Heatsinks are falling off in 6400 and 6600 models.

Wayne

Thanks for your reasearch Bill.

Bill -VA3WTB

Wish I was an expert, but I'm not, I am trying to share what I know, and I trust the engineers at flex to do what works best, they have a lot of skin in the game so to just throw something out there hopping it works?. They are very good at what they do, in my opinion.

Gerald-K5SDR

The back of the board is a much better thermal sink that the chip top, which is plastic.  The chip is designed to sink through a thermal pad to the ground plane under the part.  The bottom of the board is solid ground plane.  We measure the results with an infrared thermal camera.

Gerald-K5SDR

The back of the board is a much better thermal sink that the chip top, which is plastic.  The chip is designed to sink through a thermal pad to the ground plane under the part.  The bottom of the board is solid ground plane.  We measure the results with an infrared thermal camera.

Gerald-K5SDR

Fred,
We emailed everyone to whom we shipped radios before April 12 so if they did not receive the email it is probably in their spam folder.  I can assure you that our intent was to notify everyone.
Gerald

Gerald-K5SDR

You can tie wrap them back on until you receive the replacements.

Gerald-K5SDR

Heat sink compound is not recommended.  Just tie wrap them back on until the new parts arrive.

Gerald-K5SDR

It is possible but there is not much exposed circuitry below the parts.

Gerald-K5SDR

The back of the board is a much better thermal sink that the chip top, which is plastic.  The chip is designed to sink through a thermal pad to the ground plane under the part.  The bottom of the board is solid ground plane.  We measure the results with an infrared thermal camera.

Gerald-K5SDR

The back of the board is a much better thermal sink that the chip top, which is plastic.  The chip is designed to sink through a thermal pad to the ground plane under the part.  The bottom of the board is solid ground plane.  We measure the results with an infrared thermal camera.

Wayne

The biggest danger I see is if the heatsink when it falls shorts out the exposed connections of which there are many where the board plugs into the main board, one picture showed the fallen heat sink very close to those connections.

KC2QMA_John

Gerald, I want to thank for being so honest with us on this small problem. I can’t begin to tell you how much it means to me that you have been honest with your customers on this issue many other manufactures would have tried to cover something like this up. To me this says a lot on how you stand behind your product.

BTW when I looked inside my radio to see if my heatsinks fell off, they were still on. But what I did notice is the quality of circuit boards that are used in the radio are Top Notch, Heavy gauge and lots of ground plane. I also noticed the quality of the case itself, well designed with good airflow.

Again thank you

John

Juan TG9AJR

I did received the PEN email and answer the survey, now just waiting, unfortunately it did happened in the meantime but team is answering, thanks !

Juan TG9AJR

Did one, will re-align and do the second one, thanks.

Jay Nation

So, as a possible workaround, pickup your Flexradio, Shake it violently, do you hear any loose parts rattling around? if so open the radio's case and remove the loose parts, and then immediately submit a help desk ticket to find out what to do next.

If nothing rattles, then while shaking the rig, slam it hard into a solid object, like your desktop, until something does rattle, then immediately submit a help desk ticket reporting what you did, and then wait for the reply you will probably get, informing you about the premature expiration of your repair warranty.

or …

If instead, you hear no rattling, and don't see any signs of any other hardware malfunctions, be Happy!!

You can skip the help desk ticket submission, like usual.

And in the future try to avoid fantasizing about problems your not actually experiencing.

Enjoying your Flexradio, might be easier than you think it is.

#FlexRadio IRC chat

   73, Jay - NO5J

W9MO

If the back of the board is a much better thermal sink, then why did you place the heat sink on the top of the chip in the first place? 

W9MO

If the back of the board is a much better thermal sink, then why did you place the heat sink on the top of the chip in the first place? 

Bill-N6RV

Hold on!!! The heat sink you suggest is now pinned between the board and the partition. Are you relying on convection alone to move the air across the heat sink. The fan is in the other compartment blowing air over the power amplifier. How does a heat sink work inside a confined space like that?

Bill -VA3WTB

It is call Natural convection, in this type of heat transfer the cooling is not done with forced air from a fan. but the air still moves. The air is heated through the cooling fins and rises and picks speed up as it continues to the top of the rows of fins. New cool air rushes in to replace the heated air and the cycle continues.

This is mostly used on applications were temp is important and the source gets warm and never hot.

As mentioned before these chips are not hot, so this form of cooling works well.

Bill-N6RV

Here is a snippet from the video you published. Show me the thermal pads and via holes as recommended by the chip manufacturer.


