Tektronix TDS210 teardown and BNC replacement

[bd139]

Recently got a Tek TDS210 from eBay for £1/MHz which I was happy with. Had sticker on one channels with "iffy" written on it but showed self test passed. Took the gamble.

Arrived with the usual wobbly BNCs on both channels, a common problem on these when previously owned by a gorilla. Wiggling the "iffy" channel stopped it from working reliably. This was confirmed as the cause by testing first with a grounded generator and then with a floating one. The grounded one by nature of the loop through the signal generator should show a waveform at correct amplitude, the floating one no when you wiggle the connector as the BNC shell lifts off the board.

Took it to bits. If you have to do one of these:

1. Lay the handle down flat and lever the sides of the handle outwards and it will pop off.
2. Undo the two screws behind the handle.
3. Pull the power button upwards to remove it.
4. Unclip all the clips on the bottom.
5. Put the unit face down and lift the back straight upwards.
6. Remove the front of the unit which is now loose. The keyboard rubber will fall out here.

You will be left with the inner chassis with all the bits attached to it. There aren't many bits: the screen, the front panel, the logic board (which is tiny) and the power supply. Nice design:





Next step is to get the logic board off for the repair. Undo the earth strap, the panel, power and LCD connectors and unclip the board from the bottom. That's it!



Examining the board shows the problem. The BNC connectors have two pins on the bottom which are soldered to the board to anchor the connector shell and act as ground. As expected, these have sheared off.



Next step, remove the existing BNCs and clean up the pads with soder wick then clean with isopropyl alcohol. Lots of high impedance stuff on scope front ends so clean, clean and clean some more!





TE connectivity / AMP part number 5414373-1 is the correct replacement part. RS sell these for £2 a pop: https://uk.rs-online.com/web/p/bnc-connectors/8218808/

New parts soldered on. You have to hit these pretty hard and use a flux pen as they are on a ground plane, not tinned and are generally large heat sinks as well. Metcal FTW. Don't use a fire stick! I left the original trigger connector on as that is fine. I don't want to do any unnecessary work on anything ever as that risks damage. The site had three-pass cleaning again afterwards.



Assembly is the same as disassembly but in reverse. No special considerations. I fired it up quickly once it had been partially assembled to make sure I'd put everything back correctly.



Final assembly and test. Working nicely.



Shiny connector money shot.

[Zucca]

Posts like this are refreshing my soul in this hot summer.

[capt bullshot]

Good job.
I'd recommend to test the power supplies output caps for ESR / capacity. I've had two TDS224 here (@work) where I had to replace them because they were dried out. Scope worked anyway, but had a quite large ripple displayed with no input signal in the lowest mV/div positions.

[Specmaster]

Excellent news, well done. I always find it amazing that they can do so much with so little these days when you compare the size of that circuit board to the analogue ones and that is also kind of scary because I doubt it very much that they did that without using bespoke hybrids which we all know become unobtainable after a short while.

I always thought that the £1/Mhz guide was about right for analogue scopes, digital always seem to be far higher and judging by what these normally sell for on Ebay and the like they generally seem to more like £3/Mhz, there are currently 3 on there going for £150, £175 and £250 as BIN and 1 on auction with £102 on bids so far and the £250 BIN one above also on auction with starting price of £150. Looking at the sold history it seems to be pretty much the same storey if you want a working one. Certainly ones listed as spares or repair do seem to be about the £1/Mhz figure, YMMV.

I want something like that to help regain some space in my lab as the scopes I have except for the Fluke PM3390B, old style analogues and are big and heavy (Fluke is big but very light and could be placed on a suitable shelf), and but the tds210 or similar could sit on my bench in front of me inside of being on another desk situated on my left and behind me making using them a bit awkward to say the least. 

[bd139]

Good job.
I'd recommend to test the power supplies output caps for ESR / capacity. I've had two TDS224 here (@work) where I had to replace them because they were dried out. Scope worked anyway, but had a quite large ripple displayed with no input signal in the lowest mV/div positions.

I will certainly look into that. There's quite a bit of noise on the low volts/div settings so good plan. I took lots of pictures of the power supply during the tear down in case I needed to replace anything in future

Excellent news, well done. I always find it amazing that they can do so much with so little these days when you compare the size of that circuit board to the analogue ones and that is also kind of scary because I doubt it very much that they did that without using bespoke hybrids which we all know become unobtainable after a short while.

I always thought that the £1/Mhz guide was about right for analogue scopes, digital always seem to be far higher and judging by what these normally sell for on Ebay and the like they generally seem to more like £3/Mhz, there are currently 3 on there going for £150, £175 and £250 as BIN and 1 on auction with £102 on bids so far and the £250 BIN one above also on auction with starting price of £150. Looking at the sold history it seems to be pretty much the same storey if you want a working one. Certainly ones listed as spares or repair do seem to be about the £1/Mhz figure, YMMV.

