1947 fada saga
 

hey all, yup im back again and still have not figured out why i cannot get any hv. the 6bg6 hot is cut off and i went over all caps and there locations that were changed as well as the values, all are right. i got another flyback from that era and the connections were the same but still no hv.double checked the values on the mica caps all are good. double checked tubes and tried subs still no hv.checked countless resistors, all checked good. sync loc coil for horiz in rear, ohms check perfect, linerity coil, perfect. rec tubes, damper voltages fine. screen voltage 280v, good, i believe it calls for 275v give or take alittle. what else in this old chassis could i be overlooking i have run out of things to look for as a cause. this is the rca 630 clone but its the same besides some cap values vary from fada to rca but i put back what i took out one by one. surely there must be someone out there that knows this chassis and the hv section and has heard of this problem befor. so please i am open to anything at this point as i am truly dead in the water on this one. if i am to look at a wave form but dont have a scope then there must be something else that can be done or checked. if the wave form was checked and there was NONE PRESENT then where would one go from there aside from what i already done. HELP..............:tears:

You changed the mica caps? They like to leak when they hit a few hundred volts and that's hard to test. What was the screen voltage and what is it spost to be?

micas in the horizontal were changed and the micas in the verticle as well and the verticle oscillator runs because i can hear it. the screen voltage is supposed to be 280volts and thats exactly what it is. there are voltages in places that are under what they should be and others that are over what they should be but then again if the whole circuit is not running right then the voltages wont be right.

it sounds like you have been at it for awile, best thing you can do when you start [ fighting ] something like this . is go work on something else or get away from it for a little bit, clear your head study the schematic for what voltage's at certain point's should be ,your polarity at the same point's , dont asume anything esp. caps. are ok check your test methid , when i test a cap in question i put it through more than one kind of test i have the usual digital test meter's but i try to make it work under a load thats were you see if it brakes down or shorts it self ,i made yrs ago a tester that is simple that can find leakage with a neon bulb & diode its only good for a certain range but has been 100percent on some of these caps that test good but fail while working / over the yrs i found that a cap thats a leaker when you use digital meter the value just can be just a slight off, if in question replace it. resisters can fool you to they can test ok with a meter but under a load not allow enough current flow starving out something else down the line or not being able to block at a certain level causeing more current to go to wrong part of the circuit .test your test methids assume nothing ,when you test voltage's make sure pretty close to what it should be. alot of time there are more than one component messing with you at the same time alone the component doesnt have a big effect on the but combine with another now its dead ,its like your car you dont notice [in town] when one headlight go,s out but you do when the last one does. relax dont fight with it ,get away clear your head ,start over make sure when you think a component is ok ,make sure that is ok . when you find the problem you will say this is what caused all this trouble .and you probley say @&^^%& then through it in the trash, or bury it in the back yard . good luck

well i did get away from it for awhile and yes i could have got a defective cap and i have checked so many resistors and any in question i changed. there is something that is stopping the horizontal drive and this then cuts off the hot and then red plates because there is no oscillations there. i dont know how many more times i can look at this area because i am not finding anything wrong but there must be a problem otherwise i would have hv. so i guess i will have to check each cap i replaced to make sure i made no mistakes and try to check for any continuity in these caps that may suggest they are bad.

How are you testing for presence of HV? I had a set that measured no HV (via HV probe under anode boot in CRT), but gave me roughly correct HV when disconnected from the CRT. This led me to believe something was pulling down the HV externally and/or a current ability problem. In this case, it turned out to be a (very) leaky doorknob cap.

disconnected the door knob cap still nothing but a red plate hot.

Looking at the 630ts schematic, the screen is spost to be 134> if its 280 something is shorted and loading the output down bigtime. Flyback, yoke, damper, one of those coils.

High screen voltage + red plate = overload.

Low screen voltage + red plate = lack of drive or drive problem.

i dont understand because my sams 630ts shows in the voltage chart 280 v for the screen voltage and i checked resistance in the yoke and tried another flyback. the voltages at the damper are close already. i think maybe the sinewave that is sent to that circuit is just not there and this is what i may have to look into next because i have not found any shorts. and yes it seems like a big short.

The output tube takes a saw tooth waveform not a sine wave, though back a ways from the output it is not really a saw tooth signal....

If you don't want to own a scope then you at least ought to find someone who will let you use theirs. There are many issues that a TV can have that are exceedingly difficult to impossible to accurately diagnose without one. If you are lucky you may be able to buy one for 10$ in working order if you keep a look out. Some of the newer scopes can be surprisingly small.

well i called it a sine wave because the original rca schematic says that a sinewave is fed to the circuit, oscillator, so i guess maybe it starts with that i really dont know at this point.

:thmbsp:well here is the kicker on this fada saga, it turns out that i was the one that screwed up and put 2 key caps in the wrong place and im not to big to admit it, i messed up. but on the up side i now have 9kv at the crt with the same flyback and i also have 2 spare flybacks for this set i picked up on ebay new in box for 31.00. here i was thinking well i put one cap at a time but thinking back when i was doing this i had people here breaking my concentration by talking to me so i decided to go back and double check and there it was. i had the set running for a few hours setting it up and was done and then the verticle seem to either fold over alittle or it came up from the bottom and came down from the top and had uncontrollable vert roll and befor this happened it had a great picture and sound that seem to be perfectly aligned . so now i have to change the verticle oscillator capacitor and hope thats it since this is the only cap that was not changed. and i would like to thank don lindsly for all the help on this project because without his knowledge helping me i would not have got it going and he has so much knowledge on this old stuff its amazing how i tell him a problem and he has the answer. so if anyone should ask don about a problem and he tells you where to look or what it is, never doubt his word or answer to the problem. so when i get the verticle cap and its stable ill post pictures. and thanks go out to other members that helped me as well with this headache.

here are the pics of the now working fada, the quality of the pics are not that great and i was a bit to close to the set.

I really like it! what size screen does it have?

:scratch2:this one has the 12lp4 crt and i dont know why being the mask cover only shows 10 inches or so. it would have been the same with the 10 inch version so i dont know what the advantage would have been.