Author Topic: Tektronix DPO4054 stucked at tektronix splash screen (Read 16607 times)

tekfanatic94 · « **on:** January 07, 2018, 03:44:54 pm »

Hello everybody,

First of all I would like to wish you all the best for the New Year!

I'm actually trying to repair a TEKTRONIX DPO4054 that doesn't boot, it stays stucked at the DPO splashscreen.
After investigating I've captured the following console port trace:

.....

Major ver num: 2 Minor ver num: 68
Initializing Mia[0]

PA Bus error. Skipping initialization of devices on PA bus
Initializing Ibm440[0]
Initializing HFD204ADC[1]
Initializing HFD204ADC[0]

.......

I've compared this trace with one of a DPO4032 that works fine:

....
Initializing Mia[0]
Adg523 detected, patching reg offsets
Initializing Tek0005[0]
Initializing Ibm440[0]
Initializing HFD204ADC[1]
Initializing HFD204ADC[0]
....

It seems that the scope failed to communicate with the ADG523 and TEK0005 ASICs, that are connected on the PA Bus .

My question is, does any one knows what is the PA BUS and which ICs on the PCB are the ADG523 and TEK0005 ?

If somebody can help me it will be great :-)

Thanks in advance for your interest and your help !

mairo · « **Reply #1 on:** January 20, 2018, 02:53:46 am »

Hi all,

I think I may have similar problem - My Tek DPO4054 is also stuck at the initial 'splash screen' - it happened yesterday.

The scope has never had any issues, or signs of such. Few years ago, I updated the firmware to the newest one available (2.68).

Yesterday while monitoring two 5V PWM signals the scope suddenly turned OFF by itself (screen and fan OFF), and then after ~1sec back ON again by itself, but this time it just got stuck at its 'splash screen'. I do not think it was a power surge as there were other equipment also running and non of them showed any sign of losing power.

Now when you turn the scope ON, it just shows the Tek 'splash screen' and I can hear the fan turning ON, but that's it, it just stays at this level. Normally, the splash screen will show up first, following by the fan and a clicking of relays, and then the screen showing the waveforms will appear.

I tried to load the firmware back, but nothing happens, just stows the splash screen, and the fan is running as well.

Any help will be greatly appreciated!

pinkman · « **Reply #2 on:** January 20, 2018, 05:56:59 am »

FWIW these scopes are quite repairable, but due to their low depreciation (they are still worth decent $ when sold by a repuatble test equipment vendor) there is not much repair info out there, and this will continue to be true until they get closer to obsoletion. As they approach obsoletion, the common failure mode will dictate whether they are even around 10 yeras from now. ASIC failures will permanently brick the scope. BOM and schematic likely will never be released. Due to limited number of these scopes in circulation and limited software upgrade potential, combined with how easy it is to activate existing software options, it is unlikely that much effort will ever be put into firmware analysis. Repairs on this series are still very expensive and most of those non-corporate persons in the know understandably won't give away the information that is out there. Due to Tek restructuring/changing hands after the development of this series, I fear that much of the really useful information will be lost forever.

If ASIC has failed, you're better off buying another scope, I do not believe that you will find a replacement. If you were able to x-ray the BGA's you might find some potential issue there but I haven't repaired enough of these to know how common this is. Make sure all supply rails are regulating properly. You should be able to use another scope to discover which bus you're looking for, but the actual problem may not be apparent unless you can compare measurements to a known working scope. Be aware that there is little difference between the MSO/DPO4000 series especially from this respect and any DPO/MSO40x2 or x4 should work for comparison. Good luck.

JohnPi · « **Reply #3 on:** February 28, 2019, 05:14:59 am »

I have 3 of these scopes stuck like this. Two are DPO 4054 and one is a DPO 4104. I opened the 4104 up to see what was inside -- there is a small blue pushbutton on the main PCB (behind the screen) -- pushing it seems to restart the (failing) boot process.

The fans are all running, and screen is bright -- but the buttons don't work and it doesn't move from the splash screen. Any ideas on what I can do to get past this ? Since both 4054 are stuck at the same point, I don't think there is any value in swapping modules.

switch998 · « **Reply #4 on:** February 28, 2019, 06:30:55 am »

Quote from: JohnPi on February 28, 2019, 05:14:59 am

I have 3 of these scopes stuck like this. Two are DPO 4054 and one is a DPO 4104. I opened the 4104 up to see what was inside -- there is a small blue pushbutton on the main PCB (behind the screen) -- pushing it seems to restart the (failing) boot process.

