本帖最後由 billymud 於 2013-10-10 12:27 編輯
jojo9326 發表於 2013-10-10 12:21 static/image/common/back.gif
C11 的68uf 450v
c11 超熱, 快d 換走! 小心爆...... 怪不得拆聲.....
可能銲錯極性了。{:1_341:}
本帖最後由 billymud 於 2013-10-10 12:43 編輯
"w18果個位d錫長到掂到個殼～係咁出火花" >>> 表示該處附近曾發生short circuit。大量電流引致overheated , 熔锡!
索返d錫之後就無熱，都唔表示已澈底解除威脅，你尚要去查找不足～
正如澳門客師兄所講: " ....電路上拆聲多數是供電問題，或供電不足，如果是大聲拆聲更多數因為電流不足而致 ."
如果調換胆都一樣，那就應該是電源問題，我在pm裡講的電源退交連電阻即是電路圖上R5，R6，R7，R8，你可以測量W27和W23電壓是否一樣，W26和W22電壓是否一樣，尤其大聲沙聲那邊，電壓應該較低，這時可拆下退交連電阻測量是否變值{:1_253:}
billymud 發表於 2013-10-10 11:35 static/image/common/back.gif
哦原來您冇反壓保護lt1084, 將來又死點算？.....
1085系列是不需這保護二極管，因為自己有短路保護，見1085系列解釋原文
Protection Diodes
In normal operation, the LT1083 family does not need any
protection diodes. Older adjustable regulators required
protection diodes between the adjustment pin and the
output and from the output to the input to prevent overstressing
the die. The internal current paths on the LT1083
adjustment pin are limited by internal resistors. Therefore,
even with capacitors on the adjustment pin, no protection
diode is needed to ensure device safety under short-circuit
conditions.
Diodes between input and output are usually not needed.
The internal diode between the input and the output pins
of the LT1083 family can handle microsecond surge
currents of 50A to 100A. Even with large output capacitances,
it is very difficult to get those values of surge
currents in normal operations. Only with a high value of
output capacitors, such as 1000mF to 5000mF and with the
input pin instantaneously shorted to ground, can damage
occur. A crowbar circuit at the input of the LT1083 can
generate those kinds of currents, and a diode from output
to input is then recommended. Normal power supply
cycling or even plugging and unplugging in the system will
not generate current large enough to do any damage.
The adjustment pin can be driven on a transient basis
±25V, with respect to the output without any device
degradation. Of course, as with any IC regulator, exceeding
the maximum input to output voltage differential
causes the internal transistors to break down and none of
the protection circuitry is functional.
jojo9326 發表於 2013-10-10 12:31 static/image/common/back.gif
無焊錯的～
就係果日空載時發現果粒超熱～
之後琴日著機時～發現呢粒野出到driver board既w18果個位～
電解電容超熱應先看看有無反接，耐壓是否足夠，這二個問題都會做成電容發熱破裂{:1_253:}
