All accepted registrations through July 14 at 7:30a ET have been activated. Thank you! -M.W.

Please note: Terms of Use have been amended effective June 9, 2019. Make sure you are aware of the new rules! Please visit this thread for details: https://www.mibuzzboard.com/phpBB3/view ... 16&t=30571

All user accounts that have been inactive since January 1, 2017 have been expunged. If you are one of these users and wish to submit a new post, please re-register. Thank you.

Schematic Diagram For Realistic STA-111

The technical side of broadcasting. Think IBOC is a sham? Talk about it here! How about HDTV? Post DX reports here as well.
CK-722
Posts: 498
Joined: Sun Dec 16, 2018 3:53 pm

Schematic Diagram For Realistic STA-111

Post by CK-722 » Mon May 13, 2019 8:08 pm

Does anyone have any ideas for finding a schematic for a Realistic STA-111 Receiver? The relay system for preventing the amplifiers from being overloaded from shorts and other impedance mismatch overload is malfunctioning, and no one seems to know where to find them. I've talked to a former Radio Shack franchise owner, radio engineers who started their careers in home Electronics repair, and looked online but no one seems to know where to find them. There's some small illegible ones online, and ones that are close Models but not identical, but no one seems to have full scale schematics. It is a common problem, apparently, the receivers take longer and longer for the relays to operate and let the power to the speakers, and then it asymptotically approaches infinite time and doesn't kick in at all.


Is THAT where they got the idea for the 486-SX?

Same (x, y, z), different (t)

Your bullet missed my trial balloon.

RTN Price. Not guaranteed. As of 12:30, 157.71 Down 0.22.

Artificial Intelligence is a Child that needs a Parent to guide it through.

FET-500
Posts: 285
Joined: Sat Nov 10, 2018 9:22 am

Re: Schematic Diagram For Realistic STA-111

Post by FET-500 » Tue May 14, 2019 7:30 am

Are you certain the electrolytics haven't failed? A old Sansui that I still have, displayed similar behavior and it's issue was power supply caps.



CK-722
Posts: 498
Joined: Sun Dec 16, 2018 3:53 pm

Re: Schematic Diagram For Realistic STA-111

Post by CK-722 » Tue May 14, 2019 5:39 pm

He said they were all right. I have a line on one at the Radio Shack in Charlevoix. Keep looking though.


Is THAT where they got the idea for the 486-SX?

Same (x, y, z), different (t)

Your bullet missed my trial balloon.

RTN Price. Not guaranteed. As of 12:30, 157.71 Down 0.22.

Artificial Intelligence is a Child that needs a Parent to guide it through.

FET-500
Posts: 285
Joined: Sat Nov 10, 2018 9:22 am

Re: Schematic Diagram For Realistic STA-111

Post by FET-500 » Thu May 16, 2019 7:33 am

CK-722 wrote:
Tue May 14, 2019 5:39 pm
He said they were all right. I have a line on one at the Radio Shack in Charlevoix. Keep looking though.
Electrolytics are often the first thing to fail. They don't always show signs of leakage on the board.



User avatar
Ed Joseph
Posts: 337
Joined: Sat Sep 10, 2005 9:27 pm

Re: Schematic Diagram For Realistic STA-111

Post by Ed Joseph » Thu May 30, 2019 2:57 pm

I second the electrolytics. I have a Sony and a Pioneer on the bench doing the same thing, and I had to recap a Toshiba for the same issue. The Sony takes like ten minutes before the relays click. High end is pretty much gone as well. All told, I have probably six amps/receivers which need recapping right now. All need large caps with working voltage of at least 71vDC.


I confirm all my information through a high, white whore's souse!

CK-722
Posts: 498
Joined: Sun Dec 16, 2018 3:53 pm

Re: Schematic Diagram For Realistic STA-111

Post by CK-722 » Thu Jun 13, 2019 11:49 pm

I'm amazed at all the problems Electrolytics can cause. And are in circuit capacitance testers accurate? I don't know if he tested them this way, but perhaps you have anecdotes about inaccuracy. I also know that some people have the philosophy that all old caps are bad, which may be a reasonable assumption.

Even air dielectric variable capacitors can develop intermittent shorts, which surprised me, even though I have and old set where it shorts above a certain frequency. I assumed that somebody bent some plates while working on it, and was going to try to put in some spark plug gapping gauges in between the plates, which might work if you didn't bend the plates further, and would also break any metal whiskers that have formed over the years.


Is THAT where they got the idea for the 486-SX?

Same (x, y, z), different (t)

Your bullet missed my trial balloon.

RTN Price. Not guaranteed. As of 12:30, 157.71 Down 0.22.

Artificial Intelligence is a Child that needs a Parent to guide it through.

Post Reply Previous topicNext topic