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Clock-Signal Repair Pictures ISR4300, ASA, ISR4400

Bernhard Roth


We have many devices affected by the clock-signal issues.

Cisco does replace the units with repaired/fixed ones.

I have received some ISR4321 routers with the fix applied (pictures attached).

The Cisco provided fix is of - well - mediocre quality (loose solder joints etc..) but works.

I am an EE engineer and am able to fix other routers of my customers as well (attached a picture of one of my fixes).

Spot the difference :)

Is there anyone which has received fixed ASA5506, ASA5508 and ISR4331 routers?

Please post pictures of your fix (hi-res if possible)

I ask because I would like to fix them as well (some of my customers) and avoid configuration, license etc. migration.

I am aware that I might void Ciscos warranty by this act of evil :)

Best regards,


84 Replies 84



is it possible to use a round carbon metal film or a round metal film resistor instead of a surface mount?

I need a temporary fix to get back my config file.



As long as the resistance value is right, any resistor will be ok.


It'll depend on your soldering skills, quality of the magnifying glass and whether you can physically get it soldered to the board......



I live in Montreal Canada and it was very difficult for me to get parts in a reasonable time because of the covid pandemic (Canada Post delay is 1 month when you order something online)...

I made it using an Arduino kit I bought for my kids a few year ago... no 150 ohms resistors in this kit but 1x100ohms + 5x10 omhs did the job, see picture attached.

I know it is ugly but it worked and I have my config file now, I don't recommend it, but if you don't mind to loose the router forever why not, it may help others in the same situation.

Hi my friends i am trying to fix the 4351 as noted in here from information in fixing other series attached suggestion to fix the 4351 can anyone confirm that it will work thanks 

This tips work fine for me.


Thx a lot


Would anyone happen to know the exact spots you need to install this 150 ohm resistor on an ASA 5516-X? Got a few V01 boxes for lab use that are still working normally, but I'd like to fix these up so they won't break down in the future. Thanks!

ASA5508 and ASA5516 are essentially the same platform, here you go:





Have fun!


Hi! I have a Cisco ASA 5512X that has a blinking amber LED and not communication on the CLI port.


Could this be fixed?





ASA5512-X is a based on a different platform and AFAIK not affected by the clock signal component issue.


As I can see in the photo, the platform is absolutely the same as in 5508/5516. So the manuals for these boxes should work for you too.


We have a 5506 V02 that has just been bricked because of this issue, what is the best way to get it replaced? it currently does not have a smartnet contract, do we need to purchase one and then get it swapped? thanks

You can attempt a repair. With a bit of luck this might bring the unit back to life.


Otherwise purchase smartnet, wait 90 days and then ask for RMA.


I've seen customers just buying a new ASA asd it's EoL anyways = cheap

Thanks, I'll give the repair a go, so its just a matter of soldering on the resistor?

Dear friends did anyone find a fix for the 4351 please share pictures thanks


I ended up soldering a 150 ohm 0603 resistor to my 5506, I can now get into the rommon but it will not boot from the image (either flash or usb) and displays the error "No kernel found to launch."


It is also showing some strange messages on boot where it doesn't seem to be able to read details from the motherboard, I guess this is linked to the Kernel error:

Failed to read macaddress from backplane
Error: platform_required_check_var: Illegal MAC address.
MAC address is not set (ff:ff:ff:ff:ff:ff).


Cisco Systems ROMMON, Version 1.1.15, RELEASE SOFTWARE
Copyright (c) 1994-2019 by Cisco Systems, Inc.
Compiled Sat 03/30/2019 7:00:46.51 by wchen64

DIMM Slot 0 : Present
Product Identifier : UNKNOWN
Serial Number - PCA : UNKNOWN
Serial Number - Chassis : UNKNOWN
Version Identifier : UNKNOWN

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