Nintendo Gameboy (1989) repair

The first portable LCD BW console which sold over 119 million units around the world! with still today considered as a cult  also very appreciated for 8 bits music with soft cartridge like little dj or nanoloop (will do some sample pack someday).

Got this Gb boxed from a lady in Milan that told me it was not working. In quite perfect shape this was a appreciated gift. Ok it just does not turn on, this must not be so difficult. First things to check is try with external PSU, which has a non so standard connector. But It worked. So next was check battery terminal for classic corrosion leakage. 

Apparently not much, but a screw near the battery was badly damaged. Next stop open the GB.
Ok first bad news: there 6 six triwing Y screws, which I don't have. So just have to order it;  quite common on Ebay, I suppose this is classic problem, but it's rather cheap:3€ shipped in EU.
before I tried to ask local electronic shops, but, as usual , they are rather scared when I step in for my "strange" requests.  

Once arrived, the corroded screw was a problem: no way to make it move, after deoxid. And of course it was stripped and  NO space at all to use pliers. So, the only way is to drill the screw head. After a 10 minutes, finally managed to cut the head and remove safely the screw without damaging the plastic body. Damm all these vibrations for such delicate parts are not so good, in fact the screen mask just fell off for tarnished glue, we'll see that at the end.

Once opened you have to remove the flat that joints the lower and upper board of the GB (pay attention not to lose the switch button). In the back you have to remove 4 Philips head screws, way easier. Not much damage anyway. The terminal on the GB was a bit dirty but not so much. A quick clean and tested with multimeter continuity.

Cleaning the pad with Isopropyl Alcohol and a good wash to the case. 

... And it worked! 

ALL ok, just reassembling putting back screws and flat. The drilled plastic column was still ok, just added a bigger screw and it seems to be stable
 A good cleaning and I just have to use double-sided adhesive tape to reassemble the front mask, since I don't like much using glue around the screen.  

■Central Processing Unit (CPU) 8 Bit, Clock frequency: 4.19 MHz, RAM: 8 Kbytes
■Dimensions 148 x 90 x 32 mm
■Weight 220 g
■Power consumption 70 - 80 mA hr. 4 AA batteries (1.5 V)
■Playing time Up to 30 hours
■Screen type Liquid crystal screen (LCD) Screen size 4,7 x 4,3 cm
■Screen resolution r 160 x 144 Pixels
■Headphone connection Yes, stereo sound via headphones
■Colours classic Grey, transparent, black, white, red, green, yellow, blue.
Accessories : Expression pedal.

■Sounds are created by four digital channels, mixed together and played in stereo:
A square wave (“pulse” duty cycle of either 12.5%, 25%, 50%, or 75%. ) channel that perform frequency sweeps,
Another square wave channel with fixed frequency
A white noise channel
The last wave channel is able to play 4 bits samples.

CPU - 8-bit Sharp LR25902 (similar to the Z80 processor)
Clock Speed - 4.194304MHz (
Work RAM - 8K Byte (
Video RAM - 8K Byte
Resolution - 160x144 (20x18 tiles)
Max sprites - Max 40 per screen, 10 per line
Sprite sizes - 8x8 or 8x16 pixels
Palettes - 1x4 BG, 2x3 OBJ 
Colors - 4 grayshades 
Horiz Sync - 9198 KHz 
Vert Sync - 59.73 Hz 
Sound - 4 channels with stereo sound
Power - DC6V 0.7W 


■ NO SERVICE MANUAL if you have it, please do contact us we will share it for free

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