Maxtrac Won't Power Up

radmano · Post by **radmano** » Sun Feb 18, 2007 8:54 pm

Have 16 pin Maxtrac, formerly working fine as a base station(receive only). Came home after being away 2 weeks, now unit is dead. Subbed out the front panel with known good one and checked onboard fuse - still no go. Any other suggestions? Thank you.

Nand · Post by **Nand** » Sun Feb 18, 2007 9:20 pm

The first check I do for a Maxtrac that doesn’t receive is to check the second oscillator xtal. Placing a service monitor probe near the xtal shows the xtal to be either running or not. Often this is the cause of a bad receiver.

Nand.

radmano · Post by **radmano** » Mon Feb 19, 2007 6:45 am

Thanks Nand, but problem is that the radio is completely dead, no front panel lights - seems like a power chain problem.

Jim202 · Post by **Jim202** » Mon Feb 19, 2007 7:13 am

Do you have the power jumper on the back acc plug?

By any chance did you blow the internal fuse that now
requires you to have ignition control?

Do you have +12 volts going to the radio?

Jim

radmano wrote:Thanks Nand, but problem is that the radio is completely dead, no front panel lights - seems like a power chain problem.

radmano · Post by **radmano** » Mon Feb 19, 2007 7:35 am

Thanks Jim - Power supply is definitely OK - checks 13.8v with VOM and continues to power two other radios just fine. I checked the fuse which is transversely mounted on the rear circuit board(near the power diode) and it has continuity. Jumper remains in place on Acc plug. This setup was working perfectly for 2-3 years, was not touched and just didn't power up this time. Is there another fuse to check?

Max-trac · Post by **Max-trac** » Mon Feb 19, 2007 8:21 am

Check the VOLTAGE on both sides of the fuse. If none then look at the power connector, sometimes they go bad or come unsoldered inside.
If you have 12V at the fuse, then check the 9.6V (the pin nearest the middle of the radio on the pins that go thru to the RF board.

radmano · Post by **radmano** » Mon Feb 19, 2007 8:35 am

Thanks Max-trac Have 13.6 on both sides of the fuse. Middle pin on rf board connector is showing +13.6 as well.

Max-trac · Post by **Max-trac** » Mon Feb 19, 2007 9:04 am

Hmmm, that end pin should be 9.6V.
You are going to need a schematic at this point.

jackhackett · Post by **jackhackett** » Mon Feb 19, 2007 12:58 pm

Was your wife at home with the radio while you were away? Wife's can have subtle ways of telling you they don't like your hobby, like microwaving a maxtrac

You shouldn't have more than 9.6V on any of the pins to the RF board (the 14 pin connector), if you're seeing 13.6 there I suspect you may have a ground problem, where are you connecting the negative lead of your meter, to the power supply? If so, try measuring the voltage on the radio chassis.. if you find 13.6 there your ground lead is open.