I was about to post a follow up note inquiring how the microprocessor
could be fried yet displaying the two lines of text. Thanks for
clarifying that point!
I think I'll write fluke.l first, see what he thinks of the situation.
I'll post the results.
Thanks everyone.
Steve
On 6/5/2011 8:00 PM, [email protected] wrote:
5V will damage the chip in not obvious ways. Some seem to be able to still
drive the display, but some peripherals stop working. That seems to be your
case.
You need to remove the 16 pin header to get to the processor. I found it easier
to cut all the pins with a fine saw and remove the left overs from the PWBs one
by one. Otherwise, the pins are a very tight fit and you are likely to damage
the PWB if you try to unsolder it directly.
The PWB I have seen has location for the 3 diodes that are supposed to drop the
voltage to something the processor can handle. Unfortunately, these locations
are filled with 0 ohm resistors instead of 1N4148 or equivalent.
I had been able to provide a few new chips to a few people last year, but it
seems Silabs has stopped making that chip in the DIP package and I am out of
stock. It is still available in the QFN package, but good luck doing anything
with that package at home.
However, if you really want to rebuild your monitor, your best bet is to buy
the Silabs Toolstick with the C8051F330 chip. I think it is $10, not much more
than the bare chip, and it is soldered to a small PWB with all the leads
accessible on pads. For another $10 or so, you can buy the toolstick base
adapter and program the chip yourself using the free softeware described on my
web page (and the wiki page it points to). It would not be too hard to fit the
toolstick inside the iCruze with a 2N2222 and a 3 terminal voltage regulator
(or 3 diodes) but I have not done it.
My web page shows a toolstick driving an LCD.
I believe Bob of fluke.l has promised a fix for those who had monitors running
on 5V.
I suggest you contact him for suggestions if you don't want to attempt a
conversion as I described above.
Didier KO4BB
Sent from my BlackBerry Wireless thingy while I do other things...
-----Original Message-----
From: Steve<[email protected]>
Sender: [email protected]
Date: Sun, 05 Jun 2011 19:34:20
To: Discussion of precise time and frequency measurement<[email protected]>
Reply-To: Discussion of precise time and frequency measurement
<[email protected]>
Subject: Re: [time-nuts] fluke.l monitor for Thunderbolt
Thanks everyone for the advice, both on and off list.
I do see voltage transitions on P0.5 of the C8051F330D, which is pin 19
on the DIP version of the microprocessor. So it appears that the serial
data pulses are making it from the Thunderbolt to the input to the
microprocessor.
However, voltage as measured from the microprocessor VDD to GND (pins 6
to 5) is 4.94VDC. The C8051F330D manufacturer's spec for VDD is 4.2VDC
"Absolute Maximum Rating." Didier's speculation seems on point . . .
overvoltage on the microprocessor has likely damaged it.
There is a caveat: The way the iCruze is constructed has the C8051F330D
sandwiched between two PCB's and not readily visible. So I am assuming
that the microprocessor is a C8051F330D, but that is not verified (at
least not by me). Getting at the microprocessor requires desoldering the
16-pin header which connects its PCB to the display PCB.
Not sure where to go from here . . . trash can?
Steve
On 6/5/2011 4:25 PM, [email protected] wrote:
Check that the serial data is going to the processor. The schematic is on my
web site www.ko4bb.com look for GPS Monitor
You should see the inverted serial data on the processor pin that is driven by
the NPN transistor used as an inverter and level converter. I forgot the pin
number and I am not in range of a computer.
While you are at it, check that the processor is powered from 3V. Some units
sold by fluke.l applied 5V to the processor. If you see 5V, the processor is
probably toast.
Didier KO4BB
Sent from my BlackBerry Wireless thingy while I do other things...
-----Original Message-----
From: Steve<[email protected]>
Sender: [email protected]
Date: Sun, 05 Jun 2011 15:23:55
To: Discussion of precise time and frequency measurement<[email protected]>
Reply-To: Discussion of precise time and frequency measurement
<[email protected]>
Subject: Re: [time-nuts] fluke.l monitor for Thunderbolt
David,
Thanks for the suggestions. There is continuity to the PCB in the iCruze.
Not sure what to make of the voltage levels on pin 2 of the DB9. Using
just a scope connected to the Thunderbolt, the voltage switches from -10
to +10. With the laptop connected, it switches from -9 to +9. With the
iCruze connected, it switches from -6 to +6.
I don't know if the -6 to +6 is normal, but it seems low to me for RS-232.
Taking the troubleshooting to the next level on the iCruze involves
desoldering a 16-pin header. I dunno . . . .
Steve
On 6/5/2011 4:56 AM, David Bobbett wrote:
Steve,
The two lines of text are what the iCruze will display when it thinks
it doesn't have any data. The RS232 input on my system can be
unplugged and that is exactly what is shown on the display in those
circumstances.
Personally, I would start with the simple stuff, just continuity check
the '232 lines from the iCruze plug all the way back to the PCB.
If that doesn't work, there's a circuit diagram of the device on
Didier's web site.
73 de David, G4IRQ
On 04/06/2011 22:17, Steve wrote:
About a year ago I installed one of the iCruze monitors from fluke.l
on a Thunderbolt GPS receiver. I paralleled the iCruze with the
serial port on my laptop PC. Sometimes the PC was connected,
sometimes not. The iCruze worked OK either way.
Last week I noticed the iCruze was no longer functioning as before.
It now alternates between two lines of text: "Trimble LED Monitor"
and "Waiting for GPS". Whether the laptop is connected or not does
not make a difference. The laptop running tboltmon works ok with or
without the iCruze paralleled across the serial data line.
I substituted another Thunderbolt and saw the same results.
The iCruze has about 10VDC on its power input.
I not particularly competent at serial communications or
oscilloscopes, but on the DB9 feeding the iCruze I can see the
transition of voltage from about -6VDC to about +6VDC. I didn't look
at those voltage levels when I installed the iCruze last year so I
don't know if that's what it has always been or not.
I have rebooted the iCruze several times as well as the Thunderbolt
and laptop, no change in iCruze behavior.
Any advice as to where to go from here?
Thanks.
Steve
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