QNAP TS-1079 Pro  (TS-879 Pro)  Backplane info - Page 1
Forum section: electronics / repair

author: charlyd
author_rank: Frequent Contributor
timestamp: April 27, 2022, 10:54:31 am
content: Hello i have this Qnap ts-1079 pro nas on my bench which doesn t recognized any of the drives. the pcb is build arround Xilinx Spartan A3 XC3S50A-VQG100AGQ and 4 marvell 88SE9125 controllers which are connected to the PCIe x4 bus.Just on the beginning of the board inside the red circle next the PCIe bus connector is a signal conditioner (Macom) M21451G located. i don t have much info about this conditioner and slo not from the circuitry arround it.my question is if anybody with a working TS-1079 is willing to do some measurement for me. on the APL1084 regulator located in the red circle on the pictureit is quit easy accesable from the back of the unit just 3 screws to take the fan panel out don t disconnect the fans.when you look inside you see the backplane and the regulator is positioned on the left side just outside the metal pcb frame. see picture.i am curious to the voltages goingINandOUT[2 or heatsink]of this APL1084 regulatorand also the ADJ  voltage, because the pcb in my unit is completely colored. the APL1084 is a 5Amp adjustable regulator.

author: charlyd
author_rank: Frequent Contributor
timestamp: May 01, 2022, 09:18:22 pm
content: Who can help me out with finding this make or part model.it a fast diode and used as ldo reverse current protection...see attachment.and yes i can use many model but i want the specs of this diodeit looks like a RBxxx. model (schottky )but the numbers what type is it?

author: tim_c
author_rank: Newbie
timestamp: June 18, 2025, 10:15:40 am
content: I'm a bit late to the party, but I have just been diagnosing a problem on my TS1079-Pro, which turns out to be the same issue you faced.In my case, drives 1 and 2 both failed at the same time but I've been having problems for several months now with slots 5 and 6 not coming up at cold boot, until you power cycle it a second time, then it works fine.U31 on the backplane board is discoloured on my board too due to heat damage. This is a 5A adjustable regulator from Anpec. This takes 3.3V in from the PCIe slot to the left of it, it converts power down to 1.8V. The voltage is set by R479 (100R) and R480 (43R), which are 0402 SM resistors to the left of it. According to the data sheet, which can be found on-line, Vout = (R1+R2)/R1 *1.250V, so adjusting R480 to 44R gives 1.8V.In my case however, the output voltage on this regulator was 1.4V and that was the fault. I replaced it with a AZ1084CD-ADJTRG1 from Diodes Incorporated, its a TO252(DPAC) package and the rail came back up to 1.8V. Having replaced the regulator and run the NAS for a bit, there are now no errors in the kernel log and everything is happy again.As further background, this regulator generates one of the power rails needed by the Marvel 88SE9125’s SATA controllers, of which there are 4 on the TS1079 and 3 on the TS879. I found a data sheet for the Marvel controllers and it needs 3V3 for Digital IO, 1.8V for its Analogue Power Supply and this in turn is used to generate a 1V0 rail, which is self generated by the device using a PNP transistor and a control output from the device - See section 4.1 of the data sheet, board schematic example. The self generated 1V0 rail then feeds into several other pins for the digital core. See section 4.4 of the data sheet. Section 5.3 of the data sheet states that the digital core required 900mA, so this explains why the regulator needs to rated at 5A.One indicator of the problem is that if you SSH into the NAS and look at the kernel log output viaCode:dmesg | lessand page through the log, you will see lots of SATA speed changes and SATA link hang / link reset messages, which is hardly surprising when the SATA chips are not properly powered.The logs will refer to sata<x> ports, which are not the same as the slot numbers. I mapped them out by swapping drives in and out and watching the kernel logs - but not using my main drives, using a spare drive that was rebuilt for testing purposes with a fresh OS on it. This was to ensure that I didn't corrupt my data on the main array.The mapping is Slot 1=sata11, Slot 2=sata12, Slot 3=sata9, Slot 4=sata10, Slot 5=sata7, Slot 6=sata8, Slot 7=sata2, Slot 8=sata1, Slot 9=sata13, Slot 10=sata14The reason slots 1 and 2 were failing first is because they are furthest away from U31, hence suffering the most voltage drop across the board. At first glance, though you would imagine they are best placed, since they are next to the large power in connector that provides +5V and +12V for drive power.Note that not all the SATA slots are run from the backplane board, Slots 1 and 2 are driven by U4, Slots 3 and 4 are driven by U5, Slots 5 and 6 are driven by U6, Slots 7 and 8 are driven by the main boards Intel C200 chipset. The signals come up through the expansion slot socket. Slots 9 and 10 come via U12. The LED control comes from the same Marvel IC's. I have not mapped out where Slots 7 and 8 LED control comes from, but I guess some extra GPIO's on the Marvel SATA chips, or possibly the FPGA ??The signal conditioner U50 has an odd M logo and is marked 21451G14, after some research, it is from Macom / Mindspeed, but it has no publicly available data sheet, other than the summary info on their web site athttps://www.macom.com/products/product-detail/M21451which statesQuoteU51 is a FLASH memory device adjacent to the regulator, it provides the config to the signal conditioner. This could account for why drives disappear too - if it gets cooked by the regulator and the conditioner can't function any more.It is not clear to me if the signal conditioner is driving the SATA signals from the main board, or the PCIe signals from the main board, but as there are only 4 channels and there are 4 SATA chips and 2 SATA interfaces, clearly not all of them go through the conditioner. I'm guessing its the SATA feeds for slots 7 and 8.I think that the Xilinx Spartan XC3S50A FPGA is doing power sequencing by controlling the SO8 dual mosfets on each channel, these switches the 5V and 12V for each drive. Other info on-line shows that they fail and there is a bodge to link them out, seehttps://forum.qnap.com/viewtopic.php?t=134212. I don't like this approach, since it will create nasty inrush currents at startup which won't help the power supply. I replaced a couple of the MOSFETS on mine with Infineon IRF7328TRPBFXTMA1, which have a slightly better spec than the FDS9933A's that were fitted. Others report they have 4957AGM.There appear to be some SOT23 transistors on the back of the board (SATA connector side) which look to be doing the gate drive for the MOSFETS, these are slightly separated from the other SOT23 transistors that are driving the LEDs. Some of the LEDS are a bit cooked from the heat of the regulator on the other side of the board.Note that the next generation TVS-EC1080 that shares a similar looking chassis has a completely re-designed backplane board, so perhaps that's QNAP's way of saying that the backplane on the TS1079 series is not ideal.