Hello,

I see there is no schematic in the manual.
As I have worked with Fenris on the schematic I can post it here.
There are two circuits on the board, a voicemod and a sound to light circuit.
Later we added a senitivity control.
The partnumbering will not be right as Fenris did the renumbering and the PCB design.

Bertus

 

Hello,

@Robo80 ,
What happens when you turn VR7 ( the sensitivity control ) ?

Bertus

 

Nothing happens then I turn VR-7.
P.S. In your last post, you put up the schematic that is marked MKIIIa. The PCB is marked MKIIIb. Is there a discrepancy?

 

Hello,

The MKIIIa has not the sensitivity control (VR7) wich is implemented in the MKIIIb.
That's why I posted the seperate circuit for the sensetivity control.

Bertus

 

I have checked over the board again and cleaned up the solder joints you indicated on the picture you posted earlier. I also checked to make sure there was no continuity bridge in the areas you indicated.

Thanks,
Ralph

 

Hello,

Do you hear the voice when you pull IC2 (4066) and connect the pins 1 and 2 of that IC-holder?

Bertus

 

May I suggest a trouble shooting method for this circuit.

1. verify the output audio amplifier is working.
- There is a 4.7uF cap between the center op-amp (no ref des.) and VR2. Unsolder and lift the pin of the cap that connects to the op-amp.
- Apply power and touch the pin with your finger. You should hear a buzzing sound from the speaker that will get loader or softer as you adjust VR2.
- If the buzzing is not heard, the problem is in the circuit to the right of the cap.
- If buzzing is heard, solder a short wire (3-4 inch) to the lifted lead of the cap. You will use the amplifier to trouble shoot the circuit to the left of the cap.

2. Verify the input amplifier.
- Remove IC2
- Touch the short lead from the cap to pin 1 of IC1A. Speak into the microphone.
- You should hear your voice in the speaker. If you do not, the problem is to the left of pin 1 of IC1a.

Perform the above tests and post the results. We will then continue.

 

Bertus:
I pulled IC2 and connected pins 1 & 2 of that socket. No effect. Still had the humming in the headset (which still changed as a function of the volume control). Running VR 7 full travel tooth ways has no effect.

Regards,

Ralph

 

Hello,

I possibly found some more spots that worry me:

Bertus

 

Bertus,
The 2 spots you referred to in the photo you just posted are free (no continuity). The pin of the capacitor u noted is well connected.
It just does not look like it is in the photo.

Regards,
Ralph

We don't know what user CP means, so how do we edit our details.
?

 

I did find my way to to my profile and put in my GMT -4. But it isn't showing up next to my name outside my profile folder. Any suggestions?

 

Hello,

Sorry for the late reply.
I have looked at your PCB and possibly found some broken traces:

Can you check them and if broken solder a piece of wire on the trace?

Bertus

 

Hi Bertus,

I have had good fortune to have a friend(electronic genius) here in the states who has offered to "Bring the Dalek to Life!", if I send the VM to him. I am going to do that and keep my fingers crossed. Will let you know if he is successful. Thanks for all your kind help.

Sincerely

Ralph