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Refurbishing a Tektronix TDS7104 Oscilloscope

tomverbeure.github.io

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Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#61

Post by Tangurena2 »

tverbeure wrote: post #14
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..

As I wrote: the TDS7104 is now sitting on a shelf in the garage, next to an Agilent 54831 and some other boat anchors. My daily drivers are a Siglent scope and a puny TDS220, which is about to be replaced by a TDS3052 that I'm bringing back to life. Hobbyists rarely need more than 100 MHz BW. I hope you're able to thoroughly test that DSA91304a before dropping $44k on it!

I hope you're aware of the TekWiki:

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.

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#62

Post by Tangurena2 »

tverbeure wrote: post #28
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! :-)

Heh, like my 100MHz scope used for audio signals.

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#63

Post by bloggie »

jlawrence6809 wrote: post #9

I just had claude walk me through refurbishing a Rohde & Schwarz signal generator from the 90s. It feels pretty cool getting a multi thousand dollar piece of equipment for 60 bucks even if you have no idea what you'll use it for.

Did you fix it? What was wrong?

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#64

Post by mikewarot »

jlawrence6809 wrote: post #15
tverbeure wrote: post #10

Earlier quoted context omitted.

Was that by any chance the R&S AMIQ that I refurbished in an earlier blog post? And yes, it's a lot of fun bringing these bargain bin pieces of kit back to life.

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!

A friend of mine bought an SMIQ-03b on a whim, we've replaced the mmic amplifier chip that seems to always fail, now we're trying to figure out why the ALC doesn't work. It generates signals just fine, but the fine attenuation does nothing.

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#65

Post by stmw »

sdcfgy wrote: post #53
stmw wrote: post #27

Earlier quoted context omitted.

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?

Other than the very bottom end ones, no. Mostly went to Hp/Agilent instead.

Thanks for answering, not surprising. I think the transition from all-hardware to Windows-driven digital hard on Tektronix and many other storied engineering teams.

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#66

Post by tverbeure »

Tangurena2 wrote: post #61
tverbeure wrote: post #14

Earlier quoted context omitted.

As I wrote: the TDS7104 is now sitting on a shelf in the garage, next to an Agilent 54831 and some other boat anchors. My daily drivers are a Siglent scope and a puny TDS220, which is about to be replaced by a TDS3052 that I'm bringing back to life. Hobbyists rarely need more than 100 MHz BW. I hope you're able to thoroughly test that DSA91304a before dropping $44k on it!

I hope you're aware of the TekWiki: 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.

TekWiki is great!

100MHz is overkill for most hobbyists use cases, and definitely repairing test equipment: it's always the power supply.

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#67

Post by tverbeure »

wkjagt wrote: post #59
tverbeure wrote: post #8

Earlier quoted context omitted.

Nice, so I'll get even more entertainment out of it! 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://tomv…

A little while ago I bought a 386 laptop. It pretty much had everything wrong with it. Spent weeks repairing it. Best $40 I ever spent.

That feeling when it finally works is great. I spent $40 on this basket case: https://tomverbeure.github.io/2025/12/24/Repair-of-SRS-DG535.... Took me ages to figure that one out.

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#68

Post by jlawrence6809 »

bloggie wrote: post #63
jlawrence6809 wrote: post #9

I just had claude walk me through refurbishing a Rohde & Schwarz signal generator from the 90s. It feels pretty cool getting a multi thousand dollar piece of equipment for 60 bucks even if you have no idea what you'll use it for.

Did you fix it? What was wrong?

Some parts. It's still a WIP!

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#69

Post by jlawrence6809 »

mikewarot wrote: post #64
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!

A friend of mine bought an SMIQ-03b on a whim, we've replaced the mmic amplifier chip that seems to always fail, now we're trying to figure out why the ALC doesn't work. It generates signals just fine, but the fine attenuation does nothing.

Yeah that pretty close to some problems I'm working on with mine. It has an "IQCON ALC loop failure" and claude was able to diagnose that the 2013 rail is around 11.44v (outside of the 10v range iirc) and the 2015 one is zero instead of the min of 0.13v. The RF paths looks mostly healthy as far as we can tell but I've only tried 10db steps and it seems consistently 4-5db low, assuming I'm using my oscope right.

Which MMIC did you replace? And what errors did you see? I have 110 and 111.

Re: Refurbishing a Tektronix TDS7104 Oscilloscope

#70

Post by mikewarot »

jlawrence6809 wrote: post #69
mikewarot wrote: post #64

Earlier quoted context omitted.

A friend of mine bought an SMIQ-03b on a whim, we've replaced the mmic amplifier chip that seems to always fail, now we're trying to figure out why the ALC doesn't work. It generates signals just fine, but the fine attenuation does nothing.

Yeah that pretty close to some problems I'm working on with mine. It has an "IQCON ALC loop failure" and claude was able to diagnose that the 2013 rail is around 11.44v (outside of the 10v range iirc) and the 2015 one is zero instead of the min of 0.13v. The RF paths looks mostly healthy as far as we can tell but I've only tried 10db steps and it seems consistently 4-5db low, assuming I'm using my oscope right. Which…

I'm not sure which he replaced, but having started trying to grok how it actually works, it's chock full of HFET and other amplifier chips, and over-stressed RF switches.

I'll report back if we ever get it actually working properly.

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