Hello all!

I am new and I was wondering if you could help me. I am working on a RCA portable EJ507J CTC22 and the B+ Boost is about 480 volts it should be 720 volts. I get a picture but the horizontal is half the size. Like I have a short in the horizontal winding of the yoke. I used a ringer on the flyback and the yoke and they both check out fine. When I first turned on the set after I recieved it and I found a puddle of wax in the flyback cage after I ran it for 20 minutes. I can supply more information if needed. If you can stear me in the right direction to solve this problem I would be gratefull. Also could someone explain the 2 damper diode in parallel.


Thanks

HV ok?

Just a guess here, but if the horz is narrow, perhaps all the Horz is weak (not just the boost) so I would start with a new HORZ tube. check the B+ and the HOT current as well. check the voltages on the screen of the HOT.

wax drippings from the fly are to be expected.

The failure rate of the SS damper diode was so high that there was a replacement consisting of two diodes strapped in parallel, intended to improve reliability. It was non-RCA sourced, IIRC.
Is that dual diode running sizzling hot by any chance?
oc

Check the Boost filter cap. If it goes open it will cause this exact issue. Its a small value cap between the boost and B+.

Ring testing a flyback will only catch hard core shorts in the primary. I have 2 flys here that ring out at 22 rings which is excellent but provide plenty of smoke when in the set.

Keep a close eye on that flyback temp, if there is an issue causing excessive heat and current you can damage an almost impossible to find part.

Thanks all for the replies. I have not replaced any of the tubes yet. I will start with the horizontal output and the hv regulator. I also checked any the capacitors between the B+ and boost found then good. The damper diodes are also good. I will replace the tubes and get back to you all.

Thanks

I tried a new HOT and regulator tube and it did not fixed the problem. I am having trouble understanding where the boost is created on this set. Where would boost filter cap be located? There are several caps on the horizontal output board that I think would create boost but I can't pin down the one that creates it. By the way this is my first tube type tv repair. Further assistance would be appreciated.

Thanks.

I think you have a B+ problem... Check the raw B+ voltages at the filter caps. Also, if there is a shorted turn in the FBT windings, it can pull down the whole line without screwing up the horizontal oscillator, and sometimes be missed by a ringer test... so hopefully that's not it in this case...

Charles

Check the b+ at point 2 like kx250 says. If you dont have an eye type cap tester replace all the caps circled. Could be the fly but usually they smoke.


http://justsmog.com/Clay/CTC22.gif

BTW. when you change those caps you MUST check the cathode current and adjust the effency coil.

out of curiosity, is your HO tube running hotter then normal after a few miniutes of the set being turned on? OR, is the HO tube showing any signs of redplating or a red spot on the plate?

The plate on HO tube does not glow red. I just ordered some orange drops for the HO board so I will wait and try it when I install the new caps. I hate admit as being new to tube tv repair I tried to check the cathode current on the HO tube and I destroyed the reset button. I did not use the .47uf cap in the instructions because I did not have one. I ordered one along with the other caps. The instructions are vague to me, what is the proper way to do it.

Thanks.

When you open the HV cage, what's it smell like in there? Any hint of a scorched odor? Or does it smell nice and 'fresh'? Old techies generally developed a "nose" for servicing which often presented the first clue to the failed component.
oc

While looking for Caps , see if the HO screen volts is being pulled down. Those leaking buggers can cause trouble anywhere.

I replaced the caps circled in the schematic and I checked the HO cathode current. It is 300ma. The horizontal efficiency coil has no affect. Bad flyback?

Thank you for your support.

check the HOT grid voltage and a scope if you have one. shold be around -50v and PP around 170vdc

300 ma?:eek: Holy makrel! Are you using a digital or analog meter?

I am using a digital meter. The grip voltage is -46v and PP 145v

just to be safe, bypass the meter with a .47 cap. 300ma is way out of whack.

horz eff coil has no effect, something not right there. I prefer analog meters for looking for the dip, its a tuned circuit, so it will have a narrow range.

That would be a good ring test candidate flyback. Could this be an issue with those damper diodes? or a bad effency coil? Something is WAY off for it to be that high.

I just used an analog meter and it is also 300 ma. The current (238-250 ma) is controllable when the tv is just starting to warm up but after the HO tube gets good and hot it jumps up to 300ma and I can't turn it down.

hmmm gassey HOT. do you have another you can sub?

I can't see why it would "jump" 50+ma. I would monitor the grid voltage. Also did you check the voltages of the regulator tube?

what I like to do is get the HV prob, the scope, the vtvm, the cathode current meter and hook it all up. then start up and see whats going on.

I just used an analog meter and it is also 300 ma. The current (238-250 ma) is controllable when the tv is just starting to warm up but after the HO tube gets good and hot it jumps up to 300ma and I can't turn it down.


does that jump come after the HV and CRT brightness are already up?

The tube will pretty much max out and red plate at 300. I bet its just thermal runaway. Its starting off to high. If C76 is leaky it can cause this.

Although the dual damper diode may check good, how hot is it running? Is it sizzling hot? (Asked previously).
oc

Sorry about the dual damper diode. It does not get hot.

I looked at the dual damper diode again and they do hot and they look like they are causing the high HO cathode current and the B+ boost problem also. What is the data on them. I have 1 with the code IOR D818 and 2 other ones with the code 010 7142 SCI.

I looked at the dual damper diode again and they do hot and..
Um.. are you saying they do run hot? If so, they are probably shot and will cause the very problem you are describing. Sorry i can't give further specs as it's been a lotta years and memory's a bit faded. I do remember that the dual diode was introduced because of the extremely high failure rate of the single. Testing the thing with an ohmeter did not reveal much, and the only real test was to sub in a new one.
oc