Boss GE-7 with defective adapter input..

[manson]

Some days ago I asked about a boss ge-7 equalizer with a malfunctioning adapter input. It only works with a battery. I bought it, received it today and tested it. It does exactly what the previous owner told me. Works perfectly with a battery, but when I plug my adapter in.. nothing. So I guess something 'blew up' in there. I opened it up, but I cannot see anything wrong. No burn marks or things like that.

Now for my question: what could be wrong with it? Which parts could be defective? I'm thinking about D1 but I'm not sure.. It's listed as a 1S2473. I'm about to order some parts from Smallbear, but he doesn't list it on his site. Could I subsitute it for some other diode? Or do I need to look at a completely different part of the schematic to find the error?

Please help me out


http://img267.imageshack.us/my.php?image=ge7pg28oc.jpg

[heyniceguy]

id say D1 is highly likely to be gone. D1 is there to protect the circuit if a numbskull puts in a reverse polarity adapter. the diode opens up and starts conducting mad current to keep that current from reaching the circuit and blowing a chip. eventually, the diode fails, but it gives you at least some time to correct your mistake.

and it may or may not be visible, so dont be mislead by the lack of burn marks. and dont sweat the part number BS. you can use a regular 1N4001 or even a 1N4148. The 1N4001 wont blow up as easily since it is able to dissipate more power than the 1N4148 will. the 4148 will blow like a fuse under reverse polarity conditions in a short amount of time.

but try it. 1N4001.

[TheBigMan]

Also possible the DC socket has gone.  I've seen this a few times with them where the switch doesn't toggle between battery and AC anymore so you end up hardwired to one or the other.  Test for continuity between the 2 positive terminals on the socket with and without a plug in the socket.

[Paul Perry (Frostwave)]

Take the batteries out, plug the adaptor in, and use your meter to track how far the voltage gets - or doesn't get.

[manson]

Thanks, I'll try some things and let you know when it's fixed 

[manson]

I fixed it by replacing the diode. Works fine now Also changed the ic's to tl072's while I was in there.

[heyniceguy]

i love it when im right.