Maxtrac Logic Board - Microprocessor Crystal

[rj_bart]

Hi,

I have an intermittently "dead" maxtrac lo-band unit. Re-flowed all interconnect points on all boards, checked vol/ctl pot for function, etc.

Seems to be hit-n-miss on power up. LED on backlight for buttons always comes on, but display/beep only happens once and a while.

Seemed to be senstive when probing around microprocessor crystal on board. Reflowed solder there..seemed better..but stll went wacky the other day.

Anyone seen the clock crystal for the micro go? Got a moto part number for this? (I don't have a manual!)

Thanks,

Bob

[Satelite]

Hello :
Maxtracs do have a known problem with the crystal component YOO52 on the schematics M Part # 48-80908W01.
The lo band maxtracs all use the same crystal regardless of whether its range 1 / 2 /3 .
However you can not take this crystal out of a VHF/UHF/800 for parts as its not the same.
Lo band crystal = 10.245 mhz
VHF/UHF/800 = 44.645 mhz
Good luck .
Satelite

[jackhackett]

Lo band crystal = 10.245 mhz
VHF/UHF/800 = 44.645 mhz

Those would be the 2nd IF crystals on the RF board, if they don't work all you lose is receive.

I don't have the info on the processor crystal at hand, I can post that later if nobody else comes up with it first. You might try checking the 5 volt supply, and if you have a good scope or service monitor you can check if the crystal is oscillating.

[WB6DGN]

The uproc clock crystal for the HLN9123A logic board (Y801) is 4880173D09, freq. is 7.776Mc. AccessPoint shows it as NLA though you can, no doubt, get one from International Crystal or Bomar. I noticed several of the other logic boards used the same crystal as well. I doubt it's the crystal, though. Usually when the clock crystal is gone, the radio is totally dead, no lights, no nothing. Good luck with it.
Tom

[wavetar]

Have you tried a known good control head? I've seen the display boards cause this issue.