| Electronics > Repair |
| Tektronix DPO4054 stucked at tektronix splash screen |
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| pcwrangler:
--- Quote from: analogRF on February 11, 2021, 08:02:30 pm ---does it consistently fail exactly at that point? It is very early on during the boot loader execution. --- End quote --- Yes, I have repeated it dozens of times to be sure it is consistant. --- Quote ---I strongly suggest you check out all voltages and DDR termination supplies (there is one or two of them on the top) and many other DC-DC converters. There are also two polyphase regulators are on the back (LTC3729 chips) but you can trace their outputs on the top. It seems to me one or more chips are not getting power. --- End quote --- I know the voltages on the top right of the board at J890 are all correct. Thanks for the guidance on the rest. I'll check those too. --- Quote ---If that's not the case then I'd try to monitor the I2C EEPROM on the back of the board (U431 a 24C01 EEPROM) I think with some probing you should be able to fix this one. You say there is activity but it is critical to see how is the "quality" of pulses. For that you need good probing techniques and low capacity probes. preferrably even FET probe but at least something like Tek P6139 --- End quote --- Unfortunately the only scope I have right now is a DS1054z and the probes that came with it. However, the quality of the address activity looks pretty good considering my equipment. I don't suspect an issue there, except how it ends abruptly at the same time the boot log stops. I2C on the other hand... :-// I do appreciate your help. :-+ |
| analogRF:
--- Quote from: pcwrangler on February 11, 2021, 08:26:10 pm ---I know the voltages on the top right of the board at J890 are all correct. Thanks for the guidance on the rest. I'll check those too. --- End quote --- no, there are other voltages on the board that dont appear on that connector plus the DDR termination supplies if all activities suddenly stop, have you checked the CPU clock? there are several crystal oscillators on both sides of the board but I think the CPU clock is generated on the bottom side. It was marked either Y650 or Y560. |
| pcwrangler:
--- Quote from: analogRF on February 11, 2021, 09:40:39 pm ---if all activities suddenly stop, have you checked the CPU clock? there are several crystal oscillators on both sides of the board but I think the CPU clock is generated on the bottom side. It was marked either Y650 or Y560. --- End quote --- 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. How else would I test these? 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. What do the DDR termination supplies look like? Do you have a location I can reference? Thanks |
| analogRF:
--- Quote from: pcwrangler on February 11, 2021, 11:01:08 pm --- --- Quote from: analogRF on February 11, 2021, 09:40:39 pm ---if all activities suddenly stop, have you checked the CPU clock? there are several crystal oscillators on both sides of the board but I think the CPU clock is generated on the bottom side. It was marked either Y650 or Y560. --- End quote --- 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. How else would I test these? 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. What do the DDR termination supplies look like? Do you have a location I can reference? Thanks --- End quote --- did you check all the crystal oscillators? there are several of them. at least two I remember were on the bottom side. Remember the CPU clock is 333MHz which is not directly generated by any crystal so there must be a PLL somewhere to multiply one of those crystal frequencies up to 333MHz or maybe the CPU has that PLL implemented inside of itself. This is the time you should start reading through datasheets of components to get a grip on how each of them is supposed to behave. I'd start by CPU architecture and pin out. IF everything is suddenly stopped and there is no activity, either a clock has stopped or the CPU is halted or reset. So finding those pins is important I think this CPU has no internal ROM (check?), so I guess that I2C EEPROM provides the small bit of code needed to start a boot loader but from where? or perhaps the EEPROM actually contains the bootloader itself? 1KB seems too small for that I guess but who knows your system is halted in the middle of that small code (or boorloader) for some reason. at that point nothing has been initialized yet I think but DDR memory is probably already in play here so checking that supply termination is a good start. That is a specialized regulator IC soldered very near the CPU I dont remember the P/N but just look around the CPU and you will see it. i dont think not having activity on that address line of the EEPROM is important. what is important is what are data/address that are going in and data coming out. maybe it's a good idea to use I2C decoding on the SDA/SCL lines of that chip and see what you get and compare with what the datasheet says about the signaling of that EEPROM. But first and foremost is (1) all voltages including the DDR termination chip (2) all crystal oscillators (3) finding out if the CPU is halted or reset |
| ApertureScience:
analogRF, I just found your thread regarding the dpo4104. I dont know how I didnt find it beforehand |O I tried the firmware update....so it gets past the boot screen, but only on firmware lower than 2.68. It still crashes afterwards with not being able to handle button presses because of errors and finally kernelpanic :-DD |
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