HiFi amp question

[Orang Goreng]

Maybe this should go in the misc section, but it's about an amp, so let's try it here first.

Anyway. Yesterday I noticed that my HiFi speakers produced a wobbly background noise while no signal was sent to the amp (just a cheap consumer-grade Philips, about 5 years old...can look up the type if necessary, but I doubt this question is model-specific). I checked the amp with my headphones, and I get the same problem. It's like there's some low-frequency oscillator active all the time. When I play music through the amp, the sound is distorted.

Does this sound familiar to anyone? Is there a fix (provided I've given enough info), or should I just buy something new? I spotted some mice on the amp recently, maybe they've pissed on the PCB through the ventilation grid or something...somehow that seems my most likely explanation at this point.

I only play music from my computer; my sound card is hooked up to the hifi amp. Would I be better off buying something else? I really like my old Yamaha speakers, so ideally I'd continue to use them, but I'm wondering if it wouldn't be a better option to get some powered monitors, or perhaps something else. My soundcard has both analog and S/PDIF outputs, if that helps. Given how I've spent about a million over the past months, I'd like something relatively cheap (unless it's good investment, i.e. will last me for many years).

Anyway, TIA for any syuggestions or help!
Z.

[luau]

If you go with a new one, check out the Onkyo TX-8222. At $150, it's a bargain IMO. I've had its direct ancestor, the 8211, for 9 or 10 years now without a single issue.

[Superfuzz]

are there some ground/earth wire that could be gone loose?

[Orang Goreng]

If you go with a new one, check out the Onkyo TX-8222. At $150, it's a bargain IMO. I've had its direct ancestor, the 8211, for 9 or 10 years now without a single issue.

Hmm, and in good European tradition the cheapest one I can find here is € 225 ($ 355)...typical.

Thanks for your replies, guys. I think for now I'll just try to score a second hand one on the flea market until I have some new funds to invest in something proper. There's a nice 2nd hand tube HiFi amp available for about € 200...unfortunately it isn't exactly local.

[Orang Goreng]

Hmpf. Just freed the amp from the shelf on which it was standing. Although I lack the tools to open it, I can see inside through the vent grid. It's mouse pee alright... the pcb looks completely oxidised in some spots. Nice big components, though. Hmm. Maybe I should get a set of those keys to open it up and then try to clean the board. Doubt if it will work though.

I need a cat...

[Superfuzz]

Tube Hi-Fi amps are cool as hell, BTW a nice mosfet amp from the mid '70 could be a killer for a steal, especially if you use it with your pc, you need something that you can easily use, without thinking of heating tubes, standby switches and so on...
I got an old Yamaha amp and preamp, one of the first mosfet ones (Yamaha developed the mosfet technlogy if I don't go wrong) and it sounds super, I got also an old Marantz wich is even nicer, but I got to test it with better speakers..
Time ago I found the same Yamaha preamp as mine for 80€..a steal!

[øøøøøøø]

Hmpf. Just freed the amp from the shelf on which it was standing. Although I lack the tools to open it, I can see inside through the vent grid. It's mouse pee alright... the pcb looks completely oxidised in some spots. Nice big components, though. Hmm. Maybe I should get a set of those keys to open it up and then try to clean the board. Doubt if it will work though.

I need a cat...

It depends if the oxidation caused short circuits, damaged PCB traces, or if it's just causing intermittent contacts.

In other words, did it fry other stuff, or is it the problem in and of itself?

If the former, you'd be screwed, but if the latter, a little Caig DeOxit could resurrect it.

[Jay]

I would try the cleaning thing...  what have you got to lose.

[Orang Goreng]

Yeah, just borrowed the required tools from work after making idle trips to the local thrift shop and flea market this morning on the way to work. I'll shoot some mouse pee pics tonight...in one spot there's even a mouse poo in a dried-up puddle of pee on the grid. Yeah, I'm great at housekeeping...

[Orang Goreng]

Yuck!



There's even three poos in there. Well, I have since cleaned the oxidised stuff away, so the components don't seem to be bridged anymore. I'll test it later.

[Orang Goreng]

Well..that didn't work. But as luck may have it, I just decided to walk into a tiny TV repair shop around my corner, to see if they had something I could use. I returned with a vintage HH Scott amp (a US-made one, not one of the recent Chinese ones). It's about as big as a house, but was only € 50 and sounded great in the shop! Pics to come.