[SOLVED] Tek MSO4104 no boot - Page 1
Forum section: electronics / repair

author: pcwrangler
author_rank: Regular Contributor
timestamp: January 07, 2021, 09:13:22 pm
content: Hi all, I just got a Tektronix MSO4104 (Serial C0204xx) that won't boot. Upon power-up the screen flashes briefly and the fans go full speed about 5-7 seconds later. All voltages except 17v are present and I don't see anything burned. I can't find what the 17v is for or where it goes on either side of the main board. Nothing significant on an infrared camera. I tried a "forceinstall" of the firmware from USB (front and back ports) but the drive never flashes so it doesn't even get that far. I have read all the threads I can get my eyes on and can't find anything that helps. A couple mention a "console" serial port to watch the power up process but nobody appears to know the location of this port or the pinout. Of course I don't have a schematic (thanks Tek) and the manuals are pretty worthless in this scenario. Can anyone provide guidance?Is this just a failed firmware upgrade? If so, is there a way to back up the calibration info before I pull the chip and program it?Any help would be GREATLY appreciated!

author: pcwrangler
author_rank: Regular Contributor
timestamp: January 11, 2021, 01:06:50 am
content: UPDATE: I am starting to believe this unit was assembled with failed parts for resale. I found 2 problems which I'm sure aren't related to the non-boot issue but are still interesting.1. Since it wouldn't read the USB drive when I tried force-updating the firmware I checked voltages and noticed the USB ports start at 5v and slowly drop. If I measure the voltage it drops quicker and when I plug in a drive it drops to 1v instantly. I traced this 5v supply to power distribution switch TPS2023 at U310. Inputs are stable during failure. The only other things I see on this line are the capacitors C410 and C220, 470uF. I will have to make sure these aren't pulling the supply down before I replace U310.2. The inverter isn't providing AC to the backlight. I can see 12V DC leading into transistor Q1, RSS075P03. I still need to investigate this circuit. I have confirmed the screen is blank with a bright flashlight.The voltage measurements are below. I still haven't determined what the 17v is for. I understand the mso4000 and dpo4000 series are similar so maybe they used this board for other revisions and the 4104 doesn't use 17v?Label--Measured-12 -11.978-5 -5.23351.5 1.49431.8 1.84152.5 2.49723.3 3.31235varly 4.08855va 5.07685 5.106510.8 10.81612 12.08317 0Probe Pwr 12v 0Anyways, I'm still at it if anyone wants to contribute. I will keep updating this thread and hope it helps someone in the future.

author: pcwrangler
author_rank: Regular Contributor
timestamp: January 14, 2021, 05:08:21 am
content: UPDATE1. TPS2023 at U310 is bad. I confirmed by injecting 5v from my bench supply and it only took about 70mA, powering my USB tester. I'll replace this when I solve the boot issue.2. The inverter is fine and wasn't receiving the enable signal. Luckily the 104PW191 by NEC has a datasheet and I was able to confirm the voltage to inject and it lit up the backlight perfectly.Next step is to check the ram activity and some of the address lines to confirm CPU activity. More to come.

author: pcwrangler
author_rank: Regular Contributor
timestamp: February 11, 2021, 07:01:25 pm
content: Thanks to ApertureScience for the serial pinout I was able to observe my boot log process.Quote from: ApertureScience on February 10, 2021, 01:28:07 pmMy Bootlog:QuoteAs seen in the thread linked above, the F should be the "Flash:" line and continue the boot process but it just halts. I confirmed all activity on the address lines also halt at this point. I have repeated this process a dozen times with the exact same results. Does this mean I have a bad CPU or maybe flash? If it is just bad instructions in flash, I can de-solder and program it manually if necessary. I assume the calibration would be lost but a working scope is an improvement.Any guidance would be great. Thanks for the eyeballs.

author: pcwrangler
author_rank: Regular Contributor
timestamp: June 27, 2021, 07:19:16 pm
content: I have returned to this project and need to consolidate parts of this from another thread (https://www.eevblog.com/forum/repair/tektronix-dpo4054-stucked-at-tektronix-splash-screen/msg3459646/#msg3459646) for my own documentation/sanity. The key points are below.The oscillator at Y650 is 27MHz and looks good, steady through the whole process.There are two LTC3728 and one LTC3729 that all look ok. The PGOOD signal on all of them isn't pulled down.The EEPROM at U431 has steady power but no activity on the one address line that isn't directly tied to ground. There are only 2 pulses low on the SDA and one on the SCL upon boot, exact same results every time.All oscillators on both sides are present and stable. The CPU does have an integrated PLL.I checked every pin imaginable from the vias under the CPU BGA. The only suspect was clkEn which enables the RAM clock. It is steady at 2.2v instead of the documented 2.5v in the CPU datasheet. However, I believe that is still within SSTL 2 specs.I confirmed the CPU bootstrap is configured to gather boot configuration from the 16 bytes on the I2C EEPROM. I believe that is telling the CPU to get the bootloader from the 4MB flash chip at U822. The CE and OE pins between the CPU and U822 start enabled and then go high at the same time the boot log stops. I think bootloader instructions are interrupted because of this. I just don't know why the CPU is doing this.I confirmed the DDR termination regulator is at U650 and is behaving as specified in the datasheet.Sadly, I have ruled out voltages, DDR termination and oscillators.U822 is a Am29LV040B PLCC. Does anyone have a dump of this chip? This MSO4104(non-B) has the same version header as others have posted from different versions of the 4000. "U-Boot 1.1.4 (Jan 8 2007 - 11:12:14) Tektronix, Inc. V1.06". I'm not sure if that means it's universal and interchangeable but I also found this same version digging through the downloadable FW update from Tek. Maybe I'll desolder and compare the two.IR Cam shows no overheating either side of board.QuoteQuote from: analogRF on February 18, 2021, 02:17:16 amvcc and clock are good on the PCI9056 at U560 but the IDSEL(thanks m k) line is stuck low. The datasheet of this chip and the 440EP CPU show their IDSEL pins as input. Anyone know the source?BTW: I programmed the flash with the downloaded and extracted bootloader.img just to see what would happen but it wouldn't even provide a boot log, completely dead. I reprogrammed it with the original code and it's back to the previous behavior. I thought I would add this here just in case someone is playing with firmware in the future. I suppose a merge of that img file with the original code might work but I believe you all are correct; if it was damaged I wouldn't get much useful info out of it.Quote from: m k on February 19, 2021, 12:32:02 pm

