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Technics SA-290 receiver problem

nicholaslawson12

Feb 6, 2022
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Feb 6, 2022
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I was recently given an SA-290 that works pretty well honestly. The guy told me it had a "volume problem" and hadn't used it in several years. Hooked it up and it worked for a couple days, sound thru the radio and through the RCA inputs. Then the radio receiver portion cuts out and the signal meter and frequency display start flashing and it seems to lock up when flashing, it will show the frequency (i.e. 94.7) but it won't respond to memory inputs. Sometimes I can turn it off and back on and the tuner will work for a bit, kinda depends. Funny thing is the RCA inputs work fine, it still puts out great sound from the other parts I have hooked up, only the tuner is screwy. Any advice/ suggestions? I'm not extremely good at figuring out electronics, fair at it.
 
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Martaine2005

May 12, 2015
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Hi @nicholaslawson12, welcome to EP.
When the tuner section locks up, do you still get volume from the radio?.
Or do you only get volume from CD/AUX and PHONO?.
When the tuner section locks up, do the headphones work on radio? Or just the other inputs?.
As this unit is approx 38 years old, there are a few things that initially come to mind.
But before we open the unit, do you have a multimeter?. Are you prepared to open it?
We’ll need clear, close photos of the circuit boards ( both sides). Then additional photos of sections we would like to scrutinise.
Is this something you’re willing to do?.

Martin
 

nicholaslawson12

Feb 6, 2022
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Thank you! I don't have the old school headphones to test that out. When the tuner locks up, if you turn the volume all the way up there's a pulsing sound in sync with the flashing. When I switch to other inputs its fine. Today the tuner's been working for awhile, good as always. I opened it up and poked around yesterday, kinda seeing if anything was obvious to a non electronics expert. Nothing was obvious and I put the cover back on. Today its doing fine as I can tell. No telling when it'll cut out again though.
 

Martaine2005

May 12, 2015
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Ok. If you can, leave the top off in anticipation of it playing up.
Grab a wooden cooking spoon or drum stick ready for poking around. When it ‘locks up’, use the wooden spoon to put a little pressure on components and the PCB in case there is a cracked/dry solder joint. You should hear sound if you get lucky.
Of course, be careful. That’s why you’re using a wooden spoon!.
Failing that, you can buy a can of ‘freeze’ spray. Using this on components can either cool a component into working again or cool the solder joint sufficiently to cause open circuit.
If you get this far, it’s time to concentrate on the area of concern.
In which case you can upload photos here for suitable replacement parts.
Have another visual inspection for swollen or leaky electrolytic capacitors. It may be time to replace them all after nearly 40 years.

Martin
 

kellys_eye

Jun 25, 2010
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Jun 25, 2010
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Yup, sounds very much like a capacitor issue - typically in the power supply section(s) and the PSU specific to the display (probably a 5V source?).

As Martaine says though, after such a period of time (and if the equipment is worth preserving), replacing ALL the electrolytic capacitors is often the 'only' way to go.
 
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