![]() I see a transistor Q452 it is perhaps open circuit Looking at the main power regulation and audio sections Then knowing its aok i would further test the p.a ![]() Usualy i would remove the whole pa module and work backwards first checking predrive I worked with pmr and ham radio for 20 years here in glasgow I used to use many such extension leeds to service yeasu and kenwood radiosĪlthough the ham radios are better thought out you do need them in some Maybe you can take a cable out of the interconnection between the pa module and its TX drive rf whilst still being able to close the case maybe you can temp remove a socket from the rear and feed one thru as a quick test of pre drive The pll will be aok and locked and tx predrive to the module will be there If these resistors are aok assuming this then So perhaps the final transistor is gone as you assumed If the main pa transistor worked it would draw more like Its safe to assume that the predrive and driver transistors in the PAĪre both working to provide a 1WATT drive level to the final transistor mrf1946 If they are metal oxide or film type they will definatly go open or high resistance They come from the battery connection and diode etc decoupling capsĪnd form safety resistors for the pa and perhaps a little current limit for the sense system Ok looking at the schematics now i got a copy from above thanks !!! for the links I cant find the diagram or i would help some more ![]() Usualy used to control power output is damaged This will show that there is not enough avalible current and a regulator Very often most transistors will survive reverse polarityĪnd youll get a burned track or chock or a regulatorĪgain check the 12v rail at the pa and press TX to see if it dips You can pull the top cover off the white box type chokes and check the colour of the copper coil see if its black or gone pale gold colour then its fried With two dots 2pin choke in series with the 12v supply to the driver and or pA.Īnd it when fried dumps any amplified rf to the 12v rail and not to the pa Ive found this problem to be a burned choke usualy a white box or blob type ![]() The 12v usualy is common to both the pa and the driverĪnd often there is a series diode in the p.a somewhere to previent this type of damage Look for anything common to a 12v supply and not further back in the mixerĪ quick test using a scope will reviel if there is drive locked frequency post mixer Its more likely the driver transistor has gone ![]()
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