Re: Faulty 2465B
Keith bravo for your work on NV Ram, beware of Chinese knock-off and old date code parts.
Use machine pin socket
Full cal is needed after RAM replacement
See service manual and proper test
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Jean-Paul
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#208031
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Re: 7904 pre-260000 PSU crackling
Hello again
Last two photos show Carbon and dirt accumulation on HV box , cables and Kapton film insulation
Needs through cleaning with 99% isopropyl alcohol.
Where is the HV cable nick, photo
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Jean-Paul
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#208030
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Re: Faulty 2465B
Hello Keith,
I also have trigger problems with my 2465B. The SRAM Dallas has already been replaced and refilled because of the old Li battery. Because the Scope also had (and still has) the error
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Juhe
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#208029
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Re: 7904 pre-260000 PSU crackling
Hi all,
I had some time so dug into the PSU a bit, swapped ot the last tantalum in there, and upgraded the aluminium 'lytics as per revisions list in the manual. The big storage caps I ran up to 195V
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James
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#208028
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Re: Faulty 2465B
So I desoldered the DS1225 nvram carefully and fitted a 28 pin DIL socket.
Took the nvram and just to see if there was still any life in it I programmed it using a TL866ii programmer, using a .bin
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Keith
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#208027
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Re: Chasing an analogue video signal - help
Very useful. Let me have a rummage and see if I can find any of the 3 units mentioned.
I agree the LM1881 ads nothing here, indeed already tried it
--
Christopher Hilton-Johnson
The Stone
By
Christopher Hilton-Johnson
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#208026
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Re: Chasing an analogue video signal - help
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
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Clark Foley
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#208025
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Re: Tek 7704 scope cover
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
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Dave Daniel
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#208024
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Re: Tek 7704 scope cover
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,
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evan foss
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#208023
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Re: Added photo album LM1881 built into type L plugin
#photo-notice
I guess I should have said proto-bord or air circuit.
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Bruce Atwood
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#208022
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Added photo album LM1881 built into type L plugin
#photo-notice
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
By
Group Notification <noreply@...>
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#208021
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Re: Chasing an analogue video signal - help
Here is the data sheet for the LM1881.
https://www.ti.com/lit/ds/symlink/lm1881.pdf?ts=1736763609625&ref_url=https%253A%252F%252Fwww.google.com%252F
I will post a photo of how I built this.
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John Williams
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#208020
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Re: Fixing a vintage Tek 465M scope: Bad HV multiplier
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
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richard ramacieri
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#208019
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Re: Faulty 2465B
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
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Keith
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#208018
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Re: Chasing an analogue video signal - help
Look at the data sheet for the LM1881. With only a little care you can use it on a bread-board.
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Bruce Atwood
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#208017
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Re: Faulty 2465B
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
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Keith
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#208016
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Re: Faulty 2465B
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
By
victor.silva
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#208015
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Re: Faulty 2465B
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
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Jean-Paul
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#208014
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Re: Tek 465m..High voltage fuse blow (1/4 A).
Here is a link to the service manual:?https://w140.com/tekwiki/images/c/c3/070-2237-00.pdfHere is one for the diagrams only:?https://w140.com/tekwiki/images/c/c9/Tek_465M_schematics.pdf
I believe
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Ananda
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#208013
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Chasing an analogue video signal - help
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
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Christopher Hilton-Johnson
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#208012
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