Troubleshoot, Repair: TP-Link UE300 USB 3.0 Gigabit Ethernet Network Adapter

Whenever I drop in to see some of my old friends, it’s almost inevitable that there would be some computer problems that need solving. This time around it was no exception. With this being the season for new researchers starting up at the department, there are always going to be bring-your-own-device hassles.

In this case, a researcher had an Apple Macbook of some description. The researcher did not have Wi-Fi credentials issued yet, so connection via Ethernet is the preferred option. Unfortunately, the Macbook has no Ethernet port, thus necessitating the use of a USB to Ethernet adapter.

The issue was initially discovered when the researcher wanted to set-up the network printer only to find the test page would not print.

The Adapter

The adapter in question is a TP-Link UE300 V1.0. The adapter has a glossy white plastic finish with rounded corners, silver branding and a small transparent pinhole for the activity/link LED.

The cable wraps around the casing when in its storage configuration.

The underside of the adapter features a cut-out to allow for the USB plug to comfortably nestle into the adapter for easy storage and transport.

The product information label is affixed to the bottom of this cut-out.

The port for the Ethernet cable is at the opposing end.

The Fault

Not being familiar with Mac OSX, I noticed that their attempt to install the printer resulted in “Invalid Address” or something to that effect appearing underneath the IP address we input. This immediately suggested to me that there was a network connectivity issue.

Calling up System Preferences -> Network, due to the way the drivers for the interfaces work in Mac OSX, the network controller remains in the list regardless of whether the device is plugged in or not. When plugged in, the listing in Network maintains “Cable Unplugged”, but it is clear that Ethernet link is established to the router.

I immediately diagnosed the printing issue as a fault with the USB Ethernet adapter, narrowing the issue down to the USB link to the Ethernet adapter. We firmed the hypothesis by immediately exchanging the adapter for a known working one and printing was successfully achieved.

Delving further, using System Information, it was clear that the adapter was not registering on the USB bus. This suggested a possible failure in the controller or a cable break. I thought maybe a surge or ESD could have damaged the unit, but then remembered the cable length was relatively limited. I then surmised that it may have been a fault in a USB 3.0 differential pair, but no damage to the connector was identified.

It was then found that plugging in the USB port only part-way, so that only the USB 2.0 connection is made and the USB 3.0 pair remains unconnected, allowed for the adapter to function and attach to the High Speed (not SuperSpeed) bus. As a result, the controller was probably okay.

So I was pretty sure it was a broken USB 3.0 differential pair connection, but instead of gracefully falling-back to USB 2.0 rates, Mac OSX seems to continue to attempt connecting at SuperSpeed rates unsuccessfully. As a result, I was given approval to take the unit into my custody for a teardown and repair.

Teardown

The unit uses a screwless design, being held together by catches on all sides. The unit is based around a single-chip design, using a Realtek RTL8153. Aside from that, the PCB houses a voltage regulator, crystal, magnetics and the port itself.

The cable comes in on the edge and is “retained” weakly by a grommet. To keep the wires from being too stressed, a weak silicone is spread all over the wires. An unidentified foreign substance seems to have contaminated the silicone causing a black speckly appearance.

It was not easy to extract the wires from the silicone without breaking them further. However, it was already determined that one of the wires may have already snapped due to external applied stress or due to damage to conductors during stripping. Regardless, this arrangement is very “low-cost” and the design doesn’t seem to be highly durable. It is also disappointing to see some EMI control ferrite beads have also been omitted on the PCB. On this side, there is a Winbond 25Q16DVSIG 16Mbit Flash chip. The PCB is marked 2001500236 20558 dated Week 13 of 2016.

Repair

Unfortunately, with the mess of silicone, stripping the remaining loose ends of the wires were almost impossible. The other issue simply lies in the brittleness of the clear wire insulation on the differential pairs and limited number of strands. It took several attempts to be able to strip it well enough and tin the ends. Eventually, the ends could be reattached, but only with tweezers due to the fine pitch. Probably not worth the hassle to repair …

As I had over-stripped the USB lead, to protect it when it goes through the case, I slipped some yellow heatshrink over the lot and then filled the area with hot glue, heating it to reflow it so as to hopefully “flood” the area and maintain the connection.

