[GRudolf94]

Hey everyone, great news. All of you with a dead Passport in a drawer, or using it as wifi-only tablet, rejoice!

You can take it anywhere that services phones, and ask the repairman to make two solder bridges for you, and your signal will be back.

Basically, there is an IC hidden under a shield on the front of the board (the side facing the chassis, hidden when you open the phone) that dies. Small little bugger. There goes your 4G.

What needs to be done? The shield has to be desoldered and two wire bridges made. 5min job, shouldn't be more than $10 to fix.

Sorry for the hurried post, I just had to join and tell the news before my battery dies. I was so excited I forgot to take before and after pics. In red are the points that need to be bridged with wire. That shiny little monolith is the culprit.

[Dunt Dunt Dunt]

Hey everyone, great news. All of you with a dead Passport in a drawer, or using it as wifi-only tablet, rejoice!

You can take it anywhere that services phones, and ask the repairman to make two solder bridges for you, and your signal will be back.

Basically, there is an IC hidden under a shield on the front of the board (the side facing the chassis, hidden when you open the phone) that dies. Small little bugger. There goes your 4G.

What needs to be done? The shield has to be desoldered and two wire bridges made. 5min job, shouldn't be more than $10 to fix.

Sorry for the hurried post, I just had to join and tell the news before my battery dies. I was so excited I forgot to take before and after pics. In red are the points that need to be bridged with wire. That shiny little monolith is the culprit.

think you posted the wrong picture.... just see a pic of the front of your phone.

That said... what is the little IC for? Phone might work without it, but is it safe without it?

[hopskirk]

Hi,this is great news. Could you send a photo. I think the fixes, or what we have to say in the service? I have a passport already too long without a signal.

Posted via CB10

[GRudolf94]

Sorry, posting from my Note8 - it's temperamental and the CB app force closes all the time. Here's the affected area...

[GRudolf94]

Ok, posting from the computer now, instead of a temperamental Galaxy Note8.

The full tutorial goes kinda like this:
1- Disassemble Passport until the point motherboard can be removed
2- Remove the baseband analog front-end shield, the one on the bottom left corner of the following image, containing the RFMD7389, which is our RF amp



You should be left with something like this. In red, the affected area. IC already removed.



With the offending IC removed, the points circled in yellow must be bridged



Finally, a mugshot of the villain, the antenna multiplexer.




That should be all. This, of course, requires hot air rework equipment and soldering experience, but it should be within reach of any decent iPhone repair stand, etc. Ask your tech to have the shield soldered back on. Care must be taken with the screws as they are of different shape and length, but any good tech also knows this.

As you can see in the first post, my Passport now has strong 4G signal even in an area with poor coverage. It's a permanent, safe fix for most cases. The 0.1% not fixed by it need usually replacemend of the RFMD IC, but that's exceedingly rare.

Cheers everyone, hope this saves a few of these good old devices plagued with this issue.

[brookie229]

Ok, posting from the computer now, instead of a temperamental Galaxy Note8.

The full tutorial goes kinda like this:
1- Disassemble Passport until the point motherboard can be removed
2- Remove the baseband analog front-end shield, the one on the bottom left corner of the following image, containing the RFMD7389, which is our RF amp



You should be left with something like this. In red, the affected area. IC already removed.



With the offending IC removed, the points circled in yellow must be bridged



Finally, a mugshot of the villain, the antenna multiplexer.




That should be all. This, of course, requires hot air rework equipment and soldering experience, but it should be within reach of any decent iPhone repair stand, etc. Ask your tech to have the shield soldered back on. Care must be taken with the screws as they are of different shape and length, but any good tech also knows this.

As you can see in the first post, my Passport now has strong 4G signal even in an area with poor coverage. It's a permanent, safe fix for most cases. The 0.1% not fixed by it need usually replacemend of the RFMD IC, but that's exceedingly rare.

Cheers everyone, hope this saves a few of these good old devices plagued with this issue.

Excellent news for those who want to fix their device and nice details of the fix. So, in your opinion, what is the exact reason for the IC? Is it faulty soldering/heat from surrounding chip or some other reason? Just curious for your explanation. Thanks again for taking the time!

