Swan Meter Problem

[Rudes]

Are there any techs here? I have this meter that reads both rms and pep. I have attached a schematic. In the rms mode the meter needle rest at the 0 mark as it should and works fine. When switching to the pep mode with no input signal present the needle rises and rest at the 5 watt point. When a signal is applied the meter swings as it should but comes to rest at the 5 watt point again and not 0 as it should. Adjusting VR4,5 or 6 does not correct this. Any ideas what the problem could be? I have not tried adjusting VR7 yet which appears by looking at the schematic to adjust voltage for the circuit.

 

[Overmodulated]

Did you verify the -15v and +15v? (can't tell for sure if that's 15v or 13v). Looks like vr7 may be what you need to tweak. Check the -15v, you may need to drop vr7 down a bit. vr4-6 look like they just adjust the top end of the scales. Also, make sure that none of the capacitors in the circuit on the lower left are leaking/swollen. May just be a cap out of spec due to age, so adjusting vr7 may work.

As with all internet-based advice, no warranty is expressed or implied.

73/k5zia

 

[Rudes]

Thanks...was thinking the same. I get 13.8 volts and not 15 so I'm down 1.2volts. I'll check the caps.

 

[Rudes]

Does anyone know how one would go about calibrating this meter?