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Old 9th April 2007, 06:08 PM   #1
braden is offline braden  Canada
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Default chip amp inside z560

Hello Everyone.

I was listening to some Grandfunk when my left front channel just cut out. I tried using different speakers on that channel and no luck. All my sats work fine, just the one channel is gone.

So what I've done is completely disassembled the entire unit, all the sats, the subwoofer, and laid all the parts out on my workbench and cleaned everything from dust and whatnot.

What I was thinking of doing was removing the rear channel amplifier chip and putting it in place of the front channel IC that is blown. I haven't disassembled the actual plate amplifier yet, as I'm not too sure I want to go there without the proper knowledge.

Basically I'd like to convert this 4.1 plate amp into a 2.1, and move the rear two speakers into a new box that I would make, that would house two Tang Band drivers each.

Does anyone have any information pertaining to which of the ICs I would have to desolder and solder in place of the front channel?

here are some pictures of what I've pulled apart.
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Old 9th April 2007, 10:46 PM   #2
jaycee is offline jaycee  United Kingdom
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Logitech love to use ST chips. Which chips is this one using?

At a guess from the pics they will be using two chips that are stereo... and two chips that are mono in bridge mode to drive the sub.. but thats just a total guess.
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Old 11th April 2007, 06:23 AM   #3
space is offline space  Norway
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I think I've read about it before. If my memory serves me well, it uses TDA7293 chips. One for each ch except sub which uses 2.

From time to time there are some of these chips on ebay. (2 pcs. a.t.m. when wrighting this)

I guess the 4 chips in one end of the amp plate is the four channels and the two on the other end is for the bass.

To figure out which of the four channels is which, you probably need to do some measurements.


space
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Old 11th April 2007, 11:49 AM   #4
AndrewT is offline AndrewT  Scotland
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Hi,
download the datasheet for the TDA and compare it to your examples.

Can you read the labelling hidden under the securing clip?

Have you identified which on is dead?
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regards Andrew T.
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Old 12th April 2007, 03:41 AM   #5
braden is offline braden  Canada
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I got off work (consisted of building dirt jumps with a local crew, volunteer work more or less) ... and went straight to disassembling the z560's amp.

I had the hardest trouble with the long plastic studs that help up the PCB board. They were hollow and had a 4" (roughly) long machine screw through them with the head hidden beneath the heatsink. the nut on the other end was exposed and easily accessible on the top of the PCB, but they used some type of wax/threadlock thats impossible to get off. I cheated and heated the nut up with a soldering gun, and went at it with a 7/32" socket and they came off like butter.

Anyway.. I took it all apart and discovered FOUR TDA7293 on one side of the heatsink (I assume those are for the FOUR sats ...) and on the other side of the heatsink was only TWO TDA7293. Beneath TDA7293 on all the chips was R880K0220 I'm not sure what that implies.

On for each of the FOUR TDA7293 (for the sats) were TWO capacitors rated @ 220microferrad, for a total of eight on that side.

For the subwoofers, each TDA7293 had TWO 1000microferrad capacitors. and the who board seemed to be powered by two massive 10,000microferrad capacitors. All capacitors were made by the brand name Chang.

I haven't located which one was damaged as of yet, but I'm narrowing it down to one of the FOUR on the one side of the amp, you'll see in the pictures. None of them look damaged, or burnt, or anything, they all look pretty clean, except for the thermal paste smeared all over them.

I really appreciate your help. If you would like any more information please ask me anything I am willing to do anything to get this to work as a 2.1 setup.

My good friend just bought a set of Mackie SR1530's on eBay, and he's giving me his set of z560's that still work perfectly with no problems. So now I have a backup set I can reference.


ohhhh here are the pictures i almost forgot.

Click the image to open in full size.

**check out the notes section for various notes

ps: about my bike, here is a picture of a new fork I just got for the season.

Click the image to open in full size.

Once again, thank you for taking the time to read this.

Regards

Braden.
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Old 12th April 2007, 05:47 AM   #6
jleaman is offline jleaman  Belgium
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Lots of little green caps, should research there values and replace them with better ones, Looks to be lots of active x-overs per channel too.

J'
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Old 12th April 2007, 06:59 AM   #7
space is offline space  Norway
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First thing I would do is check the 4 IC's to see if one really is broken. (Maby there is a faulty/broken wire somewhere.) Measure output on all with and without inputsignal. Check for DC when testing with no input. Check AC at output with a constant AC input. (Best to connect a AC input directly on the IC input.) Remember to have some kind of heatsinking on IC's. (Fast turn on/off will probably be ok without heatsink. (TDA7293 have overtemp safety shutdown.)

space
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