[TV MAN]

Ron, perhaps I misunderstood. I thought that you were building the bias adjuster because the tubes were red plating. I mentioned this that the original problem may have been weak tubes (before building the bias circuit).  Anyway, I do like the idea of separate adjusters. Had this problem on an amp some years ago and found the tubes were weak and couldn't handle the current anymore. New tubes fixed. Anyways, is why the mention. Glad you have the problem solved!

[Ron Ramirez]

Tim

No problem, glad you checked in, thanks for your thoughts.

It was one of the used-tested 6П14П tubes that was red plating. This was before I learned that the 6П14П has lower ratings than the 6П14П-EB. It now has a new set of 6П14П-EB tubes. I ran it for around 20 minutes or so earlier during (and after) adjusting the IBAM trimpots, and I never saw any hint of red in any of the 6П14П-EB tubes.

So...did you ever find a power tranny for your Fisher 500-C?

As for this TA-600: I've installed the inrush current limiter and it is playing right now through a bucking transformer (107.4 volts instead of 125). In a few minutes, I'm going to shut it off and button it up (reinstall bottom cover, front panel, and reinstall in case). Having re-cleaned the Selector and Mono-Stereo switches, the left channel is now coming up along with the right as the tubes warm up. No more snap, crackle, or pop.

[morzh]

Ron


Have you installed the bucking xfmr inside or it is an outside unit?

[Ron Ramirez]

Outside. It is built into a metal electrical box and has its own off-on switch in addition to a twin receptacle (one in bucking mode for 110, the other for straight line voltage). A kind Phorum member built it and gave it to me several years ago.

There is no room for a bucking setup inside the 600 chassis. It is already jam-packed as it is. I did well to find a place to install the IBAM board. In fact I had to remove the inrush current limiter due to lack of space - as I was buttoning things up, I found that it would have interfered with one of the screws which secures one of the feet in place.

[morzh]

It is a pretty simple thing and inexpensive to build, as bucking setup is non-isolating and so requires a fairly cheap transformer with around 12V/2A output to power just about any radio or two.
Or, to make a bucking strip, find a 10A 12V unit and do exactly the same.
If I find a suitable box I might build me one too.

[TV MAN]

I'm still looking for the p-trans (500c or 800c). Saw a bunch in January on Ebay, but since I decided I needed one, none to be had.

May be a dumb question, but on yours, why the bucking trans? Line voltage too high where you live? I had to run my old Dyna MK3 amps off an adjustable isolation transformer years ago, otherwise it would turn those nice shiny Sprague cans into nice shiny sticks of dynamite! Yea, my line voltage was 127-130v at that time, til a coon blew the house transformer! Funny how much stuff wouldn't work after the power co. changed the trans. I think stuff adapted to the higher voltage. Now, I am around 120-123v.

[Ron Ramirez]

Tim

> Why the bucking trans?

Where I live, my AC line voltage is usually 125 volts with occasional spikes to 126. Yes, I should contact the electric company but I keep forgetting to do so...

Now please allow me to bring this thread to a close with this photo...

[Image: http://www.philcoradio.com/images/phorum...00_037.jpg]

This is the longest I have played the TA-600 since I restored it. It has been running for 45 minutes or so. No red plating (not that I expected any). My FM transmitter is coming in a bit fuzzy here in my home office, but other FM stations are OK. I always seem to have some difficulty with my FM transmitter in my home office, but in other areas of the house it is A-O-K.

It is as if this TA-600 and my Bozak E-300 speakers were meant for each other. Low lows and crisp highs.

With the heat those 6П14П-EB tubes are putting out, I could use this thing for supplemental heat in the winter. But the side of the metal cabinet is cool! Not so the right side of the grill above the output tubes, though...

And that is it for the TA-600 restoration thread. Thanks to everyone who commented and who helped (especially Mondial here, and a few guys on AudioKarma).

[rocketeer]

Well done Ron. Yes, they can put out a lot of heat. my C-810 Fisher was hot until I hooked it up to a bucking transformer. That knocked the heat down quite a bit.

[gregb]

Looking real good Ron, Enjoy!

Gregb

[Ron Ramirez]

Larry, I brought my bucking transformer upstairs along with the TA-600, and when I was running it earlier, it was running through my bucking transformer. 110 or so volts is better than 125-126 for certain. Besides, this way I can use the on-off switch on my bucking transformer to turn the TA-600 on and off, saving wear and tear on the (working, original) power switch.

[rocketeer]

Yeah, that's another reason I like to use a bucking transformer box w/switch, it saves wear and tear on the old (unobtanium) switches. My Fisher C-810, for instance, has a unique combo double power switch + volume control that is irreplaceable. I've been hunting for an extra for 5 years and have never even caught a whisper of one. It not only turns on the receiver but also dual rear panel mounted AC outlets (350 watts rated) for accessories in addition to functioning as the volume control.

Note the S-2 double contact switch for the outlets to handle the potential 350 watt (max) surge.

[Image: http://i863.photobucket.com/albums/ab191...g~original]

[Arran]

I wonder if that switch is similar to those often used in farm battery radios and many tube portables? Those use a single throw, double pole, power switch to turn the "A" and "B" supplies on and off simultaneously.
Regards
Arran

[Ron Ramirez]

At the workbench.

One more thing and we can put this topic to rest...

I just completed AM and FM alignment of this TA-600. AM still isn't the greatest but I am in the basement right now, where AM signals typically aren't great anyway.

But FM...wow, what a difference! It is now picking up signals across the band without an antenna!

A word of warning. Avoid the solid state FM multiplex decoder being sold on eBay by a Canadian seller. It does not play nice with the TA-600. Sure, it picks up stereo, but it also produces a very tinny, flat sound with no bass.