low output on vox continental?

[mikeydee77]

Hi
First post here. I am an amp tech that recently got asked to fix a vox continental with a bad F# note.  I was able to fix this as the oscillator had a bad transistor.

I have returned the item to the client but we were discussing the output being a bit low side. Sorry I don't have numbers just now but just wondered if anyone knew what level one should expect in volts or dB?

[The Real MC]

Each oscillator board has a bias trimpot.  These trimpots are open frame that exposes them to airborne debris and they tend to fail.  The bias may need to be set (I don't know the procedure) or the trimpot is bad.

[Alan Lenhoff]

When you say the output is low, are you referring to the output of a particular key or from the F# board?  Or do you mean the output of all the keys? (If the latter, there is a gain trim pot on the preamp board.)

Alan

[mikeydee77]

Each oscillator board has a bias trimpot.  These trimpots are open frame that exposes them to airborne debris and they tend to fail.  The bias may need to be set (I don't know the procedure) or the trimpot is bad.

Thanks for the reply, to clarify this unit did have a bad F# note which I was able to fix by replaceing the osc transistor.  But I did also repalce the bias pot as it was a alittle flakey with age.

[mikeydee77]

When you say the output is low, are you referring to the output of a particular key or from the F# board?  Or do you mean the output of all the keys? (If the latter, there is a gain trim pot on the preamp board.)

Alan

Thanks for the reply Alan.   In fact the output of all the notes is a little low to my ears but as I have no experience with these keyboards this could just be normal. 

Yes I was aware of the pre-amp board and even did check all the resistors on the pre amp board and quite a few of the carbon ones had drifted north in value more than 20% so I thought it wise to replace those effected.  This did improve the output a little, but even with the preamp gain control set to maximum the output was still a bit lacking. I subsequently started wondering whether those transistors had lost their mojo but of course they are difficult to obtain being germanium. 

Would you be able to help me out and measure the voltage coming out of one of your own keyboards and let me know the voltage of a certain note at max volume?   If I have that figure then I will have a normal figure as a baseline and I believe be able to figure it out.