Magnum Delta Force

[dxing.bruce]

Hey: Gang.
I'm working on a Magnum Delta Force 10 meter radio. It works perfect on all modes except USB. No tx or rx on USB. I did some internet searching & seen that I should check crystal x103 & I did & there was a lots or rot from that nasty brown glue so I cleaned the board & replaced the 10.6975 with a new one. I also removed the other two crystals & the glue had not eaten the legs yet but I cleaned everything well & re-soldered them back to the pcb. I also read to check D207 - D208 & D209 I did & there fine. I seen they also said to check Q167 & it seems to test fine. Any ideas ? Is there a common fault with these radios with USB not working ?. Any help would be greatly appreciated. Thanks in advance.

 

[nomadradio]

A separate trimmer coil is in series with the 10.6975 crystal, one for each mode. My schematic file is a bit grubby, but the callouts look like L124, 126 and 127. Can't tell easily which one is for USB, but check to see that all 3 of them have DC continuity. Might not be the problem, but it would fit the symptom.

73

 

[dxing.bruce]

A separate trimmer coil is in series with the 10.6975 crystal, one for each mode. My schematic file is a bit grubby, but the callouts look like L124, 126 and 127. Can't tell easily which one is for USB, but check to see that all 3 of them have DC continuity. Might not be the problem, but it would fit the symptom.

73

Thanks. I check those pots to see if there working.

 

[dxing.bruce]

A separate trimmer coil is in series with the 10.6975 crystal, one for each mode. My schematic file is a bit grubby, but the callouts look like L124, 126 and 127. Can't tell easily which one is for USB, but check to see that all 3 of them have DC continuity. Might not be the problem, but it would fit the symptom.

73

You are correct. L127 is the one for USB & it's dead. Thanks.