[置頂] 維修筆記(Notes on Diagnosing and Fixing Everything Electronic)


前言

本人維修的一點經驗記錄。

維修的意義是什么呢?”How to Diagnose and Fix Everything Electronic - by Michael Jay Geier”(book_how)這本書中給出了參考:

  • It might be easier, but it’s usually not cheaper! Sans the cost of labor, repair can be quite cost effective. There are lots of other good reasons to become a proficient technician, too: ?
  • It’s fun. You’ll get a strong sense of satisfaction when your efforts yield a properly working gadget. It feels a bit like you’re a detective solving a murder case, and it’s more fun to use your noodle than your wallet.
  • It’s absorbing. Learning to repair things is a great hobby to which you can devote many fruitful hours. It’s good for your brain, and it beats watching TV any day (unless you fixed that TV yourself!).
  • It’s economical. Why pay retail for new electronics when you can get great stuff cheap or even free? Especially if you live in or near a city, resources like craigslist.org will provide all the tech toys you want, often for nothing. Lots of broken gadgets are given away, since bringing them in for repair costs so much.
    They’re yours for the taking. All you have to do is fix ‘em!
  • It can be profitable. Some of the broken items people nonchalantly discard are surprisingly valuable. When your tech skills become well developed, you’ll be able to repair a wide variety of devices and sell what you don’t want for yourself.
  • It can preserve rare or obsolete technology. Obsolete isn’t always a negative term! Some older technologies were quite nice and have not been replaced by newer devices offering the same features, utility or quality. The continued zeal of analog audio devotees painstakingly tweaking their turntables offers a prime example of the enduring value of a technology no longer widely available.
  • It’s green. Every product kept out of the landfill is worth two in ecological terms: the one that doesn’t get thrown away and the one that isn’t purchased to replace it. The wastefulness of tossing out, say, a video projector with a single capacitor is staggering. To rip off an old song, “Nothing saves the green’ry like repairing the machin’ry in the morning….”
  • Your friends and family will drive you crazy. Being a good tech is like being a doctor: everyone will come to you for advice and help. Okay, maybe this one isn’t such an incentive, but it feels great to be able to help your friends and loved ones, doesn’t it? Being admired as an expert isn’t such a terrible thing either.

可見,這涉及到經濟、環境(綠色)、學習、樂趣、保護稀有技術、潛在的收益等等。樂趣在於你努力過后裝置正常工作,所帶給你的強烈滿足感與成就感,畢竟動一動腦子比揮一揮皮夾更有趣!這就像親手為心愛的女孩做花要比買得更讓自己刻骨銘心!

心得

檢修步驟

  • 先檢查外觀,如電源線及插頭有無燒焦或斷裂。若有則修復,然后進入下一步;無則進行下一步。
  • 拆機,觀察電路板及元器件,看有無損壞現象,如:電路板折斷、保險絲熔斷、電阻發黑、電容鼓起、焊點脫落等。
  • 用萬用表歐姆檔最高檔測試輸入端電阻,應較大,再測試輸出端電阻,應較小。
  • 根據上步結果,觀察電路板,鎖定可能壞的元件,進行檢測。若壞則予以更換。確保所有元件均完好后,進入下一步。
  • 通電檢查,若仍不能正常工作,則應先檢測電源供應部分,若電壓與標准值相差較大,則應先維修電源模塊。否則測試其它模塊電壓。

實錄

電磁爐

故障現象:開機無任何反應
維修日期:2014年寒假

檢測與分析:數字式萬用表,二極管檔,可以在板初步檢測出:保險絲、IGBT、整流橋已壞。但是什么原因導致這三個元件損壞呢?仔細觀察線路板,發現一個個頭大的電容的引腳已經脫離板子(焊接有問題),是它造成的。

損壞元件:保險絲(熔斷)、IGBT(擊穿)、整流橋(擊穿)

補焊電容引腳並更換損壞元件后正常工作至今。

衛星機頂盒

衛星機頂盒

故障現象:開機無反應
維修日期:2014年暑假

檢測與分析:詢問了具體情況,得知暴風雨晚打雷打閃后,出現此故障,於是猜測是雷電帶來的點擊損壞。首先懷疑電源模塊有問題,在確定電路中無明顯元件損壞、電路沒有短路的前提下,從其它正常機頂盒上取下電源小板,試機正常!故更換電源小板,淘寶有售,10元左右。

機頂盒&遙控器

故障現象:按任意鍵,無任何反應。
維修日期:2014年寒假

檢測與分析:使用手機攝像頭檢測遙控器,正常,懷疑是機頂盒接收電路已壞。然而,檢測機頂盒后,發現接收頭輸出端電壓隨遙控按鍵按下變化,單片機輸入腳電壓也變化。后來,用萬能遙控器,成功實現遙控。

數碼播放器

故障現象:揚聲器正常,插入耳機耳機無聲音,調大音量,耳機揚聲器同時有聲
維修日期:2016年3月21

檢測與分析

  • 拆機:這個機器稍微有點難拆。背部1顆螺絲釘,前部數碼管保護罩下一枚,揚聲器防塵防護網罩下5顆,不對,是六顆,哈哈,見圖:
    揚聲器防塵防護網罩下5顆
    不對,是六顆,哈哈

  • 檢修:經觀察發現無明顯元器件損壞,於是上網查原理電路,了解到,數碼播放器有靜音腳,耳機插入時,該引腳作用,緊接着微控制器控制關斷音頻功放輸出(耳機功率小,不需要功放的,記得初中有個無需電池的收音機電路,直接利用無線電能量就能驅動耳機)。
    數碼播放器原理框圖

此款播放器,采用YX8002D單聲道音頻功放,4歐姆揚聲器,沒有查到該芯片資料,不過查到了TC8002D音頻功放,完全兼容,如下圖:
數碼播放器音頻功放原理圖

補張耳機圖以后備用:
耳機結構圖

可見:對於含有4引腳的耳機母座,插入只有3極的耳機,相當於母座3、4腳同接GND,所以一般靜音控制為低電平使能;美標耳機與國標耳機不應混用,雖然能夠正常聽音,當控制鍵和話筒不起作用或錯亂。

重點查耳機靜音線、靜音控制線、音頻功放、主控

經檢測,無論插入耳機與否,音頻功放8002D的關斷腳(1腳)電壓恆為 0V ,將8002D拆下后再檢測,正常,故更換8002D。可惜西安中工、電子市場都跑了,沒有,無奈只能淘寶(0.1~2.0¥不等)。

損壞元件:單聲道音頻功放8002D

參考資料

[book_how]: “How to Diagnose and Fix Everything Electronic - by Michael Jay Geier”


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