple... What do they mean when they indicate 32 volts unreg... Do they mean really 32 vdc...and if you look at the value of the 75 vdc capacitor, this value would be ok if the applied voltage is 32 volts instead of 56 volts... What is your opinion on this...
Best reguard's
RR

Ah sorry Victor, when I wrote that I had not noticed the SM caps on A5.
They do look OK - no leakage - and measure OK in circuit as far as I can tell. But they probably should be replaced.

Keith

Look at the data sheet for the LM1881. With only a little care you can use it on a bread-board.

Thanks Jon, I have a DS1225 on order from Mouser. When you say 'use EEPROM programming to load default CAL' what do you mean - is there some default binary for the NVRAM?

As regards the triggering issue, I have already replaced all PSU caps and verified the voltages. The A5 board SMU caps aren't leaky and measure OK too. I'm wondering if it could be an issue with U500? I may be able to lay my hands on one of those.

cheers

Keith

Keith,

I just notice this statement in your first post: "It's a 1996 model but no surface mount caps."
Are you saying the A5 controller is not using surface mount parts?

--Victor

Keith

The error message indicate dead NVRAM battery

Needs ver careful removing, place low profile machine pin 28 pin socket, get new genuine Dallas Semi replacement, use EEPROM programming to load default CAL


Perform a complete CAL according to the service manual.

All other faults....check PS and HV for failed caps, check A5 control board for leaks of SMD lyrics.

See both Tektronix forums on groups.io and EEVblog 2465 teardown thread.

Also Condor Audio and hams for 2465 rebuild notes

Bon chance


Jon

Here is a link to the service manual:? is one for the diagrams only:?
I believe you are referring to Fuse F558 which is a 0.25 Amp fuse. If so, there is a good possibility that the U550 HV multiplier is shorting. These are very old now and are prone to failure very easily. One way to check this is to disconnect Pin 10 of the HV transformer T550 or Pin 11 of the multiplier and switch it on with a new fuse. If it does not blow, then you know that the unit is faulty.
I have a 465M and some parts somewhere. Let us know.
Ananda

Hi Gurus>
I have a badly behaving analogue RGBHV video signal.
Whilst VSync pulses repeat steadily every 49.99 Hz, HSync is all over the place Both H & V pulses are negative going from 5v to 1v).
I have developed an HSync substitute, which mimics the 4.7us HSync pulses and starts on the tail end of each VSync pulse (210us).
These are 271 lines to a frame, thus 271 HSync pulses per frame.
Unfortunately because only the front end of the HSync train of 271 pulses is tethered to the VSync pulse the last video line is not necessarily complete before the HSync pulse starts.
The attached display knows its got an incoming signal but cannot display it because the frame/line rate is not stable.
I have several ideas on how to solve it, but to do so I need to see the last line of the frame, before the VSync pulse starts.
I can use a 7854 or 7844 or 7904 and have the usual timebases to work with them. So either I need to trigger on the 270th HSync pulse or extend the display to show all 271 lines at a display rate of 500ps per sec and trigger on any HSync pulse. HSync counting is in binary.
I realise I can extract the relevant HSync pulse, but to do so I will have to make up new PCBs, AND that will only get me the one pulse out.
Anyone got any ideas ?

So I finally received the capacitors I ordered from DigiKey on 1st Jan, apparently there was an IT issue that caused the order to be delayed, then the weather affected shipping... Anyhow, I replaced all the electrolytics on the A2A1 and A3 boards, plus the rifa's on the A3 inverter board.

Made up a load board with a 2.2ohm 20W for the +5VD, and 100ohm 5W resistors for the +5V, -5V, +15V, -15V, -8V. But 8.2K for the 84V and 4.3K for 42V rails as it seemed the current draw would be a bit OTT for those rails with 100ohms.