author: pcwrangler
author_rank: Regular Contributor
timestamp: October 09, 2021, 02:34:26 pm
content: UPDATE: SOLVED! User adrianh resolved a different issue on his 4104 in this thread:https://www.eevblog.com/forum/repair/tektronix-dpo-4104-kernel-panic/So I asked him about my issue and with his guidance I replaced the DRAM. Problem solved! I can't believe it was that simple the whole time. I'm very grateful to adrianh as this saved a very expensive (to me) piece of gear.Anyways, in that thread he speculated that this line of scopes might have failing/faulty RAM and that definitely fits my case so I encourage anyone that is having early U-Boot problems to keep this in mind.

author: pcwrangler
author_rank: Regular Contributor
timestamp: October 09, 2021, 03:55:32 pm
content: For the record: The bad ram was the bottom one on the back side (opposite of CPU) of the board.

author: daveyk
author_rank: Frequent Contributor
timestamp: November 11, 2022, 09:55:43 pm
content: Wow; congrats. Yes these are expensive scopes. What kind of ram was it? SMD with legs, or ball grid?I got mine at Goodwill auction but still had to pay about $3400.Dave

author: pcwrangler
author_rank: Regular Contributor
timestamp: November 19, 2022, 09:43:29 pm
content: It was a 66 pin TSOP I believe. Exact model is MT46V16M16. Now I just have to worry about the inevitable CCFL failure/dimming. Still, it's a great scope.. especially after you add licenses. Check other threads about the MSO/DPO series if you are so inclined.

author: myhobo
author_rank: Regular Contributor
timestamp: February 22, 2023, 03:23:27 am
content: Hi pcwrangler, I need the boot code in AM29LV040B, my MSO4034 can't start u-boot, please send me the file, thank you very much.

author: pcwrangler
author_rank: Regular Contributor
timestamp: March 09, 2023, 04:40:13 pm
content: I'd be happy to send that to you but I would be very surprised if that was your problem unless you have a specific failure of that chip or some other indication that the code has gone bad. Have you dumped the existing code from that chip yet? What's the boot log look like?I'll send you the dump I have but remember it is the MSO4104(NON-B). I doubt that matters having examined how the firmware updates work but I could be wrong. Check your messages in the next few minutes.Good luck

author: pcwrangler
author_rank: Regular Contributor
timestamp: March 09, 2023, 04:47:19 pm
content: It appears I cannot attach files in a PM. Well, hope this doesn't get taken down. Here you go.

author: myhobo
author_rank: Regular Contributor
timestamp: March 11, 2023, 09:02:33 am
content: thank you pcwrangler, It's working

author: myhobo
author_rank: Regular Contributor
timestamp: April 25, 2023, 03:13:25 pm
content: excuse me, I need you help , this is my serial port output information :CPU: AMCC PowerPC 440EP Rev. C at 333.333 MHz (PLB=133, OPB=66, EBC=66 MHz)I2C boot EEPROM enabledInternal PCI arbiter enabled, PCI async ext clock used32 kB I-Cache 32 kB D-CacheBoard: Tektronix Route66 IBM 440EP Main BoardVCO: 666 MHzCPU: 333 MHzPLB: 133 MHzOPB: 66 MHzEPB: 66 MHzI2C: readyDRAM: 128 MBFLASH: 64.5 MBPCI: Bus Dev VenId DevId Class Int00 13 10b5 9056 0680 1800 15 1002 4c59 0300 17DISP: Type 1In: serialOut: serialErr: serialEnter password - autobooting in 3 seconds## Booting image at f0000000 …Bad Magic Number## Booting image at f0180000 …Bad Magic Number=>What should I do next?

author: daveyk
author_rank: Frequent Contributor
timestamp: June 24, 2025, 03:00:18 pm
content: Hello PC Wrangler,I have another MSO4104 scope. It works fine, but had to get a limited calibration due to the DC Balance on CH2-4 being out of tolerance on 1M Ohm Input, 1mv range. I never use that range, and channel 2 is only used in A/C mode, so the limited calibration does not affect how I use the scopes, BUT my OCD wants it perfect.In all your discovery of this scope, have you figured out how to adjust the calibration table or where that calibration table is stored?Tektronix wants $900 for a factory calibration on the MSO4104, to correct the offset issue (the built-in Baseline offset routine cannot correct it).I'm not sure it is worth $900 to make my OCD happy. The scope passed all other ISO17025 Test results with flying colors.Apparently, since Tek will still calibrate the MSO4104, they have not released the routines to adjust the internal calibration table like they have the TDS3000 series and older scopes.

author: analogRF
author_rank: Super Contributor
timestamp: June 24, 2025, 03:04:39 pm
content: if I am not mistaken on this series and many other tek scope from that era when you start the factory cal (switch at the back) it will guide you through the processbut the thing is it requires a 4-ch scope calibrator (fluke) and you can only do the factory cal in full (everything from start to end) you cannot perform partial calibration.the factory cal files are in the flash but it is a binary and encrypted file and even if you have the file you cannot "adjust" a scope by playing with cal tables!