Techincs SU-Z22

[sir-les-mp]

Ok more Hi-Fi Problems.

I have already posted about my Technics SB 3050 Speakers requiring new foam and where to get some. ( this is now in progress of some further reasearch )

I also have the Vintage stereo to mactch the speakers headlined by the Technics Stereo Integrated amplifier SU-Z22.

I bought this full setup at least 15 years ago if not more and when i bought it was surprised to find the original recipts from the original purchase in december 1981 ( yes i did say 1981 ).

So now getting back to my issue slowly, i have not had the system running for some years now due to my old home not having enough room for me to set it up properly.

I have recently moved and to my delight i have the room now to show off and use my vintage ( old, geriatric, or choose your own word ) stereo system, which in my oppionon still rivals some of todays new technology for Quality Sound.

I had set up the system the other day and wired in my backup Warfedale S 500 speakers placed a cd or 5 in my muliti changer and decided to set up the sound for Bass,Treble ect.

This was all going well untill i decided to turn the volume down from a massive 2 to around 1.5 - 1 for general listening ( lets be honest its not about the volume of the music but more the quality that it is being reproduced at ) only to find that the volume would jump extremely loud with a hissing/scratching sort of sound before settling at a muffled volume.

Now as a precaution and to rule out my huge fat fingers i did this several times only to get the same result.

I have swapped out the Technics amp for my back up Pioneer SA 740 again a vintage amp and have had no issues with this sound problem.

So i wondering if anyone here could tell me what could possibly be causing the issue and if it was repairable and then worth the repair.

The only diagnosis i can come up with would be the Variable resistor which is used for the volume control is wearing/worn out and needs replaced, having had a similar issue with a set of creative labs computer speakers where the volume control was so full of muck preventing proper contact and therfore resistance.

Note

I would like to recover my Pioneer amp for upstairs to connect my computer through

 

[Kei]

It'll probably need a clean. Get some deoxit D5 and give the potentiometer a small squirt and then turn the volume control up and down quickly for a few minutes to allow the cleaner/lubricant to do its work.

There are usually gaps in the pots that allow you to spray the cleaner in, like these. (on my Luxman amp from the same period)

If its not been done already, i'd recommend getting the electrolytic capacitors replaced as they will be well out of spec by now. I've done a lot of vintage devices and they have all been improved massively by doing this. (can cure things like hum, background noise and even tone issues like HF or LF loss, a lot of these issues aren't easily noticeable as they come on progressively over time. You only notice once you replace the parts and get the WOW effect. (had quite a few of those now)

 

[sir-les-mp]

It'll probably need a clean. Get some deoxit D5 and give the potentiometer a small squirt and then turn the volume control up and down quickly for a few minutes to allow the cleaner/lubricant to do its work.

There are usually gaps in the pots that allow you to spray the cleaner in, like these. (on my Luxman amp from the same period)

If its not been done already, i'd recommend getting the electrolytic capacitors replaced as they will be well out of spec by now. I've done a lot of vintage devices and they have all been improved massively by doing this. (can cure things like hum, background noise and even tone issues like HF or LF loss, a lot of these issues aren't easily noticeable as they come on progressively over time. You only notice once you replace the parts and get the WOW effect. (had quite a few of those now)

So you defineatly think its worth looking at and trying to sort it out.

as for deoxit D5 i take it any electrical point lub would suffice, ive got some i use for my pc fan bearings when i clean them periodicly

 

[Kei]

For cleaning contacts you won't get much better than deoxit. I personally use electrolube and ambersil 50+. Definitely worth sorting these things out, but i wouldn't go spending a fortune on it as there are better amplifiers out there that can be had for a reasonable sum.

 

[sir-les-mp]

For cleaning contacts you won't get much better than deoxit. I personally use electrolube and ambersil 50+. Definitely worth sorting these things out, but i wouldn't go spending a fortune on it as there are better amplifiers out there that can be had for a reasonable sum.

I wont be spending a fortune on it, however i would like to try and get it running properly again as it gives a nice clean sound even at volume