No TX. Everything else works great. Changed final, driver,ic4 voltage reg,mode switch and a few others. No TX? TP7 and TP8 have no voltage? 0.11volts. I no it should be 12.8volts. Pa mode works. Also radio next to it will move the meter. Any help? Thanks, TJ
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I can tell you that mic wires can simulate that problem when they accidently touch or ground out. Sometimes a ground is loose or capacitor leaks. Check standing wave ratio. SWR 1.5 or less prefer 1.2 or 1.3 read. Antenna cables replacement and new ends. Dirt in mic switch. Mine did this with a power mod capacitor near final(without proper discharge 100 ohm resistor). I turned back power to 1 1/2 watts to 4 swing a Tx tuning slug *redpaint on it. I let it talk on low key an when i speak it jumps to 4 or 5 watts on meter. When a mod has been done some people don't know that capacitors discharge and it will leak back current. Thats why on a Cobra/Uniden company radio the instruction properly call for a 100 ohm resistor to be placed in parallel with Capacitor near final on bottom of circuit w/ capacitor on top spkr side(i call it top its on spkr side bottom when radio is upright (super mod kit). Or replace jumper J1 to factory deadkey of 4 watts and see no swing in talk except to 4.5 watt slightly(factory tune)
I know you don't want to hear this, but the Maxon radio you own, and many similar radios (Cobra 19, Midland CB-1, Midland NT-CB-1001LWX, Uniden PRO-505XL, etc) are on the bottom of the performance list. These are for those who just need a crappy radio for the summer time traveling, and about keeping the cost as low as possible. Here are a few of my favorites that have good-LOUD audio: Galaxy, Connex, General Lee, and some of the older Uniden radios like Grant XL, PC-76XL or older Cobra 29 LTD, 25 LTD models. Please stay away from Stryker radios, Magnum radios, Northstar radios and any radio which has a NITRO-KNOB. These are ticking time bombs. In other words, they WILL fail and it wont be an easy fix either. Most Strykers and Magnums have PCB Chip failures. They are next to impossible to replace. And finally, don't be so quick to buy the pretty radio with all the flashing lights either.
Initially, pls confirm that there is modulation (transmit audio). The reason I asked is if IC4 (TA7222P) is blown, then the radio would have no audio amplifier which would explain no receive audio. Additionally, the final and pre-final (TR15 & 15) gets is modulated TX+12 through D8 from T1 which in turn is the output of IC4 through C48.