CTC177 bad eeprom ??

Question

For all of you people familiar with this chassis: Set came in dead. I knew immediately it was the tuner grounds problem so I did that. Now set comes on just fine but without any audio. I can order a new eeprom, but why have my customer wait if there are indications that it may not be the eeprom ? For example, disconnecting emmiter of Q903 does not help. Pin 29 of the micro is not high, so the mute circuit is not activated. I replaced the audio output IC. All caps check ok. I tried to see if the speakers are in the OFF position by disconnecting pin 8 of eeprom after set comes on, but i could not see this option in all the menus ( I am familiar with this procedure). Does every CTC177 chassis have this option ? If so, how do I get to it ? I am afraid I may have to wait for this $2 part after all. Thanks for your ideas.

moonlite

Leonard Caillouet · Accepted Answer

Why did you replace the output? Do you have audio at its input? Have you traced the audio at all? Where do you have it and where not? Does it have audio on the aux input?

Which version of the CTC177 is it? I have some good EEPROM data stored if you have an interface to read and write the data if you want to try that. I agree, it does not sound like a bad EEPROM if pin 29 is not high, however.

Leonard

Andy Cuffe · Answer

I've seen some really strange problems caused by corrupted EEPROMs. I had one set that wouldn't come into horizontal sync no matter what I adjusted the H freq to. Another set refused to change to the A/V input, but was otherwise fine. A new EEPROM fixed both sets.

If you have any EEPROMs from similar RCAs in the junk pile, give one a try. It will probably work well enough to tell you for sure if the EEPROM is causing no sound. Andy Cuffe

snipped-for-privacy@psu.edu

dkuhajda · Answer

If it is a stereo set check the alignment parameters in the eeprom.If those are off, there is a good chance that several other eepromvalues have been changed and you might still replace it and do a fullchassis eeprom alignment.

CTC177 bad eeprom ??

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