Line 6 duoverb head problems

[wkalata]

A friend gave me a totally non-working Line 6 duoverb head (He explained that a cabinet of his had been wired to 2 ohms by mistake). I took it to a line 6 authorized repair shop (roughly 350 miles travel time to drop it off and then retrieve it), and they returned it to me with the TDA7293 chips replaced. When I plugged it in, it was easily drowned out by my 10 watt practice amp, and didn't sound very good at all. After a short phone call with a tech at the repair shop, he postulated that one of the chips he installed could have been DOA.

I am not experienced with repairing electronics at all, but I would be confident in desoldering/replacing one of these chips. Can anyone offer me any advice on what steps I would go through to test them to see if the tech's hypothesis is true? I already looked at the board and there aren't any apparent cold solder joints or the like.

Thanks,
Walt

[Enzo]

I would be willing to bet that when the 7293 chips burnt out, they damaged the muting circuit on the main board. No, I have no idea where that is on the Line 6 product.

[BStringThumper]

Hi Enzo. Can those chips be tested in circuit or out with a digital meter? Thanks.

[Gtr_tech]

Whatta crappy "repair shop" then....

[BStringThumper]

Yeah, that poor guy. The tech must not have even checked it after replacing the chips. I have no output on mine and it looks like someone has already replaced the TDA7293 chips. I was hoping I could test this and go from there. Line 6 will not release the schematics for their products.