| Posted By
nc513
on 2022-04-02
17:38:47
|  Plus/4 310163 board with TED and CPU inserted the wrong way
Hi,
I've just received a PAL Plus/4 310163 board with TED and CPU inserted the wrong way, i.e. rotated 180 degrees.
After installing the chips in the correct orientation, the board outputs a black screen. Reset works (pin 40 of the CPU goes high) and I've got 17.73 MHz at pin 14 of the TED.
I've got 5V DC at pins 2 and 1 of the user port and 9V AC at pins 10 and 11.
The tape drive's motor doesn't get power when trying PLAY/FF/REW while the board is powered on with the black screen.
I get a black screen also with a Diag264 ROM installed at U24.
Do you guys happen to have some tips for how to start troubleshooting this board? And is there any chance the TED and the CPU are still good, despite the fact that someone went and installed them backwards?
For the TED, apparently V_dd was connected to DB3, V_ss was connected to A3, and so on.
For the CPU, V_cc was connected to P6, V_ss was connected to /RES, and so on. Complete list of pairings below.
** 8360 TED **:
BOARD-----CHIP;
A2------DB0
A1------DB1
A0------DB2
V_dd----DB3
/CS0----DB4
/CS1----DB5
R/W-----DB6
/IRQ----DB7
MUX-----SND
/RAS----BA
/CAS----AEC
PHI0_CLK_OUT-A15
COLOR---A14
CLK_IN--A13
K0------A12
K1------A11
K2------A10
K3------A9
K4------A8
K5------A7
K6------A6
K7------A5
SYN/LUM-A4
V_ss----A3
DB0-----A2
DB1-----A1
DB2-----A0
DB3-----V_dd
DB4-----/CS0
DB5-----/CS1
DB6-----R/W
DB7-----/IRQ
SND-----MUX
BA------/RAS
AEC-----/CAS
A15-----PHI0_CLK_OUT
A14-----COLOR
A13-----CLK_IN
A12-----K0
A11-----K1
A10-----K2
A9------K3
A8------K4
A7------K5
A6------K6
A5------K7
A4------SYN/LUM
A3------V_ss
** 8501 CPU **:
BOARD-----CHIP;
PHI0_IN-A14
RDY-----A15
/IRQ----GATE_IN
AEC-----P7
V_cc----P6
A0------P4
A1------P3
A2------P2
A3------P1
A4------P0
A5------D7
A6------D6
A7------D5
A8------D4
A9------D3
A10-----D2
A11-----D1
A12-----D0
A13-----R/W
V_ss----/RES
A14-----PHI0_IN
A15-----RDY
GATE_IN-/IRQ
P7------AEC
P6------V_cc
P4------A0
P3------A1
P2------A2
P1------A3
P0------A4
D7------A5
D6------A6
D5------A7
D4------A8
D3------A9
D2------A10
D1------A11
D0------A12
R/W-----A13
/RES----V_ss
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Posted By
gerliczer
on 2022-04-03
03:54:40
| Re: Plus/4 310163 board with TED and CPU inserted the wrong way
First, you should test those two chips in working machines to see if they survived the ordeal. Third suspect to cause blackout would be the PLA. You should check that too. Go to Bo Zimmerman's Commodore Archive and read the Plus/4 Service Manual for further steps. Tape is powered form a separate supply circuit. You should check that too with the help of the manual and the schematics. Those can be found there too.
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Posted By
nc513
on 2022-04-03
18:17:14
| Re: Plus/4 310163 board with TED and CPU inserted the wrong way
Thanks. Yeah, I guess I might have to bring my dusty old scope out of storage.
I don't currently have access to any other Plus/4 boards, or even a C16. Might have to do something about that.
Just for the heck of it, I've desoldered all 8 DRAM chips as well as the multiplexers U9 and U10. They all tested good in my C64, so I installed IC sockets on the Plus/4 board and reinstalled those 10 chips. I've also removed the ACIA. The symptoms haven't changed one bit.
Brute force repair might not be the best strategy for this particular board ...
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Posted By
JamesC
on 2022-04-03
22:26:08
| Re: Plus/4 310163 board with TED and CPU inserted the wrong way
"After installing the chips in the correct orientation, the board outputs a black screen."
What colour was the screen before you rotated the chips?
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Posted By
nc513
on 2022-04-04
03:11:57
| Re: Plus/4 310163 board with TED and CPU inserted the wrong way
Absolutely no signal (through the A/V port of the Plus/4, on my TFT display) and the TED and CPU were cool to the touch. If I remember correctly ... :P
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