Hope you are feeling better Kevin. The uMatic built in paddles are touch sensitive, the external paddles are contacts, hence the difference in input circuitry. According to the CD4013 spec sheet all inputs are protected by diode and resistor networks. Of course there's a limit to what those protection networks can handle, but they are something. Protection and touch sensitivity are a tradeoff, but some series resistance might go a long way to prevent punch-through on the on-chip protection diodes. 73 de w6akb
I had one of those keyers for years and years. I had the same problem way back when I touched the paddle with static on my body. Blew the same chip. Replaced the chip which was available at Radio Shack at the time in the mid 80s. I sold the keyer at the Richmond VA Frostfest hamfest a few years ago.
Try cleaning the surface and the contact points where the pads plug into the unit. It's probably just resistance from dirt at the connection point or oil and dirt building up on the pad surface.
Hello Kevin. I have just recently been given one of these units and would love to repair it. What is the DC voltage at the input? My first memory in ham radio in maybe 79 or 80 was a shack with the keyer going and learning morse. Thanks
Hope you are feeling better Kevin. The uMatic built in paddles are touch sensitive, the external paddles are contacts, hence the difference in input circuitry. According to the CD4013 spec sheet all inputs are protected by diode and resistor networks. Of course there's a limit to what those protection networks can handle, but they are something. Protection and touch sensitivity are a tradeoff, but some series resistance might go a long way to prevent punch-through on the on-chip protection diodes. 73 de w6akb
I had one of those keyers for years and years. I had the same problem way back when I touched the paddle with static on my body. Blew the same chip. Replaced the chip which was available at Radio Shack at the time in the mid 80s. I sold the keyer at the Richmond VA Frostfest hamfest a few years ago.
My pad is getting "stiff". Is there any way to rejuvenate it? It takes more finger pressure on the key pad to activate the selection.
Try cleaning the surface and the contact points where the pads plug into the unit. It's probably just resistance from dirt at the connection point or oil and dirt building up on the pad surface.
Hello Kevin. I have just recently been given one of these units and would love to repair it. What is the DC voltage at the input? My first memory in ham radio in maybe 79 or 80 was a shack with the keyer going and learning morse. Thanks
Sorry, I don't remember. That unit was another hams, I was just repairing it. I don't have one myself.
@@Aviation.Safety. Thank you very much.