Need Help with Admiral 17T1

[Winky Dink]

Sorry if it's rude to bring my own post back to the top. Five days of staring at the Admiral hasn't improved anything. I've rechecked everything I can think of.

If someone has the time to look at my issue and give me some direction, I'll be very grateful.

- Winky

[Phil Nelson]

I peeked at the schematic (from http://www.earlytelevision.org/image...1_telaides.pdf ) and your set looks very similar to the Admiral 19A11 that I'm finishing up.

Like your set, mine had previously been partially recapped. Based on the appearance of those replacement caps, that work was done a long time ago, perhaps the 1960s or 1970s. The "newer" caps in my TV were plastic-coated cylinders, similar to the infamous bumblebees, but with different colors and markings. I assumed that they were the same junk -- paper caps in a plastic shell -- so I replaced all of them, too.

Since you have lost voltage on the plates (pins 2 and 5) of the vertical output tube (V15), I'd start by checking the components connected to that tube, particularly capacitors, and especially any newer caps installed by someone in the past.

A sudden change (loss of raster) suggests that some component failed. This is not unusual in restorations. Some component was marginal in the first place, and it croaks after an hour or two when exposed to voltage again. Capacitors (including micas in deflection circuits) are likely suspects, but resistors can fail, too.

Other possibilities include a funky tube socket, an intermittent ("cold") solder joint, crumb of dropped solder, bent component lead that makes a short circuit, dirty potentiometer, or a wiring mistake. When a set has been worked on before, you can't assume that all of the work was correct.

It would be easier to diagnose your problem with an oscilloscope, but it should be possible using your brain and a multimeter, although it may take longer.

Phil Nelson

[Don Lindsly]

The 300 volts on pin 2 (6SL7) is derived from a bleeder chain starting at the DC high voltage. Look for a bad 1B3 or shorted 6KV cap on the DC side. That would explain the missing 300 v and no raster. Easiest way to test is to clip the low voltage end and check for high DC voltage on the open end. The raster will reappear when you find the bad one. Start with C-59

If no progress, check the bleeder chain starting at the low end and work backwards to the 1B3 filament. You need meter that safely measures up to 6KV as you work up to the 1B3. Without that, if you don't get any voltages at the low end, you can assume the chain is OK and there is no high voltage. The resistors may be off value, but none so far as to kill the high voltage without some arcing or smoke.

Don

[radiotron]

Originally Posted by Winky Dink

Sorry if it's rude to bring my own post back to the top. Five days of staring at the Admiral hasn't improved anything. I've rechecked everything I can think of.

If someone has the time to look at my issue and give me some direction, I'll be very grateful.

- Winky

resolder the points around the damper tube my philco pedicta did that to, and it fixed it