tsuen shing wt-405

This PMR-handheld is very easy to modify to act as a 70cm ham tranceiver. Though few annoying features remains. One of these is this so called "roger"-beep. Does anyone of you have access to schematics of this radio so that this little modification could be done ?

Otherwise it is very funny little radio and compared to the 50 euro price (a pair) quality is acceptable (technically).