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Refurbishing a Tektronix TDS7104 Oscilloscope

tomverbeure.github.io

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Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#21

Post by jlawrence6809 »

tverbeure wrote: post #17
jlawrence6809 wrote: post #15

Earlier quoted context omitted.

My model is an SMIQ03E actually! I've grown quite addicted to going to my local 2nd hand electronics store in recent months scrounging for anything with an rs232 port!

I looked for a SMIQ for quite a while to go along with the AMIQ, but eventually settled for the R&S SFQ TV test transmitter that you can see here: https://tomverbeure.github.io/2026/06/28/Rohde-Schwarz-AMIQ-... . It can be used a vector RF signal generator with I/Q inputs. The only limitation is the reduced input bandwidth.

Very cool! Yeah I lucked out finding mine. It was in the intake section at my 2nd hand electronics store. It had a broken power button so they were selling it "as-is". A button repair and battery swap later I have a 3.3Ghz VNA. Can't complain!

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#22

Post by wowczarek »

tverbeure wrote: post #20
wowczarek wrote: post #19

I went through a similar process recently with an HP/Agilent 54845A scope (1.5 Ghz, 8 Gsa combined) - a great tool if you need reasonably fast rise times and a reasonably fine time base resolution - the only issue is that it has an abysmally low sample memory for today's standards, so you get to see the trigger and "just a bit more". Well the other issue is that it pushes a lot of air... Like a lot, jumbo jet a lot.…

Not sure if you saw it, but before doing the TDS7104, I refurbished two Agilent 54831 scopes: https://tomverbeure.github.io/2026/03/28/Repair-of-Two-Agile... . For the one that still had a HD, copying the image from to an SSD worked without any issues. However, I also had a 54825A where it didn't work (I sold it, no blog post about that one.) So it's clearly hit-and-miss. I found the 32 screws of the TDS7104 less of…

> I found the 32 screws of the TDS7104 less of a pain than the dismantling the Agilents which had less screws.

Yeah sliding the whole thing out of the shell and the (curses) front panel ribbon that gets in the way, and the best part is that if it pops out on the front panel end, the tab is held in place by a metal prong that you have to bend (break away) to undo the tab to secure the ribbon. The prong is not screwed down, it's riveted. Breaking that thing away was the best thing I could do without ruining the panel. I ended up also gluing that ribbon to the chassis so that it doesn't get caught again.

Edit: I also bought mine to use it, hence all the extra bits around it.

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#23

Post by tverbeure »

wowczarek wrote: post #22
tverbeure wrote: post #20

Earlier quoted context omitted.

Not sure if you saw it, but before doing the TDS7104, I refurbished two Agilent 54831 scopes: https://tomverbeure.github.io/2026/03/28/Repair-of-Two-Agile... . For the one that still had a HD, copying the image from to an SSD worked without any issues. However, I also had a 54825A where it didn't work (I sold it, no blog post about that one.) So it's clearly hit-and-miss. I found the 32 screws of the TDS7104 less of…

> I found the 32 screws of the TDS7104 less of a pain than the dismantling the Agilents which had less screws. Yeah sliding the whole thing out of the shell and the (curses) front panel ribbon that gets in the way, and the best part is that if it pops out on the front panel end, the tab is held in place by a metal prong that you have to bend (break away) to undo the tab to secure the ribbon. The prong is not screwed…

My 54825A had a power-up problem: if you unplugged the AC cord for a few hours, pressing the front-panel button wouldn't power on the scope. But if you plugged in the AC for about 5 minutes, it would work fine again.

That sounds like an easy thing to fix, but the whole power-on architecture was a baffling Rube Goldberg device from the button on a small support PCB to the front panel PCB to the PC plug-in card to the power supply. I've never seen anything like it.

I disclosed the flaw to the buyer (the price was very low) and he was excited to have something to work on. :-)

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#24

Post by dematz »

A bit ago a semi-retired guy came back to help with some stuff including debugging serial ports. It was very cool to see him fiddle with the knobs and be like "oh those squiggles look good" "no that doesn't look right" etc. https://i.imgur.com/R5aEXbq.jpeg

Meanwhile total mystery to everyone else how to operate/interpret the machine but a lot of fun

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#25

Post by wowczarek »

tverbeure wrote: post #23
wowczarek wrote: post #22

Earlier quoted context omitted.

> I found the 32 screws of the TDS7104 less of a pain than the dismantling the Agilents which had less screws. Yeah sliding the whole thing out of the shell and the (curses) front panel ribbon that gets in the way, and the best part is that if it pops out on the front panel end, the tab is held in place by a metal prong that you have to bend (break away) to undo the tab to secure the ribbon. The prong is not screwed…

My 54825A had a power-up problem: if you unplugged the AC cord for a few hours, pressing the front-panel button wouldn't power on the scope. But if you plugged in the AC for about 5 minutes, it would work fine again. That sounds like an easy thing to fix, but the whole power-on architecture was a baffling Rube Goldberg device from the button on a small support PCB to the front panel PCB to the PC plug-in card to the…

There are exceptions to the "Winscopes" from the same era in the 1 GHz+ space (RTOS like VxWorks but with Ethernet and modern goodies) that are not HP/Tek/R&S, but I'm not listing them because I'm out on an active hunt for one ;-)

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#27

Post by stmw »

sdcfgy wrote: post #6

Give it a month and the acquisition ASICs will blow up and the caps will eat through the board traces. Can’t stand these scopes.

For a brief second, I thought this was about an original 7104.

Are there specific TDS models that you have found to be better, btw, reliability-wise?

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#28

Post by tverbeure »

dematz wrote: post #24

A bit ago a semi-retired guy came back to help with some stuff including debugging serial ports. It was very cool to see him fiddle with the knobs and be like "oh those squiggles look good" "no that doesn't look right" etc. https://i.imgur.com/R5aEXbq.jpeg Meanwhile total mystery to everyone else how to operate/interpret the machine but a lot of fun

One totally needs a 500 MHz oscilloscope to debug a kHz range serial port signal! :-)

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#30

Post by amelius »

jhallenworld wrote: post #13

Yeah 1 GHz is nice, but that tiny 200 MHz Siglent is going to be much more useful in practice for most things. Speaking of boat anchors, I'm trying to get my company to buy a DSA91304a (13 GHz scope with SERDES debugging). ~$44K with all the options, but still Windows-XP. The Windows-7 ones unfortunately don't have the options I want. Maybe there is a hack..

200 MHz is good enough for most things. And for modern computing electronics even 1GHz is too slow, e.g. monitoring USB3 or high speed PCIE data lanes.

Did you get a price quote for that keysight oscilloscope? I see that you can also rent them for $2000 a month.

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