Help!

[octavedoctor]

Does anyone have access to a circuitry schematic for a Parker P-38 with the Powerbridge and onboard powerchip?

I've got this POS on my bench and I keep buying powerchips and they keep turning up faulty...

I just need to know if it's something I'm doing wrong before I sound off at the distributors.

[larry_emder]

'bout time i could help you out. This is for my parker p-40 but i'm guessing they have the same schematic (they have same pickups and switching options). I emailed parker to get it so if it doesnt work for you, email them

http://martinrotolo.googlepages.com/...0HSSwiring.pdf

[octavedoctor]

Wow, thanks Larry that was so quick!

Did they really send you that circuit diagram? It loks like it's ben scribbled on the back of a paper bag...

My friend worked for the former distributors here in the UK and he said they offered no technical support to the distributors at all, not even circuit diagrams. I can see why...

Still, any schematic is better than none. I'll probably redraft it in more legible form and post it on here for you.

Thanks again for your help, I appreciate it.

Eltham

[LesStrat]

Too bad you're a tech. Otherwise, I'd advise you to send it to one.

After "installing" the Brobucker in my Fly Deluxe, I started giving this advice:

If you ever get the chance to work on the electronics in a Parker, DON'T!

I ended up paying a tech to finish the job.

[octavedoctor]

Yes, I'd echo that.

The problem is that even if you are a tech, you can't do anything with faulty modules.

The circuit diagram Larry provided has allowed me to establish that there is nothing wrong with the wiring to and from the Powerchip; in fact I have corrected a battery drain problem caused by either the factory or a previous repairer connecting the negative leg of the battery clip directly to earth instead of via an open-shorting switch.

The story so far is this; the P-38 was brought to me suffering with "windrush" noise on the transducer side of the module. This is the random crackling and hissing that usually characterises the breakdown of a chip, or leakage of a DC potential onto a signal path.

Multi layer PCBs and surface mount components make tracing an individual faulty component not worthwhile as the labour time exceeds the value of the component so replacement is the only option. Even if you could replace the chip, the chances are the manufacturers will usually have erased the ID on the chip so you can't identify it...

Unfortunately, the replacement Powerchip was just as noisy, so I handed it over to a tame engineer who decided that it was probably just a "noisy" chip, which wasn't much help.

It lay fallow on my bench for a time, while the distributors tried to lay hands on a circuit diagram. Eventually they came up with one which suggested the addition of a 0.1µF cap and a 1KΩ resistor at various points on the board. So I tried this, and that didn't work. In desperation I ordered a second Powerchip.

Fantastic this one is totally noise free!

The problem is there is no output from the electromagnetic side of the module and the gain from the piezo side is way too high, and clipping. The trim pot makes no difference.

The module comes pre-wired so the only soldering you have to do is to connect the output cable of the Powerbridge to the PCB pads and the output from the 3-way toggle to the relevant PCB pad on the other side so I'm confident it's nothing I've done. I can pnly assume I received two faulty Powerchips in a row.

Fishman circuitry is normally reliable so I'm really surprised I'm getting these problems...

Also I really can't believe the shoddy quality o the schematics posted on the Parker website! They really do look like they've just been thrown together. What on earth do the factories use for installation? If it was my compnay I'd be thoroughly embarrased to post that kind of useless crap on the website masquerading as technical support.

But this kind of slovenly incompetence is exactly what I've come to expect in an industry that accepts tripe like the Fretwave and the Feiten system as gospel...

[larry_emder]

Yes, please do re-post it! I've all but given up on fixing the electronics in my parker. I Swapped a pickup out a while back and wrecked the wiring somehow...havent been able to get the piezo to work since.

[octavedoctor]

Yes, please do re-post it! I've all but given up on fixing the electronics in my parker. I Swapped a pickup out a while back and wrecked the wiring somehow...havent been able to get the piezo to work since.

I'm working on it now Larry but it might take me a little while to get it finished as I've a lot on over the weekend.

Thanks.

E