Took on a new challenge but need to be pointed in some directions

spooney · 17th December 2010, 01:39 AM

Well I decided I would attempt to make a repair on this off brand amp I came across. I mean it is a cheap amp how bad could it be right? Well man this thing has been to hell and back. For starters it is a very cheap single sided pcb. PS fets are shorted and have failed explosively(somebody tried to solder in a pair of voltage regulators in place of two of the ps fets

) The through holes for two or three of the ps fets have been burnt out of the board. With the help of Perry's tutorial this was easy enough to work around. I soldered in a pair of temporary ps fets and got the power supply up and running. I have +/- approximately 35 volts at the rails. One channel produces clean audio(outputs are ktb688 and ktd718). The other channel had shorted outputs (the ktb688's) . With the ktd718's in circuit the amp powers up fine but I have nearly full rail voltage at the output terminals in this channel. The ktd718's are not reading as shorted. Where do I take this repair from here. My mind is failing me at this point . I have a feeling it is a driver or pre driver but perhaps I am way off.

spooney · 17th December 2010, 01:47 AM

Oh yeah also wondering if anybody feels that fja4213 and fja4313 would be good subs for these outputs

17th December 2010, 01:39 AM	#1
spooney diyAudio Member Join Date: Dec 2006	Took on a new challenge but need to be pointed in some directions Well I decided I would attempt to make a repair on this off brand amp I came across. I mean it is a cheap amp how bad could it be right? Well man this thing has been to hell and back. For starters it is a very cheap single sided pcb. PS fets are shorted and have failed explosively(somebody tried to solder in a pair of voltage regulators in place of two of the ps fets ) The through holes for two or three of the ps fets have been burnt out of the board. With the help of Perry's tutorial this was easy enough to work around. I soldered in a pair of temporary ps fets and got the power supply up and running. I have +/- approximately 35 volts at the rails. One channel produces clean audio(outputs are ktb688 and ktd718). The other channel had shorted outputs (the ktb688's) . With the ktd718's in circuit the amp powers up fine but I have nearly full rail voltage at the output terminals in this channel. The ktd718's are not reading as shorted. Where do I take this repair from here. My mind is failing me at this point . I have a feeling it is a driver or pre driver but perhaps I am way off.

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17th December 2010, 01:47 AM	#2
spooney diyAudio Member Join Date: Dec 2006	Oh yeah also wondering if anybody feels that fja4213 and fja4313 would be good subs for these outputs

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