Squealing. More volume, more squealing. Quite annoying.

Pretty obvious it needs filters. Can't seem to find service info on the thing though. I think I can do it without but I would really like to see how it comes apart before tearing in to it. It has the flip top like a laptop and you know how those can be. I don't want to screw it up, rip the main ribbon to the lid or anything like that.

Actually I am doing music equipment now, amps, mixers etc. and am not actually finding as many bad caps as in brownwares. More bad solder joints etc. Is there ac chance that's the problem here ? If I had history on it, if the problem used to be intermittent, great.

At first I figured this lil thing has to be class D, but a post on the net alludes to it using LM3866 which is not. Who knows right now ? At this point though, both channels are doing it so I am leaning toward the PS. As small as this thing is, I will probably have to search Digikey for good enough, snall enough caps for it.

Seriously though, right now I am concerned about getting in there without killing the patient. Anyone have one of those things apart ?

Thanks.

wrote:


Squealing. More volume, more squealing. Quite annoying.

Pretty obvious it needs filters.

** Main filter caps ?

Not bloody likely.


Can't seem to find service info on the thing though.


** How odd.

It's an utterly obscure make and a looks like a **** awful pile of Italian junk.


Actually I am doing music equipment now, amps, mixers etc. and am not actually finding as many bad caps as in brownwares.

** No fooling.

More bad solder joints etc.

** Yep, music equipment gets transported a lot and subjected to intense vibrations.

At first I figured this lil thing has to be class D, but a post on the net alludes to it using LM3866 which is not.

** Yes, I found that post.

LM3886s can deliver about 60 watts into 4 ohms so that dos not tally with the 200wpc rating.


Who knows right now ? At this point though, both channels are doing it so I am leaning toward the PS.

** Bad multipin connections and cracked solder are far more likely culprits.


As small as this thing is, I will probably have to search Digikey for good enough, snall enough caps for it.

** Drivel.


Seriously though, right now I am concerned about getting in there without killing the patient. Anyone have one of those things apart ?

** Looks like the piles of **** were never retailed outside of Italy - most Google hits are in Italian or Greek.

Music gear, once sold, tends to travel all over the place and way beyond any support networks that exist. Owners never understand this and expect miracles from service techs, performed while they wait and imagine peanuts is sufficient reward.



..... Phil

"LM3886s can deliver about 60 watts into 4 ohms so that dos not tally with the 200wpc rating. "

That was only an internet post somewhere. I should have spekled out I did not give it much creedence. not make sense, 200 watts from 30 watt chip. Of course them Italianas well soma timesa you never really a know...

It might be 200 watts Peak Insttantaneous Power If Lightning Strikes, which was a popular form of rating aftermarket car stereos until me and the boysa showed up in town and showed them what 100 watts was. but that ws a long itme ago. ;Enough drivel, I do not want to wear your snippers out.

this is pretty straight up here, the more loudness comes out of it, the more squeal at about seems maybe 6 K.

I guess I'll **** with it Monday. Maybe. I could set it aside and they won't care.

And THEN, yesterday (was off today) god damn ****ing Ampeg, little wonder ampeg. Has SMPS, pretty sure class D, VERY small. Bows the breaker/fuse in the wall at plugin.

the ****heds used too long screws for the little rubber feet on the bottom and it caused a short across the power switch wires.

Damn. Where the **** ere the engineers ?

Whatever. I also have to figure out the debauchery involved with that Fender or whatever, Chorus thing. Someone changed that pot. W H Y ? the **** would go wrong wth that ? I smell a leaky, not leaking electrolyte, not juicing up the boarrd with its wondervul acid and ****, but electrically leakey. Right around an oscillator that is supposed to run at a low frequency, OR perhaps a higher one hetrodyned... dunno.

Problem here is like anytime you follow someone else. ****ing don't know if they were right and the part is wrong, if they were wrong and the part is right, or what.

Been thinking. (ummm)

Looks like the ribbon cable is on the right side. (as you face the unit open) I think I am going to apply a piece of tape to the left side to help prevent rippage of the ribbon. It does look a bit heftier that one to the display of a laptop, but still. the lid as well as the base of this thing are heavy amd that is part of my concern. In fact they must have tried to use the unit because three people told me "Watch the lid on that ****ing thing because it'll pinch the **** out of your fingers".

Then I need something to support it upside down at the spine. At that point I guess I have to just start taking screws out. That should be safe enough.. then I need a box because this place does not have a proper stock of electronic parts. In fact it is almost time to talk solderwick, and I don't care how much he swears by his suppliers (and he does), if they don't have Chemwick and LPS-2 then these things will have to be procured (EGAD !) from somewhere else.

However I will have to wait maybe until I am there a couple weeks to bark out orders and change their whole M.O. lol. But there are some things we simply need. I run into that all the time. I want to see what happens when the parts get ordered. I have seen people deal with the ****tiest ****ing parts places and swear by them. won't consider anyone else. What, is that your brother in laws company or something ?

I'll get my way. Just like when I took my ex-bosse's card and made a Digikey order and fixed four plasma TVs the next day. And he had no ****ing clue where to get some simple ass MOSFETs. Nothing special about them at all.

Idiocy is annoying and that is why I try to keep jobs and not move aroud. they find out that I am right, but with each new place the process starts all over. Let's hope it goes well again, like it has the last few times.

****ing people do not undersatand to even keep fuses in stock ? I MEAN IT. Damn one place I gave them the fuse rack for the wall.

Well I don't want to bitch about it, I just hope I don't run into problems. I heard from one guy there that the boss is stuck up on his suppliers kinda, let's see how bad it is.

Enough ranting, it is Saturday so I am going to find something constructive or destructive to do.

Thanks for your input. When I get the ****er cracked open I'll let you know what lurks inside. I bet it's a class D, it is just too small to not be. Sure it has forced air cooling, but that doesn't mean it isn't class D.

That squealing sounds like about 6 kHz, it is probably the difference between what the power supply is running at and the chopping rate of the output stage.

And really, what makes it junk ? I know it is too small and probably underbuilt but that is true of alot of things.

Anyway, enough for now.

What makes it junk ? I just barely started to take it apart and I think that I might just not need an answer to that question.

I had a nice tight bit in those allen screws and the wanted to strip. Don't they harden metal in Italy ?