Tw5/tw6/gemini 3 Circuit Board Diagram And Wiring Diagram Needed

[cas]

I just got a Fisher TW5 and the speaker is not working. Head phones are working ok, and cant find anything obviously wrong with the circuit board, speaker, switching or wiring. Maybe somebody disabled the speaker ?? Not sure, so a diagram would be much appreciated. I have the Operator Manual for TW6 and Gemini 3, nothing in them about troubleshooting the speaker circuit. Many thank for any suggestions you might have.       

[Geotech]

TW5 is fairly old. Since the headphones work then the audio circuitry is working. Most likely culprits are (1) a bad speaker or (2) headphone jack contacts are dirty.

[cas]

Hello,

thanks for the reply...yes, TW5 is old, but it appears to be very similar to TW6, and to Gemini 3, and the circuits are pretty simple on all of them .

I suspected bad speaker, but it checked out ok. Headphone output and all meter work ok 

Only thing not working is the speaker.  

It looks like someone has modified the speaker switch to function as on off switch, and disconnected the speaker

from audio output. 

So, what I need is the original receiver wiring diagram for any of them,TW5, TW6, Gemini 3,  to see what the wiring is supposed to look like and then figure out what someone did to change it.     

[cas]

So I talked to Fisher in Texas, and guess what they wont give me any product information other than an operator manual.

They will not provide any technical information at all.

They will inspect and repair the unit if you send it to them, but of course they wont tell you how much that will cost.

I dont think I will be doing business with Fisher again.

If anybody out there can help with a wiring diagram for TW5/TW6/Gemini 3, it will be much appreciated. 

  

[Geotech]

Here is the circuitry around the speaker & headphone jack (TW6):

[cas]

Oh, thanks a lot...I think that is exactly what I need, I will print it out

I tried to locate some underground pipes today...and the tw5 seems to be working, but is erratic as hell...

The guy I got it from was using it as a signal generator , running two 9 volt batteries in parallel....which is not a whole lot of current compared to the original Burgess battery, which was pretty good size, and the TW6, which uses a pack of AA cells in series.

I am thinking that the 9 volt cells do not have enough poop to generate sufficient transmit signal 

Seems like it will take some power to push 82 khz down  10-20 feet

I have no idea what the MW output is supposed to be on the transmitter, and also what minimum microvolt signal strength is on the reciever.

Might anyone have specs for that?

Anyway, first check circuit diagram, then try bigger batteries,

If no joy then on to freq counter and wattmeter for transmitter power check/calibration ,  HF signal generator for reciever calibration/signal sensitivity check        

Any comments are appreciated :) :) 

 

[Geotech]

Can you post photos of the control panels? MW might be "modulated waveform," makes a different sound in the receiver.