apc SUA1500 Repair

[quantumleap]

APC SUA1500 Ups problem.
This ups was in the junk pile for a high pitch squeal whenever the unit was plugged in. Found a apparent short at one of the caps near the micro-controller. After de-solder of the suspect cap, the short appeared in the pc board where the component was removed. Traced this back to the micro-controller. After removing the micro-controller the short was gone. The micro-controller is a P87C51FB-4A. I was able to read the program code off the damaged micro-controller and burn it to a new P87C51FB-4A. Installed the new micro-controller and re-soldered the cap. Unit now restored to full working order.

[fzabkar]

Re: apc SUA1500 Repair

Nice work! I find it strange that the security bits weren't blown, though. It seems you were lucky.

[quantumleap]

Re: apc SUA1500 Repair

Yes,
I thought the same thing when I tried reading it in my burner, but it copied OK to the new device. Attached is the bin file I used to burn the new processor.

[alas3376]

Re: apc SUA1500 Repair

I've got the same issue and i've changed the micro-controller.very nice . thank you for sharing

[fzabkar]

Re: apc SUA1500 Repair

How is it that the BIN is so much larger than 16K?

[quantumleap]

Re: apc SUA1500 Repair

I just checked the file on my system and it shows 16k, both the original and after I unzipped it. The zipped file shows 9k. Is that what you see?

[fzabkar]

Re: apc SUA1500 Repair

The ZIP contains a single file named APC1500G (17920 bytes). This file encapsulates the APC1500G.BIN OTPROM dump (16384 bytes) within a 0x200 byte header and 0x400 byte footer (padded with zeros).

[quantumleap]

Re: apc SUA1500 Repair

That's not quit right. The zip file on my system shows 9.0 KiB(9,242) bytes. and the APC1500G.BIN files shows 16.0 KiB(16,384). The extra 384 bytes in the APC1500G.BIN file just reflects the true file size. I guess just like 1 meg of memory is really 1024 KiB. In any case I double checked the file I copied from the device and it is correct, also it burned correctly to the new device which was also 16k(same part number as original). The unit has been working properly since the repair. I checked the output voltages both while on wall power and when on battery, did a runtime calibration and checked the battery charge voltage. All looks good.

[fzabkar]

Re: apc SUA1500 Repair

I use 7-Zip.

The first screenshot shows the 17920 byte APC1500G file. Double-clicking this file produces the second screenshot which shows your 16384 byte APC1500G.BIN file.

If I extract the first file and examine it in a hex editor, it looks like this:

Offset(h) 00 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E 0F

00000000 41 50 43 31 35 30 30 47 2E 42 49 4E 00 00 00 00 APC1500G.BIN....
00000010 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
........
00000050 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000060 00 00 00 00 30 30 30 36 34 34 20 00 30 30 31 37 ....000644 .0017
00000070 35 30 20 00 30 30 31 37 35 30 20 00 30 30 30 30 50 .001750 .0000
00000080 30 30 34 30 30 30 30 20 31 32 36 36 37 37 30 35 0040000 12667705
00000090 37 30 36 20 30 31 33 36 31 34 00 20 30 00 00 00 706 013614. 0...
000000A0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
........
000000F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000100 00 75 73 74 61 72 00 30 30 6D 6A 73 74 65 66 6C .ustar.00mjstefl
00000110 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000120 00 00 00 00 00 00 00 00 00 6D 6A 73 74 65 66 6C .........mjstefl
00000130 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00000140 00 00 00 00 00 00 00 00 00 30 30 30 30 30 30 20 .........000000 
00000150 00 30 30 30 30 30 30 20 00 00 00 00 00 00 00 00 .000000 ........
00000160 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
........
000001F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

<16384 bytes ROM dump>

00004200 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
........
000045F0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

ISTM that your software encloses the 16KiB ROM dump in some kind of wrapper. This wrapper is what confused me.

[Mumxek]

Re: apc SUA1500 Repair

The ZIP file is in fact an tar.gz archive... and the file owners name is "mjstefl". Its a good dump rev .3, probably GEN3.6. This is to my knowledge the last generation where schematics are available. The newer GEN4 has slightly different hardware, i found that the Chip select between the ADC and 93C56 eeprom is using only pin (I think) P3.7 and unfortunately the CPU goes to the CS of the ADC and the eeprom CS is connected directly to a inverter output. So I had to solder the memory out because it was impossible to read in circuit. But from two units i had enormous luck and can provide the dump for GEN4 REV13 CPU. Its a NXP P87C51FB-4A. I soldered a socket and tried a replacement CPU AT89C51RB2, which can be programmed by FLIP over UART. Just disable the bootloader bit. I hope it will help you and there is a lot of new commands in the PROG mode. Its a lot of code, but you can freely analyze it. This dump is 100% correct, the same one found on russian sites is bad.