Posted: Sat Nov 04, 2023 21:27 Post subject: Soldering. EA6350
hello, sorry for stupid question)
I’m trying to restore the ea6350, but I’m not very good with a soldering iron) in general, I’m “afraid” the second evening I’m trying to somehow solder the wiring and it still doesn’t work, I’m afraid not to harm the board, question Here's the thing, I started from the point which is GRND, but I'm trying to grab it with soldering from the top of the board, and there's actually nothing there for me to solder on and catch on, so... Can you tell me if it's possible to solder right through the boards in these places, Well, for example, a pin, and already grab it from the bottom side of the board with soldering, won’t I do any damage if I try to penetrate it?
Posted: Sun Nov 05, 2023 2:18 Post subject: Re: Soldering. EA6350
pljaskin wrote:
hello, sorry for stupid question)
I’m trying to restore the ea6350, but I’m not very good with a soldering iron) in general, I’m “afraid” the second evening I’m trying to somehow solder the wiring and it still doesn’t work, I’m afraid not to harm the board, question Here's the thing, I started from the point which is GRND, but I'm trying to grab it with soldering from the top of the board, and there's actually nothing there for me to solder on and catch on, so... Can you tell me if it's possible to solder right through the boards in these places, Well, for example, a pin, and already grab it from the bottom side of the board with soldering, won’t I do any damage if I try to penetrate it?
I received your PM. Luckily I also checked here before replying to your PM. In the future you can put the link to this topic in your PM so that I reply in this topic instead.
Have you soldered anything before?
Make sure the soldering iron temp is correct and the solder wire is correct.
You need to keep the soldering iron tip clean & shiny by applying some solder & wiping on a wet sponge, repeat as many times as needed (my teacher told me to treat my soldering iron as a knight treating his sword).
I suggest to use IPA to clean the black residue on the PCB first, then check if there's any damage before continuing.
The GND pad is the hardest to solder, because it's linked to the whole GND plane of the PCB, so it's not easy to be heated up hot enough to melt the solder.
The GND, TX, RX of your EA6350 are through-hole but they're covered with solder (by manufacturer), you can melt that solder in the hole and insert the wire/header pin through the hole, it's intended to be that way.
I'm not good at teaching, most of the actions I do during soldering are from habits and I do them almost subconsciously, so there can be things that I miss out. I suggest you pass the job to someone with electronic soldering skill, or learn more online and practice more on something else first before working on your precious/delicate/expensive hardware.
I've been working through my de-bricking pile so I'll pass on some tips:
1) This ain't your grandpappy's lead/tin solder anymore, sonny, this here is EU-mandated lead free silver solder alloy. It does NOT melt at the lower temp of lead/tin solder. Pure silver solder melts around 600C alloys used in electronic work melt around 450C, tin lead melts around 390C
Using some "radio shack hobby iron" from the 1980's is going to burn up the circuit board long before it melts anything. You need a modern temperature-controlled soldering iron. You can get a nice little kit from China like this https://www.ebay.com/itm/196063790977 very cheap there's tons of them.
Be careful buying solder off EBay some of the sellers use camera tricks to make it seem like you are getting more solder than you really are. Lead/tin solder is commonly used for re-work but you still need the hotter iron to melt the silver solder already on the board.
Note that during use at high temp 450C or so the iron tip can build up enough carbon so solder won't wet and stick to it anymore so you can't just run the iron at high temp all the time. It'a balancing act you will have to move the temp up and down in use.
2) Desoldering holes full of solder can be done 2 ways: using solder braid, use a solder sucker. Some holes work with 1 some with the other. Sometimes all you can do is use braid to remove enough solder to create a dip in the center of the hole that can be used for centering a drill bit. One trick I've used for tough ones is when the liquid solder in the board melts to blow with my mouth as hard as I can at the board, this can sometimes blow the solder right out of the hole on to the workbench.
3) Ebay is full of cheap circuit board drill bits and kits, here's an example:
https://www.ebay.com/itm/234524232742
Generally you can twist a circuit board drill bit through solder with your fingers or a screwdriver. These are handy for holes going into ground planes which are very hard to clear with just an iron and a solder sucker or braid.
