[TenTec] Centurion 422b troubleshooting help needed

[allen richmond]

Thanks, Jim. I think something is amiss on the display board. All of the metered parameters (both meters) are reading about 1/2 their correct values. All the resistor values in the chain that are on the HV filter board check OK. In my judgement, it’s unlikely that both meter movements would go south, and a.ll of the metered parameters get “processed” on the display board. The output power LED bargraph reads OK (compared to my Bird), but it does not share the board components that are common to the other metered parameters. Using a calibrated HV probe/meter, I confirmed that the plate voltage that initially read 1600v on the multi-meter was actually 3200v. I was able to bring the meter reading to 3100v using the R2 cal trimpot, and that was at the end of the trimpot’s travel. Was also able to bring the metered FORWARD power value up to the actual value. It was also initially reading 1/2 the actual value. Sure seems like I’ve got something on the display board that's common to all parameters that’s shunting the voltages. Haven’t yet removed the display board for t-shooting, but it’s looking like that’s unavoidable.
Assuming I can locate and correct the 1/2 scale problem, I’ll still need to know what values of voltage are at the input to the display board for calibrating the plate current and grid current. Just tuning up by “peaking” the output power, without knowing what the plate and grid currents actually are makes me nervous. But so far, neither the amp or the 3-500’s have complained, and the output signal is clean according to contacts with pan scopes.
73,
Allen—W7GIF 
> On Mar 1, 2016, at 4:03 PM, Jim Brown <k9yc at audiosystemsgroup.com> wrote:
> 
> On Tue,3/1/2016 2:55 PM, P C Andy Anderson wrote:
>> Allen, have never seen a procedure for calibrating the meters  or I would be glad to send it to you.
> 
> Somewhere I found calibration instructions for meters in the Titan 425. It involves the use of a voltage source applied to certain test points, as I recall. It's been a long time. :)
> 
> 73, Jim K9YC
> 
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