Refurbishing a Tektronix TDS7104 Oscilloscope(tomverbeure.github.io) |
Refurbishing a Tektronix TDS7104 Oscilloscope(tomverbeure.github.io) |
And yes, it's a lot of fun bringing these bargain bin pieces of kit back to life.
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..
I hope you're able to thoroughly test that DSA91304a before dropping $44k on it!
https://w140.com/tekwiki/wiki/Main_Page
Mine is a TDS224. Cheap, but I only use it for keeping my Eurorack synth going. 100MHz is overkill for audio. Although some modules use STM32 microcontrollers, so maybe the speed will come in handy.
Cute little thing. The reality is you hope that's all you need.
Did you get a price quote for that keysight oscilloscope? I see that you can also rent them for $2000 a month.
You just can’t characterise power rail noise well with less than 500MHz of bandwidth.
That said, anything with a floppy drive scares me because it undeniably indicates how old it is. My SDS7102V is no Tektronix, but an honest 1 GS/sec and at the time, under $200 on eBay.
I just mainly love the retro-moder look of it. Here's a link to how it looks, for those curious:
https://x.com/slhomme/status/1965131874734584291
I had now idea there was such a huge second-hand market for those. It was such a great opportunity to learn about this tech.
I was initially confused how you managed to get amber and green screen together, but I guess you put an LCD in ..
The equipment that's bought and sold at the electronics flea market typically isn't used as a means to an end, it is the end. There's disappointment when you buy something there and it just works. There's no fun in that.
I don't really have a use for a R&S AMIQ, but replacing all the PC motherboard caps taught me a lot about good desoldering practices. https://tomverbeure.github.io/2026/06/28/Rohde-Schwarz-AMIQ-...
These are just exceptionally bad.
Are there specific TDS models that you have found to be better, btw, reliability-wise?
I've got one, they are very cool. I also have a 7834 (storage tube), cool in a different way. On the other hand, they are taking up a lot of space... I also have two 485s, one with a broken trigger.
I'm just wondering how difficult it would be to use a more modern bit of kit in there instead of the Celeron.
People have replaced the RadiSys motherboard with one from a Gateway PC. There aren't a lot of other options though: the motherboard must be an NLX type and that was a short-lived format. It's different for scopes like the Agilent 54831 (https://tomverbeure.github.io/2026/03/28/Repair-of-Two-Agile...) that I revived a couple of months ago: people do crazy things with that, making it work with higher resolution LCD panels, upgrading to completely different CPU classes, running Windows 10 etc.
It's remarkable that these scopes have both a PC and a PowerPC motherboard. I think they were a reaction to Agilent scopes: they wanted a PC front-end and reused the PowerPC infrastructure with VxWorks OS that they already had from other generations, so they just slapped an extra motherboard on it.
Still, entering an easy to generate license key is less intrusive than removing a resistor.
Meanwhile total mystery to everyone else how to operate/interpret the machine but a lot of fun
This is one of the cases where it might be better to lease it.
I was going down the same route as the blog post (MSATA->PATA adapter), but simply imaging the HDD onto flash also didn't work.
The scope had to go into storage so I never finished this, but the SSD was being detected albeit at a lower capacity and no amount of twiddling with LBA and CHS geometry made a difference. My next step is going to be zeroing the drive, booting the scope with it as secondary, and then imagining it from within DOS/Windows. My hope is that the data will just end up at some offset. Or not even imaging it - just partitioning it, formatting it and doing XCOPY + SYS.
You may want to image the drive every so often and accessing the drive is a bit of a bastard (fewer than 32 screws on the HP but it's a pain regardless) - so it might make sense to actually get an SD->PATA adapter and mount it onto a PCI blanking plate, so that you can take it out easily. You may need a longer ribbon cable. There are also some 2.5 inch HDD brackets that mount onto a PCI blanking plate. Possibly a DIY job to replace the FDD with a plate that has the SD card mounted. Mine came with a ZIP drive.
I added the following software extras to the OS which I would recommend to anyone with an old scope like this that has an Ethernet port:
- An SNTP client so that you don't have to worry about the time and date (https://www.timesynctool.com/) - open source, win95 and up, just disable all logging to disk so as not to introduce extra writes and drive wear.
- TightVNC (1.3.10 I think) - a version that works on older Windows. Accessing it while the scope app is running slows things down significantly, so this is only for configuration changes and whatnot, also this particular scope writes directly to the VGA framebuffer, so you don't actually get to see the scope output via VNC!
- Shared some folders from the scope. This required a significant amount of fuckery to mount an SMB1 drive elsewhere without ruining one's existing Samba config, but it helps quite a bit to be able to exchange files with the scope.
Hardware extras that proved useful in a lab setting:
- One of those cheap VGA to USB frame grabber adapter things - they are detected as a video device, don't need drivers and you can watch your scope with VLC or your OS's built-in camera app.
- A remote-controlled power outlet. Speaks for itself - no need to touch the scope to shut down and restart an experiment from wherever you are.
- A GPIB to USB adapter if your scope has a GPIB/IEEE 488 port. Current Linux support is in a bit of a state, but anyway, this will allow you some degree of automation when reading the math / stats / other data, and will sometimes allow you to do more than the scope's UI will. I know for example that with GPIB I can control the signal on the AUX port on my scope, for which the GUI has no options.
- Not tried yet: this scope uses a PS/2 mouse (remember that they are not hot-pluggable) and a DIN keyboard. This bad boy: https://github.com/rasteri/HIDman - will let you plug in your wireless USB dongle and control your scope with your everyday keyboard and mouse.
The above significantly improves the "workflow" so that you hardly need to touch your scope or even swing your chair, or can use it remotely, and applies to most of the late 90s - early 2000s Windows scopes.
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.
100MHz is overkill for most hobbyists use cases, and definitely repairing test equipment: it's always the power supply.
It can be used a vector RF signal generator with I/Q inputs. The only limitation is the reduced input bandwidth.
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. :-)
That doesn't leave a whole lot of alternatives, Mr Lecroy.
NuColor CRT displays going bad. Bad capacitors. Dallas NVRAM units battery running out of juice
Fried electronics are pretty rare.
