SAE 8000 Tuner Schematics

[ARCANE]

Folks,

I was wondering if anybody has a copy (PDF preferably) of the SAE 8000 Tuner schematics. I am trying to repair the LED issue and to replace some components to make it more palatable to modern high-end standards.

Thanks in advance.

Yves

[quadtech]

If it is the 7 segment LED display you are referring to, there was
a thread on it recently over at AK -

Alternate 7-segment display sought - AudioKarma.org Home Audio Stereo Discussion Forums

[ARCANE]

Thank you. I had read that thread before and it is very interesting.

However, I really would like the schematics of that tuner as I am trying to rebuild it and improve the components and the overall quality.

Thanks
Yves

[BrianEno]

Please!

Does anybody know how to rewire the unit for 220~230 Volts?
Thanks in advance.

[ARCANE]

As you can see from the schematic, it is not possible to rewire the unit for 220-240 V European voltages. I just re-did the power supply of my Tuner 8000 and can confirm that the primary of the transformer has only a single winding suitable for 110V AC.

The original transformer is a 110VAC primary and 2 x 10VAC secondary. By replacing that transformer with a small 220VAC primary and 2 x 9VAC secondary you can easily retrofit your Tuner for European countries. It shoudl be a piece of cake to do, and you can even install a small toroid transformer which will work better than the old box from the 70's.

Yves

[BrianEno]

Thanks for the info Yves
Good Luck with te update of your 8000.

[ARCANE]

Brian,

If you have the schematic of the Digital readout section for the 8000, could you post it?

I only had the Mark VIII schematic and there are a few differences with the 8000 Tuner. For instance, on the Mark VIII, the main switch cuts the primary of the transformer, whereas on the 8000, it is the secondary which is switched.

I have reworked my 8000 to have a power supply more in line with the Mark VIII as I do not like to leave the transformer on at all times.

Yves

[DF96]

This tuner has 5 ganged circuits in the VHF front-end, and 5 ceramic filters in the IF followed by a ratio detector. This suggests to me that it was designed to cope with lots of input signals on nearby channels, and audio quality might have been less important. Or possibly just aiming at specmanship; 5 filters sounds so much better than 3 filters in a glossy ad (and forgetting about phase response). I could be wrong of course. The Foster-Seeley discriminator seems to have been preferred by most high quality units before they all switched over to using a chip-based quadrature detector.

Sprinkling in a few new components won't change the basic design.

[ARCANE]

That is true. However, listening to Radio is not my top priority, and the quality of the sound is more than acceptable.

I am basically restricting the replacements of components to the power supply and the Audio stages, as well as the currently defective digital readout (missing LED segments). Once it is done, I will get a nice antennae connected and will enjoy some local classical radios from time to time.

Yves

[DF96]

OK. I doubt if you will notice much difference, unless some components have aged and changed value. I guess this is old enough that it might use carbon composition resistors? If so, some of them might need changing.