NEC Home Consoles - TurboGrafx-16, etc

[channelmaniac]

Fixed: TruboGrafx-16
Symptom: Dead. Only gives light blue screen

There is a definite lack of deep level hardware information on the web for this console.  Thanks to this, I worked backwards and pinned out the CPU a bit (address, data, power, reset, clock) and the HuCard socket from the pinouts on the Work SRAM IC.

Checked the reset line and it wasn't being held low long enough. Replaced the capacitor on the RC network feeding the reset line. Reset was working better but was not the cause of the problem.

Found a bad trace on address line A2. Patched that but was getting strange signals on the SRAM with the logic probe. Replaced the IC. Signals were better looking but system was still not booting. Cleaned the card slot (folding rough paper over the end of the card, wetting it with pure alcohol, and feeding in/out repeatedly) then resoldered it. There were quite a few solder connections on the connector that were cold - they bubbled when heated - which had to be desoldered and resoldered.

Game now boots and plays.

[channelmaniac]

Here are the pinouts for the HuC6280A CPU (a modified 65SC02) and the HuCard.

Keep in mind that these were reverse engineered from the pinout of the SRAM IC, power and ground connections, as well as the clock and reset connections. It is said that the HuCard has the same pin connections as a JEDEC style EPROM so I used that in labeling some of the higher address pins.

Email or PM me if you have any info that can be used to update these.

Code:

CPU: 

1 - A5
2 - A4
3 - A3
4 - A2 ?
5 - A1
6 - A0
7 - GND
8 - VCC
9 - 
10 - CLK
11 - RESET*
12 - 
13 - 
14 - ?? HU #35
15 - VCC
16 - GND
17 - 
18 - 
19 - VCC
20 - 
21 - GND
22 - 
23 - 
24 - 
25 - 
26 - 
27 - 
28 - 
29 - GND
30 - 
31 - 
32 - 
33 - 
34 - 
35 - 
36 - 
37 - 
38 - 
39 - 
40 - 
41 - 
42 - 
43 - ?? HU # 37
44 - 
45 - 
46 - 
47 - VCC
48 - GND
49 - D2
50 - D1
51 - D0
52 - D3
53 - D4
54 - D5
55 - D6
56 - D7
57 - VCC
58 - GND
59 - 
60 - 
61 - SRAM CE1*
62 - SRAM OE*
63 - SRAM WE*
64 - ?? HU #24
65 - ?? HU #3
66 - A18 ?
67 - A17 ?
68 - A16
69 - A15
70 - A14
71 - A13
72 - A12
73 - A11
74 - A10
75 - GND
76 - VCC
77 - A9
78 - A8
79 - A7
80 - A6

Code:

HuCard:

1 - Back panel connector: pin C3
2 - Audio in ?? Back panel connector: B1
3 - CPU # 65  ??
4 - A16
5 - A15
6 - A12
7 - A7
8 - A6
9 - A5
10 - A4
11 - A3
12 - A2
13 - A1
14 - A0
15 - D7
16 - D6
17 - D5
18 - GND
19 - D4
20 - D3
21 - D0
22 - D1
23 - D2
24 - CPU # 64  ??
25 - A10
26 - SRAM OE*  ?? SAME AS SRAM's OE*
27 - A11
28 - A9
29 - A8
30 - A13
31 - A14
32 - A17 ??
33 - A18 ??
34 - SRAM WE*  ?? SAME AS SRAM's WE*
35 - CPU # 14  ??
36 - RESET*
37 - CPU # 43  ??
38 - VCC