Vibe slick A3 problem

kirkmiles · 04:35 PM

Hi,
My Vibe A3 amp was going into protect mode. I opened it up and after some research i tested the o/p transistors and found one of them to be reading near 0 ohms. On the transistor its marked K D998 0632. I searched around for a replacement and found a K D998 0.8D. I have replaced the damaged one with this and now amp not hitting protect mode but little to no output on channel 4(assuming this was faulty channel)? Have i fitted an unsuitable transistor? or could something else be at fault? I have some electronic knowledge/experience but im only learning

Any help would be much appreciated and thanks in advance.

Perry Babin · 25th March 2011, 05:26 PM

The problem is not likely to be due to the transistor.

Operate all potentiometers and switches through their entire range with a speaker connected to the weak channel. Does the audio play through at a normal level when operating the controls?

kirkmiles · 25th March 2011, 06:37 PM

I tried moving any controls and didnt seem to improve? I havent checked any other components as yet but would the amp go straight into protect mode if components were at fault?

Perry Babin · 25th March 2011, 07:26 PM

It depends on which component was faulty.

On the dead channel, measure the resistance from the speaker terminal that's used for bridging to the third leg of all of the output transistors. Do you read 0 ohms for two of the transistors?

Is one of the transistors the one you replaced?

kirkmiles · 25th March 2011, 08:07 PM

I got near 0 ohms on 2 of the transistors but wasnt the one I replaced? The one I replaced turned out to be on channel 3

and channel 4 is the one thats down???? maybe worth testing again and having a good fiddle with all the controls but I also tested it in 2 CH mode (3&4 together) and CH 3 worked but no 4? Confused...

Perry Babin · 25th March 2011, 08:21 PM

Can you post a good quality photo of the inside of the amp?

kirkmiles · 25th March 2011, 08:53 PM

Here it is

[IMG https://lh4.googleusercontent.com/_M...2/P1000207.JPG[IMG]

[IMGhttps://lh4.googleusercontent.com/_M...0/P1000206.JPG[IMG]

Thanks

Perry Babin · 25th March 2011, 09:49 PM

Can you send me larger, higher resolution photos?

Which of the 4 groups of transistors (top left, top right...) is the dead channel?

Do you read the same DC voltage on the center legs of the output transistors in that channel as you do in the other channels?

kirkmiles · 26th March 2011, 10:20 PM

I get the same DC voltage on all middle legs of the transistors? Tested again and channel 4 definately dead. CH3/4 bridged seems to work? can I send you pics via email? does not seem to be letting me upload at full res?

kirkmiles · 26th March 2011, 10:30 PM

Got photo to upload, dead channel circled in red

Imageshack - amphighres.jpg

All help is much apreciated

25th March 2011, 04:15 PM	#1
kirkmiles diyAudio Member Join Date: Mar 2011	Vibe slick A3 problem Hi, My Vibe A3 amp was going into protect mode. I opened it up and after some research i tested the o/p transistors and found one of them to be reading near 0 ohms. On the transistor its marked K D998 0632. I searched around for a replacement and found a K D998 0.8D. I have replaced the damaged one with this and now amp not hitting protect mode but little to no output on channel 4(assuming this was faulty channel)? Have i fitted an unsuitable transistor? or could something else be at fault? I have some electronic knowledge/experience but im only learning Any help would be much appreciated and thanks in advance. Last edited by kirkmiles; 25th March 2011 at 04:35 PM.

25th March 2011, 05:26 PM	#2
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	The problem is not likely to be due to the transistor. Operate all potentiometers and switches through their entire range with a speaker connected to the weak channel. Does the audio play through at a normal level when operating the controls? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

25th March 2011, 07:26 PM	#4
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	It depends on which component was faulty. On the dead channel, measure the resistance from the speaker terminal that's used for bridging to the third leg of all of the output transistors. Do you read 0 ohms for two of the transistors? Is one of the transistors the one you replaced? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

25th March 2011, 08:21 PM	#6
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Can you post a good quality photo of the inside of the amp? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links

25th March 2011, 09:49 PM	#8
Perry Babin diyAudio Member Join Date: Nov 2003 Location: Louisiana	Can you send me larger, higher resolution photos? Which of the 4 groups of transistors (top left, top right...) is the dead channel? Do you read the same DC voltage on the center legs of the output transistors in that channel as you do in the other channels? __________________ Links >> Basic Car Audio Amp Repair --- Basic Car Audio Electronics --- Basic Transistor Testing --- Basic Switching Power Supply Design --- Basic Computer Skills << Links


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25th March 2011, 06:37 PM	#3
kirkmiles diyAudio Member Join Date: Mar 2011	I tried moving any controls and didnt seem to improve? I havent checked any other components as yet but would the amp go straight into protect mode if components were at fault?

25th March 2011, 08:07 PM	#5
kirkmiles diyAudio Member Join Date: Mar 2011	I got near 0 ohms on 2 of the transistors but wasnt the one I replaced? The one I replaced turned out to be on channel 3 and channel 4 is the one thats down???? maybe worth testing again and having a good fiddle with all the controls but I also tested it in 2 CH mode (3&4 together) and CH 3 worked but no 4? Confused...

25th March 2011, 08:53 PM	#7
kirkmiles diyAudio Member Join Date: Mar 2011	Here it is [IMG https://lh4.googleusercontent.com/_M...2/P1000207.JPG[IMG] [IMGhttps://lh4.googleusercontent.com/_M...0/P1000206.JPG[IMG] Thanks

26th March 2011, 10:20 PM	#9
kirkmiles diyAudio Member Join Date: Mar 2011	I get the same DC voltage on all middle legs of the transistors? Tested again and channel 4 definately dead. CH3/4 bridged seems to work? can I send you pics via email? does not seem to be letting me upload at full res?

26th March 2011, 10:30 PM	#10
kirkmiles diyAudio Member Join Date: Mar 2011	Got photo to upload, dead channel circled in red Imageshack - amphighres.jpg All help is much apreciated

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