RCA ColorTrak 2000 (CTC 158B) won't power on.

[Mrx3750]

RCA sets, for the most part I love them (well the ones made up to the late 90's) For the most part they just work, or can be fixed fairly easily.

I'm hoping this is the case with my ColorTrak 2000.

This is a 19" ColorTraK 2000, manufactured in March 1991 and it has the CTC 158B chassis in it. Now, I've done some work on this TV in the past. I found it on the curbside (working), and as a precaution, I replaced the thermistor, and several capacitors, and made adjustments to the screen and focus sections on the flyback to achieve the best sharpness possible. The TV worked beautifully afterwards.

The TV has been used infrequently since I've owned it. I make sure to power it on every once in awhile to keep it in shape.

I moved a few months ago and the TV has been sitting in storage. I went to use it yesterday, plugged it in, hit the power button, expected to hear the CRT scanning and see the "AUTOPROGRAMMING" notice, but nothing happened. There might have been a faint click from the relay, but hitting the power button again did nothing. I was hoping it was just the fuse. Nope. Fuse is fine.

I have the TV apart now, and pics of the chassis are attached. If you're familiar with the chassis, you might notice the thermistor is different. I jury rigged in a thermistor from another TV because the junky one that Thomson put in fell apart when I touched it.

[bluto]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

What does the front of it look like? It it one of those Dimensia models? Those were badass back in the day.

[Mrx3750]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

What does the front of it look like? It it one of those Dimensia models? Those were badass back in the day.

Here's a picture of it from back when it was working.

[ben7]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

Since you said you moved it around, I immediately suspect a cracked solder joint or two.

Have you checked the HOT?

[Mrx3750]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

Haven't checked a thing yet, not sure where to start. I last worked on this TV in 2008, and I can't find a service manual to download (not without paying an arm and a leg).

Can I test the HOT in circuit or should I just remove and test?

[Mrx3750]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

Well, testing the HOT in circuit reads as a near short in all three pins, which is not encouraging. I'm going to desolder it in a bit and test it out of circuit.

Okay out of circuit test is more encouraging.

50 ohms from emitter to collector (left and right pins)
175k ohms from emitter to base (left to middle pin)
6.1 mega ohms from collector to base. (middle and right pins)

I think the HOT is okay.

(Odd. I dropped the HOT on the floor by accident and went to test it again, now I'm getting 6 mega ohms from emitter to base and infinite ohms from base to collector.)

[R_J]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

The h.o.t. may have internal resistor from base to emitter, also there may be a damper diode from emitter to collector, check the number for the specs. if it is shorted I would check and resolder the connections on the drive tranformer and there may also be a small coil from the transformer to the base of the h.o.t. resolder it as well.

[Mrx3750]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

Yeah I'm pretty sure the HOT is just fine.

Like I said, the TV worked fine the last time it was used. It sat in storage for a few months and was moved from one house to another.

Where could I start checking voltages?

[Tvbob]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

There is a micro processor a crystal and a 5 volt standby supply inside the (metal fence) you should have 3 to 5 volts on most of the keyboard pins and it should change when the buttons are pushed. IF the micro is running and scanning the key pad.

[RON_CET]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

couple things to check to make sure your start-up circuit is working.The items circled in red is a start,now if you have all the standby voltages take look at the two circled in green,these to are necessary to kick start the horz drive ic make sure both of these are occurring when the power switch is depressed will go further upon these results hope this is a help attached is partial schematic of the start-up circuit

[Mrx3750]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

I think the micro is running. The button panel is hard to get to, so I grounded to the tuner can and started probing pins where the front panel connects to the chassis. Got a 4.6 volt reading on one of the pins, other pins read at 13 or 20 volts. If there's a specific pin I need to test, let me know.

RON CET, okay that's helpful! I'll start looking for those.

Well it's helpful in that it labels the components, but where on the chassis would R4170 be?

[RON_CET]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

look on on top and bottom edges of board you'll see numbers @ top and letters on side you use those like a map to locate components on the board R4170 and Q4162 are located @ k42 location on board

[Mrx3750]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

Ohhh that's what those are for. Okay!

[Mrx3750]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

Okay, so I found this PDF for a CTC 159 (Which I hope is close enough for troubleshooting purposes) and I got about as far as Step 3.

Tested pin 14 on the U3300 IC, and got the 11 volts on standby. Hit the power button, and the voltage briefly dropped, then went back to 11 volts. The voltage kept dropping, then going back to 11 volts, like the TV was trying repeatedly to power up.

Grounding pin 14 to the tuner can with a jumper wire did not make the HV come up.

Checked the collector on the HOT and got no appreciable voltage, now I'm stuck because I don't know where the regulator circuit is.

[RON_CET]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

Attaching images for regulator run mode and off mode,horz drive,horz output
NOTE!!! voltage readings with triangle mark are reference from HOT gnd
with set plugged into ac and in stand-by mode you should have approx 145/150 volts dc to HOT gnd @Q4401 and when you press power button when set goes into run mode you should have approx 130volts dc to HOT gnd @Q4401 this tells me that your regulator circuit is working,now if the set is pulsating or trying to start but shutsdown then tries start again you might be missing a run voltage example 26 volt run 9 volt 6.8 volt

[Mrx3750]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

Okay, the heatsink for the HOT says it's HOT grounded. Should that be where I test? Where should I connect the leads of my multimeter?

[RON_CET]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

yes you can use the heat sink for your HOT gnd,so your neg or black test lead would attach there if you can get to bottom side of chassis I would use pin12 of T4401 for your voltage test with your pos or red probe of your meter set to about 200volt scale for readings if you can't get to bottom then locate TP4008 @ 29G or G29 for your reg B+ for the Q4401 Note!!! service lit says not to read voltage directly @ Q4401 casing with multimeter

[Mrx3750]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

Okay, so I could connect my multimeter leads to the HOT heatsink, and TP 4008?

[RON_CET]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

yes

[Mrx3750]

Re: RCA ColorTrak 2000 (CTC 158B) won't power on.

Looking at my board, using those markers on the sides, the G 29 area has TP 110 and TP 119. There are little triangles there

Also my board uses two letters for the alphabet, AA, BB, CC, DD and so forth, if this matters.