The PHILCO Phorum
Philco Bristol update - Printable Version

+- The PHILCO Phorum (https://philcoradio.com/phorum)
+-- Forum: Philco Radio Discussions (https://philcoradio.com/phorum/forumdisplay.php?fid=5)
+--- Forum: Philco (and Other) Television (https://philcoradio.com/phorum/forumdisplay.php?fid=10)
+--- Thread: Philco Bristol update (/showthread.php?tid=25916)


Philco Bristol update - MuzzcoVW - 08-05-2025

    So after a few months of waiting I finally had a chance to fire up the newly restored chassis for the first time yesterday. It's great to see beautiful vertical deflection without even having made any adjustments yet. The horizontal, well a couple problems. The first problem that I realized about 2:00 a.m. overnight is that I forgot to install the new horizontal AFC diodes! Second the flyback was doing its best impression of a tabletop candle with small wisps of acrid smoke gently wafting out of the high voltage housing. I don't think my issue for getting the diodes would have anything to do with that. This flyback was suspect when I pick the setup a long time ago and I have a replacement to install. So at least we sort of had a raster, stand by for further updates.     

RE: Philco Bristol update - MuzzcoVW - 08-05-2025

The new flyback is installed and now we have a good raster. This is the best picture I could get today. My pattern generator is under the knife so I'm using my vcr... and can't find my 75 to 300 ohm adapter. Next are some centering and linearity adjustments to perform     

RE: Philco Bristol update - RodB - 08-05-2025

Just in time for Saturday morning, It's Howdy Doody Time.

RE: Philco Bristol update - MuzzcoVW - 08-13-2025

So I have things cleaned up a little bit now. I still don't have my pattern generator repaired but this is where we sit at this point. I'm having trouble centering the picture. This is as good as I can get it with the centering magnets and horizontal adjustments. Checking B+ it's good through some areas of the chassis, but in others it's 20 volts low. Time to start testing and seeing what's dragging it down. Also I need to go back and double check component values as I had a bit of an issue regarding the resistors when I started working on the board    

RE: Philco Bristol update - MrFixr55 - 08-14-2025

Almost there!! Vertical linearity, size and centering looks pretty good. You are right, Horizontal linearity, centering, and / or drive is at an issue. There is often a cap in series between the horizontal yoke coils and the flyback Check thqt. Also check the boost voltage if you have a meter that can measure it.

RE: Philco Bristol update - MuzzcoVW - 08-18-2025

A small update dealing with trying to find the cause of lack of screen width on the right side. I've confirmed values of components I installed restoring the sweep board. A couple things I noticed... I failed to replace 2 silver mica caps in the 6CG7 horizontal oscillator circuit. My brain thought they were ceramic disc. I probably should change them. Also I missed the resistor at the base of the H.V. rectifier tube, and it reads high, so that will get replaced. I'll also replace the resistor at the horizontal width switch as it is original as well. And MrFix55, there is no capacitor at the yoke however there are two resistors. I suppose I should check these. My thought process is that not filling the right side of the screen can be caused by the horizontal output tube, or circuit. New tube did nothing, so it,s off to the circuit. I'm also planning on running the chassis on the bench with yoke hooked up and H.V. lead in a glass jar. It'll make voltage checks easier

RE: Philco Bristol update - Bob Andersen - 08-21-2025

I wouldn't mess with the mica caps or the HV resistor. The resistors in the yoke are for damping the vertical windings. The most likely cause is the resistor on the width switch or HO components. Did you replace the HOT cathode resistor?

RE: Philco Bristol update - MuzzcoVW - 08-21-2025

Bob, I was so focused on the sweep board that I missed the resistor on the width switch. I had to replace the HOT as the original was smoked, and left the resistor that came with the replacement installed. It is a Triad brand. This weekend I'll replace the resistor on the width switch and then if it doesn't help, start running voltage tests