The fans are all running, and screen is bright -- but the buttons don't work and it doesn't move from the splash screen. Any ideas on what I can do to get past this ? Since both 4054 are stuck at the same point, I don't think there is any value in swapping modules.

I don't have a 4054 to help, but outside of verifying the required voltages, I would start out by finding a UART port and capture the console output to find where the scope is freezing and perhaps execute a couple commands if a prompt is available. If there is an onboard lithium cell / battery backed RAM chip (particularly if it has an integrated RTC), you might want to verify they are still good since some scopes can freeze if those are not working properly.

Edit: I see that the first post has a sample output from another user. If you have a bus error like the OP I would suggest X-Raying the BGAs like another user suggested. Here's a an issue on the DPOP7104 where a rework on the ADC resolved their issue: https://translate.google.com/translate?hl=en&sl=zh-CN&u=http://www.uxcer.com/NewsShow.asp%3FBid%3D20&prev=search

pbarton · « **Reply #5 on:** February 28, 2019, 05:49:07 pm »

A possible fix here.....?
https://forum.tek.com/viewtopic.php?t=140138
Try replacing the prescaler for the PA bus. U380 (HMC438)

JohnPi · « **Reply #6 on:** March 03, 2019, 01:50:36 am »

Is there any particular reason this IC is likely to fail ? on 3 units ?

p.s. where is it on the board ?

mairo · « **Reply #7 on:** March 30, 2019, 07:17:53 am »

Where on the board is U380, I still have mine. After all I am sure it is not a major issue just a single component somewhere ... I did take mine to a Tek repair centre, they spend 3 weeks on it and the final verdict was that it possibly needs a new US$3k main board... either these guys know nothing about theirs scopes, or are trying to take advantage and make money of it ... just ended up paying $100 for the check up.

mairo · « **Reply #8 on:** April 12, 2019, 01:22:25 am »

My scope is alive! Changed U380 and now boots and works well. It was originally stuck on the splash screen. Early last year when the problem occurred, I took it to Tek service center, where after staying for 3 weeks, the verdict was that it 'probably' needs a new mother board, which will cost ~US$3000.00, but also not 100% sure if it will work after the swap

. I told them that I will not be going ahead with this 'repair' and so they offered me a 'free' disposal of the unit, however I still had to pay AU$110.00 for the service of looking at the scope. .... I payed the service fees and took the scope back - I can sell just the buttons for 5-10 bucks each ...

Thank you to whoever found and shared the solution!

Forgot to add: The exact part number I used is HMC438MS8GE, from Digikey. P/n 1127-2962-ND. Hot air is required for the rework as the IC has a pad underneath.

stj · « **Reply #9 on:** April 12, 2019, 11:15:09 am »

Quote from: mairo on April 12, 2019, 01:22:25 am

I took it to Tek service center, where after staying for 3 weeks, the verdict was that it 'probably' needs a new mother board, which will cost ~US$3000.00, but also not 100% sure if it will work after the swap .

sounds like you took it to Apple!!

pinkman · « **Reply #10 on:** June 20, 2019, 02:51:31 pm »

This is an excellent follow-up, there should be a thread dedicated to fixing these scopes due to the small amount of information out there. Nice work.

dogbert · « **Reply #11 on:** June 28, 2019, 12:25:58 am »

Any idea about where the console port is? Thanks

analogRF · « **Reply #12 on:** December 28, 2019, 07:53:34 pm »

Quote from: mairo on April 12, 2019, 01:22:25 am

My scope is alive! Changed U380 and now boots and works well. It was originally stuck on the splash screen. Early last year when the problem occurred, I took it to Tek service center, where after staying for 3 weeks, the verdict was that it 'probably' needs a new mother board, which will cost ~US$3000.00, but also not 100% sure if it will work after the swap . I told them that I will not be going ahead with this 'repair' and so they offered me a 'free' disposal of the unit, however I still had to pay AU$110.00 for the service of looking at the scope. .... I payed the service fees and took the scope back - I can sell just the buttons for 5-10 bucks each ...

Thank you to whoever found and shared the solution!

Forgot to add: The exact part number I used is HMC438MS8GE, from Digikey. P/n 1127-2962-ND. Hot air is required for the rework as the IC has a pad underneath.

did you also look at the debug serial port? can you let me know where the serial port is located?

mairo · « **Reply #13 on:** September 06, 2020, 10:18:25 pm »

No, I have not looked at the serial port, neither know where it is. The fix was just done by replacing the IC.

winniethepooh_icu · « **Reply #14 on:** September 07, 2020, 06:41:14 am »

Congrats on fixing an excellent scope. We have quite a few of these on the bench with their TDP active probes and everyone loves them. I prefer one over any of the new agilent machines we have. We have had to open a few of them up over the years (the ones that get left on all night every night by the old timers) but have only had power supply circuit failures. Beautiful machines.

