Hello,I'm having trouble repairing a kenwood DTS Amp model: KRF-7775D. I have the service manual but still could not find any faulty components. Problem with this is that it works on it's own, seems it has a mind of it's own, so I seviced and replaced the memory backup caps near the main u-com and it fixed the "Mind" problem. Now it's doing exactly what I want it except no Audio output. checked everything, output stage, protection, muting etc. no luck. But if I remove the DSP assy ( which has the DAC's, sub u-com and the DSP chip) I can get audio from the dvd 6 channel direct input. sounds great. but if I insert the card the d**n thing goes mute.so I checked the card ( voltages and the resets) found that the DSP power (3.3V) is missing. the funny thing is this voltage is present at power on and dies when the protection relay switches on and mute deactivates. The DSP is powered down and is not activated in any sound modes or input modes, so my guess is with the DSP power down the DAC's are not workin, and with the card removed the u-com bypasses this stage. I replaced the sub u-com chip but nothing happened. further checking revealed that after the sub u-com recieves the master reset from the main u-com, it powers down the 3.3V AVR. So after few seconds the after power on the 3.3V dies. I donno why, cud not think of anything, but I did find the master clk from main u-com to the sub u-com is at 3 volts. But to my knowledge it should be 3.3V. Cause it the clk goes via level shifter 5V-3.3V IC.so the input being at 5V with no data or clk output is 3V. All the gates of this IC show's 3.3V at high level. So may be this is a problem but the funny thing is I can see the clk from this out put, when change the sound modes which indicates the sub u- com is RX'ing it's data. so wht gives, why no sound. Pls can any one give me a hint on this issue.Rifaa
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