Broke my TDS3000B


 

A bit ago I reported a problem with ripple on calibrator trace of my
TDS3014B (up-hacked to TDS3064B):
https://www.eevblog.com/forum/testgear/tds3000b-trace-ripple/msg3492464/#msg
3492464

I replaced the tantalum caps on the main board and that problem is gone, but
I've broken it - I got a bit of solder splatter on a few pins of what I
suspect is the main CPU (the one marked
EX388/ADG360C/MM9595-AUW/156-7644-01) and on two pins of one of four ICs
marked ES336AC/ADG361D/MM9916-VJG/156-7645-01 which I failed to notice and
powered it on in that state.

I've since removed the splatter but now any horizontal sweep rate faster the
400uS breaks up into a mess, and autoset doesn't work right. I'm thinking
I've probably killed it >:(

Of course it happily passes the self test.

Before I put on my scrap pile and weep over the loss of a nice scope has
anyone any thoughts - I've carefully re-checked for any further solder
bridges - none found.

D.


maxim.vlasov@...
 

TDS3000B are built on the MPC860 PowerQUICC. This is the main CPU. So, it has no boot ROM or the full fledged custom secure bootloader (too old), which is a great advantage for repairman. So, this thing can be sourced and replaced, IMHO.

Are you referring to the big PQFP240 National Semi thingy, right? IMHO, this is not the CPU, it's the ASIC DPO emulator with the ADC/RAM/etc crossbar, ADC clock generator PLL and DMA functionality.

Could you, please, check at which sampling rates you have a garbled response? If you run in X/Y mode, do you have the same stuff? Is it the same when running from the external trigger? Are all the traces garbled or just a subset of channels? Try to remove all the plug-ins and extension cartridges.
Also it could be the SRAM too (just two chips next to the ASIC). How about the linear power regulators in the vicinity of the tantalum cap? Are they OKAY?
Try to go around the o-scope and check the logic levels around the SRAM and National Semi ASIC. Maybe you can find a burned buffer or something. If it breaks below 400us, it could be the PLL.
I would go around and note the voltages and levels and post it to the forum.
Also the thermal image would be a good indication of something awkward.
You said that built-in self test runs OKAY. But how about running the calibration and service routines, would these fail?


durechenew@...
 

On Thu, Mar 11, 2021 at 11:43 AM, David C. Partridge wrote:


up-hacked to TDS3064B
Hi Dave,
Worked long ago with 3054, loved that scope (some people don't like Tek, I do). Unfortunately I never looked inside one so far (seen something on you tube) and I'm afraid I could be of no help here. It would be interesting though to read if you posted somewhere information about how you "...up-hacked to TDS3064B".
All the good luck (you'll need a lot)
TT


 

Up-hack is discussed on EEVBLOG.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of durechenew via groups.io
Sent: 12 March 2021 00:24
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

On Thu, Mar 11, 2021 at 11:43 AM, David C. Partridge wrote:


up-hacked to TDS3064B
Hi Dave,
Worked long ago with 3054, loved that scope (some people don't like Tek, I do). Unfortunately I never looked inside one so far (seen something on you tube) and I'm afraid I could be of no help here. It would be interesting though to read if you posted somewhere information about how you "...up-hacked to TDS3064B".
All the good luck (you'll need a lot)
TT


 

All channels equally impacted. Yes I was referring to the big National Semi IC. Sweep rates of 400us and slower are just fine. Anything faster is a total mess. I see the MPC860 now - right next to the ethernet connector (J910) at the other end of the board.

Is it OK to operate this beastie with covers off for any length of time - loath to inflict further damage that way.

D.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of maxim.vlasov@meteor-m.com
Sent: 11 March 2021 22:10
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

TDS3000B are built on the MPC860 PowerQUICC. This is the main CPU. So, it has no boot ROM or the full fledged custom secure bootloader (too old), which is a great advantage for repairman. So, this thing can be sourced and replaced, IMHO.

Are you referring to the big PQFP240 National Semi thingy, right? IMHO, this is not the CPU, it's the ASIC DPO emulator with the ADC/RAM/etc crossbar, ADC clock generator PLL and DMA functionality.