While it doesn’t look aesthetically as nice with the glue bead and yellow heatshrink …

… it does work on my home PC. By downloading USBDeview, it seems that it was possible to have it connect both in USB 3.0 and 2.0 mode depending on which ports I connect to.

Conclusion

When it comes to troubleshooting, it pays to check that your car has tyres and they’re inflated before you complain that you can’t drive down the freeway at 100km/h. In this case, what manifested itself as a printing problem was actually a network problem, but was easily missed as the physical link was maintained and the link lights suggested a connection was made.

Because of the behaviour of Mac OSX, the network adapter appears in the list even when unplugged, so a lack of USB detection is not made clear unless you examine System Info under USB. It also seems that the OS does not gracefully fall back to USB 2.0 in case of USB 3.0 communication issues, so plugging in the USB port only just far enough to allow USB 2.0 pins to touch while the USB 3.0 pins remain disconnected did allow the laptop to operate the adapter at reduced USB 2.0 rates.

Regardless, the problem boils down to some rather poor design with weak/flexible silicone and limited cable retention failing to mitigate stress on the point where the thin wires met the PCB. Ideally, crimped/socketed connections or a proper moulded strain-relief would make for a more durable design, but with the cost-sensitive consumer electronics market, it seems that such compromised designs are still sufficiently robust to sell with potential for “repeat sales” when it eventually fails.

Posted in Computing, Electronics | Tagged , , , , , | 1 Comment

Tech Flashback: Diamond SM56LE-PCT V.92 56k Internal PCI Modem (I56PSP-F40)

A while back, I posted an article with what I termed the “definitive” collection of V.90 modem sounds. If you’re not familiar with it already, the characteristic sound that V.90 modems emit when they are attempting a “high speed” connection is known as a digital impairment learning sequence and this differs between different chipsets and vendors.

At the time, I termed it “definitive” as I thought it to be highly unlikely given the era that we are in, that I should encounter any of the elusive chipsets that have not yet been demonstrated and be able to find the supporting driver software necessary to make them work, while obtaining these modems before V.90/V.92 modem banks are turned off for good. As far as I am aware, I only have access to two POPs with such digital modem banks and it seems very likely that they will not see many more years.

But as if by miracle, I found a machine dumped on the side of the road – a lowly Pentium 4 so inefficient it was not worth taking. But what was worth taking was the internal modem, as it had a chipset marked HSP688T. Something I haven’t had in my collection.

The Modem

The modem was a rather unassuming internal modem of the PCI variety on a green PCB. The board is dated Week 49 of 2003, with a part number of 100-00006-1R1. Not much else identifies the board from the front, of which we can see that it is likely to be a rather late model modem as it has a silicon hybrid DAA – a Silicon Labs Si3017. This is paired to a chipset marked with HSP688T, without so much as a brand. This was no big surprise – once I looked it up, it turned out to be a PCTel HSP modem chipset. PCTel sold their business to Conexant (Rockwell), but were not particularly well liked as all of their offerings were basically softmodems, some of which worked with regular sound-cards connected to phone lines through AMR/CNR cards.

The rear has the identifier I56PSP-F40, with an FCC number of 2H9M500BI56PSP. Unfortunately, due to the FCC shutdown, I was not able to determine who was behind this modem.

However, from the rear, it was rebadged as an SM56LE-PCT by Diamond Multimedia with a label.

The Drivers

To get this working, I had to rely on my old Windows XP box. Luckily the modem drivers were archived by a few online sites, so I was able to obtain one that worked. It seems Diamond customised the driver from PCTel.

The specific driver is dated 24th April 2003, Version 11.300.14.0.

