Diagram of Circuit Board

[Edwin]

I purchased a Palatino EUB from eBay and arrived DOA, no output on amp/preamp circuit board ! I need a schematic diagram of audio circuit from either Palatino or Harley EUB which are the same audio circuits. Please send a PDF file to [email protected].

Thank You in advance.

Edwin

[NickA]

Doubt anyone has a circuit diagram .. and the PCB is surface mount; not easy to repair.  Maybe rip it out and go passive into a piezo pre-amp (sans amp or similar).  You'd lose the on board tone control and headphone socket is all.

[Passinwind]

On 15/11/2020 at 05:50, Edwin said:

I purchased a Palatino EUB from eBay and arrived DOA, no output on amp/preamp circuit board ! I need a schematic diagram of audio circuit from either Palatino or Harley EUB which are the same audio circuits. Please send a PDF file to [email protected].

Thank You in advance.

Edwin

 

Hi  Edwin,

I think your best best might be to work through the posts here: https://www.talkbass.com/threads/the-definitive-palatino-eub-modification-thread.303366/ , and then maybe in the associated longer TB thread as well.

Repairing surface mount boards like that is actually fairly easy for many decent techs these days, but IME the learning curve could be kind of daunting for DIYers. Reverse engineering is often times a PITA because the small capacitors often have no labeling. Since replacing the stock onboard preamps seems to be a popular thing perhaps you can score a working unused stocker with a little luck. In any case, I'd suggest verifying that the pickup system is working properly before diving into the preamp section.

 

 

[DanOwens]

I agree wholeheartedly with Mr Wind above; start by checking the pickup is sending a signal. If so then all you need is a simple impedance matching circuit (like the mint box   http://www.scotthelmke.com/Mint-box-buffer.html) and you can do the rest in your amp.

 

i should say that I own about 300 preamps but sometimes simple is best.

 

[itu]

Start with wires. If they and battery are fine, the connectors are the next. It should not be impossible to find the voltage from the circuitry. If the voltage comes to the board, then there may be a failure in the board or the piezo. Piezo is prone to braking, it should not be bent. Please take your time.