I need help


I have, since 1975, an integrated amplifier by Sansui model AU 7700.

It had what I think were jumpers connected to the right and left entry RCA connectors of Phono 2 that I suppose were, in the absence of the Phono 2, to simulate it.

I also suppose that the jumpers have an specific impedance.
I recently send it to maintenance and the technician lost these jumpers.

If anyone is familiar with this equipment, and what I am calling jumpers, could you please check if I am right about my idea of their function and, if so, which is their  impedance so that I can manufacture a replacement?

Thank you very much for any information.

Fabio

fabio_zaidan

What I have used with phono preamps in the past...

1:  A basic RCA which has the Hot shorted to the Ground for use in unused INPUTS.

2:  An RCA plug with a resistor soldered between the Hot and Ground for use in unused OUTPUTS (think I used a 100 K OHM in mine, but don’t recall why).

I used the 2 above to reduce RFI and other noise contamonants on really inexpensive ($25) battery powered stereo phono preamps used as mono preamps (thus the unused inputs and outputs).

The variable load switch on your amplifier only affects the phono 1 inputs (phono 2 is set at a fixed 47 - I think, but it is "fixed" to a single setting).

I would just use phono 1 for now and see how it sounds on the different settings.

I agree with Parker that your technician should be remedying the situation.

PS:

I can't see the photo you linked, but I'll Google later to see if I can find something.

 

DeKay

 

Here’s a downloadable user manual (I was off by 3 as phono 2 is fixed @ 50-:).

https://steampoweredradio.com/pdf/sansui/manuals/au7700%20operating%20instructions.pdf

I’ve seen/used this amp when it was new (lots a veteran’s were buying it @ PX discounts just after the end of the Vietnam war) and I do not recall the plugs you are referring to - nor could I find a pic of them in use.

My brother-in-law used one with AMT1's for a while and the pics brought back memories.

DeKay

 

It had what I think were jumpers connected to the right and left entry RCA connectors of Phono 2 that I suppose were, in the absence of the Phono 2, to simulate it.

I also suppose that the jumpers have an specific impedance.

Those are plastic cover to protect the RCA jack from dirt, dust, oxidation or corrosion, not a shorting plug or phono impedance plug.

You can purchase them on eBay or Amazon...

 

OK - found a pick of Sansui RCA Phono Input shorting plugs on a later Sansui model from 1978, but you have to be registered (AudioKarma) to view the pics.

It’s the pic in the first post and the plugs have a paper instructional tag attached to them.

I don’t post there, but I recently registered because I like the site.

https://audiokarma.org/forums/threads/installed-phono-shorting-plugs-no-difference-noted-but-not-surprised.1078302/

 

DeKay