Once installed, I went through the regular steps of checking it out with a few AT commands:

ati1
A129/C02
OK
ati3
PCtel HSP56 Modem 11.0300
OK
ati4
PCtel HSP56 Modem Data/Fax/Voice/Speakerphone/V.80
OK
ati5
V.92
OK
ati6
Build 0014
OK
ati10
A129/C02

Looks like we’re ready to place some calls.

The Sound

Unfortunately, having no fixed line broadband poses an even greater challenge than usual, as now I have to attempt to get a successful V.90 connection through an ATA, connected to a VSP via a triple-NAT’ed LTE connection.

But never say never … I managed to do it despite having a few problems reassembling the audio. As a result, there are a few crackles on the outbound channel because of incorrect packet timestamps. I suspect the VSP and LTE transport was just having one of those days and emitting strange timestamps. However, as it was so difficult to get a successful V .90 handshake, I settled for this.

The handshake is uploaded as a WAV file here: PCTel Handshake – left channel is originating modem, right channel is the answer modem.

The associated stats show that the unit managed a 38666/24000 bps connection initially, falling to 32000/24000 bps when I hung up the connection. Quite a few errors – but it’s VoIP, it was never meant to work anyway and is my last resort to demonstrate these modems.

at#ug
DIAG : revision            [00]=10
DIAG : media mode          [02]=00
DIAG : DTE-DCE interface   [03]=00
DIAG : V.8  CM             [04]='C165D794272A0D'
DIAG : V.8  JM             [05]='C1651394478D'
DIAG : rx sig level(-dBm)  [10]=22
DIAG : tx sig level(-dBm)  [11]=17
DIAG : noise level (-dBm)  [12]=64
DIAG : rnd trip delay(ms)  [17]=170
DIAG : tx modulation       [20]=V.34
DIAG : rx modulation       [21]=V.90
DIAG : tx symbol rate      [22]=3429
DIAG : rx symbol rate      [23]=8000
DIAG : init tx data rate   [26]=24000
DIAG : init rx data rate   [27]=38666
DIAG : carrier lost count  [30]=1
DIAG : rate reneg count    [31]=1
DIAG : retrain requested   [32]=0
DIAG : retrain granted     [33]=0
DIAG : final tx data rate  [34]=24000
DIAG : final rx data rate  [35]=32000
DIAG : rate reneg req      [36]=1
DIAG : rate reneg gra      [37]=0
DIAG : frame size          [41]=128
DIAG : link timeouts       [42]=0
DIAG : compression result  [44]=V.42bis
DIAG : tx flow control     [50]=CTS
DIAG : rx flow control     [51]=RTS
DIAG : chars from DTE      [52]=3
DIAG : chars sent to DTE   [53]=62
DIAG : tx chars lost       [54]=0
DIAG : rx chars lost       [55]=0
DIAG : tx frame count      [56]=2
DIAG : rx frame count      [57]=3
DIAG : rx frame errors     [59]=19
OK

As noted, it sounds slightly different, with a bit of a symmetry that seems to be different to the others along with a bit of a raspy buzzy note. Originating modem sends SCR during the DIL sequence.

Conclusion

A street-side find ends up adding yet another chipset to my collection and not one minute too late as well, as the V.90 POP is still alive. Once they disappear, it will only get more difficult to hear this sound – as overseas connections are fraught with even more latency, packet loss issues and potential codec mismatches (a-law vs mu-law).

I wonder if I will stumble across any others before the local POP goes offline for good?

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Tech Flashback: KDS Converter/Measure/Calculator 5m (YS-5010ME)

There was a time in the not too distant past when, in order for something to be cool, it had to be electronic. Often this meant attaching an electronic clock or calculator to the side of the device for an immediate boost in its status. This sometimes resulted in rather quirky and silly cases of calculator crazies, such as the Calcu-Pen.

But there are other times it genuinely can come in handy, especially when it’s more than just your average $2 8-digit calculator from a variety shop.

The Product

The unit was given to me by a former family friend as they were clearing out their house. They thought that, as a piece of “vintage” technology, it might interesting. It certainly is! But unfortunately, since I’ve been so busy, it’s taken over a year to get online.

