Sylvania Hybrid D16 - low h-drive

[DavGoodlin]

After testing the resistors and finding several out of tolerance, especially those machine-inserted half-watt resistors, I then just replaced all orange and dk green drop caps.

I measured the old caps and they too were way off. The new mylar caps were right on, using my Fluke 177. It seems, with all these off tolerance values, vertical sweep and of course convergence would have been greatly affected.

After a power-up, vertical hold was right in the middle of the control range. There is still an issue with the Vert lin control being maxed out just to get enough sweep at the bottom. Maybe its time to try a tube, though the 6LU8 looks new.

An initial set-up of convergence showed the R/G vertical lines going to 1/2 inch apart at the bottom of the screen. After tweaking the right side R/G vert coil, I was able to readjust the static and get the bottom issue much better. The R/G vertical lines at top and left have good range and adjusted easily.

[DaveWM]

wow that is a big diff, I presume the left and center vert RG convergence was ok?

You may want to check the pots/resistors etc... if its not working right.

Glad to hear you are making progress on it.

maybe even try with out the conv board in (you may have to sub in a resistor 100ohm in the vert circuit if its like an RCA to get the full vert deflection).
Just to see how it looks without edge compensation.

[DavGoodlin]

Last problem here - I need a 6CE3/6CD3/6DT3/6DU3 damper tube.
There is a 6BW3 in it now, and I noticed a light green glow in the cathode--plate region.
At one point, I heard a snap and lost raster breifly, only then I noticed the incorrect tube.
NFW am I running it now, until I get the right tube and risk losing the NOS 6LR6.

What is odd here is that the basing diagram is the same, but the Sams Tube Substitution book No. 18 lists only 6CD3/6DT3/6DU3.

Per the 1981 RCA tube handbook, most characteristics are equal between the 6CE3 and 6CG3/6BW3 except heater current; 2.5A vs 1.8A and plate dissipation; 11 w vs 6.5 w.


Of course I have no NOS tube so I have to dig deep in my pre-sorted bins and hope for the best...and I found 3! plus 5 34CE3's.

Put a used Sylvania 6DU3 into service, no green glow and HV up to 30 kV.
Increased R440 to 22 meg and HV drops to 27 kV, turn up the brightness (Sams HV adj procedure is to measure HV with normal viewing brightness) and it lands on 25, with control at minimum.
This has to be done!
Attachment 186707

Attachment 186708

[Jon A.]

Good to see such progress on this set. It was a rat's nest of troubles for a while but worth the effort to fix.

I'd like to see a pic of the whole thing if you don't mind. Also, what's that little Heathkit box visible in the background beside the Sencore VA48?