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Does a noisy transistor sound like a cheap speaker?

gazman

gazman

Active Member
As in, there's some slight distortion, and the music is a little fuzzy - basically its the sound small cheap speakers make compared to proper ones.

But not echoes, hiss, pops or crackles, nothing obvious like that.

Is that a noisy transistor or am I being too literal?
 
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If there's a speaker relay involved, I'd be checking that. The "fuzzy sound" complaint is textbook speaker relay problem.
 
Why yes there is - thanks very much for that, probably saved a lot of misdirected half-assed freeze-spraying :)
 
It's often (but not always) possible to confirm trouble at the protection relay contacts by sharply increasing the volume, assuming you have adequate speakers. If the sound snaps back to normal, but eventually gets weak and distorted again after reducing volume, then relay contact problems are almost certain.
 
gazman said:
Why yes there is - thanks very much for that, probably saved a lot of misdirected half-assed freeze-spraying :)
Click to expand...

Hope you get it solved soon. I'd like to pass on an observation to a budding technician: I don't use freeze spray very often to troubleshoot. I only use it if I'm certain it's a thermally related fault. The stuff's expensive and can normally cause a shift in circuit operation. Jus' tryin' to help! :D
 
i have had a few experiences where (over the course of a few weeks) the output on one channel would begin to distort at declining levels of volume. each time, the final result was a failed channel due to a bad output. I have not had one simply sound bad without eventual failure.
 
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Thanks everyone!

I'll try the volume thing first, but a dirty relay fits - I haven't actually ever cleaned/sanded a relay because the (few) things I've cleaned up didn't seem to need it so it just kind of slipped from my mind as a possibility. Got all fixated on caps and transistors.

Thanks on the freeze-spray too. That's good to know - I haven't actually had much luck with it, but thought I was unlucky or it was me and have been using it as a first step anyway. So far the two things I've found the problem with (not the ongoing 430 saga in Solid State) have been with a multimeter. I'll lay off.

And its expensive, but not compared to DN5 deoxit in tiny little spray cans which is all we seem to be able to get in Australia because of hazardous good shipping rules :)
 
Okay, slight my bad here. Update, and also for anyone finding this later :)

I took the relay out, had a fifteen minute fight with it trying to pry the little %#$@ open gently, gave up and forced it, sanded the contacts with fine sandpaper, put it back in.

The noise is still there, but DC on one channel that was a bit wobbly has now settled down, so cleaning made some difference.

Of course, then I searched AK for relay cleaning info and found, (a) I shouldn't sand it, and (b) if I do should flush it with deoxit afterwards and (c) relays need adjusting sometimes.

At this point I think I'll get a replacement and just swap it out - I'm really not sure if I made things worse in the long term by scraping off coatings or leaving sanding dust in there, or thumping it around to open it, so for parts cost vs risk, I'm thinking a new one is best.

I did the volume thing, but didn't get any noticeable results - small/mid-sized test speakers though.

Thanks for the help everyone!
 
The "fuzzy sound" complaint is often caused by a 'dirty' relay, but not always. That's just one of the first things to check. 'Dirty' switches can also cause that sound. Check any Tape Monitor or input selector switches too.

Caps that are opening can cause that sound, cracked solder joints, and, to a lesser extent, transistors too.

Opening the relay and cleaning it should've caused some change in behavior if it was the culprit. The change should have been; it got better, it got worse, or had some change even if it didn't fix it. It was the right relay, yes? Not a power on relay, right?
 
Sorry, I should have said - this has been recapped (everything except the tuner section). It had a bit of a 60hz buzz thing going on which I assumed was power supply caps being bad. Recapping fixed that, and cleared up the sound enough I could then hear this distortion - it's very slight.

There's only one relay, just I'm not sure listening if it's changed or not - it's at that borderline annoying level where you end up imagining some of it if you concentrate. I'm also thinking putting in new parts when I'm not sure lets me see before and after which is useful for learning.

But - you saying what you did got me thinking. I was sitting here about to type that I'd done the deoxit, so it isn't pots/switches, then I thought - I've had this thing sitting around for more than a year being broken, waiting for me to learn to solder and try to fix it. And I've never heard it working. So I should definitely reclean the switches and not assume.

Damn.

I also haven't checked the solder joints so I'll do that.

Thanks for this - this is very useful. This wasn't meant to be a troubleshooting kind of post, but it turned into one. I think its me :)
 
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