[GRudolf94]

To everyone asking what the IC actually is, sorry, I missed that before.

Its full name is an "RF directional coupler with an isolated load port", it sits directly on the signal path of the main antenna, I have no idea why it dies, but it probably was a bad design by STMicro, since I don't see it being a custom part for RIM. With that info, the interested folks can research what a coupler does, and see its current replacement (which doesn't fit the Passport), the ST CPL-WBF-00D3.

Cheers!

[Dunt Dunt Dunt]

To everyone asking what the IC actually is, sorry, I missed that before.

Its full name is an "RF directional coupler with an isolated load port", it sits directly on the signal path of the main antenna, I have no idea why it dies, but it probably was a bad design by STMicro, since I don't see it being a custom part for RIM. With that info, the interested folks can research what a coupler does, and see its current replacement (which doesn't fit the Passport), the ST CPL-WBF-00D3.

Cheers!

What I found was an article taking about couplers in smartphone...

Couplers with high directivity (above 15dB) and symmetrical performance are critical for the
precision monitoring of Incident and Reflected power signals. They increase the accuracy of the
power control circuit

I'd suggest that you find someone with a RF radiation meter and spend some time testing your fix in different conditions. Till then I'm not sure what kind of fix this was.

Signal transmission might be much better than before...

[GRudolf94]

The phone still is within the specified SAR. If I had the cabling I could couple it to my SDR and take a capture, but 100% TX power is still harmless, if that were to be the case

The lab I used to work at has more equipment I could use to acquire data on radiated energy, but that is now closed due to the pandemic.

[Jake2826]

I love posts like this. Thanks @grudolph94

[Chuck Finley69]

To everyone asking what the IC actually is, sorry, I missed that before.

Its full name is an "RF directional coupler with an isolated load port", it sits directly on the signal path of the main antenna, I have no idea why it dies, but it probably was a bad design by STMicro, since I don't see it being a custom part for RIM. With that info, the interested folks can research what a coupler does, and see its current replacement (which doesn't fit the Passport), the ST CPL-WBF-00D3.

Cheers!

Should I have a cancer policy in place first?

[GRudolf94]

Let me find a piece of microcoax strapped to an MCX and I'll report back with TX power.

A cancer policy might be adviseable if you intend on holding the phone to your ear for the next 2.3 billion years.

[Dunt Dunt Dunt]

Should I have a cancer policy in place first?

Nah.... But make sure you use one of these stylish EMF Beanies

[Chuck Finley69]

Nah.... But make sure you use one of these stylish EMF Beanies

Seems about right

[GRudolf94]

Managed to get it tested, kinda. Calling via LTE results in about 200mW being dissipated as RF by the cellular radio, give or take 15mW. Test setup has last been calibrated quite a while ago, but measurements are within what is to be expected.

Bottomline: it's no more harmful than your average, factory-stock Passport. Of course, you can still choose to leave your unit broken if you're paranoid. But in that case, I'd also avoid any other phone, since a beanie will do nothing

[paulie87]

Hi, will this solution fix the passport problems with gps signal also? Thank you!

[GRudolf94]

Hi, will this solution fix the passport problems with gps signal also? Thank you!

No. The GPS antenna is attached to another circuit. That said, the Passport has notably bad antenna contacts. You can try removing the rear cover and seeing if all the springs are good. Be careful, they bend easily.

[Shanmukh Gudivada]

Well we both are in the same road then. I too left my passport for over a year now. Have you fixed it up by that solution?

[EchoTango]

Ok, posting from the computer now, instead of a temperamental Galaxy Note8.

The full tutorial goes kinda like this:
1- Disassemble Passport until the point motherboard can be removed
2- Remove the baseband analog front-end shield, the one on the bottom left corner of the following image, containing the RFMD7389, which is our RF amp


With the offending IC removed, the points circled in yellow must be bridged




As you can see in the first post, my Passport now has strong 4G signal even in an area with poor coverage. It's a permanent, safe fix for most cases. The 0.1% not fixed by it need usually replacemend of the RFMD IC, but that's exceedingly rare.

Cheers everyone, hope this saves a few of these good old devices plagued with this issue.

This is really great news. In my earlier career I used to repair circuit boards so I'm quite comfortable making these type of mods. Still have my old solder sucker !

