Trunker M383 and a BC785D audio tracking problem!!!!!

[parker4782]

Hello All

My computer has one serial port so I order a Super Data Slicer
then feed the control channel data from my pro-95 which I installed a tap in this works fine. It shows me the information but when I plug in the BC785D in the back of the Super Data Slicer it just stops decoding tell I remove it. What is the problem? Any help would be great thanks!

sterling

 

[cpetraglia]

Slicer problem

I have had the exact same problem, but can't remember which PC I had the problem with. I suspect that when the second PC is connected it is causing the 12V derived from the com port to drop or go away. Easy fix if you have an open PCI slot. Add on serial port cards are inexpensive and very easy to install. Configure Trunker to get data on one port and send on another. Another way is to use an external power supply(+12 and -12) for your slicer. A pair of 9 volt batteries will work well. Apply the voltage at the diode input to prevent reverse polarity. The diagrams of the super slicer are available right here on this site. (Get started using Trunker). I have built many slicers and found the externally powered ones are much better. I can help if you want to experiment around with this.

Chuck.

 

[parker4782]

different computer

when i set it up the same way on a different computer it works then on another it does not. it least it works on the laptop

 

[cpetraglia]

Track scan

I still suspect it's a voltage problem with the com port although it could be some sort of setting. The available current at any comport will vary by MB. If the slicer just slightly goes above this, it will shut down or reduce the accuracy a bunch. You could actually open the slicer and get a voltage reading at the chip pins to see if that is the problem.

Chuck

 

[crayon]

If you can get everything to work on computer and *not* on another, I agree with cpetraglia, comm port voltages on that motherboard is to blame.

As he suggested, external power is the only way to overcome this problem.

 

[Pro-95]

I agree with cpetraglia, comm port voltages on that motherboard is to blame.

I certainly hope you are both wrong. The output of a serial port should be 12V because that is direct feed via the motherboard from the power supply. Now yes a power supply could be going but I think because of inadequate voltage you'd be having more problems than just a serial port error.

Now because I've seen some crazy stuff in the computer world I wont rule out the motherboard is robbing voltage but first.....

An old kluge from the DR-Dos is that serial ports don't like to be allocated on the fly. Serial ports are a rudimentary interrupt (Pre-IBM XT) and if not allocated the interrupt goes to something else in a Windoze environment, then the serial port will never re-awaken with out a cold boot. Now some motherboards can "Plug-n-Play" a serial port but some still cannot. Some even give-a-way the supposed to be comx interrupts to things like mice, modems, SCSI, Sound Cards.... the list goes on.

Designate/allocate/activate the serial ports on boot up. Yes even Windoze will allow you to still have a config.sys(config.NT) and a autoexec.bat specifially for this purpose.

Use the following commands to designate your com port.

Config.sys:
Comx=96,n,8,1

Autoexec.bat:
Set Comx:96,n,8,1
Mode Comx:96,n,8,1

replace the "x" with the com port you are trying to use.

HTH and YMMV cause if it is a voltage thing..... expect bigger problems in your future.

 

[Pro-95]

Also some i/o chips won't allocate the interrupt unless there is something physically connected to the port during POST (bootup). Give it a shot let us know if that works.

 

[crayon]

I certainly hope you are both wrong. The output of a serial port should be 12V because that is direct feed via the motherboard from the power supply. Now yes a power supply could be going but I think because of inadequate voltage you'd be having more problems than just a serial port error.

This has been discussed around here before, and with 99.9% confidence it will be the voltage level of that specific comm port, or rather, the lack thereof.

Laptops are usually the worst offenders, and for good reason. Battery life. Speaking in generalites, TTL circuits do not need 12v to properly operate, only 5v. Therefore, depending on who the motherboard mfg is, you will find differing voltages on the comm port.

For those that have low voltage comm ports, and are techinally inclined, I would recommend dropping the diode bridge found on most data slicers circuits. From my personal experience, I have found that it drops too much voltage and prevents a TL082 slicer from firing up.

 

[pro92b]

I have found that it drops too much voltage and prevents a TL082 slicer from firing up.

Choosing a more appropriate op amp (of which there are many) would help cure that problem. The diodes are in the circuit to protect the op amp from reverse voltages. The state of the serial port can vary and it is best to leave the diodes in. Changing from silicon to Schottky diodes will cut the diode drop by 50 - 70%.

The voltage available from a serial port when driving a slicer will vary. My desktop sources 10 volts while the laptop can only provide 8 volts. A minimum of 5 volts is needed to meet the RS-232 standard. Most RS-232 drivers are CMOS rather than TTL.

It should always be possible to use a port powered slicer even with the wimpiest serial port. Schottky diodes and a rail to rail op amp might be needed but both are available. I've never run into a situation where external power was necessary.

 

[Pro-95]

RS232 standards are defined by EIA/TIA (Electronic Industries Alliance /Telecommunications Industry Association). RS232 defines both the physical and electrical characteristics of the interface. RS232 is practically identical to ITU V.24 (signal description and names) and V.28 (electrical). RS232 is an Active LOW voltage driven interface and operates at +12V to -12V

 

[crayon]

I *knew* that just metioning a TL082 would nudge pro92b into action. As always, your expertise is valued.

Most RS-232 drivers are CMOS rather than TTL.

Yes, but most of the IC's used in a slicer are TTL rather than CMOS, correct?

You should plug your website again for the searchable impaired ..

 

[pro92b]

The EIA/TIA-232 standard known to us oldsters as RS-232 defines a minimum driver voltage of +/-5 volts. A driver like the MAX232 is powered from +5 volts only and has on board charge pumps to generate +/-10 volts. In a PC the +/-12 volt supply has nothing to do with the serial port driver unless the PC is very old. When loaded the output of the MAX232 will drop to +/-8 volts. The links below explain the various data comm standards.

http://dbserv.maxim-ic.com/appnotes.cfm/appnote_number/723
http://www.national.com/an/AN/AN-216.pdf

I *knew* that just metioning a TL082 would nudge pro92b

Well the TL082 must be good for something, but I'm still trying to figure out what.

TTL (transistor-transistor logic) is a term exclusively applied to logic devices. It identifies a series of devices built with bipolar device technology rather than CMOS. Op amps are considered linear devices and may use bipolar, jfet, or mos devices either singly or in combination. In the slicer we use the op amp like a logic device rather than an amplifier but it still wouldn't be called a TTL device.

 

[Pro-95]

ACK. I wasn't insinuating that the driver has anything to do with the voltage but that tickling the driver/port during POST and bootup tends to "fix" a dead port issue. Not a voltage issue.

BTW, and FWIW the links you offered refer to RS232 as 12 volts, RS422 as 10 volts and RS485 as 5 volts.

I do see where I was obviously confused, because to me, a serial port is an RS232 port. Damn old schooling. Now where did I put my 300 Baud modem.

Cheers.

 

[loumaag]

I do see where I was obviously confused, because to me, a serial port is an RS232 port. Damn old schooling. Now where did I put my 300 Baud modem.

Hmmm... Is that an acoustically coupled modem? (Ahhhh, the good old days... :roll: )

 

[crayon]

Hmmm... Is that an acoustically coupled modem? (Ahhhh, the good old days... )

One of the reasons why I dumped my Timex Sinclair 1000 was for TI-99 4/A and it's acoustically coupled modem option!! (and also for a real monitor instead of using a TV set. blech. )