CTC177 bad eeprom ??
 

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

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

"moonlite" wrote in message
oups.com...
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

On 27 Aug 2005 13:26:33 -0700, "moonlite" wrote:

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

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

-- Use this address until 12/31/2005

-- Use this address after 12/31/2005

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 eeprom
values have been changed and you might still replace it and do a full
chassis eeprom alignment.