Kenwood KAC-628

[dazzler22]

Hi All

I have this amp that as far as im aware was working when i removed it from the car a few years ago, I went to install it into my new car last weekend and it is not powering up.

the fuses are all ok and the correct power is coming through the Batt+ and remote to turn it on.

any tips or help anyone can give on where to start testing to see if i can find the fault would be greatly appreciated.

Pics attached below.

Thanks
Daz

 

[Perry Babin]

Post the DC voltage on all pins of IC4. Copy and paste the following into your reply. I don't have the manual for the 628 but it looks like the 629 so that's what I'm using as a reference. Let me know if something I suggest doesn't seem right.


Pin 1:
Pin 2:
Pin 3:
Pin 4:
Pin 5:
Pin 6:
Pin 7:
Pin 8:
Pin 9:
Pin 10:
Pin 11:
Pin 12:
Pin 13:
Pin 14:
Pin 15:
Pin 16:

 

[dazzler22]

Hi There,

thanks for the reply,

I have nothing reading on any of the pins, i guess that is the first problem right there, there is no power getting to that chip.

could this be a grounding issue on the board?

Cheers
Daz

 

[Perry Babin]

If you have 12v on the center leg of Q17, post the DC voltage on all 3 legs of Q36 and Q37.

 

[dazzler22]

On the center leg of Q17 i have .01v (double checked on a bigger scale, actually fluctuating between .004 and .005)

don't seem to be getting any ready on Q36 or Q37....

I really appreciate the help so far, thanks!

Cheers
Darren

 

[Perry Babin]

Are you sure that the fuse isn't blown?

 

[dazzler22]

Just put a new fuse in just in case it was the connection that was dodgy on the old one, no difference.

one thing i did just check though on powering it up the middle leg of Q17 started off at almost 1v and steadily dropped with the meter on it down to .001v.

Cheers
Daz

 

[Perry Babin]

If you don't have an auto-ranging meter, set it to the lowest DC voltage range.

With the black probe on the main ground terminal and the red on the 3rd leg of Q17, what is the voltage?

With the black probe on the B+ terminal and the red probe on the center leg of Q17, what is the DC voltage?

 

[dazzler22]

If you don't have an auto-ranging meter, set it to the lowest DC voltage range.

With the black probe on the main ground terminal and the red on the 3rd leg of Q17, what is the voltage? With the meter set to 200M the center leg is reading 04.6v

With the black probe on the B+ terminal and the red probe on the center leg of Q17, what is the DC voltage?-12.37v

 

[Perry Babin]

If the fuse is OK, it appears that you have a burned trace between the B+ terminal and the center-tap of the power transformer. You'll need to pull the board to look for it

 

[dazzler22]

ok, i have removed the board, here are some pics:-










What is the best way to test these?? or do you see anything that looks out of place?

Thanks
Daz

 

[Perry Babin]

Broken solder connection. Add new solder, desolder then re-solder.

Clamp transistors down before applying power.

 

[dazzler22]

You Sir are a Hawk-Eyed Genius!

amp is now powering up,

you are awesome!

Thanks
Daz

 

[dazzler22]

Just to let you know I have tested it out and it is all good.

Next on the list is a vibe amo I have that is powering up but not doing anything... Separatethread for that when I get round to it.

Cheers
Daz

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