Admiral 14R12 Restoration

[Kevin Kuehn]

You mentioned it was out of focus earlier in the thread. It could simply be the combination of a tired electron gun and it being over driven to achieve what seems like normal brightness and contrast. The further the beam deviates from center the harder it is to maintain focus. You may be able to tweak the ion trap and get the outer edges a little better, at the expense of less focus in the center.


I kind of miss the plated chassis. I thought it looked really nice after you cleaned it up, not that it looks bad now, I guess I just prefer the plated look.

[Kevin Kuehn]

You also might want to double check that the dag contact spring is making good ground contact through the painted chassis.

[Crist Rigott]

Originally Posted by Kevin Kuehn

You also might want to double check that the dag contact spring is making good ground contact through the painted chassis.

Good idea! I'll clean that area up to make sure I have good contact.

[Crist Rigott]

Originally Posted by Kevin Kuehn

You mentioned it was out of focus earlier in the thread. It could simply be the combination of a tired electron gun and it being over driven to achieve what seems like normal brightness and contrast. The further the beam deviates from center the harder it is to maintain focus. You may be able to tweak the ion trap and get the outer edges a little better, at the expense of less focus in the center.


I kind of miss the plated chassis. I thought it looked really nice after you cleaned it up, not that it looks bad now, I guess I just prefer the plated look.

Kevin,
I'll play with the ION trap a bit to see if it improves.

The plated chassis had a lot corrosion, not rust, but corrosion. I tried to rub it off but then that area was "polished" and still had the discoloration from the corrosion on it. I think at one time somebody spilled something down into it or most likely sprayed something into it.

[Electronic M]

Originally Posted by Crist Rigott

The plated chassis had a lot corrosion, not rust, but corrosion. I tried to rub it off but then that area was "polished" and still had the discoloration from the corrosion on it. I think at one time somebody spilled something down into it or most likely sprayed something into it.

If that 'corrosion' was green/white-ish green(sometimes yellowy) and fairly even then it is not corrosion, but rather Cadmium plating. It is natural for cad plating to turn green-ish with age, and it does not hurt anything when in that state. Best not to polish cadmium...It is rather toxic. I always leave the metal on cad plated chassis alone.

[Crist Rigott]

Originally Posted by Electronic M

If that 'corrosion' was green/white-ish green(sometimes yellowy) and fairly even then it is not corrosion, but rather Cadmium plating. It is natural for cad plating to turn green-ish with age, and it does not hurt anything when in that state. Best not to polish cadmium...It is rather toxic. I always leave the metal on cad plated chassis alone.

Tom,
This chassis didn't seem to have the CAD plating on it. The corrosion consisted of many, many small dots. It wasn't an even coating. Some areas even left some small pits in the metal.

[WISCOJIM]

I really like the appearance of your painted chassis, but I was always afraid that paint may interfere with good chassis ground connections. And most (radio) restorations with a painted chassis looked bad because it left all the other visible pieces looking old/cruddy. I wonder what will happen with those tubes so close to the high voltage cage. One looks like it has got only 1/8" clearance. Are they going to cook, burn, or blister your paint job? And the possible smell...

.

[Crist Rigott]

I've done some troubleshooting.

I did a voltage check on the 3 tubes V15 a 6SN7GT Horizontal AFC and Osc., the 6BQ6GT Horizontal Output, and the 6W4GT Damper tube. Here are my findings. 2nd values are my readings:

6SN7GT
1 -2.8v -25v I thinks SAMS made a mistake here. Riders shows -40v.
2 100v 105v
3 -22v -16v
4 -60v -59v
5 235v 190v

6BQ6GT
4 140v 128v
5 -8.6v -8.6v
6 220v 190v
8 5.6v 6.3v

6W4GT
3 320v 250v
4 320v 250v
5 220v 190v
6 310v 255v

The voltages don't look too bad. Most are a little low.

I did hook up my scope to the grid (pin 5) on the 6BQ6GT tube and here is what I got:



I then checked point "C" on L19 per Sams on adjusting the Horizontal Sweep Circuits. This is what I got after I adjusted "B3" on L19.



I don't know what the frequency was but the time dial was set 10us.



Here is a picture of the schematic showing the area:



I also ohmed out the fly-back and it checked out pretty reasonable.

EDIT! I remembered that I can hook up my frequency counter to my O'scope and I then adjusted the Horizontal Frequency "B2" to get 15,734 cps.
Another EDIT! I added the voltage on the 6BQ6GT Pin 8.

[Crist Rigott]

Is there any way to test what's going on with the flyback? Like seeing the voltage from the 6BQ6GT plate cap? Like measuring the voltage there? Everything I've checked so far checked good. I'm getting about 3Kv right now and have a faint raster. So I am getting some HV, just not enough. I don't have a flyback checker. How can I check the door knob cap? I'm trying to find out why my HV is so low.

Thanks for your help.

[Kevin Kuehn]

Your horizontal drive signal basically looks good, but your boost voltage is 70 volts low originating at pin 3 of the damper, which is why some of your other voltages are low. What is your scopes volts per division setting when you measured the signal at the grid of the horizontal output? Have you by chance tried another damper and HV rectifier?