Oscilloscope repair question

Dave_D

I was wondering if anyone knows where I could get an oscilloscope repaired.

I have a Tektronix TDS340 which worked for a while, but now comes up with diagnostics errors during booting up.

I have tried Tektronix themselves, but unfortunately this product is now 'end of life' and thus not supported anymore. I reckon the problem is on the motherboard somewhere. Tektronix have no more motherboards.

Ideally I would like not to post it abroad, as I know a company in the UK that might be able to fix it.

Any help would be much appreciated.

DublinDilbert

What's the error message your getting?

Tektronix scopes are usually quite reliable....

What sort of things are you using it for?

There are many cheaper alternatives out there now, coming from china in particular, I'm not sure it would be worth getting it repaired. I bought a Rigol scope for around €450 and its quite good I won't even start listing the features are i'll be here all night....

Dave_D

Actually I made a mistake, it's a TDS380 not a TDS340. It is the 400MHz version. I use it just for hobby. I picked it up secondhand. It did work initially but in a short time started with these errors. It was stored in a large warehouse, which I suspect was cold. I have suspected plugging it in when it was cold, and a small bit of condensation caused problems (really don't know)

On powerup it comes up with a message "FAIL ++ Cal initialization (see error log)"
Error log:
diagAcq_fisoCell
diagAcq_acqMemPat
diagAcq_acqMemAddr
diagAcq_fastFisoAcq
diagAcq_fisoCell
Cal Error, sampler gainrange
Cal Error, fast sampler mode
Cal Error, sampler gain/offset

It seems to point to 'Data Aquisition' and 'Calibration' which could point to a memory chip (only guessing though!)

When I try and measure a sinewave for example. I can see the signal on the screen, but it looks 'corrupt'. All of the text on the screen is perfect.

I might just go down the Rigol route as well, cheers DublinDilbert

DublinDilbert

It sounds like a Rigol would be fine for what your doing.... I got a 2 channel one with a 16 channel logic analiser, it works really well... Allows me to work on mixed signal stuff.... It cost around €500.

I love that you can just pop a memory key into the usb slot on the front and save waveforms / images directly... I've used both Tek & HP scopes and this one is up there with them....


Then when you get your Rigol up and running use it to fix the front end amplifier in the tek, as that's where it sounds like the problem is

Dave_D

Can I ask where you got your scope? Did you have to import it, or is there somewhere in Ireland that sells them? I see a good few on eBay, but mainly from Hong Kong!!!

Turbulent Bill

If you think condensation is the problem then maybe a day or two in a warm room (don't cook it!) might do the trick.

Otherwise a third-party repair / calibration service might help if Tektronix won't support it directly. It's a shame to see older kit being dumped over what might be a minor repair, though if it isn't easily fixeable then it's probably uneconomic to rescue it.

DublinDilbert

Dave_D wrote: »

Can I ask where you got your scope? Did you have to import it, or is there somewhere in Ireland that sells them? I see a good few on eBay, but mainly from Hong Kong!!!

Yea got mine on ebay... it looks like they've upped the cost of the one with the logic analiser built in....

Turbulent Bill wrote: »

Otherwise a third-party repair / calibration service might help if Tektronix won't support it directly. It's a shame to see older kit being dumped over what might be a minor repair, though if it isn't easily fixeable then it's probably uneconomic to rescue it.

I would definintely give fixing the Tek a go.... the service manual can be gotten from http://www.raybel.com/manuals/TEK_TDS340A_360_380.pdf
but they don't seem to give the schematics

Dave_D

I thought it was condensation, but this is going back a while. I have since dried it out (if it was even damp at all). I have also left the lid off and had it on for a few hours. But the exact same problem still exists. I have tried freezing the IC's one at a time to fault find. One of the IC's does change the display a bit, although I wouldn't say makes it better when I freeze it.

So if it was condensation it is long gone now, and the damage is already done.

@Turbulent Bill: Do you know of any third party in Ireland that would repair stuff like this. I remember looking before, but the art of fault finding to component level seems to be dying. I was told by many people/companies to get a new motherboard...it was my best chance. Although there is no motherboards being made for this anymore. I did however source a UK based company that would look at it for me. They said if they did fix it, there would be a 30 day guarantee, and I would have to pay shipping to and from Ireland and the repair cost. Also they might not be able to fix it. I just don't think it's worth all the cost for possibly no fix. I wouldn't mind paying some company here in Ireland if I was able to deliver and collect it myself. Shipping CRT based devices is no fun either

@DublinDilbert: Thanks for the link. I actually already have that PDF. I also have the circuit diagram. But to be honest it's a bit beyond me. I might have had a go if I had a scope to do it with

DublinDilbert

Just had a look at ebay, it looks like the basic rigol is coming in a little over $400, (400.00 USD=283.769 EUR).... You could pay that for a multi meter in radionics!

I've done alot of work with my rigol, and at this stage I prefer it to my tek....

Turbulent Bill

Dave_D wrote: »

I thought it was condensation, but this is going back a while. I have since dried it out (if it was even damp at all). I have also left the lid off and had it on for a few hours. But the exact same problem still exists. I have tried freezing the IC's one at a time to fault find. One of the IC's does change the display a bit, although I wouldn't say makes it better when I freeze it.

So if it was condensation it is long gone now, and the damage is already done.

@Turbulent Bill: Do you know of any third party in Ireland that would repair stuff like this. I remember looking before, but the art of fault finding to component level seems to be dying. I was told by many people/companies to get a new motherboard...it was my best chance. Although there is no motherboards being made for this anymore. I did however source a UK based company that would look at it for me. They said if they did fix it, there would be a 30 day guarantee, and I would have to pay shipping to and from Ireland and the repair cost. Also they might not be able to fix it. I just don't think it's worth all the cost for possibly no fix. I wouldn't mind paying some company here in Ireland if I was able to deliver and collect it myself. Shipping CRT based devices is no fun either

@DublinDilbert: Thanks for the link. I actually already have that PDF. I also have the circuit diagram. But to be honest it's a bit beyond me. I might have had a go if I had a scope to do it with

Off-hand I don't know of any Irish third-party repairers, but you could try dealers like PEMA or Butler Technologies for advice. I know for old HP networks analysers there was decent third-party support, as things like CRTs would fail well before the rest of the instrument; I assume there's something similar for Tektronix. If you have to ship it abroad it'll probably be too expensive to repair.

Might be work asking Tektronix for their technical repair guide for the scope, or posting a query to one of their support forums. Even if they don't support the scope directly, people are generally willing to give non-guaranteed advice to help out. It's already broken - how much more damage can you do .

Dave_D

I did actually email Tektronix a while back. Unfortunately they just said it was an 'end of life' product and didn't seem to want to know too much more.

I will shoot an email to those 2 companies you mentioned. Maybe they could point me in the right direction if they don't service scopes themselves. Thanks.

piddy0504

Hi your problem could be that the electrolytics of the scope have dried up and it needs new caps.How old is it.

Dave_D

Thanks for the reply piddy0504. But since this thread is from 2009 I got it sorted a long time ago.
What it turned out to be was a bad memory chip. I found that out by turning on the scope and looking at the screen and applying Servisol freezing spray to each IC on the motherboard. When I got to the memory IC, it went from a bad display, to near perfect when frozen. So I replaced that chip and now it boots up fine and passes all diagnostics.