I do not see any. The thermal impedance must be really bad! Combine that with the heat sink stuck between the PCB and a metal partition and the thermal issue is still a concern.

Bill-N6RV

Bill- VA3WTB

Are you a thermal engineer? I am not. I did work on satellite hardware at component level, unit level and I oversaw the design of satellite payloads. I also worked on ground based rack mounted comm hardware and hardware that had to survive Aircraft Uninhabited Fighter (AUF) specifications plus I worked on rack mounted satellite special test equipment. I have a healthy respect for thermal design. In all the designs, if the junction temperature of a device exceeds the specified limit, the MTBF of the device is severely degraded. The reliability goes to ****! No telling what happens to the device. The manufacturer specifies a certain temperature range and they do not usually indicate what happens when that range is exceeded. They do not want you to go there!

I think publishing the thermal imaging data will help. But that is the case temperature and there thermal impedance from the case to the junctions hence the junction temperatures will be proportionally higher! A full thermal analysis is required not just tongue in cheek comments.

Bill -VA3WTB

I think I have said all I will say. On to other things. And Gerald has answered many questions. I really believe they know their doing.

Pat N6PAT

Some points to consider:

Gerald- K5SDR said in reference to putting the new heat sink on the back of the board:


The back of the board is a much better thermal sink that the chip top, which is plastic.  The chip is designed to sink through a thermal pad to the ground plane under the part.  The bottom of the board is solid ground plane.  We measure the results with an infrared thermal camera.

If that is the case then why was it designed with the heat sink on top of the chip in the first place and did the original design result in overheating the components by not providing enough protection?

Also wayne suite brought up a good point:


Bill if the heatsinks for the chips are left off for so many other applications I dont understand why they are so necessary and if they are so necesary then its more than prudent to say the chips when heated must have been affected or damaged if the symptoms we are seeing cause the radio to go deaf. Its kinda like overheating your engine and causing the block to **** after it cools down the engine will still run buts its no longer reliable with the white smoke coming out. Of course the adcs dont have smoke coming out but there is no way to determine the internal damage thats been done to the adc by being overheated.

If the heat sinks are required to avoid damage how can anyone be certain that their radios did not suffer some amount of damage while the heat sink was detached? Many owners say they keep their radios powered up 24/7 so shouldn't they be concerned about possible damage that may have occurred? How long can a radio be powered up safely with the heat sink detached?

Would it be prudent for Flex to replace the boards to ensure that no future problems develop due to any overheating experienced while the heat sink was detached?What is the cost of replacing one of those boards ?

If I owned one of the affected radios I would certainly be requesting new boards.

Cal N3CAL

I'm deeply concerned about the condition of my 6600!  It was put in operation on Feb 21, 2018 and ran 24/7 for eight weeks straight before the  receive went out.  When trouble ticket was submitted I was instructed to send it back to Flex for repair for a known thermal issue with the A-D Converters. This was Apr. 26, 2018 which was before the PEN was announced.   The only repair done was the addition of the new  heat sink which is now a PEN.    The fact that the thermal issue takes out / degrades receive should be enough to effect a chip replacement.   I will have to wait and see how the receive is once I get it back???  It's currently on a brown truck heading my direction.  

Cal/N3CAL

KC2QMA_John

The sky is not falling and it’s not the end of the world. It’s a small problem and so far FRS has addressed it so let’s all take a deep breath and relax it’s technology and humans are not perfect. There are recalls and engineering updates all the time by companies at least in this case it’s not a gas pedal getting stuck or an airbag blowing up in your face.

I am no design engineer but if the new heatsink works well then there is nothing to worry about. From what I can figure the only time the ADC chip temp has the potential to rise out of the safe zone is when the user has the Preamp enabled in SmartSDR (+8, +16, +24 +32dB) because it pushes the chip a bit harder.

As for me I think I will install the new PEN heatsink on the back of the board and clean and re attach the original heatsink to the chip top again using quality thermal adhesive. Then it will be even better cooling. 2 heatsinks are better than 1!

I think a solution that most of could live with is after we all have the PEN update done if within in 2-3 years we start to see numbers of ADC boards failing that FRS will offer free replacement boards.

I’m just glad that FRS did not try to cover this issue up it says a lot about how honest flex is with there customers. Not many companies today are as forthcoming. 

Anyone remember the FT-2000 preamp problem, Yaesu still won't admit there was a problem after all these years.

https://www.youtube.com/watch?v=o8vu_4Qy1Dg

Gerald-K5SDR

Hello all,

Please let me clear up some of the FUD (Fear, Uncertainty, and Doubt).  I designed this part of the radio so you are getting it right from the horses mouth.  That means you can blame it directly on me.  I apologize for any inconvenience you may experience while we do the heat sink replacement.  