I do need a little more clarification. When you say "bridged" do you mean jumpered ? Do you have a pic of the board with the "bridges" (jumpers) in place ? Can you provide a better pic showing the EXACT points ?

In my experience jumpering the wrong contacts can blow up a board. And yes, I've done that before.

Thanks again !

[EchoTango]

While we're waiting on a response from GRudolf94, has anybody done this fix to the their dead Passport and what was the result ?

[brookie229]

While we're waiting on a response from GRudolf94, has anybody done this fix to the their dead Passport and what was the result ?

@GRudolf94 is not a frequent poster (only a few posts) and may not check this thread often (if at all anymore). Hopefully he can get back to you with your questions.

[GRudolf94]

I do need a little more clarification. When you say "bridged" do you mean jumpered ? Do you have a pic of the board with the "bridges" (jumpers) in place ? Can you provide a better pic showing the EXACT points ?

Yes, jumpered. Be warned, the points that need to be jumpered are perhaps 0.5mm in diameter. Also, I must stress that this is not a task that can be accomplished with just a soldering iron - Hot air rework capabilities are mandatory.

In my excitement to test it, I tacked the shield back on and closed the device, forgetting to take pics of the finished repair. This is the best I can do to explain, without resorting to the previously attached pics. The component marked in steel blue must be removed, and the points marked blue and green must be jumpered.

[EchoTango]

Yes, jumpered. Be warned, the points that need to be jumpered are perhaps 0.5mm in diameter. Also, I must stress that this is not a task that can be accomplished with just a soldering iron - Hot air rework capabilities are mandatory.

In my excitement to test it, I tacked the shield back on and closed the device, forgetting to take pics of the finished repair. This is the best I can do to explain, without resorting to the previously attached pics. The component marked in steel blue must be removed, and the points marked blue and green must be jumpered.

Hey GRudolf94 !

Thanks so much for responding with more details and I (and I'm sure others here) really appreciate your clearly well qualified support. I'm very hopeful this will work for my two bad passports. Since posting, have you done any further testing or even used the repaired passport ?

I'm assuming based on your new diagram the multiplexer has six "legs" and the four outside legs are jumpered north to south with the center contacts left unconnected.

I'm not sure what hot air rework is, but I suspect it's using a hot air gun to melt the solder as opposed to a soldering iron. I've changed hundred of IC chips with a soldering iron and a solder sucker with boards up to five layers. I do agree the contacts are much smaller than I've seen in the past. In anycase, I'll follow your advice and try and find a shop similarly equipped. I will remove the board and take it to the shop as opposed to leaving them with the phone as I suspect they will not want to power up the device after the mod is made.

Again thanks very much for the help !

[anon(5597702)]

Love that this thread went from "there's nothing you can do" to an actual fix! Great knowledge share, thx, everyone!

Posted via CB10

[GRudolf94]

Hey GRudolf94 !

Thanks so much for responding with more details and I (and I'm sure others here) really appreciate your clearly well qualified support. I'm very hopeful this will work for my two bad passports. Since posting, have you done any further testing or even used the repaired passport ?

I'm assuming based on your new diagram the multiplexer has six "legs" and the four outside legs are jumpered north to south with the center contacts left unconnected.

I'm not sure what hot air rework is, but I suspect it's using a hot air gun to melt the solder as opposed to a soldering iron. I've changed hundred of IC chips with a soldering iron and a solder sucker with boards up to five layers. I do agree the contacts are much smaller than I've seen in the past. In anycase, I'll follow your advice and try and find a shop similarly equipped. I will remove the board and take it to the shop as opposed to leaving them with the phone as I suspect they will not want to power up the device after the mod is made.

Again thanks very much for the help !

Hey, glad to help. Yes, I have used the repaired Passport until maybe a month ago. Now it has no SIM because I changed phones, but if I pop one in, the radio will still be working.

Correct on the pins.

Hot air rework in this case implies specialized equipment with controlled flow and temperature, and a small nozzle. It's absolutely a requirement because you can't cleanly pull the metal shield can that covers those components with only a soldering iron. In any case, most phone repair guys will be able to do it.

Keep us posted, and good luck!