I want something like that to help regain some space in my lab as the scopes I have except for the Fluke PM3390B, old style analogues and are big and heavy (Fluke is big but very light and could be placed on a suitable shelf), and but the tds210 or similar could sit on my bench in front of me inside of being on another desk situated on my left and behind me making using them a bit awkward to say the least. 

Yeah there's bugger all in it. This is a good thing as the general design approach leads to quite good electrical reliability and long life. Only the power supply is under any stress and that looks relatively easy to repair anyway.

My rules are:

1. £1/MHz for analogue scopes in fully working condition up to 100MHz then 50p/MHz after that
2. £1.50/MHz for digital scopes in fully working condition up to 100MHz then £1/MHz after that
3. Take £0.50/MHz off for broken, untested.
4. + more for interesting features.

This was listed at £75 but the seller took a £60 offer which is in line with the above rules. Also he showed it passing self tests which was an instant buy for me.

This takes up literally no room at all so big win for bench space. Actually takes up slightly less room than the DS1054Z does.

If you want a cheap DSO this appears to be a good option if you can snag one.

[mnementh]

Yeah, you got a proper deal on that one; over here they're starting at $150 DOA and $250 "tested working" without probes.  That's just cray-cray. 

It was pretty much exactly the same 2 years ago when I bought my wRigol.  If I'd been able to find one like yours, I might not have gotten the 1054Z; but I'd probably have replaced the EXT-TRIG BNC just to have the matching shiny. 

That said... having used the "upgrades" on the 1054Z a few times, I don't regret a penny spent on it.


And it seems that eBay KNOWS I'm looking at Flukes again... 


mnem
But wait... there's more... Now How Much Would You Pay?!?™

[Specmaster]

Yeah, you got a proper deal on that one; over here they're starting at $150 DOA and $250 "tested working" without probes.  That's just cray-cray. 

Yeah I know, our Ebay brings up the USA items as well and some them after the conversion to £ was done looked pretty attractive until you add on the postage and import duty 

And it seems that eBay KNOWS I'm looking at Flukes again... 


mnem
But wait... there's more... Now How Much Would You Pay?!?™

I know I have said this before but seriously Flukes??, yes I know that they are good meters but you also pay for that and if you look at some of Joe Smiths YT videos on multimeters, some of the Flukes just don't survive the tests that he puts them under but the Brymens do and they are less expensive but have more bells and whistles and are even more robust than the renowned Flukes  I'm beginning to notice that more and more of the YT electronic bloggers are putting Brymens on their benches and using them as their goto meter for most things.

[bd139]

It was pretty much exactly the same 2 years ago when I bought my wRigol.  If I'd been able to find one like yours, I might not have gotten the 1054Z; but I'd probably have replaced the EXT-TRIG BNC just to have the matching shiny. 

Yes I have to agree. Genuinely I wouldn't have bought the Rigol if I had this on the bench at the time as well. But I needed a digital scope right there right then and only had a Tek 465 available that worked.

Don't mention the trigger BNC. It is already annoying me in its incompleteness. I may just swap it out yet.

To steal tggzzz's signature, I'm having fun doing more with less these days so I wonder if I should lose the Rigol and live with this. It means at least £320 off the credit card after the FT-818 left some burn marks and I've got a genuine pre-Danaher made in America Tektronix digital scope in really good condition.  It has that indefinable quality about it. Quality as in Zen and the Art of Motorcycle Maintenance quality.

I have ordered a couple of Wittig 100MHz probes for it from my usual probe dealer (wild-pc on eBay). These are really nice probes for the money: https://www.ebay.co.uk/itm/162693385317 ... I'll grab some genuine Tek ones if I see any go past for a reasonable fee. Probes cost more than scopes these days

I know I have said this before but seriously Flukes??, yes I know that they are good meters but you also pay for that and if you look at some of Joe Smiths YT videos on multimeters, some of the Flukes just don't survive the tests that he puts them under but the Brymens do and they are less expensive but have more bells and whistles and are even more robust than the renowned Flukes  I'm beginning to notice that more and more of the YT electronic bloggers are putting Brymens on their benches and using them as their goto meter for most things.

Yes exactly this.  I am in the process of shifting my U1241C because I don't use it now other than for a current meter. I am considering filling the gap with an 87V just because I am a member of TEA however

[Specmaster]

It was pretty much exactly the same 2 years ago when I bought my wRigol.  If I'd been able to find one like yours, I might not have gotten the 1054Z; but I'd probably have replaced the EXT-TRIG BNC just to have the matching shiny. 