Here are the facts regarding the ADC heat sinks:

1. The AD9467 ADCs do not require heat sinks to safely operate.  We have been using these parts first in government and later in ham applications for 10 years and have never used a heat sink on the parts until the new radios.  That means there are no heat sinks on the 6300/6500/6700 ADCs and they have been in continuous operation since 2013.
2. The AD9467 has a maximum junction temperature rating of 150 Centigrade (302F).  It is rated  to operate in an ambient temperature of 85 Centigrade (185F).  There is NO risk of damage to the part in your radio with no heat sink.  The PCB is designed to sink the heat into two layers of ground plane through 36 ground vias on the chip's ground pads.  This will keep the chip perfectly safe without an external heat sink.  We will not replace the boards because there is no sound technical case to do so.
3. The heat sinks were added to increase to increase spurious free dynamic range by a few dB and to hold the clock alignment within a tighter range.
4. Each time you boot the radio, it does an automatic synchronization of the ADC clock with the FPGA to find the optimal timing.  If the heat sink falls off, the timing of the clock changes and it may lose sync.  This causes the noise floor of the receiver to go up dramatically or you can lose receive all together.  Since the entire system is clocked through the first ADC, it can affect transmit as well.
5. Simply replacing the heat sink with a tie rap to hold it in place as others have shown here will get you right back in operation if you have not yet received the replacement heat sink kit.
6. The copper heat sinks we used were selected because they are copper, cost effective, easy to get in volume, and fit the part well.  They were marketed to be used on the Raspberry Pi chip.  Unfortunately, the quality of the thermal adhesive was not what we expected.  
7. The adhesive problem did not show up on our prototypes or on our our alpha/beta test team until three months after being placed in operation.  
8. The thermal adhesive on the new heat sinks are rated to require 36 pounds of force at 100C (212F) to remove them after they are properly applied.  
9. The radios are rated for an ambient temperature in operation of 50C (122F) so I doubt any of you have gotten near the maximum ambient operating temperature of the chip of 85C (185F).  If you have, you are a lot tougher than me.  ;>)
10. Why didn't I use the heat sink on the bottom to begin with?  Of the thousands of design decisions you get to make in designing a radio, I just didn't think of it.  I had no idea that the adhesive would fail on the one I chose and it was fine thermally to meet the requirement.  I learn something new with each new design.
11. We have mailed kits to everyone who requested it when we communicated the PEN announcement.  Please complete the survey in the notification if you have not already to receive your kit.

That is the whole story.

Sincerely,
Gerald

Gerald-K5SDR

See my official comments below.

Gerald-K5SDR

Paul, see my official comments below in this thread.  There are 36 ground vias under the ADC.  The design is exactly as in the datasheet but with 3x more vias than they require.  These connect to two solid ground planes, one of which is the bottom of the board.

Gerald

Steve-N5AC

@W8QB the preamp enhancement procedure involves adding two 0402 capacitors to each receive preselector. An 0402 cap is 1.0mm x 0.5mm. We don’t expect any customers to perform this work. To be done correctly, it requires a microscope and other specialized tools. In light of this, we don’t plan to create a video on how to do it. Our internal documentation simply says which components go in which locations on the board (since our electronic technicians know how to solder a cap on a board).

Steve-N5AC

Actually, the IC in question has a plastic package, not ceramic or metal. The plastic material does a relatively poor job of conducting heat from a part and was not intended for this purpose. The part was designed the dissipate heat through a large thermal paddle on the bottom of the chip and into the PCB. Page 31 of the ADC data sheet describes this (http://www.analog.com/media/en/technical-documentation/data-sheets/AD9467.pdf) which we followed to the letter. Of course, engineering is a science. I don’t think Analog Devices expected the thermal dissipation area to be as small as our PCB (which was done for modularity that we’ve already discussed). As a result, we decided to add a heat sink in the prototype phase of the project, before radio made it to even our Alpha Team. And we saw no issues during the Alpha test and we didn’t, frankly, think to ask everyone to open their radio and see if the heat sink was sliding down the IC! When we realized what was happening, it took a couple of weeks to devise and test a solution that would work. We were honestly surprised how well the heat sink on the rear of the PCB works. We used an IR thermal camera to do comparisons of several solutions. Knowing that we had a solid plane connected to the IC through vias and the plane is on the rear of the board, it makes sense. The solution we are presenting is the best we found and the IC runs COOL with this solution. It’s cooler that I suspect Analog Devices would expect us to run the part.