Eventually people will get over their 24v hardons.
----- Mike Hammett Intelligent Computing Solutions http://www.ics-il.com Midwest Internet Exchange http://www.midwest-ix.com ----- Original Message ----- From: "Forrest Christian (List Account)" <[email protected]> To: "af" <[email protected]> Sent: Thursday, January 21, 2016 10:49:01 AM Subject: Re: [AFMUG] To Cambium With Love - Replace the bad ePMP units. One more picture... Now I have it in my hand these are definitely obvious: Inline image 1 See all the 33R2 resistors scattered around, all in parallel.... I count three in the memory can, and ten in the Atheros processor can. These are 1206 size, which usually equates to 1/4W maximum dissipation. The value is consistent with a heater design as well. 3.3V rail, subtract 0.3V, divide and you get around .25W of dissipation per resistor. Multiply by 13, you get about 3.25W of heating. Definitely enough to shift the voltage down into no mans land when these are on. -forrest On Thu, Jan 21, 2016 at 9:28 AM, Forrest Christian (List Account) < [email protected] > wrote: Ok, I popped the lid here... after realizing it's able to be opened withoud desoldering. I take it back... There are several 33.2 Ohm resistors which are wired suspiciously like heaters.... This now is starting to make some sense. On Thu, Jan 21, 2016 at 9:19 AM, Forrest Christian (List Account) < [email protected] > wrote: <blockquote> Darn FCC site... expires links way too quickly. The SM pictures look like they MIGHT have one. On Thu, Jan 21, 2016 at 9:15 AM, Forrest Christian (List Account) < [email protected] > wrote: <blockquote> I remember hearing the same thing, which is why I went looking at the photos. See https://apps.fcc.gov/eas/GetApplicationAttachment.html?id=2053606 There aren't any that I can see, even under the cans. I thought that perhaps looking at the actual board would reveal some, but I sure don't see any. On the SM perhaps? On Thu, Jan 21, 2016 at 9:08 AM, Adam Moffett < [email protected] > wrote: <blockquote> They have said there's a resistive heater. I heard it in ePMP training in Albany and I've seen it stated on this list. If I remember correctly (I might not), they wanted the CPU to hit a certain temp before starting up. If it was too cold you'd see a delay in startup of up to 2 minutes while waiting for this heater to bring the CPU up to temp. I've never actually observed the delay, so I guess they're talking about Alaska cold, not NY cold. On 1/21/2016 10:47 AM, Forrest Christian (List Account) wrote: <blockquote> I looked at the high resolution photos on the FCC site and didn't see anything obvious. Now I've got the one I have on the bench out of the case, I still don't see anything obvious heater-wise, but again I'm not going to pop the shields off the board (requiring desoldering), to be 100% sure... On Thu, Jan 21, 2016 at 8:30 AM, Steve D < [email protected] > wrote: <blockquote> Just throwing this out there, but don't the epmp's have a small heater in them that could be turning on when it's cold, drawing additional power? I recall it was supposed to pre-heat components to avoid freezeup on first boot but I can't recall if that's the only time they run or not. -Steve D On Thu, Jan 21, 2016 at 1:44 AM, Forrest Christian (List Account) < [email protected] > wrote: <blockquote> I do want to clarify one item: This is not necessarily related to the cambium DRAM issue. I don't want to claim that problem, since this isn't the same thing. This is more of an issue where you have ePMP's which seem to start having power-related issues. If moving to a 30V brick makes your problem go away, then the issue I describe below probably is your issue. If moving to a higher voltage doesn't fix the issue then this probably doesn't relate to your issue. Regardless, it is my intent to recommend that my customers move to 48V as soon as I confirm that this seems to fix at least a decent number of the problems without causing others. Unfortunately this might be a case of the cold weather aggravating two separate issues (or for that matter, the cold weather causing increased current consumption in the ePMP, which then requires a higher voltage to operate correctly). -forrest On Thu, Jan 21, 2016 at 12:43 AM, Forrest Christian (List Account) < [email protected] > wrote: <blockquote> A bit of an update from the PacketFlux side. Late this afternoon I received a ticket from Tyson in relation to these issues. In particular, sync from a PacketFlux SyncInjector dropping off on an ePMP when it's cold. I have spent a bit of time this evening investigating this issue. The following is a summary of what I found. It's a bit long-winded so that those experiencing the problems can understand my current working theory and help me figure out if this is the case. WARNING: The following is based on a limited amount of testing with a single ePMP with no traffic and no clients and on a bench. This is likely the best case scenario. The field is only going to be worse. The setup is as follows: ePMP 