Old Salora stereo (70's?)

Hi!

I recently inherited an old stereo. The left channel doesn't work properly. There is sound comming out of it but it lacks bass. The tonecontrolls on the unit work, you can hear the bass and treble change on both channels when they are adjusted. I have attached an mp3 where I have faded fully to the right, then to the left, once more to the right and finally back to left. I did not touch the tonecontrolls when doing that.

You can clearly hear the difference, what might be the cause of this?

Edit: The left channel sounds a bit distorted aswell.

NOTE: The .zip is actually a mp3 (renamed it to .zip so that the forum would allow me to upload it), so rename it to .mp3 and it will work.

hantto said:

The left channel sounds a bit distorted as well.

Click to expand...

Check the left audio output and driver transistors. Looking at your picture of the innards, I see someone has replaced one of the output transistors with a non-original type. That transistor has a package different from the transistors in the right channel.

PNP power transistors often go open collector in some audio amps, causing distortion and low output. When this fault happens, there is no further damage. (Unlike when shorted transistors take out every other transistor direct coupled with it.)

Bob

Hantto, there is an excellent forum that specialises in vintage audio try
https://www.vintage-radio.net
Cheers RH

A transistor does not dry up and reduce low frequencies. An leaky electrolytic coupling capacitor does.

Bob Scott said:

Check the left audio output and driver transistors. Looking at your picture of the innards, I see someone has replaced one of the output transistors with a non-original type. That transistor has a package different from the transistors in the right channel.

PNP power transistors often go open collector in some audio amps, causing distortion and low output. When this fault happens, there is no further damage. (Unlike when shorted transistors take out every other transistor direct coupled with it.)

Bob

Click to expand...

I checked the solder joints of the transistors, it looks like they have all been changed sometime. I'll head out and buy new output transistors when I have the time. They are a pair of TIP41 and TIP42.

audioguru said:

A transistor does not dry up and reduce low frequencies. An leaky electrolytic coupling capacitor does.

Click to expand...

I checked the output capacitor, it measured the correct 1000µF. I'll look if I can find a faulty capacitor.

Basically try to clean the controls with I switch cleaning or any Iso-propyl alcohol.

As the equipment is rather old - Try general check up for any dry solders.
You may replace a set of electrolytic caps to renovate, if the exercise is not costly for you. Try to indicate the MODEL No
Luckily it is modular
you can service the modules easily, i feel.

hantto said:

I checked the solder joints of the transistors, it looks like they have all been changed sometime. I'll head out and buy new output transistors when I have the time. They are a pair of TIP41 and TIP42.

Click to expand...

The TIP41C and TIP42C are good replacement audio output transistors. During my years of repairing stereo amps, I used dozens of those as a universal replacement for many amplifiers - usually to replace cheaper transistors in low-end department store brands, especially Sears. None of the TIP replacements ever failed.

Use the white thermal compound. Good luck!

Bob

hantto said:

I checked the output capacitor, it measured the correct 1000µF. I'll look if I can find a faulty capacitor.

Click to expand...

That doesn't mean anything, there are other coupling capacitors that might have dried up or it might have gone high ESR.