EEVblog #565 - Tektronix TDS3054 Oscilloscope Repair - Part 2

[vaualbus]

I think that the central asic is not a mux (that indeed should be a demux) but the trigger asic, when dave freaze it the trigger point move and the wave not trigger for a moment.
Is more probably that the mux is near the memory or even inside the main fpga.

[burra7]

Seems like newer tds 3000c series uses the same frontend and singal processing chips.
See page 72

http://www.afc-ingenieros.com/uploads/Afc/Productos/Tektronix/Manuales/Osciloscopios%20TDS3000C/TDS3000C%20Service%20Manual%20-%20071-2507-00.pdf

[burra7]

More updates: rev 3

https://www.dropbox.com/s/054heh5j2penkfk/tek%203054%20blockschema%20r3.odg
https://www.dropbox.com/s/4wixip0lpix6vc7/tek%203054%20blockschema%20r3.pdf

Edit: added to here for future modifications:
https://bitbucket.org/burra/tds-3054

[toomas]

If the adc is 9 bits, then maybe it outputs them all in parallel. If you could locate those pins, then maybe you can probe them or force them to high or low and see what the waveform on the screen does.

[vaualbus]

Definitly the middle chip is the trigger asic.
Indeed there is this patent associted with that: http://www.google.com.tr/patents/US6219094

[Fryguy]

Has anyone noticed the "Dallas Timekeeper Ram" chip at the top center of the board ? If i'm not mistaken , these chips will KILL the scopes when the lithium battery inside drops dead !
I remember seeing them on old computer mainboards (i386 + i486) and on gamemachine mainboards . The ram is hooked up to the battery inside the chip - and when the battery voltage has dropped below a certain level , the ram loses it's programm and the machine drops dead - most likely forever .   

If that is the case here , all these scopes will definitely die in 100% working condition . . . and i will stop buying Tek equipment forever . People who put self-destruction-devices in expensive top quality lab equipment deserve the spanish inquisition . 

Sorry if i'm a bit emotional on this but nothing drives me as crazy as some a**h***s wasting perfectly good stuff .

[Hydrawerk]

Oh shit, there is a 3V battery in my DSOX2002A, too. But is there a Dallas-Timekeeper-Ram??

[Fryguy]

You should feel lucky if you can replace the battery in your scope - The "Dallas-Timekeeper-Ram" or "Dallas-Clock-Chip" was specifically designed to kill the machines . . .

Keyword : planned obsolescence

Seeing the datecodes on the chips (98/99) and knowing the nominal lifespan of the "Dallas" devices is about 10-15 years makes me wonder how long these scopes will continue to work . . .

Did the "Australian Forces" know about it . . . ?

[philpem]

You should feel lucky if you can replace the battery in your scope - The "Dallas-Timekeeper-Ram" or "Dallas-Clock-Chip" was specifically designed to kill the machines . . .

Keyword : planned obsolescence

Seeing the datecodes on the chips (98/99) and knowing the nominal lifespan of the "Dallas" devices is about 10-15 years makes me wonder how long these scopes will continue to work . . .

Did the "Australian Forces" know about it . . . ?

They weren't designed specifically for that reason -- they were designed to maintain data (typically data which is updated often enough to wear out an EEPROM) across power cycles. If the manufacturers choose to use it to store program code or critical data without providing a means to reprogram said data then that's their decision and may hellfire rain upon them for it.

[c4757p]

People who put self-destruction-devices in expensive top quality lab equipment deserve the spanish inquisition . 

They deserve it, yes, but can you really blame them for not expecting it?

[Hydrawerk]

Here is the dallas killer scope device. There is probably no similar component in my DSOX2002A. http://www.flickr.com/photos/eevblog/sets/72157626631250619

[Fryguy]

You should feel lucky if you can replace the battery in your scope - The "Dallas-Timekeeper-Ram" or "Dallas-Clock-Chip" was specifically designed to kill the machines . . .

Keyword : planned obsolescence

Seeing the datecodes on the chips (98/99) and knowing the nominal lifespan of the "Dallas" devices is about 10-15 years makes me wonder how long these scopes will continue to work . . .

Did the "Australian Forces" know about it . . . ?

They weren't designed specifically for that reason -- they were designed to maintain data (typically data which is updated often enough to wear out an EEPROM) across power cycles. If the manufacturers choose to use it to store program code or critical data without providing a means to reprogram said data then that's their decision and may hellfire rain upon them for it.

These chips were keeping the bios data on the old computer mainboards - how often was that updated in it's lifetime ? once ? or twice ? that won't wear out an EEPROM . On the gamemachines i've seen the "bios" getting updated literally zero times .

I'm pretty sure they were expecting it at some point c4757p - they put the timebombs in there 

Hydrawerk - the battery is inside the "Dallas" device ( that's why the chip is 3x thicker than the other chips - it contains a RAM chip , a realtime clock chip , a clock crystal and a lithium battery - if i'm not mistaken - i teared some of those chips apart a long time ago ) - if you see a battery , you don't have to look for that chip .

However - i'm curious what Dave's got to say about this huge  .

[vaualbus]

The real name of this chips are nvram,
no volatile ram. In almsot old 80/90 instruments are used to mantained calibration data and information about the instrument options.
This chips not spread acid on the board. They are made by dallas semicondactors, now is maxim (some of this ics still be in free sample on the maxim site indeed) and just not mantain data when the internal battery go away.
There is good reason to not place the calibration data on eeprom sometime calibration is made every time you turn on the intrument (for example in network analyzer) and there is no reason to place the data on a eeprom.
The IC maxim life time is about 10 years but the ic still work also for a longer time (recently I change on of this ic and was made in the late of 92 but still work).
Best regards, Alberto.

[sync]

These chips were keeping the bios data on the old computer mainboards - how often was that updated in it's lifetime ? once ? or twice ? that won't wear out an EEPROM .

They hold the BIOS data. Uncritical data. They didn't contain the BIOS code.

[EEVBlogViewer]

There are a a couple of repair videos in the eevblog - but when its not a damaged fuse it seems that a repair is impossible.

[EEVblog]

There are a a couple of repair videos in the eevblog - but when its not a damaged fuse it seems that a repair is impossible.

That's murphy at work every time.

[Hydrawerk]

What is going on, Dave?

[SeanB]

The case was worth more than the scope on Ebay?

[wesphillips]

Dave,
  How can you say that the hybrid is working? you didn't check the output of the hybrid when the ch3 timebase setting caused the display to  disappear. I would be interested to see the output of ch3 when there is no display at all for ch3.

[Monittosan]

The scope sold on ebay for a pretty penny so it may just stay a 3ch scope for now