EEVblog #690 - TDS220 Oscilloscope Autopsy

[EEVblog]

Dave dissects and then powers up the Tektronix TDS220 oscilloscope used in the Mud Run. Did it survive?
The Mud Run video:

[dr.diesel]

Ha, that's awesome!

And it was underwater during most of this part:

[EEVblog]

And it was underwater during most of this part:

Yeah, totally under for a while in a few places.
And you can see the tape had come off the vent holes by this time too.
I'm shocked there is hardly any residue inside.

[woox2k]

I was waiting for that video after seeing the Mud Run one.
I am amazed how well it survived. Old gear but at least it has still some toughness left inside! This thing was not made in the Wun Hung-Lo factory, that's for sure.

[artag]

I think the braid coil under the shielding is to link it to the nickel plating.

[justanothercanuck]

Could that screen issue be the video "data" cable?  Since it's still working for the most part, it kindof looks like a connectivity issue. 

[nitro2k01]

Request: Take the crustiest of the pots (or rotary encoders?) and desolder it and dissect it. Not only to look for mud, but to see the internal construction of it.

[Tek_TDS220]

"Rusted with age."  I don't think so, mine is perfect inside and it is 18+ years old.  Based on the corrosion on the boards, nickel plating, and steel chassis, yours must have been exposed to a corrosive environment.  It's a surprise it still mostly works.

"Slow as a wet week."  The refresh rate is slow by modern standards, but mine boots much faster than my Agilent, and the controls are very responsive.  It's nice to use when you want a quick answer.

[RJFreeman]

Couple of things:
I replaced one of the BNC connectors on my TDS210 a couple of weeks ago. It was a very do-able job job, I had to remove the top shield in order to get access to the solder joints for the bottom shield which I had to remove in order to get enough room to desolder the joints on the BNC connector  - although if I had a finer tipped desoldering iron (I have a Hakko 808) I might not have had to bother but it was reasonably straight forward to replace.
It is s slightly odd ball BNC connector, made by TE Connectivity / AMP - I used part no  6274127-1 as it was available from Element 14/Farnell

Mine has had the mod (well it was sent back for it, and has a sticker saying it was carried out at least - is that being cynical?), and the Ground wire runs from the back of the mains connector across to a spade lug on the 'main board' the same is that one, and I would be surprised if the Australian Defence Force had not sent theirs back to be modified (they tend to be very fussy about such things).

[84GKSIG]

the one i bought off ebay didnt have the strap  so is mine a fake  i personally dont think theyre a bad scope at all regardless of its age and i think daves just proven how rugged they are, did the power supply board look to have like a clear protective coating of some sort over the whole thing or was that just me?

[Vgkid]

I was surprised it survived that well, cool that i ran when first powered up.

[digital]

I bought one of the TDS220 scopes of Daves on ebay and the display on mine is far superior than the display on my Rigol 1052.The Tek will now replace the Rigol.

[G7PSK]

I think that scope has been to sea at some time. The insides look like salt exposure. I have seen lots of stuff looking like that coming off the oil rigs and boats on the North sea.

[84GKSIG]

I bought one of the TDS220 scopes of Daves on ebay and the display on mine is far superior than the display on my Rigol 1052.The Tek will now replace the Rigol.

same here but mines replaced my siglent SDS 1102CML    i cant fault the TDS  220 for what i do its over kill but its helped pick up a couple of things i had no luck with due to the lag on the siglent

[tautech]

Couple of things:
I replaced one of the BNC connectors on my TDS210 a couple of weeks ago. It was a very do-able job job, I had to remove the top shield in order to get access to the solder joints for the bottom shield which I had to remove in order to get enough room to desolder the joints on the BNC connector  - although if I had a finer tipped desoldering iron (I have a Hakko 808) I might not have had to bother but it was reasonably straight forward to replace.
It is s slightly odd ball BNC connector, made by TE Connectivity / AMP - I used part no  6274127-1 as it was available from Element 14/Farnell

Mine has had the mod (well it was sent back for it, and has a sticker saying it was carried out at least - is that being cynical?), and the Ground wire runs from the back of the mains connector across to a spade lug on the 'main board' the same is that one, and I would be surprised if the Australian Defence Force had not sent theirs back to be modified (they tend to be very fussy about such things).

Did exactly the same with one I scored some years back.
It was a common breakage, those BNC mounting pins. Even replacements break the pins.
Remedy: scrub some of the conformal coating off the adjacent GND plane on the top side of the PCB and strap the BNC's down with a strip of thin copper sheet soldered to GND plane and BNC's. Quick work with a big tip and hot iron required. They don't come loose again.  With care it can even look quite neat.

Also had a failed backlight inverter in mine. Confirmed with the bright torch test.  IIRC it was a 0.33 uF cap that set the frequency for the primary switching transistors for the 1150 V backlight inverter. Cap had drifted to a value in the pF region.  30 c fix.
This unit had around 600 power cycles in its log.

Did some research on the "earthing" issue and my PCB was a SN after the recall, so Tek must have revised the PCB. All that stuff used to be on the Tek website, not sure now.
Had a look through my files and all I have now is the Users and Service manuals in PDF if anybody needs them.

[Muttley Snickers]

Here's the recall notice and like tautech I have a truckload
of PDF manuals on these thing's, why I will never know,
I dont even have this model.

Muttley

[tautech]

Here's the recall notice and like tautech I have a truckload
of PDF manuals on these thing's, why I will never know,
I dont even have this model.

Muttley

Me neither any more, but as Dave says they can go for good money and are reasonably easy to fix for their specific common faults.
Unfortunatly they were pre USB otherwise they would have been a good first scope even today.
It doen't take much in a modern scope to run rings around them though, but they have good basic functionality.

[lampbus]

It's nice to see inside, I envisaged the main PCB would be vertical like the PSU board...from looking in the vents on my TDS210.

I love my TDS210, but long for the TDS2MM module that is no longer available anywhere...and people want silly money for complete units on ebay...more than the price of a far more capable brand new Rigol.

I found a mention on another forum of code that could be flashed into a TDS2CM module to make it into the MM type...never found a download though. (THe CM has the comms ports...the MM added measurement routines to the CM)