PRO-94 "wired"

[amusement]

PRO-94 shows "wired" after being turned on.

Here's the list of things I have done:

* Pressed 2 + 9 while turning on the scanner to clear the settings
* Use the PC/IF cable (which works on my PRO-95) to clear "wired"
* * Set serial port to 8, N, 1 and 8, N ,2 with no success
* * * Used demo of Scan lite
* Verified PRO-94 was running at 9.6Kbits by pressing the "4" button
for 2 seconds

Both the cable and serial port are working. I can content my PRO-95 with no
problems.

I disassembled the PRO-94 and located J203 (PC/IF) jack.
J203 has three solder points. Two points are common and one isolated
until a plug is inserted. This results in three common (or shared)
points. Hope that makes sense.

------------------------------------------------------------
Solder points for PC/IF jack

J203 * common
* switched via plug insert
* common
------------------------------------------------------------

The tip and ring should be RX (receive) and TX (transmit). But they
are all common electrical points. Which confuses me. The service
manual for the Pro-94 DOES NOT include a reference for
J203 in either the schematics or parts.

I need a schematic that does include the J203 jack and the modem IC.

Any constructive suggestions are very much welcome at this time.

 

[pro92b]

The programming cable should terminate in a mono plug. The tip is for transmit and receive signals. The ring or barrel of the connector is ground. The data signal goes right to the CPU and there is no modem chip.

There are three versions of the PRO-94. Only the latest one has a PC/IF jack. The service manual has not been revised to the latest level and it is unlikely it will ever be.

Although the PRO-93 is a GRE radio and the PRO-94 is Uniden, the programming port should be similar since both interface to the same programming cable. The attached schematic section is for the PRO-93.

When nothing is plugged into the PC/IF jack all three terminals are connected to ground and the schematic indicates 0 volts. If the jack has a bad contact and is not grounding the tip pin as it should, the radio will hang in Wired mode.

Note that the CPU is directly connected to the outside world via the jack with no isolation at all. It is possible that it was damaged by static electricity even though there are clamping diodes present.

This is almost certainly a hardware problem and software will not clear it.

 

[amusement]

Thanks prob92b. I will ship this one another (soon to arrive) to the shack repair depot for service.

 

[MacombMonitor]

Does the PRO-94 have one of those tiny holes for a reset button?

 

[amusement]

Does the PRO-94 have one of those tiny holes for a reset button?

The PRO-94B doesn't have a hole for a rest button. Pressing the " 2 " and " 9 " keys while turning PRO-94B on clears the PRO-94B's memory.

I must of dissassembled the PRO-94 4 or 5 times yesterday in the attemp to isolate the possible problem. I believe it's a surface mount component (capacitor, resistor, diode) that has failed. The reasons supporting this hypothesis is all functions supporting "wired" such as; bit rate, light, clear (reset), button beeps, and 'pro94' welcome screen all seem to function.

One interesting effect of removing the PC/IF (J203) was a slight difference in the impediance. It was zero prior to the removal and after the impediance was -100 ohms.

I changed probe positions and recalibrated the ohm meter and received the same -100 ohms. I understand their can't be -100 ohms so ... it's probably the battery in the multimeter is getting low but, not low enough to set off the "change battery" display.

 

[amusement]

Here's two images. PRO94B image was created by me. PRO94 is from the FCC database.

 

[amusement]

Here's two images. PRO94B image was created by me. PRO94 is from the FCC database.

http://wiki.radioreference.com/index.php/Image:Pro94-logic.jpg

The differences are significant enough to be a pain in the arse.

I will send my PRO94 on Monday, May 15th to get fixed. Will post results when it's returned and retested by me.

 

[Al42]

One interesting effect of removing the PC/IF (J203) was a slight difference in the impediance. It was zero prior to the removal

As it should be, since the jack shorts the line to ground.

and after the impediance was -100 ohms.

I changed probe positions and recalibrated the ohm meter and received the same -100 ohms. I understand their can't be -100 ohms so ... it's probably the battery in the multimeter is getting low but, not low enough to set off the "change battery" display.

Assuming that you took the batteries out of the scanner before you made the measurement, there's still some residual voltage on the point you're measuring (look at the schematic - I'll bet the line going up from the junction of R224, R225 and D204 goes to a voltage source with a decent size capacitor on it).

 

[amusement]

There was no batteries in the PRO94B during impedance testing.

The diagram above is slightly different than the Uniden logic board in the August 2005 Pro94B. It was necessary to post an image of of the August 2005 board to show the difference. Expected a cap leak down. I changed the battery in the multimedia and haven't witnessed the -100 omh resistance.

 

[VintageJon]

The NC connection of a jack is ALWAYS suspect, SOMETIMES a quick squirt of DeoxIt-5 and repeated plug-unplug-like-5-times will fix it to some extent.

Surface Mount is ALWAYS suspect though.

I'd try the Deoxit-5. Apply sparingly, do the old in and out at least 3 to 5 times...

Good Luck and 73's,
Jon