Tektronix TDS210 teardown and BNC replacement

[bd139]

Im not convinced there is anything wrong with mine yet.  Interestingly I can tune into that noise in my FT450 and it still occurs when the scope is turned off. Hmm.

I will turn everything in the house off one by one when I get two mins and see where it’s coming from.

[Old Printer]

Nice job 

Good idea with the LEDs as well. I imagine that would increase the reliability considerably.

This is my go to scope as well now.

Could you guys expand on the why's of why you like this scope so much as compared to.....  I only know a little about digital scopes and sometimes scopes similar to this show up locally cheap. Replacing a handfull of caps, as long as they haven't blown all over the place, is not that overwhelming. Thanks.

[bd139]

Small, light, quiet, easy interface, nothing to go wrong, well put together.

[Old Printer]

Small, light, quiet, easy interface, nothing to go wrong, well put together.

Performance, math & measurement functions, features?? Are you giving much up for those conveniences? I do understand your point. I have a TEK 475 sitting next to a TEK 2225. If I just want to look at a signal, 99 times out of 100 I turn on the 2225. The 475 is a beautiful scope, but the 2225 is easy/simple. If I want to "play" I turn on the 475. Thanks

[tautech]

My noise floor on Channel 1 @2mV div and 100uS is (with averaging 16 turned on) 883KHz and 640uV so it seems to be quieter than yours but at far higher frequency?, No probes attached.

Pic ?
Averaging OFF.

[Specmaster]

My noise floor on Channel 1 @2mV div and 100uS is (with averaging 16 turned on) 883KHz and 640uV so it seems to be quieter than yours but at far higher frequency?, No probes attached.

Pic ?
Averaging OFF.

I'll do a pic later, but I put averaging on to get a average value of ripple and frequency as with it off it jumps all other place.

[bd139]

Small, light, quiet, easy interface, nothing to go wrong, well put together.

Performance, math & measurement functions, features?? Are you giving much up for those conveniences? I do understand your point. I have a TEK 475 sitting next to a TEK 2225. If I just want to look at a signal, 99 times out of 100 I turn on the 2225. The 475 is a beautiful scope, but the 2225 is easy/simple. If I want to "play" I turn on the 475. Thanks

I love the 475s. Wish I hadn’t sold mine

I’m not sacrificing much feature wise, comparing to DS1054Z. I lose some measurements, memory depth and FFT really. It’s got cursors and I’ve got a brain, mem depth is nice but not essential and FFT sucks balls on every low end digital scope. What I mainly lose was £300.

Ideally I’d have a 2465B on standby and the TDS210 (or a 220) on the bench.

[Specmaster]

My noise floor on Channel 1 @2mV div and 100uS is (with averaging 16 turned on) 883KHz and 640uV so it seems to be quieter than yours but at far higher frequency?, No probes attached.

Pic ?
Averaging OFF.

Ok then, here's the pic with the same settings but averaging switched off.

[tautech]

My noise floor on Channel 1 @2mV div and 100uS is (with averaging 16 turned on) 883KHz and 640uV so it seems to be quieter than yours but at far higher frequency?, No probes attached.

Pic ?
Averaging OFF.

Ok then, here's the pic with the same settings but averaging switched off.

If it looks similar at a slow timebase setting, say 10ms/div, then its just normal open input DSO noise.
You could also place a 50 ohm or a short on the inputs to get a better idea of internal noise if in fact there is much.

Have you checked the PSU rail's ripple meets spec ?

[Specmaster]

Ch1 set to 2mv/div and 10ms produces much the same trace but with the frequency now averaging somewhere around 6Khz and pp of 1.6mv.

I have not as yet opened this up to look inside I'll do that tomorrow and see what the actual rail ripple is.

[tautech]

Ch1 set to 2mv/div and 10ms produces much the same trace but with the frequency now averaging somewhere around 6Khz and pp of 1.6mv.

Looks as expected without the Trigger level being within the waveform. 

I have not as yet opened this up to look inside I'll do that tomorrow and see what the actual rail ripple is.

Optional of course and only for peace of mind. 
But it does offer the benefit of spotting swelled or leaking caps, sus solder joints and other things that don't look right.

Welcome to the world of DSO's, use and enjoy .....and watch that trigger level. 

[Specmaster]

Trigger level was repositioned to the 0 line and nothing changed at all, zero changes in the waveform or the readings.

Its all stripped down ready for ripple measurement in the morning, had a good visual check on the caps etc and everything looks smick and clean apart from a couple of miniature cobwebs in it, all cleaned out now.

Chips used in it all have the date code of 1997 week 48 and the caps are looking OK, no bulging or leakage anywhere, infact everything looks just as you would expect it to on an instrument with so few power cycles in its 20.5 years life.

Tomorrow I'll hook this up via my isolation tranny and use the Fluke 3390B to check the voltages and ripple as per manual, or there again I could make use of my Brymen BM867 as it will show me what the ripple component of the rails is.

[Miti]

Mine looks pretty much like Specmaster's.