1000 GPS AP, with no GPS hockey puck attached, connected to a Gigabit Syncinjector (Rev H and Rev I - I have a special one with a port of each 'type' ;-) ). I am powering the injector with a variable power supply so I can vary the voltages in. The AP is connected to the Injector with ~100m of CAT5 cable. The Antenna connectors have terminators on them, the AP is in transmit mode, but isn't passing any traffic since there are no clients. When feeding the injector with 24V, I get about 23V at the AP. This is pretty consistent with what I would expect in this situation. The AP seems to work fine, at least on the bench and without doing any real work. However, as the voltage drops, things start to get weird: At around 22V in, (21V at the AP), Sync becomes flaky. This is consistent on both H and I version ports on the injector. Sometimes it works, sometimes it doesn't. Note that 22V is the bottom of the rated voltage inputs for the ePMP. At around 20.5V in (19.5V at the AP), the radio just turns off. It won't turn back on until around 22V. Now here's where some total speculation comes to play. On the bench, this unit is drawing around 3W. Let's assume that under load, and when temperatures are cold, this unit draws closer to 6W. This would double the current, and quadruple the voltage drop. Now, assume 24V in, this puts you at around 20V in at the AP, which is about the turnoff point. Remember this is on 100m of wire, and a total speculation about a the power draw of a cold, under load AP. But the point is valid, regardless of the cause - if the circuit resistance when combined with the power load causes a low enough voltage at the AP, weird things will happen. And since weird things seem to start to happen around 22V, there just isn't much headroom at 24V. This explains why things work well at 30V. For those who are having this problem I'd recommend trying increasing the voltage into the SyncInjector. The Revision H injectors can safely handle up to around 56V or so. Assuming all of the radios on an injector are either ePMP or the newer 450i's, using 56V into a SyncInjector is perfectly acceptable and the ePMP's are rated up to 56V as well. So the summary: Try a 48VDC voltage source instead of 24V and see what happens. -forrest On Wed, Jan 20, 2016 at 11:00 AM, Tyson Burris @ Internet Communications Inc < [email protected] > wrote: <blockquote> Hello Cambium, At the MidWest-IX launch party last night, several of us Indiana WISPs compared notes on the ‘cold weather’ problems we are seeing with ePMPs. It was very interesting to learn we are experience identical problems across the spectrum. We all understand this is a DRAM issue with certain units you have identified. We also understand the firmware RC that has been made available to fix this short term. The bottom line is we are very frustrated and grow tired of dealing with it. Our concern is simple. If your software fix ‘degrades’ the performance of the product or triggers other issues, as it has been suggested, we would prefer a full recall and replacement program immediately. If the suggestion that the fix will degrade the product performance is inaccurate and not cause other issues, I would like for this to be made public. Thank you, Tyson Burris, President Internet Communications Inc. 739 Commerce Dr. Franklin, IN 46131 317-738-0320 Daytime # 317-412-1540 Cell/Direct # Online: www.surfici.net ICI What can ICI do for you? Broadband Wireless - PtP/PtMP Solutions - WiMax - Mesh Wifi/Hotzones - IP Security - Fiber - Tower - Infrastructure. CONFIDENTIALITY NOTICE: This e-mail is intended for the addressee shown. It contains information that is confidential and protected from disclosure. Any review, dissemination or use of this transmission or its contents by unauthorized organizations or individuals is strictly prohibited. -- Forrest Christian CEO , PacketFlux Technologies, Inc. Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 [email protected] | http://www.packetflux.com </blockquote> -- Forrest Christian CEO , PacketFlux Technologies, Inc. Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 [email protected] | http://www.packetflux.com </blockquote> </blockquote> -- Forrest Christian CEO , PacketFlux Technologies, Inc. Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 [email protected] | http://www.packetflux.com </blockquote> </blockquote> -- Forrest Christian CEO , PacketFlux Technologies, Inc. Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 [email protected] | http://www.packetflux.com </blockquote> -- Forrest Christian CEO , PacketFlux Technologies, Inc. Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 [email protected] | http://www.packetflux.com </blockquote> -- Forrest Christian CEO , PacketFlux Technologies, Inc. Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 [email protected] | http://www.packetflux.com </blockquote> -- Forrest Christian CEO , PacketFlux Technologies, Inc. Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 [email protected] | http://www.packetflux.com
