A Confession

[DaveWM]

shunt tube? does the HV adjustment work? when you say stuck to you mean max?

[Phil Nelson]

Originally Posted by Hagstar

HOUSTON WE HAVE STABLE HIGH VOLTAGE AGAIN.

Pardon my slowness, but could you describe in a little more detail exactly what you hooked up and where? Might be useful for anyone needing to do this in the future.

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

[Hagstar]

Originally Posted by DaveWM

shunt tube? does the HV adjustment work? when you say stuck to you mean max?

Well it can be adjusted up to 22.5 kV, control works but adjusts exactly as before with flyback working- 21-22.5 kV. By stuck though I'm more referring to the way all reports I've seen say other CTC4 owners get this same slightly low max high voltage. It's true I haven't unhooked shunt tube to check that system- will do so.

John H.

[Hagstar]

Originally Posted by Phil Nelson

Pardon my slowness, but could you describe in a little more detail exactly what you hooked up and where? Might be useful for anyone needing to do this in the future.

Well as described early in thread I removed most of the old flyback "tire" (down to about 1/4") and insulated the loose end. This was tricky as it was too burned to unwind and that would take months- I clipped the tire deeply through all layers and found the end far down instead. Then I hooked up the tripler IN pin to the horz. output voltage terminal top of the assembly. The OUT is a thick insulated red wire- I soldered this to the terminal in the plexiglass cup beneath the high voltage rectifier. The REF(GND) pin I grounded. F (focus) will receive a 66 meg at 6000 volt resistor to ground to keep the voltage there sane. That's about it. The tripler fits easily with wire ties to the side of the high voltage cage.

John H.

[DaveWM]

used a tripler not a quadrupler correct?

[Hagstar]

Originally Posted by DaveWM

used a tripler not a quadrupler correct?

It was a tripler yes, of course this is not literal though. Triplers don't use 3 stages for TV use, this was a 6 stage and there are 5 stage ones also. The waveform from the horz. output is so uneven that's what's needed to multiply the voltage 3 times. A quadrupler would put it near 30 kV, well above spec 25 kV.

What I used- http://www.ebay.com/itm/112011512150

John H.

[miniman82]

Originally Posted by Hagstar

Well it can be adjusted up to 22.5 kV, control works but adjusts exactly as before with flyback working- 21-22.5 kV. By stuck though I'm more referring to the way all reports I've seen say other CTC4 owners get this same slightly low max high voltage. It's true I haven't unhooked shunt tube to check that system- will do so.

You're not talking about mine then, all my early color sets make an easy 25kv. More if you aren't careful... Only sets I was never able to get more out of are the CTC-5's of course (my Wingate tops out at 22.5 no matter what I do), and some of the other RCA's like the 7's and 9's. Some of their later sets had better HV production, but those used compactron output tubes not octals.22/22.5kv isn't bad though, as long as it isn't sagging or blooming on high brightness scenes you'll be OK. Voltage is only one piece of the pie, have to have the current as well or it won't perform.

On the shunt regulator adjustment, you should be able to pull a full 1ma on the shunt tube's cathode with brightness all the way down. If it's higher than that straight off the bat, you may have to play with the grid circuit resistance to get it in spec. Not at all uncommon, the Silvertone I'm working on right now had a badly drifted 6BK4 grid resistor that caused hv to sag all the way down to 8kv. Changed out that resistor, boom got a full 24kv without breaking a sweat.

[DaveWM]

Originally Posted by Hagstar

It was a tripler yes, of course this is not literal though. Triplers don't use 3 stages for TV use, this was a 6 stage and there are 5 stage ones also. The waveform from the horz. output is so uneven that's what's needed to multiply the voltage 3 times. A quadrupler would put it near 30 kV, well above spec 25 kV.

What I used- http://www.ebay.com/itm/112011512150

John H.

how do you know it put it near 30kv? is that assuming its being driven as it was designed vs how you are using it in this application?

[Hagstar]

Originally Posted by DaveWM

how do you know it put it near 30kv? is that assuming its being driven as it was designed vs how you are using it in this application?