[tautech]

Trigger level was repositioned to the 0 line and nothing changed at all, zero changes in the waveform or the readings.

Its all stripped down ready for ripple measurement in the morning, had a good visual check on the caps etc and everything looks smick and clean apart from a couple of miniature cobwebs in it, all cleaned out now.

Chips used in it all have the date code of 1997 week 48 and the caps are looking OK, no bulging or leakage anywhere, infact everything looks just as you would expect it to on an instrument with so few power cycles in its 20.5 years life.

Tomorrow I'll hook this up via my isolation tranny and use the Fluke 3390B to check the voltages and ripple as per manual, or there again I could make use of my Brymen BM867 as it will show me what the ripple component of the rails is.

Use both as always try to catch a piece of kit out ! 
Fluke CRO will always be best for SMPS ripple measurement.

[Miti]

Nice job 

Good idea with the LEDs as well. I imagine that would increase the reliability considerably.

This is my go to scope as well now.

Could you guys expand on the why's of why you like this scope so much as compared to.....  I only know a little about digital scopes and sometimes scopes similar to this show up locally cheap. Replacing a handfull of caps, as long as they haven't blown all over the place, is not that overwhelming. Thanks.

In my hobby activity, 99% of the time I only need to see slow, simple waveforms like a PIC or AVR clock, PWM for servo control, ripple or overshot on the output of a switching power supply, etc. so a Tek 210 is more than adequate. It is robust, quiet, small, it came at the low price of... free. And it has that hard to explain feeling of vintage. Is like driving a vintage car. But when it comes to special trigger, zoom, FFT, I like my Rigol. I would like a Tek or an Agilent better but I can't afford them.

[Specmaster]

Trigger level was repositioned to the 0 line and nothing changed at all, zero changes in the waveform or the readings.

Its all stripped down ready for ripple measurement in the morning, had a good visual check on the caps etc and everything looks smick and clean apart from a couple of miniature cobwebs in it, all cleaned out now.

Chips used in it all have the date code of 1997 week 48 and the caps are looking OK, no bulging or leakage anywhere, infact everything looks just as you would expect it to on an instrument with so few power cycles in its 20.5 years life.

Tomorrow I'll hook this up via my isolation tranny and use the Fluke 3390B to check the voltages and ripple as per manual, or there again I could make use of my Brymen BM867 as it will show me what the ripple component of the rails is.

Use both as always try to catch a piece of kit out ! 
Fluke CRO will always be best for SMPS ripple measurement.

Just did a quick run through with the Brymen and the results that gave are;
Pin 1&2  4.997v with 4mv ripple
Pin 3 GRD
Pin 4 -4.300v 4mv ripple
Pin 5 -23.672v and 20mv ripple
Pin 6 GRD
Pin 7 should be 1.4Pk Pk on a square wave, I'll check that in the morning but I suspect that going to OK as I read .877V on the BM867 which is a true RMS meter.

I'm off to bed now to try and get some sleep in this heatwave that we are having over here.

[Miti]

I'm off to bed now to try and get some sleep in this heatwave that we are having over here.

   Who's she? 

[Specmaster]

My noise floor on Channel 1 @2mV div and 100uS is (with averaging 16 turned on) 883KHz and 640uV so it seems to be quieter than yours but at far higher frequency?, No probes attached.

Pic ?
Averaging OFF.

Ok then, here's the pic with the same settings but averaging switched off.

If it looks similar at a slow timebase setting, say 10ms/div, then its just normal open input DSO noise.
You could also place a 50 ohm or a short on the inputs to get a better idea of internal noise if in fact there is much.

Have you checked the PSU rail's ripple meets spec ?

Ok, today I have checked the PSU rails using the Fluke PM3390B and all of the rails as far as voltage goes meet the published specification but the manual does not state what the ripple should be anywhere that I can see in the manual. But using a probe 1:1 I'm getting a peak to peak ripple of around 10mV on the rails and given that the actual ripple will vary according to the loading of the circuit I'm wondering what the validity of doing a ripple test is. I suspect that maybe if it showed something in the magnitude of say 100mVpp then I might have a problem.

Does anyone actually what the ripple for the smps in the 210 should be at all?

   

[bd139]

It's less of a problem than it looks because the lines all have LC pi filters on them as they come in to sensitive parts of the circuit.

Have traced the noise in mine to an external source. Tassimo coffee machine power supply. Popped cap on the secondary side. Still works though which is pretty cool!

[Specmaster]

Thanks, I was beginning to think I was I on a wild goose chase as even with the inputs shorted to ground there was no difference in the on screen noise whatsoever so it was not an airborne noise or open input noise at all. I suspect that it is present on the mains supply because we use so many smps units in the modern home these days, phone chargers, LED drivers, even monitors etc use them so it is possibly coming via the mains and all I can do is tour the house pulling the plugs on as many items I can think of to see if it has any effect.

Once you know how to get into it, its a doodle, just 2 screws and is very cleverly put together internally as well, neat. I love it already.