The unit seems to have been very well cared for in its time – possibly used infrequently. It came complete with its original box, printed in a very limited number of colours (red, black, orange and blue). The front of the box depicts a line-art image of the unit itself, branded KDS model YS-5010ME of 5m length.

The rear of the box advertises the features of the unit, which is made by Kyoto Measuring Instruments Corporation. I suspect this is now Muratec-KDS Corporation, a company that still produces measuring tapes today.

The side of the box again reflects the product details – CMC standing for “Converter Measure Calculator”. Catchy.

The unit has a decidedly grey-beige coloured body. Very tech, considering all the computers of the era came in similar colours. The branding is a label pasted into a slight recess in the case.

Information about the unit is moulded into the case, along with the width of the unit which is 3.75″. The unit is held together by screws, making this potentially serviceable and repairable in case of damage. Even the tape is secured into its retractor by a hooking mechanism allowing for the tape blade to be replaced.

From the top, we can see the red stripe carries over from the top through to the bottom panels, with the stopping device having a textured recessed button – a nice touch. A look at the bottom shows a similar amount of care in providing a notch to allow for easier opening of the protective flap that covers the calculator.

 

On the side, there is a hole for a lanyard strap and a battery door. Behind the door, two AG13/LR44/A76 cells are used to power the calculator, with the cells in series to provide 3V. On the other side, we can see the “unbreakable” stopping device plunger and the hook for the measuring tape itself.

In Use

From just handling the unit, the Japanese quality of the unit is apparent. Pulling out the tape is a smooth experience, with the tape feeling of high quality with clear markings and not crinkling randomly. The hook itself feels sturdy as well, despite the smaller width of the tape – the reason? The calculator consumes quite a bit of the front of the casing.

That being said, the unbreakable stopping device is a lot more positive than most average “friction locks” which merely drive a plastic wedge into the tape. The mechanism operates on a toggle – push to lock, push to unlock and doesn’t seem to do any damage to the tape with no obvious clinks or clanks as it is actuated.

Of course, the main attraction is not the tape, no matter how good it is. The calculator is accessible by opening the flap on the side. Comprised of hard-wearing glossy plastic dome-shaped keys, the unit seems to be able to take some abuse compared to rubber-buttoned counterparts. The label inside the lid offers guidance on conversion operations, with most operations fairly straightforward. Without using any of the orange keys, you can use the unit as a regular calculator.

But if you want to perform a conversion, it’s simple – just push the associated direction key, followed by the corresponding key for that conversion and the answer will appear. In the case above, I punched in 10, then hit the right arrow key, then hit in<->cm. As a result, it claims that 10 inches is equivalent to 25.4cm, which is correct.

If you really “torture” the device by converting multiple times back and forth, it’s possible to see some rounding errors, although generally they’re pretty small. Despite having fresh batteries, some of the segments on the LCD seem a little weak – a sign of its age and possible degradation in the components within, but at least it still works.

One potential downside is due to its plastic bodied nature, the unit could be subjected to harsh working conditions and the lid may be damaged. This unit, however, is still in relatively good condition (save for some engraving that had been photoshopped out).

Conclusion

The KDS Converter/Measure/Calculator is basically what it says on the box – a measuring tape with a unit converting calculator slapped on the side. While it genuinely served a useful purpose and is rather easy to use, the design seems to show the compromises necessary to integrate the calculator into the design including a reduction in tape width.

That being said, such a device is rare to see as it is well and truly obsolete despite still working perfectly adequately. This is because unit converter applications on smartphones are convenient and easy to use, but also because your average search engine and voice assistant is capable of doing the same. Furthermore, even the concept of a measuring tape is under threat, as newer laser-distance measurement devices are becoming popular and even some smartphones can use their inbuilt sensors to measure in three dimensions with fairly rough accuracy in any unit the user selects.

As a result, you won’t see any tradie walking around with one of these …

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