Alinco: Alinco DX-SR8T won't key with Mic

[WD8WV]

Good Morning,
New to the forum and I have a question that I hoping someone can help me with. I just purchased a used Alinco DX-SR8T very very very cheap from an individual who had been using it for digital work. He had a SignaLink with the appropriate board and cable hooked to it. The radio stopped keying, it won't key with the microphone at all, I even tried the microphone from my SR8T that I have that I know works still won't key. I hooked a straight key to the back, before doing that I turned off the paddle in the menu. I was able to key the radio with the key, saw 100 watt output, and the receive/transmit light changed to red as it should, but when I unkey the key the transmit light stays on and doesn't go back into receive until I power it off. I am hoping someone may be able to tell me what the problem is before I consider sending it to one of Alinco's repair shops. These are great radios, other than the transmit audio not having any mid or low audio levels.

Thanks in advance to anyone who can help.

73 DE WD8WV

 

[W5lz]

I think the key words in that is "very very very cheap". There's usually a reason for that...

 

[WD8WV]

Yes, the PTT won't key the radio. But everything else functions fine, well except the CW, it will key the rig and transmit a tone at 100 watts but when the key is release the relay stays in transmit and won't go back to receive. Other than those issues, everything works fine. I would make a great receiver rig, but I would like to get it transmitting again. Thanks for your reply, but it looks like I will just have to send it back to one of Alinco's out of warranty repair shops. If I can get it repaired for $200 or less I will be happy. I only have $50 in it right now! That is why I posted very very very cheap!!

 

[majoco]

It might not be broken - the PTT line at the microphone connector may have been disconnected and routed to some other connector. Time to learn something about the inside of the rig and get a schematic diagram.

He had a SignaLink with the appropriate board and cable hooked to it.

 

[WD8WV]

It might not be broken - the PTT line at the microphone connector may have been disconnected and routed to some other connector. Time to learn something about the inside of the rig and get a schematic diagram.

Already been inside the rig.

I know a little about repairing, heck I have taken a Kenwood TS-440S that had the dreaded "dot" issue, the previous owner had removed the glue but the dots were still there. Come to find out after carefully tracing the schematic and looking and the VCO I found several broken diodes. Now instead of only 3 bands working I have 6 bands working. The last three bands I had to order the specific diode direct from China. I ordered several of them, I just now have to put it back on the bench to replace that one and all 9 bands should work fine.

The Alinco is a different story, everything is surface mount components and IC chips. The 8 pin mic connector is actually soldered directly to the a circuit board with trances that go to a IC chip. The front of the radio is the control head and is removable with its on circuit board, that is where the PTT takes place. It is a little harder to work on than the old Kenwood. You almost have to have a jewelers eye piece to see some of the surface mount components. I haven't given up, I was hoping that someone may have had a similar issue if they were running digital on a Alinco DX-SR8T.

Here is a picture of the radio. That whole front part comes off and you could put the main body under a desk and use a CAT 5 cable to connect the head to the main body. Here in the picture I was testing the radio to see if I could key it with the microphone from my working SR8T that I already own. I thought maybe something was wrong with the microphone that came with the radio. Then I hooked up the Signalink and the Signalink would show PTT when I was transmitting FT8, but the Alinco was not keying. Again the PTT connector is soldered to the circuit board on the control head.

 

[bharvey2]

I only own one Alinco so I'm far from an expert. However, I had a thought: You mentioned that the previous user used it for digital modes. It may be that there is a menu setting that disables the mic when using it in digital modes and allows the TNC to control the keying. Perhaps you could try a factory reset (if there is one) and see if things play nice afterward. I purchased a used Yaesu FT450D that wasn't doing what I expected until the factory reset.

 

[WA8ZTZ]

Do the factory default reset and see what happens (you may have to turn off the electronic keyer after reset).
If that doesn't work and you are sure nobody has made any wiring "mods" to use for digital work (you have a
known good radio of the same type for comparison) then a component failure is likely. My hunch would make
the main CPU IC101 the prime suspect.

 

[WD8WV]

I only own one Alinco so I'm far from an expert. However, I had a thought: You mentioned that the previous user used it for digital modes. It may be that there is a menu setting that disables the mic when using it in digital modes and allows the TNC to control the keying. Perhaps you could try a factory reset (if there is one) and see if things play nice afterward. I purchased a used Yaesu FT450D that wasn't doing what I expected until the factory reset.

Thanks for the response. I thought of that as soon as I got home with it. It does have a factory reset and I performed it twice and you still can’t get the mic to key the radio.

 

[WD8WV]

Do the factory default reset and see what happens (you may have to turn off the electronic keyer after reset).
If that doesn't work and you are sure nobody has made any wiring "mods" to use for digital work (you have a
known good radio of the same type for comparison) then a component failure is likely. My hunch would make
the main CPU IC101 the prime suspect.

Exactly what I am suspecting. There have been no modifications to the radio. I removed the covers and check both boards thoroughly and then with the control head off I removed the back and didn’t discover any modifications to the circuit board there neither. I am thinking I am going to have to send it to the guy in Georgia that does repair work for Alinco.