The PHILCO Phorum

Finally, last night, I had just enough time to reinstall both boards in the receiver and quickly try it out with headphones.

It sounded fine...

This evening, I connected a couple speakers and let it go. Immediately, I noticed that the left channel seemed flat while the right had more brightness. I'll have to look into that.

But the important thing for now is...it has played for over three hours with absolutely no static.

Glad to hear the progress Ron. Did you rebuild the tone control board too?
If not take a look at that board.  Maybe rebuild time too.

Thanks,

Mike

...good call...I was thinking the same thing...

Ah HA! The control unit board W15-080 (bass and treble controls) has one electrolytic in each channel (two total)...they probably should be replaced with polyester.

Okay,

Regarding the lack of brilliance in one channel: Nevermind.

It was the speakers!

Having some time to experiement this evening, I decided to do the simple test of switching speakers before proceeding further.

Yup...the brilliance was now in the left channel while the right channel sounded flat.

So...I quickly substituted a different pair of speakers and...it sounds fine in both channels.

Now it will go into my home office and become a "daily driver" for awhile. With the new LED bulbs in every position save for the FM Stereo indicator (which is still incandescent), it looks as good as it sounds.

I did take notes of the passive components needed for the tone control board, and I may rebuild that in the near future anyway just as a preventive measure.

That is it for this thread. (see below) Thanks to those who participated, and to those who demanded that it be reopened.

I bragged too soon.

Oh, it still plays just fine, no static, even fidelity in both channels...EXCEPT in phono mode - the right channel is dead in phono mode!

Back to the workbench with it tomorrow for some signal tracing...

Gotta be something simple.

Hoping so...

    I have a sony with phono.   same thing r/s not working  on phono
will be watching post pics too

me`s freind

Well, it's fixed - and a real DUH! moment for me.

I traced the loss of signal to Q3 on the head amp (phono preamp) board (see schematic below).

Then I took a close look...

...and saw that, yes. I had installed Q3 backwards (collector and emitter switched).

Like I said, DUH...

Removed Q3, tested it and (amazingly) it was still good. Reinstalled, making sure the leads were in the proper positions this time.

Worked like a charm...



The SX-1500TD is back in my home office now. I'm listening to the smooth tones of Nat King Cole playing on my Technics turntable as I type. And even though the record (Love is the Thing, 1957) is in mono, the music is coming through both channels...nice and clear...sounds great.

So now, that is it for this SX-1500TD thread.

Actually it is not amazing that it is still good. Low current plus the fact that transistor is somewhat symmetric (kinda) as it is NPN affer all. Just the two diodes are a bit different. Has it been large current with large V then maybe it would croak. Here it was simply very low gain amp

Glad you got it. I have a pile of "stuff'" that will out croak me too.

Thanks, Bill. One week later and the SX-1500TD is doing very well indeed. The LED lamp that illuminates the AM tuning meter is intermittent, but otherwise, this receiver is doing quite nicely as a daily driver. I'm also using it to amplify my computer audio instead of using separate computer speakers.

Shortly after my last post, I opened the Pioneer back up to find that I hadn't tightened the bulbs behind the AM and FM tuning meters adequately. That problem was quickly solved and the receiver has been an excellent, highly reliable daily driver for five months now.

...and now it's gone.

I sold it to help pay for my "new" (to me) 1964 Bozak Urban speakers.

Well, I'll have to restore my Pioneer SX-9000 this winter...it's much like the SX-1500TD with the addition of a built-in reverberation unit.