Hi folks,
Helping a local ham club (W1BST) troubleshoot their weather station (Peet Brothers Ultimeter 100) hooked to the Byonics MTT4BT. We noticed erratic operation, but programmability is fine. Upon further inspection we found a burned diode. It's labeled D6 on the silk screen, and according to the schematic in the manual (very hard to read/low resolution), I think it feeds the 12 V regulator U6, which I can't find, unless it's under the microassembly near U5, which is labeled. The PCB diagram in the manual is no help, no reference designators and it appears to be the wrong board, or an earlier version.?
Anyway, if I'm reading the manual schematic correctly, I believe D6 and D7 are there to protect from reverse polarity being applied to the inputs, not sure what else.
The failure mode? The unit worked well for over a year. The club recently rewired the shack and was chasing ground loops in the station. At some point in the process we noticed that the MTT4BT only powered up when the unit was grounded through the antenna, whatever that means! Then we noticed the burned diode.
Now my questions:
1. Is there a service contact for these boards? What are the arrangements, costs etc?
2. I see the Byonics web site says they are out of stock on these boards. Is there a similar replacement?
3. Where does one procure SMT diodes? And what would I specify? What is the part number? Are they available from Byonics?
In any case, please confirm that this is a reverse protection diode and could be jumpered out. Also, a good schematic would be helpful.
Thanks all. I've really enjoyed getting to know APRS and this application and look forward to a solution.
Ralph Simons
KC1RWK
