[cups.general] Fwd: very strange dot-matrix printer problem: randomly wrong print result (ghostscript-esc p2)

[Gene Heskett]

On Wednesday 13 September 2006 12:38, Ambrose Li wrote:
>[It looks like the CUPS mailing list's spam filters are misconfigured.
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>---------- Forwarded message ----------
>From: Ambrose Li <ambrose.li at gmail.com>
>Date: 13-Sep-2006 12:29
>Subject: Re: [cups.general] very strange dot-matrix printer problem:
>randomly wrong print result (ghostscript-esc p2)
>To: "Mirror of cups.general Newsgroup" <cups at easysw.com>
>Cc: wangpenghui at realss.com
>
>On 13/09/06, <zhangweiwu at realss.com> wrote:
>> I very much like to try it! Actually, most everything I print is plain
>> text (though not ASCII, it's Chinese. The printer has embed Chinese
>> fonts too, only need to know how to enable it), I use graphic mode only
>> because I need to print spreadsheets with table columns and table
>> lines. If there is a good application that can convert an openoffice
>> spreadsheet into text table (with data correctly aligned of course)
>> then I'll like it.
>
>Since you are printing Chinese, you can ignore the suggestion to print
>in text mode, because Chinese can only be prined in "graphics mode".
>
>One additional thing you might want to check is the cables. This is
>not very likely, but it is possible that a bad cable or a loose
>connection can cause some data to randomly drop out, causing the
>problem you describe. I have seen this before.
>--
>cheers,
>-ambrose

Another thing that bitten me before, and I'm reminded of it by the OP's 
statement about using the parport, is the write pulse and the valid data 
times on the parport are too narrow, and by the time it actually gets a 
logic zero thru the fcc mandated per pin rc filtering in the printer, the 
lag has compromised the data.

This was particularly troublesome with the 2nd generation of the shacks dmp 
printers, rendering them quite worthless even for raw text if the port 
wasn't latched down till the printer actually issued the ack.  Most 
drivers bypass that ack check as it can cut the transfer speeds quite 
noticably.  I had a situation where the write strobe and the data was 
valid was derived from the cpu clock and was only .5 u-secs wide.  I had 
to open the printer, and cut one of the two .005 ceramic caps free on 
every active pin of its centronix port.  That was a major improvement but 
still miss-fired occasionally.  It was also good enough that it drove me 
to go spend $700 on a decent epson since it was obvious I could never get 
even cartoon quality color out of that POJ.  Epsons first ink squirter, a 
Stylus Pro.

Such deep digging into the hardware with an oscilloscope is of course not 
for the technically challenged.  And since that pin pounder now probably 
has enough mileage on it the quality is going downhill, pin wear etc, the 
OP would probably be far better off at the end of the day to go get a new 
epson c88 or similar printer. USB driven, does excelent photographic color 
& even with a full set of spare ink cartridges, probably less than he paid 
for the pin pounder when it was new.

If however he needs the tractor feed to handle forms, I'm not aware of an 
ink squirter that has a tractor feed, so the OP may be stuck.  Maybe this 
might be a clue he could have checked.

-- 
Cheers, Gene
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Copyright 2006 by Maurice Eugene Heskett, all rights reserved.