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

[tom66]

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

0.05 ohms is basically shorted, do you mean 0.05 kohms or something similar?

[budm]

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

The Gate and the Cathode of the SCR will show real low Ohm due to low resistance of the Gate drive transformer winding.

[Mrx3750]

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

0.05 ohms is basically shorted, do you mean 0.05 kohms or something similar?

Nope. 0.05 ohms, varies from pin to pin but readings go from 0.03 to 0.05 to 0.07 ohms.

I guess if I have to I can get it out of there and test out of circuit, but those clips are a pain, to put it mildly.

Okay pulled the SCR out of circuit. Getting 70 ohms from left to right pin. Right to middle pin, also 70 ohms. Left to middle pin, 0.05 ohms.

[RON_CET]

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

from your posted reading on SCR4101 it's bad RCA replacement part# 194320 when replacing don't forget to reinstall the small insulator back to the heat sink before installing SCR

[Mrx3750]

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

Oh boy. if SCR 4101 is bad then this is gonna have to wait until I can get some money. The resistor isn't a huge hassle. Getting the SCR might be.

Yeah a quick Google search for the part number and I'm not really seeing it. (Man I wish I still had that XL-100 chassis)

[RON_CET]

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

here's the data sheet,also this can sub over to a NTE5424 also a GE part# EP15X217
will work I do have some NOS (new old stock) EP15X217 I'll be glad to send you one just PM me your address

[Mrx3750]

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

Hey i was just about to post the NTE 5424 here.

However reading a post, the NTE 5424 subs for a 780-7 SCR I have a 780-9 SCR.

Does that matter?

[RON_CET]

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

go here put in your info in search box http://nte01.nteinc.com/nte%5CNTExRefSemiProd.nsf/$all/4DCD3806DD157815852579100081094D?OpenDocument


try this http://www.nteinc.com/

[Mrx3750]

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

Hm seems their server is having search troubles.

In any case I guess I gotta put this on hold for now. Thanks for the help. I plan to return to this once I get the parts.


What would happen if I replaced the resister and tried to run it with the "shorted" SCR? I was getting readings of 70 ohms on two of the 3 pins.

[RON_CET]

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

it would open R4001 resistor again

[Mrx3750]

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

Okay, I caught a lucky break and managed to get to the electronics store. I got a 25 watt 2.7 ohm resistor, and an NTE 5424 SCR.

I have a few concerns before I put these in and try it out. The heat transfer pad on the SCR heatsink is intact. Can I reuse it?

The resistor is 25 watts instead of 15 watts, should the SCR fail again, will the higher resistor wattage cause problems?

Finally I removed the HOT for testing, and I saw that it has no heat dope. Should I put some on it before putting it back in?

[RON_CET]

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

If the insulator which mounts behind the SCR transistor isn't damaged ,then yes you can reuse,but as a rule thumb if my new transistor has one supplied with it I always replace with new one.The increase wattage on your replacement resistor will be ok,yes you can apply some heat sink compound to the Horz output want hurt

[Mrx3750]

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

See attached photo.

That's a kludge if I've ever seen one.

But does it work?

Mmmm, no. Won't power up, and I smelled something funny. That resistor got pretty hot, and it was maybe plugged in for 30 seconds. Oddly when I flipped the switch on the power strip that the TV is plugged into, a lamp that's also on that circuit dimmed for a second. I think this means I have a major short somewhere.

Yep, the fuse is blown now.

I don't know if it's worth pursuing this further. I think I have a fire hazard on my hands.

[kc8adu]

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

busted solder joints on the h-drive transformer are common.
anything that runs hot or mounted to a heatsink should also be resoldered.
put your meter in diode test and check e-c on the board where you removed the hot.
you might read the damper one way but should be open except for charging a cap.
e-b will be low.if not look at the h-drive secondary and solder joints.
good sets for the most part and no pesky tuner on board.
i should not complain as those things were my bread and butter for many years!

[kc8adu]

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

i have also seen h yoke return cap short and cause this too.

[Mrx3750]

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

Where's the H yoke return cap?

[RON_CET]

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

does your meter have diode function? If so with set unplugged what is your reading @ horz output in set? reading should be to HOT gnd . neg probe HOT gnd, pos case of transistor reading, then reverse leads for second reading.

[RON_CET]

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

also during your previous removal of the Horz ouput did you make sure you put the transistor insulator back onto the transistor before mount back to heat sink?

[Mrx3750]

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

What transistor insulator? Oh that plastic on the back of it? Yeah that's fine. Doesn't matter I would think because the HOT is attached to the heatsink with a metal clip.

So you want me to set my meter to diode function, clip the negative lead to the HOT heatsink, and the positive to the casing of the HOT? Well, doesn't make sense, but did that and got no reading either way.

[RON_CET]

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

I don't have the schematic in front me it's on my desk @ work but you should get a reading in 1 direction E-C which Emitter is HOT gnd and no reading the reverse direction i'll review the schematic Monday and post again
What i'm looking for is potential low resistance or short on the 150 volt raw B+ which would take out the 2.7 ohm resistor and open the fuse