4) It's possible to accidentally catch and yank out the brass/gold hole inserts in the board if you are too rough on things, if you do this OR if you overheat and char the board with too low a temp iron, or if you use too large a drill bit to clear a hole, you WILL ruin the board. These hole inserts often connect to multilayer traces buried in the board.
For newbies I do NOT recommend soldering headers into the holes in the board, even though this is what people do who are testing new builds because of the very real potential for bricking devices repeatedly, it makes it easy to connect and disconnect serial ports.
Instead get your wire, strip a small amount of insulation from the end, and using your iron build up a blob of solder on the end, make sure it's hot enough so that surface tension makes it a circular blob, then touch the blob to the hole and the iron on top of that, and if the solder is hot enough to melt the silver solder in the hole in the board, then it will bond and you will get a nice tough joint to your wire. Then if you want you can run about 6 inches of wire off that and solder that to a header then when debricked you can tape up the header so it does not short anything and tuck it out of harm's way when you close up the router.
Joined: 08 May 2018 Posts: 14249 Location: Texas, USA
Posted: Thu Nov 09, 2023 18:26 Post subject:
To add, if you have a non-conspicuous place, it's easiest to install a 1/8"/3.5mm stereo audio jack so you
'never have to open the router up again' to attach serial and de-brick.
OP PM'ed me saying he's in the war zone with limited access to resources and first-world conveniences such as online shopping. He has asked for someone to solder for him with a price befitting war time. I'm not sure if it's true, but if he's really in such situation let's pray for his safety and peace.
Back to topic, nice writing for the soldering tips. I just want to remind other readers that some tips above may not be suitable for beginners (blowing onto melting solder on PCB, forcing drill bit through PCB hole) because they have high potential risk of injury or damaging the PCB mechanically or electronically.
Thanks for sharing the audio jack hack and signal issue with long cable. I think I've run into both issues in the past. For true RS232 port, it's better not to let it touch the router PCB because its voltage levels can be from -9V to +9V (most parts of router are running at 3.3V). _________________ ▫ RSS feed for DD-WRT releases (2024): https://rsseverything.com/feed/7d36ab68-7733-46c3-bd8a-9c54c5cef08c.xml
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Joined: 08 May 2018 Posts: 14249 Location: Texas, USA
Posted: Fri Nov 10, 2023 2:42 Post subject:
IONK wrote:
OP PM'ed me saying he's in the war zone with limited access to resources and first-world conveniences such as online shopping. He has asked for someone to solder for him with a price befitting war time. I'm not sure if it's true, but if he's really in such situation let's pray for his safety and peace.
Definitely not a fun situation to be in, if it is indeed true.
IONK wrote:
Back to topic, nice writing for the soldering tips. I just want to remind other readers that some tips above may not be suitable for beginners (blowing onto melting solder on PCB, forcing drill bit through PCB hole) because they have high potential risk of injury or damaging the PCB mechanically or electronically.
2M work can be tricky, indeed.
IONK wrote:
Thanks for sharing the audio jack hack and signal issue with long cable. I think I've run into both issues in the past. For true RS232 port, it's better not to let it touch the router PCB because its voltage levels can be from -9V to +9V (most parts of router are running at 3.3V).
The audio jack mod has been around a while, apparently. I thought that PC DB9 RS-232 ports had ±12V potential, not ±9V. I think I remember reading a thread on here about how to make a cable for using a regular COM port vs USB port... _________________ "Life is but a fleeting moment, a vapor that vanishes quickly; All is vanity"
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To add, if you have a non-conspicuous place, it's easiest to install a 1/8"/3.5mm stereo audio jack so you
'never have to open the router up again' to attach serial and de-brick.
