EHX Holier Grail disaster

Started by superferrite, June 10, 2011, 10:31:17 PM

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superferrite

I traded for a Holier Grail I understood was not working and now it looks like the previous owner had tried to "fix" it himself.  Ugh!  He was no professional!

I can't even think of how to proceed.   The circuit is not too buggered, but looks like a big transistor was poorly half-soldered in place and a few wires are just randomly hanging about.

Any ideas?
It does have a couple of nice pots, switches, LEDs and jacks if worse comes to worse ;-)

Psychedelic Garage Metal

anchovie

Bringing you yesterday's technology tomorrow.

superferrite

Here are some pics of questionable parts.
The only dangling wire I'm unsure about is the red wire from the power jack to the board.   Where does it hook up?


Is this the right component? 


Soldered like a real winner!   What's up with the black and brown wires?   IS that standard?


150 ohm resistor in series with board?!?!?
Psychedelic Garage Metal

anchovie

I take it pic #2 is the underside of pic #1. The large part is a 7805 5v voltage regulator. The browned patches around it on both sides suggest that the original part got a wee bit hot.

As you have noted, the replacement hasn't been well fitted - the two pins bridged by too much solder won't be doing anyone a favour! Also looks like some of the original pads were destroyed when the old part was taken out. When I've fixed similar botched repairs for people, I've found the safest option is to work out the next component each damaged pad should be going to and use jumper wire to guarantee those connections.

Goodness knows what the wires are for, but I'm pretty sure that isn't how EHX makes them. If I were to take a guess, the 150 ohm resistor was put in based on a theory that limiting the current would stop any future 7805s from overheating. Not really a solution as it doesn't solve the problem of the circuit pulling way too much current in the first place.
Bringing you yesterday's technology tomorrow.

superferrite

Right, that is what I thought about the voltage regulator.
If I get a response from New Sensor, I'll try and fix it, otherwise, it is a mine of parts and a sweet box .
Psychedelic Garage Metal

cfran00

Hey, this is an old thread but i'd figure id point this out.
1) most importantly, 4r7 is completely blown. you need to replace it or just go point to point with a lead. 4.7 ohms is basically nothing.
2)there is no grounding screw through the transistor.

im sure once those are both replaced this would have resolved the issue. hopefully im not too late lol.