ALINCO DR-605 Investigation & Repair


This nice little rig from Alinco is on the bench for repair. Initial checkes showed it pretty much dead on arrival, except for the LCD backlight on one side. It was understood that it may have suffered lightning damage.

First checks with the covers off showed IC206 (7808 voltage regulator) to be open circuit. I have to say that this rig is a nice piece of kit to work on, with easy dissasembly. So removing this pcb was pretty straight forward and a new 7808 was fitted. But there was still no life from the set. 

Next step was to remove the front panel assembly and check the voltage rails for the logic system. Here R446 was found to be high in value and when applying power direct to the 7805 voltage regulator, it was running hot. So I replaced the resistor and the voltage regulator. Now the logic rails are correct and the processor runs at switch-on, with the display text appearing -  but the info on the display flashes. There is also no audio.


The UHF board with the regulator on the right.



The front panel assembly 







One of the front panel bulbs is blown, so replaced both with 3mm warm white LED's. Not perfectly even illumination, but ok I think.

Back to the UHF Board..... found that Q230, a PNP switching transistor was faulty, along with IC206, a 10v linear regulator. With these two replaced, the 10v rail is restored and I no longer get the flashing display. Nice.  But still no audio. Applying a test signal though, on 2m and 70cm shows the S-Meter working, so looks like the receiver itself is alive.

The audio amp is a LA4425, connected to the 13.8V rail via a 2.2ohm resistor. The resistor is open circuit and the LA4425 has a short on its supply pin. Another casualty. Now long obsolete, the only source seems to be from China.  So will order some and wait.....

Replacement LA4425's arrived from AliExpress, new one fitted, along with a new 2.2ohm resistor, and proper audio restored. So this rig is now back to working condition on receive.

However, both power RF modules are blown - see photos. These are still available, but are not cheap. I did find the 2m version on Ali for $25, so decided to go ahead and order that one. The UHF modules though are around $40, so will leave that for now.

Replacement 2m power module fitted and working great, so full operation restored on 2m.








Finished and back on-air:



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