Yes I have to agree. Genuinely I wouldn't have bought the Rigol if I had this on the bench at the time as well. But I needed a digital scope right there right then and only had a Tek 465 available that worked.

Don't mention the trigger BNC. It is already annoying me in its incompleteness. I may just swap it out yet.

To steal tggzzz's signature, I'm having fun doing more with less these days so I wonder if I should lose the Rigol and live with this. It means at least £320 off the credit card after the FT-818 left some burn marks and I've got a genuine pre-Danaher made in America Tektronix digital scope in really good condition.  It has that indefinable quality about it. Quality as in Zen and the Art of Motorcycle Maintenance quality.

I have ordered a couple of Wittig 100MHz probes for it from my usual probe dealer (wild-pc on eBay). These are really nice probes for the money: https://www.ebay.co.uk/itm/162693385317 ... I'll grab some genuine Tek ones if I see any go past for a reasonable fee. Probes cost more than scopes these days

I know I have said this before but seriously Flukes??, yes I know that they are good meters but you also pay for that and if you look at some of Joe Smiths YT videos on multimeters, some of the Flukes just don't survive the tests that he puts them under but the Brymens do and they are less expensive but have more bells and whistles and are even more robust than the renowned Flukes  I'm beginning to notice that more and more of the YT electronic bloggers are putting Brymens on their benches and using them as their goto meter for most things.

Yes exactly this.  I am in the process of shifting my U1241C because I don't use it now other than for a current meter. I am considering filling the gap with an 87V just because I am a member of TEA however

Surely your joking??? look at this Joe Smith video, Brymen 869 V Fluke 87V

[bd139]

Oh yes 100% it's inferior but sometimes they pop up for bugger all cash (outside of ebay) so it's a good investment.

[Specmaster]

I wish you could get Brymens like that, on Ebay the 867 is way more expensive then what we paid If you could, I'd buy a few more of them and maybe sell on my bench meters 

[bd139]

Yeah it's being sold by littlediode which doesn't surprise me. Probably bought them from Telonic and resold. Found a picture of littlediode the other day:

[Specmaster]

Not everything from Littlediode is more expensive, I've actually brought a few bit and bobs from them over the years. Been thinking about maybe getting a BM235 for £76.80 from Telonic, its the same meter as the first EEVblog meter.

[tautech]

Yep, a stock standard repair for these TDS210's and 220's.

As bd139 says the ground plane can suck a lot of heat and for those with substandard irons will struggle with this apparently simple repair. Without a proper chassis mount BNC and a securing nut any scope with a 2 ground pin BNC is subject to the same failure. Most scope manufactures have learn the folly of this style of input construction as not only is it subject to damage but also microphonics without robust BNC mountings.

As the area where the BNC's are is only 2 layer there are further improvements that can be added by strapping the BNC's 'up and over' with a strip or a strand of copper soldered to the top of the BNC and onto or through the ground plane. Once beefed up in this manner you have peace of mind that the chance of them breaking again has been eliminated. 

[bd139]

Indeed it was a boring repair. I am owed some karma due to that D83 

The best option to stop the BNCs coming off is not to let a gorilla near your test gear

[Specmaster]

Yeah, you got a proper deal on that one; over here they're starting at $150 DOA and $250 "tested working" without probes.  That's just cray-cray. 

It was pretty much exactly the same 2 years ago when I bought my wRigol.  If I'd been able to find one like yours, I might not have gotten the 1054Z; but I'd probably have replaced the EXT-TRIG BNC just to have the matching shiny. 

mnem
But wait... there's more... Now How Much Would You Pay?!?™

You don't have to replace the external trig BNC, if its safely soldered, which I expect it is because most people don't use it, just use a bit duragilt on it and it'll come up nice and shiny to match the 2 new ones.

[orin]

I have ordered a couple of Wittig 100MHz probes for it from my usual probe dealer (wild-pc on eBay). These are really nice probes for the money: https://www.ebay.co.uk/itm/162693385317 ... I'll grab some genuine Tek ones if I see any go past for a reasonable fee. Probes cost more than scopes these days

Don't bother with the type of Tek probes that came with the TDS210 - they were garbage.  The compensation trimmer has come loose in one.  They are molded so can't be taken apart to fix it.  The tip has broken loose in the other.  Still works, but pull the grabber off and the tip remains pull out too.  Needle nosed pliers are then needed - or give up on using the pointy tip and shove the grabber back on.

