Having trouble with an old receiver I 'recovered' (Toshiba SA-7100)

[andrewc2232]

So my father owns a few small commercial buildings that he rents space in. A photographer who was renting a decent sized office suddenly left his office one day and never came back, neglecting to pay his rent for about 6 months, and so my father finally got around to changing the locks and getting court permission to seize everything he had left in the office as partial payment towards what the guy owed him (something approaching 10k in back rent). My dad invited me to come with him and see if the guy had left anything there that I might be able to use.

I had been looking around for a cheap stereo receiver to put upstairs in my new place, and I saw what looked like an old 70's receiver sitting under a pile of lighting equipment. It looked like it was in near new condition. The thing powered on so I packed it up and took it home and hooked it up.

But I seem to be having some trouble with it. I am trying to hook it up to my computer via analog stereo cable through a headphone jack. But the only way I can get the thing to play anything is to use the 'pre-main' inputs. I don't know enough about audio equipment to even know what 'pre-main' entails. All I know is that using these inputs I cannot adjust the volume using the receiver's volume control. No treble/bass/balance settings toggled on the receiver affect the output. I can change volume/settings on the PC, though.

In addition, the sound (at any volume) is terrible. On both channels there is so much fuzz and cracking that I can barely listen to it. I wonder if it is defective hardware, maybe why the wayward photographer wasn't using it anymore? I have sent signals from a couple of different sound cards and audio devices: same issue.

Also, I am forced to set the volume settings on the computer to just a notch above the lowest interval. Even a few bars up and it's way too loud--as if the receiver is running at max volume (which I cannot change). Would the bad sound quality be a result of the receiver trying to run a very low signal strength at decent volume? I really wish I knew more about this equipment.

Anyway, was hoping someone here could give me some insight into what my problem here is. Also, if anyone happens to know anything about this particular receiver, I would be very interested to hear.

Thanks in advance

 

[markw]

By using the mains in as your input, it IS running at full blast. The volume control is way before that.

Now, did you say that there are pre outs? These are generally in the vicinity of the mains in. If so, you may need to run a jumper* between the pre outs and the mains in. If this is like most receivers, you shoud now be able to use the front part of the receiver.

Ain't no guarantees nothing else is though, but it's a start.

*simply a pair of inexpensive interconnects.

 

[andrewc2232]

I am using the 'pre-main inputs' because none of the other inputs on the back panel (aux/tape1/tape2 inputs and 'adaptor') will play anything at all, regardless of which speaker channels I use (1 switched, 2 unswitched). Why wouldn't these other inputs be working?

What exactly are the pre outs? Pre-main outputs?

I have a few jumpers (or at least objects capable of jumping) laying around. Do you mean jumping the pre-main inputs to one of the other main inputs? Inside or outside the receiver enclosure? Sorry, still struggling to understand exactly how a signal flows in these things.

Thanks for your help.

 

[markw]

Look carefully at what you call the "pre-main inputs".

I've never seen a receiver with a "pre-in". A "pre-out" and a "main in", yes, but none with a "pre-in" and a "main-in" in the sense you describe.

Generally, they are in pairs, a pair of preamp outputs and a matching pair of main amp inputs. This would entail four RCA jacks.

Many receivers use this configuration and, to complete the circuit, the pre outs must be connected to the main inputs by some sort of jumper.

If that ain't it, I got nuttin'.

 

[andrewc2232]

Found a photo of the back panel, though the forum won't let me post the full link. Either way, it's at

grandcanyontuberadio.com/Toshiba/Toshiba SA-7100 001.jpg



I tried connecting the pre-main ins to the pre-main outs via a short rca cable, but I cannot get a signal to play using any of the other inputs.

Edit: Ok, forgot that I had the volume basically set to zero earlier. I can now play using the other inputs, but the sound quality issue is still there. Also, I now understand my confusion: there are pre outs and main ins, not pre-main ins and outs. Makes a lot more sense!

 

[TLS Guy]

Found a photo of the back panel, though the forum won't let me post the full link. Either way, it's at

grandcanyontuberadio.com/Toshiba/Toshiba SA-7100 001.jpg



I tried connecting the pre-main ins to the pre-main outs via a short rca cable, but I cannot get a signal to play using any of the other inputs.

Edit: Ok, forgot that I had the volume basically set to zero earlier. I can now play using the other inputs, but the sound quality issue is still there. Also, I now understand my confusion: there are pre outs and main ins, not pre-main ins and outs. Makes a lot more sense!

If you look on the back panel on the right of your picture, there are two black U shaped jumpers connecting the main outs and ins. These are the sockets that need to be jumped with RCA cables.

Connect your computer, to the Aux input terminals. If you use the phono inputs it will sound terrible. Set the volume control about half way, or a little under, and set the output of you computer until the sound is at a reasonable volume.

If the sound is bad then, the receiver is junk. By bad I mean distorted. If there is hum or buzz, then the issue is a ground loop, which is easy to get hooking up to computers.

 

[markw]

If you look on the back panel on the right of your picture, there are two black U shaped jumpers connecting the main outs and ins. These are the sockets that need to be jumped with RCA cables.

Connect your computer, to the Aux input terminals. If you use the phono inputs it will sound terrible. Set the volume control about half way, or a little under, and set the output of you computer until the sound is at a reasonable volume.

Sumptin' tells me that if those jumpers were there, we wouldn't have needed posts four through five.

Not using the phono input is excellent advice, though.

If the sound is bad then, the receiver is junk. By bad I mean distorted. If there is hum or buzz, then the issue is a ground loop, which is easy to get hooking up to computers.

Now I'll buy THAT for a dollar!