Converter putting out 16.5V, some appliances don't work.

By far the best solution is to replace the converter section with the PD4045 replacement. In the mean time, you might be able to "tame" the output by adding the largest capacitor you can find- the actually make a "battery eliminator", which is actually a 1 farad 35 volt capacitor.

Some of that 16 volts you see may be due to the meter you are using- there is no filtering on the output, so a lot of that is AC ripple. Some meters will rectify that voltage to DC.