L***6 Schematic needed for repair

[christobean]

i just received a L... 6 Spider II HD head that was 'broken"  i opened it up and the only thing wrong appears to be teh two blown power amp chips.  i am confident that i can fix this, but the chips are burnt and i cant make out the code on them.  does anyone know where i could find a schematic or something, any information on this amp's circuitry?
any suggestions appreciated.

[$uperpuma]

this is the second instance I've heard of this happening with a Spider II, just this week.... the other one was a combo, but come on...whats the deal?

[Cliff Schecht]

this is the second instance I've heard of this happening with a Spider II, just this week.... the other one was a combo, but come on...whats the deal?

It's happened to a few people on the Guitarworld forums as well. The only Line 6 head I would even consider buying is the Vetta II head, which is a $1600 head (if I remember correctly).

[The Tone God]

BTW you don't need to * out names as they are allowed to be posted here and using names helps people when using the search function.

Andrew

[Ronsonic]

Line6 uses LM3886 for the output devices.

Usually when I find those gone, there's nothing else wrong.

No telling what people plug these into to blow them up. The 3886 is a fairly robust device and usually protects itself well. Wouldn't be surprised if these are getting connected to mono speaker cabs, or even the same speaker. Who knows.

Anyway - replace the chips and bob's your uncle.

Ron

[Mark Hammer]

Since it is a single power amp chip that comes in a fairly modest-sized package, I would imagine that appropriate heat-dissipation is crucial to maintaining operation.

This suggests several things to consider:

1) Is there enough thermal paste between chip and heatsink?

2) Is there enough heatsink?

3) Is there enough airflow around the heatsink so that it works right?

Both NatSem chips and Line 6 products have good reliability and decent reputations, so this shouldn't be happening.  Either the amps are somehow underdesigned, or are too often misused, or perhaps are juuuuuuuust underdesigned enough that some folks are going to find a way to push them past their limits.  Maybe they need a fan installed.  Maybe they need bigger heatsinks.  Maybe they need more goop.  Or maybe they just need to be used far enough away from the wall that air can flow through and let the heatsinks work.  Maybe its what happens when you feed the chip supply voltages juuuust below the max for maximum output, feed the amp a highly compressed distorted input, keep it dimed, and park it near the wall in a stuffy basement rehearsal space.

[christobean]

thanks for the info about not using **, i thought that was a rule since ive seen a bunch of people do it.  i am not sure how it was blown, just that a kid sold me a speaker cab for 60 bux, and threw in the blown head for free.  it looks like the chips have 2 extra pins than the 3886, but i will check again.  id say theres a good chance they were blown when someone accidentally flipped the switch on teh cabinet to mono, which put 4 ohms on each channel of the amp when it is specified for 8 ohms each.  also, there is a lot of corrosion on the metal pieces so the thermal connection could have been messed up.  it does have a good sized heat sink on it though, so i would imagine it would do a good job as long as there was good thermal flow. thanks for the feedback...if anyone else has anything, keep it comin 
thanks again

[christobean]

ok, it is definately Not the LM3886, it is a TDA7-----(the burn marks make it illegible past the 7).  anyone have an idea on what chip this could be?

ive been searching for a few hours and cant come up with anything.  the chip also has "singapore" printed on it and "ST" seems to be the logo for the company that made it.  the amp claims 75 watts per side, and there is a seperate chip for each side, so i am guessing it puts out ~75 watts mono at 8 ohms. 

[Johan]

could be a tda 7492/3/4..mosfet good for up to 100 watts..
johan

[JimRayden]

Email the company. Some of them send a digital copy of the schematic free of charge. Others require purchasing a paper copy.

----------
Jimbo

[christobean]

will do..thanks

[bajaman]

Hi
I fixed one of these a while back - they use TDA7293 chips. After I replaced the chips I checked the rest of the circuit - no problems. Just be careful with the mounting bolts and insulating spacer and you should be okay.
Cheers
Steve

[christobean]

thanks!!! yea it looks like everything besides the 7293s is fine, so once i find the chips i should be good.
any hints on sourcing these chips?

[christobean]

i found them here http://www.electronix.com/catalog/product_info.php/cPath/6_311/products_id/12337 which isnt extremely expensive, although we'll see what shipping costs are. not too bad though considering i got the head for free.

[Gladmarr]

Mouser has them http://www.mouser.com/search/ProductDetail.aspx?R=TDA7293Vvirtualkey51120000virtualkey511-TDA7293V  I don't know if this is the right package for you, but this is the only one they have in stock.  Also, Digikey has them for about the same price you already found.  http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=10851&Row=201130&Site=US

...hope that helps.

[christobean]

thanks, i ordered them from electronix last night. i should be receiving a ups tracking number anytime now. hopefully it gets here soon cuz i cant wait to fix it n blow away the neighbors with the 150 watt head