Could you, please, check at which sampling rates you have a garbled response? If you run in X/Y mode, do you have the same stuff? Is it the same when running from the external trigger? Are all the traces garbled or just a subset of channels? Try to remove all the plug-ins and extension cartridges.
Also it could be the SRAM too (just two chips next to the ASIC). How about the linear power regulators in the vicinity of the tantalum cap? Are they OKAY?
Try to go around the o-scope and check the logic levels around the SRAM and National Semi ASIC. Maybe you can find a burned buffer or something. If it breaks below 400us, it could be the PLL.
I would go around and note the voltages and levels and post it to the forum.
Also the thermal image would be a good indication of something awkward.
You said that built-in self test runs OKAY. But how about running the calibration and service routines, would these fail?


John Miles
 

I've since removed the splatter but now any horizontal sweep rate faster
the
400uS breaks up into a mess, and autoset doesn't work right. I'm thinking
I've probably killed it >:(
Are you sure you got *all* the solder?

-- john, KE5FX


 

I went in and checked over and partially redid the cleanup under the
microscope yesterday pm. Still need to put back together and test.

D.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of John Miles
Sent: 12 March 2021 08:04
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

I've since removed the splatter but now any horizontal sweep rate faster
the
400uS breaks up into a mess, and autoset doesn't work right. I'm thinking
I've probably killed it >:(
Are you sure you got *all* the solder?

-- john, KE5FX


 

And the bad news is - it's still broken ☹

D.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of David C. Partridge
Sent: 12 March 2021 10:20
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

I went in and checked over and partially redid the cleanup under the
microscope yesterday pm. Still need to put back together and test.

D.


 

Hi David,

were you able to verify the type of pin that you shorted, or presumably shorted? I mean if its a supply line (low impedance), or inputs or 3 state or whatever? In my experience digital logic is rather robust and it was rare to cook a chip just by shorting one of its pins to another, even to GND or VCC.

cheers
Martin


 

I have no clue as the IC's in question are custom ASICs.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Martin
Sent: 12 March 2021 11:29
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

Hi David,

were you able to verify the type of pin that you shorted, or presumably
shorted? I mean if its a supply line (low impedance), or inputs or 3 state
or whatever? In my experience digital logic is rather robust and it was rare
to cook a chip just by shorting one of its pins to another, even to GND or
VCC.

cheers
Martin


 

How many Tantalums did you replace on that board?
How sure are you that there is no problem with a solder joint on or around one of these?

cheers
Martin


 

Just one more thing... (Columbo)

Can you check the suspect lines with a another scope?
Do they look stuck? Is there any correlation with good/bad behaviour of the TDS?

cheers
Martin


 

I've no idea what I should be looking for and those pins are mighty small
and close together.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Martin
Sent: 12 March 2021 13:28
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

Just one more thing... (Columbo)

Can you check the suspect lines with a another scope?
Do they look stuck? Is there any correlation with good/bad behaviour of the
TDS?

cheers
Martin


 

Eight of them - I've checked everything now using the stereo microscope.

D.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Martin
Sent: 12 March 2021 13:20
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

How many Tantalums did you replace on that board?
How sure are you that there is no problem with a solder joint on or around
one of these?

cheers
Martin


 

I've no idea what I should be looking for and those pins are mighty small
and close together.
Oh yes, thats not easy.

I was thinking about checking if the lines are totally stuck or are looking normal, i.e. change state every now and then.
Or if a line is moving a little when you switch below 400us... things like that, to confirm or not if the ASIC really has a problem.

cheers
Martin


 

I've just put it back together after yet another cleaning session, but with no change ☹

However I do have something to report which may be useful: If I bring up the acquire menu, and select "Fast Trigger" (500 points), then the calibrator wave form is display correctly down to a sweep speed of 20us/div (400us/div in "Normal Resolution" mode). If I go down 10us/div it all breaks up into a mush again.

I'm sure this means something useful to someone who knows more about how this beastie works.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Martin
Sent: 12 March 2021 13:52
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

I've no idea what I should be looking for and those pins are mighty small
and close together.
Oh yes, thats not easy.

I was thinking about checking if the lines are totally stuck or are looking normal, i.e. change state every now and then.
Or if a line is moving a little when you switch below 400us... things like that, to confirm or not if the ASIC really has a problem.

cheers
Martin


John Gord
 

David,
The TDS3000 series scopes have a fast-in, slow-out chip that is used for the higher sample rates. Apparently that chip is enabled for sample rates above 2.5 million samp/sec, but a normal ADC is used at 2.5M samp/sec and slower.
--John Gord

On Sun, Mar 14, 2021 at 04:54 AM, David C. Partridge wrote:


I've just put it back together after yet another cleaning session, but with no
change ☹

However I do have something to report which may be useful: If I bring up the
acquire menu, and select "Fast Trigger" (500 points), then the calibrator wave
form is display correctly down to a sweep speed of 20us/div (400us/div in
"Normal Resolution" mode). If I go down 10us/div it all breaks up into a mush
again.

