Date
1 - 7 of 7
TM-D700A head in TM-V708A body
|
Greetings All!
Just got a TM-V708A Body which seller says it is working OK, but no head. He said it was tested with a TM-D700A head. I got a TM-D700A head, built the cable and the set mostly works. I can transmit and receive on both bands, but no audio/beep The missing things are: - Both bands show "busy", there is no squelch action - Both bands are mute, as the beep from the panel - I cannot enter adjust mode pressing F+TONE and turning the radio on Has anyone tried to use a TM-D700A head into a TM-V708A body? Both radios uses the same pcb/panel. and I'm investigating the possibility of converting the 708 to a 700 adding the parts not soldered to the board. I believe there will be a firmware difference, but at least I want to try. There is no audio on both the inputs of the LA4446, I'll have to completely disassemble the radio to get to IC702, the crosspoint switch, and monitor the inputs for audio. So thats why I am asking Thanks! Alexandre, PU2SEX -- ---8<---Corte Aqui---8<--- https://www.tabalabs.com.br - Main site https://tabajara-labs.blogspot.com - My blog https://www.tabalabs.com.br/esquemateca - High-Quality Schematics FREELY avaiable |
|
|
|
Follow-up to my own question:
toggle quoted message
Show quoted text
I was able to fix the broken TM-D700 I got the panel from. The squelch/volume problem appears in the D700 to, although I can hear the beep. So PROBABLy there is a problem on the panel too. I measured the voltage output of all 4 pots and they vary from 0 to vcc, so if there is a problem, probably it is on the panel CPU. Toast. Beyond that, all functions (but volume/squelch) work The radio didn't entered service menu because it needs a jumper on front. My fault 73 de PU2SEX Alexandre Em 16/08/2022 18:55, Alexandre Souza via groups.io escreveu: Greetings All! --
---8<---Corte Aqui---8<--- https://www.tabalabs.com.br - Main site https://tabajara-labs.blogspot.com - My blog https://www.tabalabs.com.br/esquemateca - High-Quality Schematics FREELY avaiable |
|
|
|
Back to my monogue... Just opened the radio and followed the audio signals. Audio go to the digital potentiometer and stays there. There is no "raise volume" command being sent to the digital potentiometer. I can get rx audio coming into it, but not out. I monitored the serial channel going out of the panel. Every button/encoder of the panel being actuated generates an event on the tx serial channel...but the potentiometers. Measured aref/avcc/agnd on radio panel, all ok. Measured all 4 analog channels, all of them are going from 0 to 4.85v. it can only means something: my panel.cpu went south. Well, if any of you has a panel cpu or preferably an entire panel, I'm looking for one. :( It can be either d700 or v708. I just want to use my radio :( Thanks and 73 de PU2SEX Alexandre Enviado do meu Tele-Movel Em ter, 16 de ago de 2022 21:04, Alexandre Souza via groups.io <alexandre.tabajara=gmail.com@groups.io> escreveu: Follow-up to my own question: |
|
|
|
Good troubleshooting, Alexandre. It's nice to have the equipment to probe serial lines and actually see something. Take more than an "appliance operator" to accomplish that. Hopefully you find a control head.
Joshua KJ7LVZ |
|
|
|
Joshua, we live in happy times...test equipment is cheap. But you can find even cheaper tools. I could have diagnosed this problem with a $10 chinese logic analyser, or a $5 logic probe. The knowledge of the system being probed is more important than the tools. TYA, 73 de pu2sex Alexandre :) Enviado do meu Tele-Movel Em qua, 17 de ago de 2022 11:14, Joshua KJ7LVZ <joshuajayg@...> escreveu: Good troubleshooting, Alexandre. It's nice to have the equipment to probe serial lines and actually see something. Take more than an "appliance operator" to accomplish that. Hopefully you find a control head. |
|
|
|
Chris Robinson KF6NFW DMR ID 3153250
The most truthful statement! Tools are great, but do nothing if you don't understand the system being worked. I use cheap meters often. Mostly because I know how, while also not being able to afford some of the more revered nameplates and prices. On Wed, Aug 17, 2022, 8:16 PM Alexandre Souza <alexandre.tabajara@...> wrote:
|
|
|
|
Yes, the knowledge is more important than the tools by far. My late grandpa gave me a Fluke automotive meter that I still use today at home. I use a half-decent harbor freight meter at work because I can't handle buying another Fluke... yet. Nice tools sure are more pleasing to use though. I probed all kinds of logic circuits with my Siglent Oscilloscope when I first got it, it was just fun!
Joshua KJ7LVZ |
|
|