CTC203 Won't turn on - Has voltages

[BobD]

I have a CTC203AAS chassis that has all the proper voltages (B+ around
180), 5v on the digital side, 12 v on the regulator. The set refuses
to come up when the power button is pressed. If I bring up voltage
with a variac, I hear the realy click in around 80% full voltage. The
HOT appears to be good (yes I removed and soldered L14401), but the is
no base drive. I checked the digital side of things and the video
processor U12101 does not appear to have any clock wave at the crystal
input. I would expect some sort of waveform here, just like a CPU.
I scoped the power pin while holding it down and I see a series of
pulses after about a second or so, then they stop and resume after a
few seconds. I tried holding Menu while pressing Power the Vol+, still
nothing.
Any ideas?

 

[Jason D.]

On 21 Nov 2003 18:45:12 -0800, rdanek@mail.com (BobD) wrote:

I have a CTC203AAS chassis that has all the proper voltages (B+ around
180), 5v on the digital side, 12 v on the regulator. The set refuses
to come up when the power button is pressed. If I bring up voltage
with a variac, I hear the realy click in around 80% full voltage. The
HOT appears to be good (yes I removed and soldered L14401), but the is
no base drive. I checked the digital side of things and the video
processor U12101 does not appear to have any clock wave at the crystal
input. I would expect some sort of waveform here, just like a CPU.
I scoped the power pin while holding it down and I see a series of
pulses after about a second or so, then they stop and resume after a
few seconds. I tried holding Menu while pressing Power the Vol+, still
nothing.
Any ideas?

On these set, B+ for the horizontal must be 140 when running, when in
off mode, it is slightly higher. SMPS is not complicated circuit,
check the TL431 (U14101) has correct 2.5V and the optisolator is good.

Push power button once and hear the relay click 3 times? That's 3
strikes and out design. This means there is problem either in digital
area or horizontal has a problem (usually flyback)

If this TV has F2PIP (PIP) module, pull it out and carefully look at
SMD resistors this bias the regulator to 3.3V. The regulator has
small steel heatsink. There is one SMD resistor has crack in solder
joint. When F2PIP IC (Big one) loses the 3.3V, the I2C bus jams and
get 3 strikes and out thing. I seen this twice, it can be a tough dog
if other didn't check the PIP module's regulator.

Secondly, make sure the horizontal driver circuit is also good.

Cheers,

Wizard

 

[BobD]

Thanks for the reply. I ended up getting the set working by probing
the I2C bus on the EEPROM (24C08). While I was probing the the clock
line with a scope, I hit the power button and the set came up! The set
now seems to work fine. Time will tell if it lasts. Weird!


jpero@sympatico.ca (Jason D.) wrote in message news:<3fbf17ef.31802697@news1.on.sympatico.ca>...

On 21 Nov 2003 18:45:12 -0800, rdanek@mail.com (BobD) wrote:

I have a CTC203AAS chassis that has all the proper voltages (B+ around
180), 5v on the digital side, 12 v on the regulator. The set refuses
to come up when the power button is pressed. If I bring up voltage
with a variac, I hear the realy click in around 80% full voltage. The
HOT appears to be good (yes I removed and soldered L14401), but the is
no base drive. I checked the digital side of things and the video
processor U12101 does not appear to have any clock wave at the crystal
input. I would expect some sort of waveform here, just like a CPU.
I scoped the power pin while holding it down and I see a series of
pulses after about a second or so, then they stop and resume after a
few seconds. I tried holding Menu while pressing Power the Vol+, still
nothing.
Any ideas?

On these set, B+ for the horizontal must be 140 when running, when in
off mode, it is slightly higher. SMPS is not complicated circuit,
check the TL431 (U14101) has correct 2.5V and the optisolator is good.

Push power button once and hear the relay click 3 times? That's 3
strikes and out design. This means there is problem either in digital
area or horizontal has a problem (usually flyback)

If this TV has F2PIP (PIP) module, pull it out and carefully look at
SMD resistors this bias the regulator to 3.3V. The regulator has
small steel heatsink. There is one SMD resistor has crack in solder
joint. When F2PIP IC (Big one) loses the 3.3V, the I2C bus jams and
get 3 strikes and out thing. I seen this twice, it can be a tough dog
if other didn't check the PIP module's regulator.

Secondly, make sure the horizontal driver circuit is also good.

Cheers,

Wizard

 

[Jason D.]

On 22 Nov 2003 15:38:21 -0800, rdanek@mail.com (BobD) wrote:

Thanks for the reply. I ended up getting the set working by probing
the I2C bus on the EEPROM (24C08). While I was probing the the clock
line with a scope, I hit the power button and the set came up! The set
now seems to work fine. Time will tell if it lasts. Weird!

Maybe, tap hard on the boards, the TV may shut off. I was curious,
does this TV have F2PIP module? If so, get that out and look at that
3.3V regulator SMD resistor that sets the voltage for cracked solder
joint. The two resistors forms a voltage divider and sets the base
voltage depending on 3.3V output power feeding PIP/AV switch IC.

Cheers,

Wizard

jpero@sympatico.ca (Jason D.) wrote in message news:<3fbf17ef.31802697@news1.on.sympatico.ca>...
On 21 Nov 2003 18:45:12 -0800, rdanek@mail.com (BobD) wrote:

I have a CTC203AAS chassis that has all the proper voltages (B+ around
180), 5v on the digital side, 12 v on the regulator. The set refuses
to come up when the power button is pressed. If I bring up voltage
with a variac, I hear the realy click in around 80% full voltage. The
HOT appears to be good (yes I removed and soldered L14401), but the is
no base drive. I checked the digital side of things and the video
processor U12101 does not appear to have any clock wave at the crystal
input. I would expect some sort of waveform here, just like a CPU.
I scoped the power pin while holding it down and I see a series of
pulses after about a second or so, then they stop and resume after a
few seconds. I tried holding Menu while pressing Power the Vol+, still
nothing.
Any ideas?

On these set, B+ for the horizontal must be 140 when running, when in
off mode, it is slightly higher. SMPS is not complicated circuit,
check the TL431 (U14101) has correct 2.5V and the optisolator is good.

Push power button once and hear the relay click 3 times? That's 3
strikes and out design. This means there is problem either in digital
area or horizontal has a problem (usually flyback)

If this TV has F2PIP (PIP) module, pull it out and carefully look at
SMD resistors this bias the regulator to 3.3V. The regulator has
small steel heatsink. There is one SMD resistor has crack in solder
joint. When F2PIP IC (Big one) loses the 3.3V, the I2C bus jams and
get 3 strikes and out thing. I seen this twice, it can be a tough dog
if other didn't check the PIP module's regulator.

Secondly, make sure the horizontal driver circuit is also good.

Cheers,

Wizard