Posted By
Tomm
on 2003-02-02
|  Need help Plus4
My Plus4 show 'break' errors on the screen, after inputs:
break
PC SR AC XR YR SP
; 0070 F8 FE 00 FF 01
when i press Reset, the Cursor is the left corner and i see damage fonts:
ommore Basic v.5 of false Byte free or another Break Message.
When i use the on/off Button i the Breaks again 
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Posted By
MIK
on 2003-02-02
 | Sounds like the TED Chip is faulty.
It's a common fault of the Plus4. If you open up your Plus4 it's the chip sat under the metal cage in the center of the board. Sometimes if you're lucky it's just a case of swapping it for another, but where do you get hold of TEDs today?
It might be an idea to get hold of another Plus4. Also keep hold of your Plus4 as spare just incase....
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Posted By
SVS
on 2003-02-02
 | Maybe a fault Rom,
if you are so lucky...
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Posted By
JamesC
on 2003-02-02
| I disagree with that diagnosis
If the unit is displaying properly before resets, then the BASIC ROM is throwing it into MONITOR to begin with. I have had some programs that redefine characters, when RUN/STOP-RESET is pressed the TED goes weird because its pointers are off in never-never land.
Tomm, if you have any of the cartridge games (Jack Attack, Pirate Adventure, etc), plug one of those in and see how the unit works. This will bypass the BASIC ROM altogether and help with your diagnosis. If the unit still acts up, then it's definately a major problem. If the unit behaves with the game cart, maybe someone locally has a dead unit that can provide a BASIC ROM, or an EPROM module and can burn a new one for you. Nice thing about the TED series, they use the more common 28 pin EPROMs, not the hard-to-find 24 pin ones like the C64. 
Also, the metal cage that encloses the TED, make sure that the white goop is still soft and flexible; if you've removed the white goop or it's hard as a rock, replace it promptly. Any computer assembler or repair shop can provide a small tube of this goop cheaply.
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Posted By
Tomm
on 2003-02-02
| thankx
I will look in ebay for an old (cheap) c16 and put the chip in the plus 4.
Thankx for helping and greetings from good old germany.
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Posted By
quink
on 2003-02-02
| change the prozessor
hi Tomm,
your problem is the prozessor-chip (U2) not the TED (U1)
Test it, your breaks:
10 print "hey"
20 goto 20
run
and you see the breaks in the tedmon. Change the U2-Chip (8501) and test it again..
- what you not can coding in asm, you must solder -
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Posted By
someone
on 2003-02-03
| On my machine (C116)
recently I've encountered something similiar.
But it wasn't the CPU or the TED but the BASIC-ROM!
On every 16. address one bit (it was the highest bit, if I'm right) was set to a steady "1".
After replacing the ROM with an EPROM I've never got such problems 'til today.
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Posted By
Mike
on 2003-02-03
| Cheap replacements...
A small reminder that ebay is a fantastic source of cheap Plus/4 replacements. usually around £5-£10 will get you a new one 
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