CTC chassis eeprom question

[Bill]

Hello all- I have a CTC187 chassis that is completely dead. voltages
on the STK regulator are perfect. Pin 8 of the eeprom has 5v. However,
pins 5 and 6 have only 3 and 2.7 volts respectively, even with the
eeprom removed. Could this possibly be my problem ? I believe those
pins should be around 5 volts each. If so, does anyone know what can
cause the voltage here to go low ? I hate to replace the micro unless
I'm certain it is the problem. Thanks.

 

[john]

Bill Does the set chirp when you plug it in ?

If not check that resistor off the Big Filter cap
its a little 1/8 watt 1.2 m or something.

kip

--
"Watch the return E-Mail addy its false"
"Bill" <elect21st@aol.com> wrote in message
news:8fb59540.0404090313.4cb68588@posting.google.com...

Hello all- I have a CTC187 chassis that is completely dead. voltages
on the STK regulator are perfect. Pin 8 of the eeprom has 5v. However,
pins 5 and 6 have only 3 and 2.7 volts respectively, even with the
eeprom removed. Could this possibly be my problem ? I believe those
pins should be around 5 volts each. If so, does anyone know what can
cause the voltage here to go low ? I hate to replace the micro unless
I'm certain it is the problem. Thanks.

 

[Bill]

"john" <va3mmTAKEOUTTHIS@niagara.com> wrote in message news:<newscache$4wowvh$aca$1@newsfeed.niagara.com>...

Bill Does the set chirp when you plug it in ?

If not check that resistor off the Big Filter cap
its a little 1/8 watt 1.2 m or something.

kip

Yes, the set chirps at plug in. All voltages are normal, except for

pins 5 and 6 of the eeprom which I'm seeking some opinions on.
Monitoring the two pins on the scope shows continuous activity, even
with a new eeprom. Thanks

Bill

--
"Watch the return E-Mail addy its false"
"Bill" <elect21st@aol.com> wrote in message
news:8fb59540.0404090313.4cb68588@posting.google.com...
Hello all- I have a CTC187 chassis that is completely dead. voltages
on the STK regulator are perfect. Pin 8 of the eeprom has 5v. However,
pins 5 and 6 have only 3 and 2.7 volts respectively, even with the
eeprom removed. Could this possibly be my problem ? I believe those
pins should be around 5 volts each. If so, does anyone know what can
cause the voltage here to go low ? I hate to replace the micro unless
I'm certain it is the problem. Thanks.

 

[David]

Continuous activity with a new eeprom? Is it a clean data at 5v peak? If
not you have something loading down the I2C data bus.

Then do not overlook the horizontal drive circuitry, it is very common for
h-drive transformer connections to go bad, causing dead set.

David

"Bill" <elect21st@aol.com> wrote in message
news:8fb59540.0404091153.2a8560ee@posting.google.com...

"john" <va3mmTAKEOUTTHIS@niagara.com> wrote in message
news:<newscache$4wowvh$aca$1@newsfeed.niagara.com>...
Bill Does the set chirp when you plug it in ?

If not check that resistor off the Big Filter cap
its a little 1/8 watt 1.2 m or something.

kip

Yes, the set chirps at plug in. All voltages are normal, except for
pins 5 and 6 of the eeprom which I'm seeking some opinions on.
Monitoring the two pins on the scope shows continuous activity, even
with a new eeprom. Thanks

Bill


--
"Watch the return E-Mail addy its false"
"Bill" <elect21st@aol.com> wrote in message
news:8fb59540.0404090313.4cb68588@posting.google.com...
Hello all- I have a CTC187 chassis that is completely dead. voltages
on the STK regulator are perfect. Pin 8 of the eeprom has 5v. However,
pins 5 and 6 have only 3 and 2.7 volts respectively, even with the
eeprom removed. Could this possibly be my problem ? I believe those
pins should be around 5 volts each. If so, does anyone know what can
cause the voltage here to go low ? I hate to replace the micro unless
I'm certain it is the problem. Thanks.

 

[Jason D.]

On 9 Apr 2004 12:53:28 -0700, elect21st@aol.com (Bill) wrote:

"john" <va3mmTAKEOUTTHIS@niagara.com> wrote in message news:<newscache$4wowvh$aca$1@newsfeed.niagara.com>...
Bill Does the set chirp when you plug it in ?

If not check that resistor off the Big Filter cap
its a little 1/8 watt 1.2 m or something.

kip

Yes, the set chirps at plug in. All voltages are normal, except for
pins 5 and 6 of the eeprom which I'm seeking some opinions on.
Monitoring the two pins on the scope shows continuous activity, even
with a new eeprom. Thanks

Bill

The pin 5 and 6 is also is one of two I2C buses from micro is
typically 4.xV But I typically see almost like 4.5V.

Anything lower you have problem. I find that one of IC is bad start
by unsoldering two pins on each IC hooked to the I2C bus or a nasty
glue under a SMD.

Cheers,

Wizard

 

[RonKZ650]

Check voltage on both ends of the on/off switch. If both pins have 5vdc then
99% of the time the eprom is bad. The LA7610 IC can also load the data lines
down and cause this. If one pin is 5vdc the other 0 then the eprom is working.
Ron

 

[David]

I forgot to ask. You did buy the correct Thomson part number eeprom for
that chassis, not just replace it with a blank generic eeprom by the number
on the chip?

The eeprom MUST have certain values already loaded in it specific to that
chassis it was designed in order for the tv set to power up.

You also have the tuner grounds to fix properly. See www.repairfaq.org.
David

"David" <dkuhajda@locl.net.spam> wrote in message
news:40775eab@news.greennet.net...

Continuous activity with a new eeprom? Is it a clean data at 5v peak? If
not you have something loading down the I2C data bus.

Then do not overlook the horizontal drive circuitry, it is very common for
h-drive transformer connections to go bad, causing dead set.

David

"Bill" <elect21st@aol.com> wrote in message
news:8fb59540.0404091153.2a8560ee@posting.google.com...
"john" <va3mmTAKEOUTTHIS@niagara.com> wrote in message
news:<newscache$4wowvh$aca$1@newsfeed.niagara.com>...
Bill Does the set chirp when you plug it in ?

If not check that resistor off the Big Filter cap
its a little 1/8 watt 1.2 m or something.

kip

Yes, the set chirps at plug in. All voltages are normal, except for
pins 5 and 6 of the eeprom which I'm seeking some opinions on.
Monitoring the two pins on the scope shows continuous activity, even
with a new eeprom. Thanks

Bill


--
"Watch the return E-Mail addy its false"
"Bill" <elect21st@aol.com> wrote in message
news:8fb59540.0404090313.4cb68588@posting.google.com...
Hello all- I have a CTC187 chassis that is completely dead.
voltages
on the STK regulator are perfect. Pin 8 of the eeprom has 5v.
However,
pins 5 and 6 have only 3 and 2.7 volts respectively, even with the
eeprom removed. Could this possibly be my problem ? I believe those
pins should be around 5 volts each. If so, does anyone know what can
cause the voltage here to go low ? I hate to replace the micro
unless
I'm certain it is the problem. Thanks.