Symptoms:
1. +12 V Power supply is out
+ 12 V of PS module #1 is not working!
Other voltages look okay.
- Trying with an external variable voltage/current power supply as shown in the picture below.
2. Both PA and SWR LED are on at the Operate position. No PTT engagement.
A. At Standby position, consume 630mA
B. At Operate position, it draws 920 mA (for one relay and two LEDs?) and PTT is not working.
Look up the schematics provided by Ameritron.
Control circuits has to be checked, especially those Diodes and CD4042 which drive those LED and protection logic.
Finally, I opened the amp cover. What a SCREWS!!
D1, D2, D3, D4, D5, D6, D7 read okay to my DMM
Touched the CD4042 to remove,, Yeap!!, the 4042 is hot!
Now I ordered a 15V 2A SMPS and a few CD4042BE from eleparts.
The T/R relays are already there at OM's home.
1. Attach and wire +15V supply. Set voltage at +14V
2. Replace CD4042
3. Change T/R relays
4. A LOT OF SCREWS!!!