Help!!!!! CTC177

[Spacedye69]

I've got a dead set with CTC177. The power does not give a click, buzz, nothing. I have found a couple of references to R4104 1.5M 1/4W being open. Not only can I not find R4104, but the parts list/schematic on the cover does not list any R4104. I can't even find a 1/4W resistor with that high of resistance. I find an L4104, but it is way to big for a 1/4W and not high enough resistance! Im stuck. PLEASE HELP!!!!!!

I've resoldered the ground shields around tuner and processor to start, but with no power, I'm dead(literally)

[Maxxarcade]

Re: Help!!!!! CTC177

Maybe the first 4 is just a schematic prefix. Is there an R104 of that value?

[Spacedye69]

Re: Help!!!!! CTC177

Found it! It was actually 1/2W in the power supply circuit. Thank God for marking the backside of the board also! It tested 1.6M, which I guess would be ok, but I will replace it anyway.

Does anyone know if the eeprom controls standby power? Also, if I replace the eeprom, how do I access the service menu to get the old settings with a dead set? Can I just replace it and hope I get a good enough picture to enter the menu?

[kc8adu]

Re: Help!!!!! CTC177

better resolder all the tuner grounds first.they are the cause of corrupt eeprom.
are you sure you have +5?
blown up psu issues are also common.

[Spacedye69]

Re: Help!!!!! CTC177

Resoldering the grounds is the first thing I did. I will check for +5v, but as the psu does not make a sound when plugged in, I pulled the resistor(which is on the +5vsb circuit) to see if it was bad. I assumed the eprom was bad because of the cracks on the tuner shield joints.

[kc8adu]

Re: Help!!!!! CTC177

if it does not chirp/tick when you plug it in its a psu issue.

[Spacedye69]

Re: Help!!!!! CTC177

I hope so. Repairing TVs without a scope is a crapshoot. PSUs I can do.

[Wizard]

Re: Help!!!!! CTC177

CTC177 is famous for all that.

This units uses same transformer for standby and full power via the STR 730-1x0 IC, that high value resistor is start up resistor and that's good one (1.6M). Get your ohmmeter on ohms and measure the Q4401 (this one on the heatsink for the flyback transformer , the tan thing with fat red wire) center leg to the either of two legs. If not shorted, good. If shorted, unsolder the fat diode with 2 equally fat ferrite beads. Recheck the Q4401, if not shorted, then diode and the STR 730-1x0 are shot. (blown fuse usually!) but the Q4401 will kill the STR 730-1x0 also.

The tuner grounds are the big money maker indeed. But, either need to find a tv shop that still have chipper checker or buy a pre-programmed EEPROM and reprogram it all over again. (no fun doing over 60 settings).

Cheers, Wizard

[ivtech]

Re: Help!!!!! CTC177

I've got a dead set with CTC177. The power does not give a click, buzz, nothing. I have found a couple of references to R4104 1.5M 1/4W being open. Not only can I not find R4104, but the parts list/schematic on the cover does not list any R4104. I can't even find a 1/4W resistor with that high of resistance. I find an L4104, but it is way to big for a 1/4W and not high enough resistance! Im stuck. PLEASE HELP!!!!!!

I've resoldered the ground shields around tuner and processor to start, but with no power, I'm dead(literally)

Replace C4406 OR
Replace R4001, U4001, CR4106 and line fuse OR
Repalce R4517 and R4702 and CR4704 OR
Replace eeprom U3201 and CR4104

[Wizard]

Re: Help!!!!! CTC177

Measure the ohms on Q4401 (this big transistor on right side) any shorts between middle pin to either outer 2 legs have to investigated. Unsolder middle leg of this and remeasure. If transistor is now open but the middle trace to either outer pads is still shorted then you are looking at shorted diode and a blown STK730-0x0.

Getting any power on secondary side of this power supply at all?

Cheers, Wizard