Hello everyone,
I received this 148GTL from someone with a bunch of ugly hack jobs done to it. The first thing i did was to undo a nasty free-band mod someone did and restored the original functionality of the front switches (nb anl etc) and fixed all the traces on the PLL. I plan to undo all of this mod stuff until i get the radio working right again,
The radio does not go into transmit mode, ive checked and the mic wiring looks fine. The LED stays in green but the receive audio does cut out. The only time the LED changes at all is when i put the radio in PA mode and it blinks off when keyed.
The receiver seems to be alive and is receiving static, but when i keyed up a walkie talkie next to it it didnt pick up my signal. Next using my signal generator and frequency counter i determined that the radio is picking up signals out of band and it seemed to only want to pick up stuff in the range of somewhere in between 27.485-27.505. Sounded pretty distorted.
Next is a weird slider/clarifier mod. I had completely missed this until later on. Il provide what was done so perhaps someone can tell me what else i should look for etc so i can undo the mod and restore the circuit to original.
Heres what i found.
*They added a double stacked pot and theyre connected together and one of the connections between them has a resistor. Ive never seen anyone use two pots like that for one of these mods.
*Off the double stack pot, Orange lead connects to one side of R44. The other side of R44 is clipped off.
*From that same side of R44 a lead connects to pin 1 of IC4.
*The blue wire of the pot was soldered to D51.
*And the red wire is still going to R175. which is 2.2k ohms.
*R174 is gone but not jumpered.
*D75 is clipped. Theres a spot for D52 right next to it but i dont know if that diode was originally never there or if it was removed.
*D53 has its anode connected to the can of a coil through a choke.
EDIT: VR5 is also gone.....
Anything else i may have missed? Could this mess be the sole cause of my radio not wanting to transmit, and my strange receive problems? Or should i expect more problems still after undoing this?
Thanks for all your help!
I received this 148GTL from someone with a bunch of ugly hack jobs done to it. The first thing i did was to undo a nasty free-band mod someone did and restored the original functionality of the front switches (nb anl etc) and fixed all the traces on the PLL. I plan to undo all of this mod stuff until i get the radio working right again,
The radio does not go into transmit mode, ive checked and the mic wiring looks fine. The LED stays in green but the receive audio does cut out. The only time the LED changes at all is when i put the radio in PA mode and it blinks off when keyed.
The receiver seems to be alive and is receiving static, but when i keyed up a walkie talkie next to it it didnt pick up my signal. Next using my signal generator and frequency counter i determined that the radio is picking up signals out of band and it seemed to only want to pick up stuff in the range of somewhere in between 27.485-27.505. Sounded pretty distorted.
Next is a weird slider/clarifier mod. I had completely missed this until later on. Il provide what was done so perhaps someone can tell me what else i should look for etc so i can undo the mod and restore the circuit to original.
Heres what i found.
*They added a double stacked pot and theyre connected together and one of the connections between them has a resistor. Ive never seen anyone use two pots like that for one of these mods.
*Off the double stack pot, Orange lead connects to one side of R44. The other side of R44 is clipped off.
*From that same side of R44 a lead connects to pin 1 of IC4.
*The blue wire of the pot was soldered to D51.
*And the red wire is still going to R175. which is 2.2k ohms.
*R174 is gone but not jumpered.
*D75 is clipped. Theres a spot for D52 right next to it but i dont know if that diode was originally never there or if it was removed.
*D53 has its anode connected to the can of a coil through a choke.
EDIT: VR5 is also gone.....
Anything else i may have missed? Could this mess be the sole cause of my radio not wanting to transmit, and my strange receive problems? Or should i expect more problems still after undoing this?
Thanks for all your help!
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