I have a realistic. Sta-2380 receiver.when I turn on the radio all it does is humm and the numbers flash.I can't change the stations either.

Question edited for clarity.

Help in the link and also specialist forums

https://www.google.com/search?q=realistic+sta-2500+stereo+receiver+service+manual

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First thing to check is the speaker. Switch them to be sure it is not the speaker. The unit was made in 1987. The capacitors that you are talking about are mounted to the main board. There are more than one. It does not appear that you are very versed in electronic repair and this could be a disaster to attempt to repair the unit. It involves soldering and attention to detail. You will have to remove the main board and all associated items that are in the way. Realistic STA 2380 Service Manual Analog Alley Manuals

hi, I have just done a search for realistic sta 220 manual and lots of results are thrown up, you need to try this as there so many results for the query.
I used bing rather than google.

Try disconnecting all the speakers and see if the volume goes up without shutting down (watch the vu meter on the front) if it goes all the way up without dropping, you will need to check your speakers. If the speakers are drawing too much current then the system will go into shutdown(protection mode)could just be a bad speaker. Secondly try blowing out the receiver with canned air and removing anything that would obstruct ventilation.(ie; another device sitting on top of it or in a cabinet where it can not breathe.

The pivot that balances the fm signal meter has jammed, it would have to be taken apart, the outer lens removed to attempt a repair, this is a very tricky operation, if you hit the receiver on the side nearest to the meter, the needle should move back and forth freely,"indicating the meter is good" but if it fails to move the mechanical part of the meter is faulty.

Try going to Realistic.com They usually have schematics and manuals.

I have a sta-2080 realistic receiver and wide range frequency equalizer plus a tape deck sct-22 all realistic.My problem is when i play the tuner or cd player witch is connected to the aux
the volume goes soft and then loud with a lot of cracking sound now ther is hardly any volume.when i play the tape deck it has it own volume control every thing is good so what parts do i need. thanks corneil

Sounds like a power supply issue, maybe the transformer when bad, it may need replacing.