MTR v2 Debug
Debugging MTR v2 SN 364
Build progressing but have ran into a problem. On startup it is cycling through the band announcement. You can hear the number for the band and it is correctly displayed on the LED then pauses and re-plays and shows the number again and continues to loop. If you change bands it will reflect the change correctly and will continue to loop showing the band info. I can hear stations between the announcements when connected to an antenna. If you key the transmitter you can see output into a dummy load but the device continues to show and play the band info.
I have used a MIC5205 to replace a missing TC1014. Apparently the MIC5205 is pin equivalent to the TC1014. The replacement device is marked KB33 so the fixed not a variable unit.
Responses from the Yahoo groups indicate this problem is pointing to a power issue potentially caused by a short / dry joint. To address go back and check the connections. I have visually checked and double checked the connections with no joy. Have progressed to the point of checking against the schematic as what ever is the issue it can’t be detected with my eyes.
Current Measurements – 31ma to 44ma @9.01v on a new 9v battery. I am looking for shorts as the consensus is the current is too high.
Have disconnected L18 and removed all connections.
To address any high resistive joints I have touched with the soldering iron all connections to reflow the solder.
Having trouble with the board and schematic. So verified the documented voltage levels around the major components hopping that would point to a issue;
U2 ok with 7=2.5 8=1.26
U5 correct to msg 13586 “MTR2 Circuit diagram error”
U10 Voltages as per manual except for 0 on both P5 and P6. Continuity to the crystal. X6 Crystal case to ground. U10 RST to 3.3v = 10K
U11 P1 3.25v P2 0 P3 1.68 P4 3.25v Top of case to ground.
Q3 D 8.04 to 0v
Q5 D 8.6v
I don’t have a fast enough CRO to watch the voltages logging for ‘snags’ so checked with the multi-meter. There are variations;
9v (8.36 to 8.43)
5v (4.89 to 4.92)
3.3v (3.61 3.68)
Checked the resistor values against the photos with the only variations being a connection from RST to R22 but as Jerry (KE7ER) pointed out, from the photo on page 4, R17 is a 47k (pullup from RST to 3.3v), and R22 is 2.2k (at the gate of Q2). Both of these are 10K (103) on the kit. I check the photo of VK3YY’s board and they are both 10K. So a variation but not my issue.
Paid particulate attention to the area around L11and shorted it out with no difference.
So from here, To ensure no issues I’ve ordered a “MICROCHIP,TC1014-3.3VCT713” and will replace the MIC5205 when it arrives (Estimated delivery: Mon. 16 Jun. – Thu 19 Jun).