Ibanez SRX300 - dead electronics, need help!

[Gastrok]

I just snagged a very clean looking SRX300 off ebay for 30 bucks (crazy, I know!)...the seller was clear about the neck being bowed and electronics being non-functional.

Turns out the truss rod was just really loose and I've got that problem sorted out...now I'm stuck on the electronics. I really have no idea where to begin. I've tried a new battery and examined the connections and verified them against the circuit diagram I got from the Ibanez website.. but nothing is jumping out at me.

This is my first attempt at this sort of thing...what should I do next?

[T-Bird]

Hi.

Hot-linking the circuit diagram (schematic) would help a ton .

Next You take your DMM, plug a cable in the output jack and start measuring where the power stops. Before that You obviously measure that the pickups are still functioning as they should.

Regards
Sam

[Gastrok]

Here are some pictures. For 30 bucks it was a steal!

[Gastrok]

More pics

[Gastrok]

...and here's the problem area.

[Gastrok]

here's the schematic.

[Gastrok]

Originally Posted by T-Bird

Hi.

Hot-linking the circuit diagram (schematic) would help a ton .

Next You take your DMM, plug a cable in the output jack and start measuring where the power stops. Before that You obviously measure that the pickups are still functioning as they should.

Regards
Sam

Hi Sam - I posted the schematic. I'm a total noob when it comes to this stuff, so I've got some questions about your suggestions:

1. what is a DMM? (digital multimeter perhaps? I've got an analog one)
2. how do you measure that the pickups are still functioning?

[T-Bird]

Hi.

1. You guessed correctly, digital multimeter it is. An analog one works just as well, even better with pickups.

2. You preferably disconnect the hot lead, middle lug in the balance pot, and measure the resistance. You can also tap the pole with something metallic, the needle should jump up if the polarity of the multimeter wires is the same as with the pickup.

Unfortunately the pic You linked is just the wiring diagram as usual, not much help there.
There was a Yamaha pre question in here just a few days ago and Yamaha had the full schematic publically available.

One possibility is an "interference method" You touch various parts on the PCB and the hot leads and trace the problem with the hum. A basic understanding of the circuit is required though.

If those pickups are Hi-Z (~8KOhm resistance) You could just buy some 250K or 500K potentiometers and a tone cap of Your preference and change the bass to a passive one.

That's what I'd do without a schematic.

Regards
Sam

[Gastrok]

I feel like I'm in way over my head here! I'm going to work on these things you suggest though; I don't understand most of it now, but eventually I'll get it.

[Gastrok]

Sam - thanks again! (forgot to say that before)

[Gastrok]

Originally Posted by T-Bird

Next You take your DMM, plug a cable in the output jack and start measuring where the power stops.

Sam - OK..so I think I did this...here's how: I put one of the multimeter leads on an exposed part of the battery wire and went through all the connector points in the circuit. Most points I got a full 9 volts. there were some places where it was lower, say 4 or 5 volts. I didn't find any place where there was nothing. Does is sound like I'm doing this right?

I hope you have the patience to continue helping me!

[T-Bird]

Hi, Gastrok.

You're welcome.

I'm afraid that without the schematic of that said pre, there's not much that anyone can do to help.

If the 9V is present almost through the entire PCB, it could suggest that the OP-amp chip (if any) has shorted out. Impossible to tell without knowing the circuit though.

Like I said earlier, if the pickups turn out to be ok, wiring the bass passive would be the easiest/cheapest/best route IMHO.

Regards
Sam

[srxaxl]

hey my srx300 had the same problem, thanks for posting the schematic guys