The clock/counter in the 1978 Cobra 2000GTL had a design boo-boo in it. They connected the output from an analog chip into the input of a digital chip. Turned out not to be too reliable.
Enter Technical Service Bulletin 1232. It shows how to fix this tiny flaw with one disc capacitor and two quarter-Watt resistors.
But how do you tell if your counter needs this? The TSB shows the radio serial numbers that are relevant. But if someone has swapped that module from another radio into yours, how would you know?
Here is the pc board number of the original 1978 Version, the one that needs the mod. Type "PC370AA".
Here is the vicinity of IC512, the SL1611 chip.
Here is the ID of the 'new' version, with the three new parts added at the factory. ID is PC370AB, (not "AA").
The sharp-eyed reader will see the new disc cap and two resistors that the first closeup of IC511 doesn't have.
If your counter module has the "AB" suffix on the board number you don't need to squint at the left-hand side of IC512 to look for the three added parts.
And knowing is half the battle.
73
Enter Technical Service Bulletin 1232. It shows how to fix this tiny flaw with one disc capacitor and two quarter-Watt resistors.
But how do you tell if your counter needs this? The TSB shows the radio serial numbers that are relevant. But if someone has swapped that module from another radio into yours, how would you know?
Here is the pc board number of the original 1978 Version, the one that needs the mod. Type "PC370AA".
Here is the vicinity of IC512, the SL1611 chip.
Here is the ID of the 'new' version, with the three new parts added at the factory. ID is PC370AB, (not "AA").
The sharp-eyed reader will see the new disc cap and two resistors that the first closeup of IC511 doesn't have.
If your counter module has the "AB" suffix on the board number you don't need to squint at the left-hand side of IC512 to look for the three added parts.
And knowing is half the battle.
73
