Know IC chips? Help me fix my cheap amp!

Hello, I just opened my non-functioning amp and found an empty place where an IC chip should be. Don't ask what brand of amp, it's an obscure cheap thang. So anyway the chip would be a 16 pin thing, long and skinny, as you can see in the middle of the photo. It's a medium size practice amp, probably only 15W or less. Anyone know what kind of IC chip that would be so I can go get one and plug it in there? thanks

~Matt

Well it's most likely a quad opamp.

You need to measure to voltage on the pins of the socket to be sure which type of amp chip.

Either pin 16 is the supply voltage and pin 8 negative supply or ground.

Thanks, I could just go in and ask for a quad opamp 16 pin chip?

An op-amp is a good guess, but I'd do some more research before trying to plug one in. You could damage the circuit if that socket was meant for something else. It also begs the question of why that particular chip was socketed, when the little 8-pin chip on the same board was not. It's possible that socket could actually be a connector meant to connect another board to the front panel board.

Any chance of tracking down a schematic for that amp?

Agreed.

It's odd for it to be socketed for a start. It's all about cost and it's made even stranger by the fact that the 8 pin IC isn't socketed leading to the suggestion it's a connector for something else or possibly the amp has been screwed around with before.

By the way, can you elaborate on not functioning.

Not turning on (no status LED or anything?) or just no sound?

Did you buy this (or otherwise aquire it) in non working condition? If so a previous owner may have put the socket there to try out different chips.

It's probably an op amp. You'll want to find the schematic and get the part # the manufacturer spec'd on the sheet to find out what kind of Op Amp it actually is. Then replace it. What kind of amp is it?

No sound. It made ugly noises before stopping all sound.

I warned you not to ask that... amp is from Central Europe and it's an amp nobody ever heard of. Probably zero chance of getting a schematic. "Van Horn Guitar Amplifier" is all it says. The shame!

I tried google for Van Horn amps and I see nothing on it, but took a shot at it anyway.

A couple thoughts.....

I have had small practice amps open for service that had the holes for an IC that evidently utilized a 14 Pin DIP IC ( typical for quad opamps ) for a reverb driver/receiver. If the amp had no reverb can.....no IC.

But none of those had a socket installed - just holes. Too much extra cost to build for the company.

And I wonder if the 16 pin socket you have had 2 end pins clipped off to fit a 14 hole position......

One of the socket holes looks damaged in the photo...looks like pin 2 - hard to tell in photo which way the socket is put in.

And if it is 14 pins soldered with 2 pins non functional - you should read the supply rails for a TL074, for example, on the middle pin of each row ( pin 4 and pin 11 of 14 avail pins ) if the supply for the amp is a bipolar supply type.

Or a positive voltage on pin 11 only, if designed that way.

Someone may have soldered in a socket perhaps thinking they would get reverb by trying an IC in it.

Of course without a rev can - wouldn't work.

And the amp would have an unfilled area in the row of potentiometers for "reverb" control too, if not orig issued with a can and peripheral circuitry....

Good luck

Could you take a photo of the underside of that socket? It would be nice to see if that's been soldered in after the fact. Also a better pic of the top of the socket would be nice.

And actually, while you're at it, a photo of the whole circuit would be good too.

this czech expat is selling a Van Horn Bass amp:

maybe he'll open it up?

Heres a shop selling them;http://www.muzikservis.cz/shop/producer/36

the Czech dudes in the discussion boards have very little love for them

heres the company

Peter Long - Van Horn, musical instruments

Sales of musical instruments and musical amplifiers.

http://www.vanhorn.cz (dead)

Contact information:

Adresa: K?inec-Nov

I'm not so certain that the empty IC holder is the issue then or the sole issue. I think there's a problem elsewhere.

It's like going in blind without any knowledge or schematics of the amp and it's even worse trying to do it over a forum. If you want to diagnose the issue with the amplifier, ideally, you need some electronics knowledge and the equipment to fault find it.

Hey y'all, thanks a million for the replies. Tedmich, excellent info, thanks -- that amp is very similar to mine.

I will get back to you all soon.

Could you take a photo of the underside of that socket? It would be nice to see if that's been soldered in after the fact. Also a better pic of the top of the socket would be nice. And actually, while you're at it, a photo of the whole circuit would be good too.

Here's the best I could do with getting to the underside. There seems to be a black cable coming from the approximate area.

I think I am going to use Tedmich's links and see if there is someone who can fix it... I would like to get it fixed and not have to buy a new one. On the other hand I have heard good things about the little amp Vox PF15R and they aren't too expensive.

Where's the other end of that wire go?

It leads to pots in the back for input levels/ reverb levels

its all in Czech, I only found them using Google's translated search engine, which is my secret weapon for esoteric info.

oh and to paraphrase Stephen King " you can't Polish a turd, but you can Czech it..." I'd s*can it and get a better amp to screw with, keep an eye on the Clist, I got a dead Bravo for $50, added a fuse and it rocks...