So funny you mention this. I just did this last week on two EA8500s. I thought it was an original idea. lmao! I guess I should have Google'ed first. _________________ Linksys EA8500 (Internet Gateway, AP/VAP) - DD-WRT r53562
Features in use: WDS-AP, Multiple VLANs, Samba, WireGuard, Entware: mqtt, mlocate
Wireless 5ghz only
Netgear R7800 (WDS-AP, WAP, VAP) - DD-WRT r55779
Features in use: multiple VLANs over single trunk port
Linksys EA8500 WDS Station x2 - DD-WRT r55799
Netgear R6400v2 WAP, VAP 2.4ghz only w/VLANs over single trunk port. DD-WRT r55779
OSes: Fedora 38, 9 RPis (2,3,4,5), 20 ESP8266s: Straight from Amiga to Linux in '94, never having owned a Windows PC.
Thanks for sharing the audio jack hack and signal issue with long cable. I think I've run into both issues in the past. For true RS232 port, it's better not to let it touch the router PCB because its voltage levels can be from -9V to +9V (most parts of router are running at 3.3V).
The audio jack mod has been around a while, apparently. I thought that PC DB9 RS-232 ports had ±12V potential, not ±9V. I think I remember reading a thread on here about how to make a cable for using a regular COM port vs USB port...
The actual RS232 standard permits up to 25v+ and 25v- for a full swing of 50v. That puts it just under the National Electric Code requirements for considering it Low Voltage cabling so in most jurisdictions it does not need to be run by someone with an electrician's license.
It was designed for SHIELDED untwisted pair (CAT-nothing, basically "telephone wire") although it will work with twisted pair. The idea was, set the voltage high enough to just ram the signal through the most electrically unfriendly environments possible. That was back in the days when that signal might be competing with other 48v ringing signals in a telephone 50 pair bundle, it was whoever had the highest voltage would stomp over the EMF from the others. LOL. Things have gotten a long way since.
PC's use 12v because with the DC voltages available from a PC power supply in a computer you can't generate 25v peak to peak signals. But a PC com port should not smoke if driven by the higher voltages, otherwise it's not adhering to true RS232 standard. In addition with some PC com ports they will NOT go into "3-wire mode" by default, they REQUIRE seeing the DTR pin active before they will open the port. This was also originally strongly implied by the RS232 standard but it's been ignored frequently - most USB-to-serial adapters for example will ignore it. You can programmically override this in software of course although many "terminal programs" are written by people who don't understand this.
There are a variety of other things in the standard for example the cable is allowed to be shorted and it is required that this not to burn up the transmitter/receiver, the "signal ground" can float separately from the "shield ground" and so on. Over time many of those allowances have not been followed, but still to this day RS232 ports on a PC are pretty tough and are immune from a lot of crap that happens to cabling.
The MAX adapters I linked to have circuitry on them that implements MOST of the toughness of a regular RS232 port.
In a PC, the serial data is formed by a UART chip clocking the data out. Timing is critical since the signal is completely unsynchronized, there is NO clock pulse you are just supposed to sort out what the hell the speed is by counting incoming data against a reference clock. Modern UARTS are very good at this, relieving the programmer of having to do it.
The "3.3v serial ports" on our gear are very likely NOT created by actual UART chips but instead by "bit banging" - that is assembly code that toggles a GPIO pin from +3.3v to 0v. Distance limits are severe and there is no support at all for DTR or the handshaking lines, they depend on the router CPU being fast enough to not lose characters without handshaking and data input to be slow enough.
The MAX chips can change that to +3v -3v and provide a deal of protection to the guts of the router but even then 3.3v is barely enough to trigger the UART in a PC com port or in one of those PC USB dongles, and it's still going to be pretty distance limited.
OP PM'ed me saying he's in the war zone with limited access to resources and first-world conveniences such as online shopping. He has asked for someone to solder for him with a price befitting war time.
I am pretty sure I HAVE an EA6350 in my library already loaded and running a dd-wrt version that he can just have for free if he can recieve a router shipment. It's US though so I don't know if the radio frequencies are the same and of course since this would be a ground shipment into a war zone it would have to go through customs and be declared and all that, he might not get it for a month, who knows. If he sends me his I'll debrick it for him, assuming it's still running of course.