Well the tripler is putting out 3 times the input voltage, 4 times would be near 30K. I would assume they are designed the same but the quadrupler would have 2-3 extra stages. As for design they are doing what they were designed to do as far as I can see- replace flybacks by turning horz. output voltage into high voltage- weren't they used this way originally at factory?

John H.

[old_coot88]

John, where you said:

Then I hooked up the tripler IN pin to the horz. output voltage terminal top of the assembly.

...does that mean it's going to the plate of the H out tube?

[DaveWM]

Originally Posted by Hagstar

Well the tripler is putting out 3 times the input voltage, 4 times would be near 30K. I would assume they are designed the same but the quadrupler would have 2-3 extra stages. As for design they are doing what they were designed to do as far as I can see- replace flybacks by turning horz. output voltage into high voltage- weren't they used this way originally at factory?

John H.

I have only seen SS triplers used in SS circuits, so comparing the output of a SS horz transistor to the plate of a horz out seems like there could be some difference in the voltages applied to the tripler. On top of that I cant say for sure but I think they were attached to a winding on the fly back that was not at the same level as the horz out from the SS or tube if so used. So the fly could have been adding some beyond the horz out level.

Regardless IF you are maxed at 22.5v with no shunt current, and you are in the experimenting with using triplers to replace flybacks, then it would seem at least worthy of trying a quadrupler IF you want to get more HV. I suppose there maybe some other limits as to what you are getting out as far as power in/power out, but without trying I don't know if I would say it can't work. One last thing, 30kv is about where old flyback systems maxed out anyway, so if 4 times would be 30k you would be right on target for unregulated voltage.

[Hagstar]

Originally Posted by old_coot88

John, where you said:

...does that mean it's going to the plate of the H out tube?

Yes, see photo of flyback in question earlier in thread. The top tab terminal goes to horz. output cap.

John H.

[old_coot88]

John, you indicated there's about a quarter-inch of the old HV winding (tire) still intact with the end tied off. Does the winding still have continuity? If so, possibly you could feed the tripler from the tied-off end, thus boosting the voltage going to the tripler. Just a thought.

[Electronic M]

Originally Posted by Hagstar

Well the tripler is putting out 3 times the input voltage, 4 times would be near 30K. I would assume they are designed the same but the quadrupler would have 2-3 extra stages. As for design they are doing what they were designed to do as far as I can see- replace flybacks by turning horz. output voltage into high voltage- weren't they used this way originally at factory?

John H.

An AC-DC multiplier is defined by it's number of diodes. A doubler has 2 diodes, a tripler has 3, a quadrupler 4, a quintupler 5, and so on. Thus a quadrupler can ONLY have one more stage than a tripler.

30KV unregulated should be fine...Some sets can hit 40KV if you disconnect the CRT and HV reg.

As long as you are not drawing more than about 1mA through the regulator with the CRT dark and the HV set to roughly 25KV, all should be well.

[Hagstar]

Originally Posted by Electronic M

An AC-DC multiplier is defined by it's number of diodes. A doubler has 2 diodes, a tripler has 3, a quadrupler 4, a quintupler 5, and so on. Thus a quadrupler can ONLY have one more stage than a tripler.

Here's a "Six stage tripler"- http://www.moyerelectronics.com/BVMo...c-83adfcdcb456

I'm sorry but this is incorrect for TV high voltage use and already covered earlier. That is quite true in pure science world. In TV use here a tripler is defined entirely by function. It is not at all like a textbook tripler based on stages, it's just what does the job of multiplying voltage times 3. In this case they don't work like in textbooks because of the irregular nature of the horz. output wave. As I explained before a "tripler" in this use NEVER has 3 stages, and quadrupler never 4. Triplers are in fact 5-6 stages. Here's a 5 stage tripler schematic I posted earlier in thread similar to the one I am using which has one more stage. These are not my ideas- they are data from forums explaining TV triplers. Normal rules regarding triplers don't apply in this case. It is not defined by the number of diodes.