Ethernet problems in 5 to 7 units from last build

[Steve Haynal]

Hi Group,

I repaired a board from this last build over the weekend. It could not keep an ethernet connection for more than a few minutes. The problem was that a KSZ9031RN ethernet phy (used in previous builds) was installed but the iset resistor R34 was 4.99K, the value required by the KSZ9021RN, instead of the 12.1K required by the KSZ9031RN. The unit worked fine after changing R34 to 12.1K.

Makerfabs estimates 5 to 7 units were shipped with this problem. Please post to this thread if you think you have one of these faulty units. Your options for repair are:

1. We will send a 12.1K resistor for you to do the repair.

2. You ship just the HL2 card to me and I will do the repair.

3. We arrange an exchange through Makerfabs.

Sorry about this.

73,

Steve

kf7o

[Jean-Baptiste GALLAUZIAUX]

A photo of the PCB showing this resistor would help. Still waiting for my HL2 to be delivered, I hope I shall not be among the fortunate Hams because with the current "snail-mail" sending it back and receiving it again would take months!

73 - Pierre - FK8IH

[Matthew]

It is on the bottom side of the PCB near the Ethernet connector. (see image attached, topmost R in image, vertically oriented)

If I read this correctly, rather than taking the board out of the case to check the resistor, a starting point is to see what phy (top of PCB near Ethernet connector) is used - if KSZ9031RN, investigate further?

73 Matthew M5EVT.

[Jean-Baptiste GALLAUZIAUX]

Is it harmless to test the R34 resistor with an electronic ohmmeter to check if I received a HL2 with the good value? Obviously I would before disconnect the power supply.

73 - Pierre - FK8IH

[Pierre Martel]

Hi 

The way I see this, since that resistor is connected directly to pin 48  KSZ9031RN ethernet IC and ground you will measure resistance of bothe the IC and the resistor. so you will read less than 12.1k for sure. 

But all hopes are not lost. 

On the datasheet of the IC we can see that the typical voltage on Iset pin (48) is 1.2 volts if a 12.1k resistor is in place. So in place of measuring a resistance, you should measure a voltage while the system is running between the ground and the side of the resistor that is connected to a short line and then going to a small pcb via. 

This will give you a good idea if the resistor is the good one or not. 

Pierre

VE2PF

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[Steve Haynal]

Hi Group,

Below is a picture. Fortunately R34 is in fairly isolated location so should be easier to replace. You should be able to read the part number of the eth phy and R34. For KSZ9031RN R34 should be 12.1K. For KSZ9021RN R34 should be 4.99K.

73,

Steve

kf7o

[Steve Haynal]

[Jean-Baptiste GALLAUZIAUX]

On the picture I can read for R34 "889". What should I read for a 12.1K and for a 4.99K resistor?

73 - Pierre - FK8IH

[Roger David Powers]

On line calculator at https://www.hobby-hour.com/electronics/smdcalc.php says:

Hope this helps,

RDP

https://groups.google.com/d/msgid/hermes-lite/ec6b14af-49df-4ec3-b8a6-7414fd38e085n%40googlegroups.com

.

[Jean-Baptiste GALLAUZIAUX]

Thanks to all. I just received my HL2. 

The eth chip is a KSZ9021RNI2111A2U211134A

and R34 marking is 688 or 889 according the way you read it, like on the picture posted by Steve. 

I guess I'm fortunate to have got the right value for R34. Could you, please, confirm Steve?

73 - Pierre - FK8IH

[Mike Brown]

No other replies visible here, so in case you don't know, the resistor seems to be a 68B, so 4.99k.

73

Mike, G4RAA

[Jean-Baptiste GALLAUZIAUX]

Thanks Mike, I'm relieved. I cannot actually test my HL2, which was delivered yesterday as, due to Covid, all non essential shops are closed here, I lack some plugs and connectors and electronic shops are marked as not essential!

73 - Pierre - FK8IH

[Steve Haynal]

Hi All,

Yes, the code for 4.99K is 68B. You can also measure the resistor pretty accurately in circuit with power off as the input impedance to the ethernet PHY is high. It won't damage your HL2 if you power it up with the wrong resistor. You will just experience an unreliable network connection.

If you purchased in the last build, then I would first look at the numbering of the ethernet PHY, U4, right next to the ethernet jack. If it is KSZ9021 then you are safe. If it is KSZ9031 then you will probably need the fix. There were 5-7 units shipped with a KSZ9031 (left over stock from a previous build), all of which had the wrong resistor value in this last build.

So far two people have reported this problem and sent their HL2 to me for repair. Please let me know if you are having any ethernet issues with a unit from this last build.

73,

Steve

kf7o

[Steve Haynal]

Hi Group,

Just keeping this thread alive. I thought I received a second unit with this problem but it turned out to be something else. So there are still 4-6 units out there with this issue of unreliable ethernet. Please contact me for repair options if you are experiencing unreliable ethernet with a unit from the last build.

73,

Steve

kf7o