I recently got a water-damaged iPhone from my mother and a drop-damaged iPhone from my step-mom about 6 months ago. I merged the two together (just swapped the screen from the water damaged one over), and voila, I had a functional iPhone 3G.

However, I am having frequent wifi drops on it. It will sit there showing full connection and then drop down to 1 bar or even disconnect at least once every 5 minutes. It will pick it up again, and then reconnect. It seems to occur frequently even when the phone is just sitting there.

It is running 4.2.1 non-jailbroken and still having the issues. Since I took it apart, I assume it could be a connection or something inside, but I am unsure where to begin. I have completely ripped apart my iPhone 4, so I am not afraid to get my hands a little dirty. Might anyone have a suggestion to fix it?

The device has been jailbroken before and downgraded to 3.1.3, but it still presented the issue then. I am unsure if it was working consistently before I received it or not.

Things I've tried:
-Resetting network settings (from iPhone)
-Changing router channel (1/7/11 tried, can only pick up 2 other wifi networks so should have worked on at least 1 of them)
-Hard rebooting
-iTunes 4.2.1 restore

Thanks,
Brett Sparkman

What baseband is on the phone? Though it's unlikely, if you had an iOS 3.x baseband and you were running iOS 4.2.1 you can have WiFi issues.

When you took it apart, were you absolutely certain sure you have a stable and tight connection between the antenna board's flex connector and the mainboard? This should be the only connection inside that could impact your WiFi.

This is happening on every WiFi network? I ask because I previously had a Linksys WRT54G that had a bad firmware on it, and when an Apple device connected to it it would slowly drop transmission rate until it was transmitting at 1Mbps, then at that point the iPhone would drop off wireless. Wait about 5 minutes and it would reconnect and the process would start all over. I reflashed the WRT54G with DD-WRT and reset it to factory defaults, set it back up, and the problem was resolved.

The baseband is 05.15.04, which should be the default 4.2.1 baseband. As a side question, would issues occur if I attempted to downgrade to 3.1.3 for the performance increase?

I am not sure if it did when I took it apart. I only replaced the LCD screen, so I did not need to remove the main board. Since the previous screen messed up because of a drop, I assume that the shock could have knocked the antenna board loose. I'll check it later tonight or tomorrow and repost.

It is happening on my home network as well as my university network. My wife's 3G and my 4 (before water damage) had no problems on either network.

I went ahead and took the phone apart all the way to the GPS antenna. It seems that some definite humidity had gotten into the phone as several of the screws (and thus screw contacts) were somewhat corroded. I cleaned all of the contacts and screws with IPA, and I think that the problem has been fixed. I've been on for 15 minutes with no drops, and the bars are staying full. Hopefully this will continue.

My question about performance and downgrading from 4.2.1 to 3.1.3 are still in question however. Also, I previously tried to jailbreak 3.1.3 and Cydia told me I needed to update it. I did this, and Cydia was stating that the OS was 4.x (at least on the Cydia screen). Whenever I installed any jailbroken apps, I would have to restart my phone to get SpringBoard to restart. Have any tips on fixing that?

Thanks,
Brett

Hmm, I hate to say I haven't had that issue, but I donated my unlocked 3G to my brother in law who doesn't really care much about jailbreaking, just wanted the unlocked iPhone on T-Mo.

Have you tried the re-spring button from SBSettings when you need to force a re-spring? I know it's not a great solution but I hate to say I don't have much more to offer...