[bd139]

You don't have to replace the external trig BNC, if its safely soldered, which I expect it is because most people don't use it, just use a bit duragilt on it and it'll come up nice and shiny to match the 2 new ones.

My OCD says otherwise

I have ordered a couple of Wittig 100MHz probes for it from my usual probe dealer (wild-pc on eBay). These are really nice probes for the money: https://www.ebay.co.uk/itm/162693385317 ... I'll grab some genuine Tek ones if I see any go past for a reasonable fee. Probes cost more than scopes these days

Don't bother with the type of Tek probes that came with the TDS210 - they were garbage.  The compensation trimmer has come loose in one.  They are molded so can't be taken apart to fix it.  The tip has broken loose in the other.  Still works, but pull the grabber off and the tip remains pull out too.  Needle nosed pliers are then needed - or give up on using the pointy tip and shove the grabber back on.

Thanks for the tip. I shall steer well away from them then

----

Anyway, it's not enough to just collect toys and not use them (I'm looking at you TEA ), so I decided to use the TDS210 to do something useful this evening with some other bits I have lying around. Firstly I have a 30m (10.1MHz) low pass filter on a breadboard floating around. Decided to actually work out if the filter is working properly and do some characterization as it was from a filter table with some hacked up capacitor values rather than a scientific calculation. For this we need a log-log plot of frequency versus power in dB.

Now you could go and buy an SNA but that's not required if you have enough crap floating around. In this case, a DG1022Z with log sweep up to 25MHz and a log power sensor I hacked up here based on the AD8307: https://www.eevblog.com/forum/testgear/test-equipment-anonymous-(tea)-group-therapy-thread/msg1430272/#msg1430272 ... original circuit here: http://www.robkalmeijer.nl/techniek/electronica/radiotechniek/hambladen/qst/2001/06/page38/index.html

Quick run through DaveCAD:



DG1022Z set to sweeep at 500ms interval, 6-25MHz, Mark at 10MHz, amplitude 1V p-p. The sync output runs the leading edge at the start of the sweep and the trailing edge at the end so you simply set it to trig on channel 2 and bob's your uncle. Vertical is 1dB/10mV (calibrated) and you sweep the marker with the encoder on the DG1022Z and make voltage measurements with cursors.



Please excuse the horrible input connection with the clip leads. I couldn't be arsed to solder another BNC on the board.

Board is a 2W output 30m CW transmitter.

[bitseeker]

Looks great, bd. Just a little polishing on that trigger input and you'll be all set. But, if you really must change the BNC, then so be it.

I was expecting some capacitor plague inside, but didn't see any alum. electrolytics on the logic board in the pics. Were only the TDS400 and TDS500 series scopes casualties of the plague?

[bd139]

I’ll try polishing it first

There are no electrolytics on that board. In fact there’s only about five tants as well. It’s incredibly minimalist. Literally nothing to go wrong.

[Specmaster]

I’ll try polishing it first

There are no electrolytics on that board. In fact there’s only about five tants as well. It’s incredibly minimalist. Literally nothing to go wrong.

That's good, but need to keep the ripple really low then.

[bitseeker]

There are no electrolytics on that board. In fact there’s only about five tants as well. It’s incredibly minimalist. Literally nothing to go wrong.

Excellent.

[Specmaster]

I’ll try polishing it first

There are no electrolytics on that board. In fact there’s only about five tants as well. It’s incredibly minimalist. Literally nothing to go wrong.

Yep, polishing it first is the way to go, replacing it for no good reason other than to play with the Metcal is pointless,[emoji41]

[tautech]

I’ll try polishing it first

There are no electrolytics on that board. In fact there’s only about five tants as well. It’s incredibly minimalist. Literally nothing to go wrong.

Yep, polishing it first is the way to go, replacing it for no good reason other than to play with the Metcal is pointless,[emoji41]

You forget bd made comment about a previous owner and the likelihood they had hair on the palms of their hands whereas bd has his fair share of troubles originating from his own digits so the chance he has to rip the Tek down again should not be dismissed. 
So for the couple of quid each getting some more BNC's might be wise where he can change that oxidised one too and then make a proper job of adding some anti gorilla BNC tie down straps too. 

[bd139]

Yeah. The previous owner was apparently a “studio” which usually means sound engineers and they are gorillas by nature. I spent a few years fixing up buggered recording kit and keyboards before I got into test gear.

I’m not going to tie the connectors down any more on this one. While it does make them somewhat more rugged, it’s ten times more risky to change them again in the future and only to a point. The connector design flaw is good in a way as it acts as a sacrificial failure mode rather than wrecking the board. If you smack the panel on this the BNCs will break off rather than crack the board. This happened to that 54602 I had and it was end of line unfortunately.