JohnPi · « **Reply #15 on:** November 21, 2020, 07:38:41 pm »

Does anyone have a photo of where U308 is on the PCB ?

analogRF · « **Reply #16 on:** November 21, 2020, 08:20:07 pm »

upper left corner, above the ADC clearly marked U380

what are the symptoms? that chip is not the only fault that prevents the scope to boot. actually
when that chip is checked by the firmware, quite a bit must have fallen into its place already,
PA Bus doesnt get accessed/checked until the scope software starts. Firmware must have been successful before that

do you have splash acreen or no acreen at all?

JohnPi · « **Reply #17 on:** November 21, 2020, 08:45:43 pm »

Actually it's a DPO 4104. The splash screen (and the fan) comes up within a second or so when powered up, but remains stuck there.

I measured the power supply voltage; it was OK.

analogRF · « **Reply #18 on:** November 21, 2020, 10:01:49 pm »

check all the voltages on the board, there are many DCDC converters, you need to check them all first but most probably they are ok

yeah, unfortunately U380 is not the only thing that can cause this...serial debug console can tell you if it is the PA Bus
that is causing this or not. If that's the case, then U380 is the culprit. YOu can also check it yourself if you have a high frequency FET probe
and high freq scope or spectrum analyzer, that chip is a simple divide 4 IIRC

have you tried to "force" the firmware via the USB stick (see the firmware installation manual)?
use a USB stick that has LED showing data activity. If the USB at least gets accessed, I think you have passed a critical point
and the scope software starts a little after that, so there is a chance that U380 is stopping it
but if USB does not get accessed, the thing is stopping in earlier steps and has nothing to do with U380...

JohnPi · « **Reply #19 on:** November 21, 2020, 10:12:54 pm »

I'll try the USB stick 1st. My SA goes to 1 GHz (my other scope is only ~ 200 MHz), I'l check if I can see anything with the SA.

Where are the debug console pins ?

analogRF · « **Reply #20 on:** November 22, 2020, 02:42:54 am »

IIRC, there is a 2GHz VCO that gets divided by 4 via that U380, so there should be 500MHz on its output (it's differential output but you can probe one line and see) if there is nothing, check to see if the VCO and U380 have received power already. I am not sure but they might be turned on only when the scope software starts which is way down the line in the boot process. In fact the last step is running the scope software which checks a lot of stuff first...

JohnPi · « **Reply #21 on:** November 22, 2020, 04:24:37 am »

The 5 V on the board is OK (~ 5.1 V). U380 also has 5 V; I can't see signals at its input or output, but my SA picks up strong 440 MHz and 880 MHz around there. If that is what is expected and it wasn't dividing, I wouldn't see this (divided from 2.2 GHz ?)

The inputs are also biased around 5V; the outputs at about 4.6 & 4.4 V which seems about right. With the scope off, I measure ~ 60 Ω at the inputs and ~ 87 Ω at the outputs -- that also seems about what I would have expected.

The coin cell (left side) is glued down (not replaceable ?); it measures 3.0 V. If it wasn't glued. I'd replace it, but 3 V is probably OK for now.

For reference, here's the back of the scope. U830 is on the bottom right.

analogRF · « **Reply #22 on:** November 22, 2020, 04:37:39 am »

the VCO is 2.5GHz and the chip divides by 5. My bad

JohnPi · « **Reply #23 on:** November 22, 2020, 04:56:05 am »

But I see 440 MHz, definitely not 500 MHz (2.5 GHz ÷ 5); also there's an 880 MHz component --> it's not a 50 % duty cycle signal. The ÷ 5 means that the output would not be 50 % duty cycle.

Just in case it was the coin cell, I forced 3.5 V on it and powered on -- no difference.

There is a small pushbutton on the main board; when I press it, the display turns off and turns on again after a couple of seconds when released.

Any hints on how to see the boot log ? Where are the Tx/Rx points ?

Jwalling · « **Reply #24 on:** November 25, 2020, 09:46:42 am »

Quote from: JohnPi on November 22, 2020, 04:56:05 am

Any hints on how to see the boot log ? Where are the Tx/Rx points ?

A question I've seen asked a number of times (myself included), but never gets answered for some reason!


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Author Topic: Tektronix DPO4054 stucked at tektronix splash screen (Read 16607 times)

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