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| Anritsu MS2721B internal CF card missing |
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| analogRF:
No, I was not talking about those two RAM chips. I have yet to see them fail in these units. The RAM chip that I had to replace once (also Shahriar replaced in one of his videos) was one of those 6 chips that are on the lower right side of the board (top and bottom side). i think there was more DC=DC converters on the backside. you can check them too. I have no picture. If there is no backlight, you should check the inverter and its input voltage. flash chips would be the very very last thing I would touch really. besides I am sure there must be a serial console port somewhere on this board I tried a little bit to figure it out but I gave up. If you can find that, you can probably force it to boot from a usb or tftp and bring it back to life if it is indeed the flash corruption. yours seems to stop very early, so i dont think you still have LAN activated but it's worth checking if you can telnet to it. by the way, have you tried to power it on in recovery mode as per service manual? But the symptoms you describe, point to a hardware failure rather than a flash corruption which I consider a software failure. So I would stll investigate hardware issues like other DC DC converters and RAM chips |
| codex0:
--- Quote from: analogRF on October 30, 2020, 03:03:04 am ---No, I was not talking about those two RAM chips. I have yet to see them fail in these units. The RAM chip that I had to replace once (also Shahriar replaced in one of his videos) was one of those 6 chips that are on the lower right side of the board (top and bottom side). --- End quote --- Could you describe the instrument behavior and how you diagnosed the RAM chip as bad in your case? Shahriar's chip was hot and the unit did not boot fully, I'm curious to know if yours was the same or different in both identifying the bad chip and how the instrument behaved. |
| brainstorm:
@analogRF: those SRAM chips you mention (6 of them on one corner and both sides of the board, near the DSPs) were fine when the instrument was functioning and going all the way towards "Application loaded!"... I did buy and substitute all them by fresh SRAM ICs (3 on each side) and the result was exactly the same: all good all the way up to "Application loaded" (with or without RF deck attached)... so those are also unlikely to be the issue either I guess :/ The Ethernet port is the one I was using back when the instrument was working and how I wrote my initial blogposts as well (dumping the RAM via metasploit against VxWorks debug functionality w/ telnet): https://blogs.nopcode.org/brainstorm/anritsu-ms2721b-spectrum-analyzer-repair-part-2/ At present, ethernet's link doesn't go up at all, I bet it doesn't even reach anywhere near the so-called "emergency mode" (TFTP) either... and USB software recovery never worked either back then, actually. I have not poked serial ports on the SuperH4, but I doubt I can get anything meaningful there either, it very much seems like pre-boot electrical issue, but I'll check them out anyway. --- Quote ---by the way, have you tried to power it on in recovery mode as per service manual? --- End quote --- Yes indeed, no effect :/ When you say "other DC-DC converters" do you mean those inside the PSU can or elsewhere? @codex0: The ICs were never hot as Shariar's video. When I received the instrument I substituted those ICs almost right away because I suspected that it was a common fault mode, but it doesn't seem to be the case with mine :-S The current behavior is 15V@300mA on power on, pushing the button next to the red LED turns in on (according to ON_OFF_FLAG silkscreen via next to the RAM ICs, going from 0V to 3.3V). Pushing that button does NOT turn the screen's backlight on, but you can see how *all* pixels change (from default "off yellowish" color of the screen to a darker color as a result of the pixels being turned on). That's all really, unfortunately :-S... under the hood it's interesting because most of the rails are up, reasonable signals are happening all across the board but there's something buggering it all XD Thanks much for following along, much appreciated ;) |
| analogRF:
--- Quote from: codex0 on October 31, 2020, 10:50:51 pm --- --- Quote from: analogRF on October 30, 2020, 03:03:04 am ---No, I was not talking about those two RAM chips. I have yet to see them fail in these units. The RAM chip that I had to replace once (also Shahriar replaced in one of his videos) was one of those 6 chips that are on the lower right side of the board (top and bottom side). --- End quote --- Could you describe the instrument behavior and how you diagnosed the RAM chip as bad in your case? Shahriar's chip was hot and the unit did not boot fully, I'm curious to know if yours was the same or different in both identifying the bad chip and how the instrument behaved. --- End quote --- those chips are 512Kx8 byte 3.3V SRAM. It's a tedious work really but in my case I monitored the chip control pins (CS, OE, WE) along with data bits (I/O) and address bits (4 channel Lecroy 2GHz scope with AP020 FET probes) and luckily on the second chip that I tried I noticed the data coming out of the chip in read cycles looked very crappy (well others didnt look good either but on this one the data was very crappy). but for that you really need very low capacitance probes otherwise the signals look very bad no matter what |
| analogRF:
--- Quote from: brainstorm on November 01, 2020, 12:39:22 am ---@analogRF: those SRAM chips you mention (6 of them on one corner and both sides of the board, near the DSPs) were fine when the instrument was functioning and going all the way towards "Application loaded!"... I did buy and substitute all them by fresh SRAM ICs (3 on each side) and the result was exactly the same: all good all the way up to "Application loaded" (with or without RF deck attached)... so those are also unlikely to be the issue either I guess :/ The Ethernet port is the one I was using back when the instrument was working and how I wrote my initial blogposts as well (dumping the RAM via metasploit against VxWorks debug functionality w/ telnet): https://blogs.nopcode.org/brainstorm/anritsu-ms2721b-spectrum-analyzer-repair-part-2/ At present, ethernet's link doesn't go up at all, I bet it doesn't even reach anywhere near the so-called "emergency mode" (TFTP) either... and USB software recovery never worked either back then, actually. I have not poked serial ports on the SuperH4, but I doubt I can get anything meaningful there either, it very much seems like pre-boot electrical issue, but I'll check them out anyway. --- Quote ---by the way, have you tried to power it on in recovery mode as per service manual? --- End quote --- Yes indeed, no effect :/ When you say "other DC-DC converters" do you mean those inside the PSU can or elsewhere? @codex0: The ICs were never hot as Shariar's video. When I received the instrument I substituted those ICs almost right away because I suspected that it was a common fault mode, but it doesn't seem to be the case with mine :-S The current behavior is 15V@300mA on power on, pushing the button next to the red LED turns in on (according to ON_OFF_FLAG silkscreen via next to the RAM ICs, going from 0V to 3.3V). Pushing that button does NOT turn the screen's backlight on, but you can see how *all* pixels change (from default "off yellowish" color of the screen to a darker color as a result of the pixels being turned on). That's all really, unfortunately :-S... under the hood it's interesting because most of the rails are up, reasonable signals are happening all across the board but there's something buggering it all XD Thanks much for following along, much appreciated ;) --- End quote --- oh OK, I didnt know you had replace those SRAMs already. Let's hope they are indeed all OK though. No, I meant I think there were some more DCDC converters on the back of the board. I cannot remember exactly. I might be wrong the fact that you do not have the -6.1V (which is designated by -5V8 on the board and in the instrument self test) might be a clue. as I said, all rails except that 24V come online right after power on. Even 24V comes on very shortly after (even with no RF deck attached) |
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