跳转到主内容

修复你的物品

维修的权力

商店

发售于2016年9月16日。型号为1660、1778。有 GSM 或者 CDMA 网络制式可选。提供32、128或者256GB 的存储空间。提供玫瑰金色、金色、银色、黑色和亮黑色。

1976 个问题 查看全部

vdd main short but no heat

so i have an iphone 7 in this morning and as title says i have a vdd main short, wire soldered on and drawing 2 amps but no sign of heat. can i raise the amps and if so what is the max

已回答! 显示答案 我也有这个问题

这是一个好问题吗?

得分 0
添加一条评论

1个回答

已选择的解决方案

Hey Daniel. Looking for a heat signature can be tricky, especially when using a DCPS as the power source. Most bench power supplies offer current limiting protection. That means that when the current reaches the maximum set output, the PS will drop the voltage output in order to maintain the max current.

So when looking for heat, you are essentially hoping some component will give off this heat as a result of power dissipation. However, P=V*I (POWER equals VOLTAGE times CURRENT) through the component. So if your current is 2A but the voltage is essentially Zero (due to current limiting), then the power will be 0W...so no heat!

So the thing to do is either increase the current setting on the DCPS so that there is some voltage drop across the shorted component or use a battery which will not be current limited. The advantage of the DCPS is that you can bring it up slowly to avoid any catastrophic damage by a sudden surge of power.

The other thing to try is to start with a lower voltage, say 2V with a max current setting and then slowly build up the voltage. This can weed out the bad component before fully activating the logic board.

这个答案有帮助吗?

得分 5

评论:

cheers @refectio , think i have burnt the short as when i connect the power lead to dc i wasnt gettin draw now its going upto 0.76 amps. when plugging dc in before pressing the button im getting around 0.16 amps before pressing power. need a new lcd to see if i have image now

完成的

@refectio any idea why im getting 0.16amp draw before pressing power

完成的

It could be just battery charging...

完成的

Battery does nothing. Short drives battery to zero immediately . No current - no heat, so this is not solution.

Also, in my case when you try with DCPS voltage drops to 0.8v / 1A, and 1.6v / 2A again ZERO heat. Same at 3A or 4A.. Just the cables heating up.

完成的

@ninos22 check vdd_main or vdd_boost

完成的

显示更多的1条评论

添加一条评论

添加你的答案

daniel 将永远感激不已
浏览统计数据:

过去的24小时: 0

过去的7天: 0

过去的30天: 8

总计 727