No TXD signal Super Serial Card II

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No TXD signal Super Serial Card II

I recently got a Super Serial Card and installed it on apple II+. I am now trying to network II+ and MacBook with using modem MGR, but I have a problem. The text entered on the mac is displayed on II+. However, the text entered on II+ side has not been sent to macbook. So when I checked the signals on the  card and I found that the TXD signal was not detected.

Next I install the same card on another apple II+ and do the same thing, The card worked fine and communication between computers work perfect.

From these, I conclud that there is a problem with the motherboard of II+.

The cards currently installed in the slot are RAM card(#0), 80 column card(#2), Super Serial Card II(#3), DiskII card(#6) and VGA card(#7). These seem to be working properly.

It would be very helpful if you could give me some advice on what to check on the motherboard.

 

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It probably isn't your

It probably isn't your problem but normally people put a SSC in slot 2 and an 80 column card in slot 3.  That's where most software expect to see them.

 

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Sorry I made a mistake

Seeing what you pointed out, I noticed that I made a mistake. Sorry.

Correct my previous post.

The cards currently installed in the slot are RAM card(#0), Super Serial Card II(#2), 80 column card(#3), DiskII card(#6) and VGA card(#7). 

What I suspect is the circuit on the motherboard that  connects “ address map and control logic on the card”. Does anyone have any opinion?

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clumpwork wrote:What I

clumpwork wrote:

What I suspect is the circuit on the motherboard that  connects “ address map and control logic on the card”. Does anyone have any opinion?

The software which handles the serial chip on the SSC (6551) reads and writes this chip very often. If either reading this chip or writing would not function properly you would not see anything in any direction of data transfer.

 

I don't think that you have a problem with a motherboard. Look onto the cables and the connections.

Get a small device like that for watching the traffic and the handshakes on the serial line:

https://www.ebay.de/itm/151824560937

 

Regards

Ralf

 

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Unlikely a motherboard issue

Unlikely a motherboard issue would cause the very specific failure you are getting.  Have you tried a different cable?

 

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yes i tried but

Yes I tried.

I tried the same setting with rev.4 and RFI board.

In the first post, I did not write the type of these two board,.

Communication with the macbook succeeded in RFI but failed in rev.4.

I believe that there is no problem with the card and cable, and the software for both II + and mac.

As a matter of fact, a similar case has occurred when I tried on CCS7710A before, so I think it may be a problem unique to the motherboard.

I am going to prepare a serial port checker commented by RalfK and try to check the signal traffic.

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Check the power supply

Check the power supply voltages on the card. Especially the -12V at pin 33 of the edge connector. Of course, you should also try the card in a different slot to make sure it's not a bad edge connector.

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Always worth making a loop

Always worth making a loop back connector for testing serial, Rx to Tx and see if everything comes back, easier than wondering if the other machine or the cable is working.

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I think jeffmazur may be on

I think jeffmazur may be on to it, with his suggestion it could be a power supply problem.  The motherboard even if it is working fine can produce weird results if one or more of the power suppy voltages are off.

 

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softwarejanitor wrote:I think

softwarejanitor wrote:

I think jeffmazur may be on to it, with his suggestion it could be a power supply problem.

That's right. The first to be checked are always(!) the voltage levels on the mainboard and the boards which are involved.

 

Without +12V the floppy cannot work. The keyboard encoder needs -12V. Means without -12V the keyboard cannot work. Both seem to work in all of these II+s. So there is one possible source of the issue which was mentioned before: the slot connector.

 

Test the voltage level of the 1488 supply pins from your SSC: pin 1 should be -12V (between -11,0 and -13,0V is ok) and pin 14 should be +12V.

Regards

Ralf

 

 

 

 

 

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The thing that makes voltage

The thing that makes voltage issues a PITA to diagnose is that some devices may continue to work even when voltages are significantly off, but others may be extremely picky and even a small amount will cause errant behavior.  Voltage levels need to be measured under load, and as Ralf notes above, ideally measured right at the IC in question.  If the voltage is off on a specific slot then maybe a trace is burned on the motherboard somewhere.  That's pretty uncommon but not impossible.  That kind of thing can happen if a card is moved with the power on and pins short.  The way to test for that of course is the obvious, move the SSC to another slot as long as the software will recognize it there.  If the software is hardwired to slot 2, then testing with another package that allows the slot to be selected would be necessary.

 

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the -12 V line dropped significantly

Thank you very much for your advice. I did not doubt the power supply line. I inspected of the power supply and found that the voltage of the -12 V line dropped significantly (almost dead!).

The power supply used for the Rev.4 board is RQ-125B manufactured by Mean WELL, and there was no problem when I got it. For the RFI board is SDS60UQ02 by XP Power and there is no problem at all.

I decide to replace with new one. I will report the results later.

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Sounds like you've found the

Sounds like you've found the problem.  To test you could probably temporarily swap in one of the known good power supplies from the other ][+ units.  It should be possible to repair or rebuild the bad power supply.  If you don't want to do that, Reactive Micro sells a replacement board that will fit into the original power supply case, or even newly manufactured power supplies for the Apple II.  If you don't feel up to rebuilding your original power supply they offer a rebuild service as well.

 

https://www.reactivemicro.com/product/universal-psu-kit/

https://www.reactivemicro.com/product/service-power-supply-rebuild/

https://www.reactivemicro.com/product/ultimate-universal-power-supply/

 

 

 

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I just noticed you are using

I just noticed you are using aftermarket universal power supplies instead of the normal Astec or DynaComp ones that Apple supplied.  Never mind my above suggestions unless you want to return to a more original style power supply.  The new Reactive Micro ones do look pretty nice.

 

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Repairing original PSU seems to be difficult ...

Thank you, softwarejanitor.

 

Repairing the original power supply seems to be difficult and has not been challenged yet. I have been thinking about purchasing at ReActive Micro Store, so I'm checking it from now.

 

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solved I replaced PSU and now it works well

The  PSU was delivered from ReAtciveMIcro in the middle of last week. I replaced it this weekend and checked the voltage of the slot. SSC works well without any problems now. Thank you all. I will try to access serial-usb from Apple II+ to my Macbook Pro as I wrote before and then Raspberry PI.

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Good news indeed!  

Good news indeed!

 

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