Anyhow testing the board with that load looked good, voltages were what they should be, so I fitted the PSU back. Measured J119 pins are now:

pin1 (-15v) = -14.957
pin 2 (+5V digital) = 5.006
pin 3 = (-15v unreg) -18.855
pin 4 (10v ref) = 10.004
pin 5 (-5v) = -4.985
pin 6 (+15v) = 15.014
pin 7 (gnd) = -0.001
pin 8 (87v) = 87.02
pin 9 (42v) = 42.46
pin10 (unused) = 0.004
pin 11 (-8v) = -8.032
pin 12 (5v analog) = 4.971
pin 13 = -1.3705
pin 14 = -1.3692

On power up, I got a test fail: 'Test 04 Fail 12 TV<6400>'. From what I read this is the Dallas Semi NVRAM cal. The datecode on that chip is '96 so I guess it needs changing?

The readout of e.g. ch1, ch2, timebase seems correct but has '?' in all the spaces... does this happen because the cal is invalid?

Lastly, there seems to be a triggering problem. On slow X axis speeds e.g. 200mS/cm I can get a correctly triggerred trace, but on faster ones the triggering either is intermittent or fails completely. It's not clear if this is an intermittent connection or something else. Any thoughts?

cheers,

Keith

The code I used on TDS7104 was in the earlier message:
=======
tempBuf=malloc(0x800)
nvMem_read(0,tempBuf,0x800)
fdescriptor=open("dbfs:c:/vxBoot/eepromdump.bin",0x0202,0777)
bytesWritten=write(fdescriptor,tempBuf,0x800)
close(fdescriptor)
=======

I have tested the code on TDS7104. I didn't compare with an EEPROM programmer but extensively looked at the contents and I convinced myself it is correct.

The code you copied is from user Wevie for TDS8000 and it differs from TDS7104.
Ozan

Bonjour, we recieved a fine TEK 492 SA, circa 1980s..1990s, fine condition CAL in 2007. SN B055xxxx
Will post photo album.

Q: Do these have the notorius SMD lytics on some PCB that leak and corrode ?
Which PCBs are suseptible?

WTB: For nonprofit museum , restoration to original condition:
Original TEK front cover
small knob (intnesity, etc)
complete service manual (2 vol, binders) original printed version
MANY THANKS !!

Have an absolutely fantastic day!

Jon

Thank Benjamin for answering....
There is a 1000mfd/75wdc cap in the circuit, so there is a filtering (regulation) on this power supply, as I look with a scope at the waveform of the 32 v unreg, it is really 56 volts... in that case, the value of the cap should be much higher than 75volts... Well, I guess that I will have to dig on that !!
Best reguard's, By the way I usually speak french, so forgive my writing ...

When you look at the diagram, you observe that there is a regulation by the addition of a 1000 mfd/75wdc cap..and if it is really 56 volts, the value of the cap should be much higher..

Hi John:
Thank you for your kind offer.
I have a great 555 scope, which I intend to keep working.
I also have types CA, D, W, 1A7, and 1A5 plugins.
Would your parts stash include those from scavenged plugins?
In particular, my W plugin likely needs some part(s) for repair of the
large reference voltage selector rotary switch. Possibly a switch wafer,
although it has been a few years since I tried a repair.

Thanks for reading!

Randy
Tek 555, 7934, 7633, 7623, and HP, Fluke, and others.

On Mon, Jan 13, 2025 at 12:37?AM Nick Bergan via groups.io <nbergan13=
gmail.com@groups.io> wrote:

Hi John,
Thanks for offering to share.
Do you have many 7000-series knobs and potentiometers?
I'm also looking for a correct graticule, light filter and CRT bezel for
my model 511 and model 422, which aren't exactly in the 500-series. If
nothing else, I might have to make my own or use parts from similar models.
I think I own or have seen just about all of the Tektronix analog scopes
in a 60-mile radius, lol.
I sure have made a lot of eBay purchases for how recent I got into the
restoration hobby. I'd hate to know how much I've paid in just shipping for
parts and tubes.