I'm sure this means something useful to someone who knows more about how this
beastie works.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Martin
Sent: 12 March 2021 13:52
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

I've no idea what I should be looking for and those pins are mighty small
and close together.
Oh yes, thats not easy.

I was thinking about checking if the lines are totally stuck or are looking
normal, i.e. change state every now and then.
Or if a line is moving a little when you switch below 400us... things like
that, to confirm or not if the ASIC really has a problem.

cheers
Martin


 

That makes sense - but which one is it and how to check the enable signal is being sent to it?

D.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of John Gord via groups.io
Sent: 14 March 2021 22:45
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

David,
The TDS3000 series scopes have a fast-in, slow-out chip that is used for the higher sample rates. Apparently that chip is enabled for sample rates above 2.5 million samp/sec, but a normal ADC is used at 2.5M samp/sec and slower.
--John Gord

On Sun, Mar 14, 2021 at 04:54 AM, David C. Partridge wrote:


I've just put it back together after yet another cleaning session, but with no
change ☹

However I do have something to report which may be useful: If I bring up the
acquire menu, and select "Fast Trigger" (500 points), then the calibrator wave
form is display correctly down to a sweep speed of 20us/div (400us/div in
"Normal Resolution" mode). If I go down 10us/div it all breaks up into a mush
again.

I'm sure this means something useful to someone who knows more about how this
beastie works.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Martin
Sent: 12 March 2021 13:52
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

I've no idea what I should be looking for and those pins are mighty small
and close together.
Oh yes, thats not easy.

I was thinking about checking if the lines are totally stuck or are looking
normal, i.e. change state every now and then.
Or if a line is moving a little when you switch below 400us... things like
that, to confirm or not if the ASIC really has a problem.

cheers
Martin


John Gord
 

David,
Take a look at the EEVBLOG two-part video at:
https://www.youtube.com/watch?v=leC-zSMbtfg
Dave tries to fix a TDS3054 with a single bad channel that has
problems at the same sample rate breakpoint you are seeing.
(He never solves the problem, but his work and the comments
may lead you to a better understanding of which chips do what.)
--John Gord

On Mon, Mar 15, 2021 at 02:47 AM, David C. Partridge wrote:


That makes sense - but which one is it and how to check the enable signal is
being sent to it?

D.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of John Gord via
groups.io
Sent: 14 March 2021 22:45
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

David,
The TDS3000 series scopes have a fast-in, slow-out chip that is used for the
higher sample rates. Apparently that chip is enabled for sample rates above
2.5 million samp/sec, but a normal ADC is used at 2.5M samp/sec and slower.
--John Gord

On Sun, Mar 14, 2021 at 04:54 AM, David C. Partridge wrote:


I've just put it back together after yet another cleaning session, but with
no
change ☹

However I do have something to report which may be useful: If I bring up
the
acquire menu, and select "Fast Trigger" (500 points), then the calibrator
wave
form is display correctly down to a sweep speed of 20us/div (400us/div in
"Normal Resolution" mode). If I go down 10us/div it all breaks up into a
mush
again.

I'm sure this means something useful to someone who knows more about how
this
beastie works.

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of Martin
Sent: 12 March 2021 13:52
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

I've no idea what I should be looking for and those pins are mighty small
and close together.
Oh yes, thats not easy.

I was thinking about checking if the lines are totally stuck or are looking
normal, i.e. change state every now and then.
Or if a line is moving a little when you switch below 400us... things like
that, to confirm or not if the ASIC really has a problem.

cheers
Martin






 

Thanks John

I'd got about as far as David Jones did in identifying what the chips did.

I'll post a screen shot on the EEVBLOG thread I created as the fault in this case is different, and is common to all channels.

David

-----Original Message-----
From: TekScopes@groups.io <TekScopes@groups.io> On Behalf Of John Gord via groups.io
Sent: 15 March 2021 21:29
To: TekScopes@groups.io
Subject: Re: [TekScopes] Broke my TDS3000B

David,
Take a look at the EEVBLOG two-part video at:
https://www.youtube.com/watch?v=leC-zSMbtfg
Dave tries to fix a TDS3054 with a single bad channel that has
problems at the same sample rate breakpoint you are seeing.
(He never solves the problem, but his work and the comments
may lead you to a better understanding of which chips do what.)
--John Gord