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How to Convert a HiRom PCB [ 1J3M ] to LoRom
http://forums.nesdev.com/viewtopic.php?f=12&t=13031
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Author:  sadponyguerillaboy [ Tue Jul 21, 2015 5:07 pm ]
Post subject:  How to Convert a HiRom PCB [ 1J3M ] to LoRom

Thought I'd post this for those who like myself went searching for an illustrated guided on how to convert a HiRom 1J3M board into a LoRom board. Granted, this isn't the most practical choice, and a LoRom donor makes way more sense, but when in a pinch, it'll do! This information can be readily sourced from these forums as well as found floating around the internet, although unfortunately the rom labratory links seems to be down.

Their guide can now be found here: http://www.slideshare.net/Metaconta2/rom-laboratory, and is a wealth of information. I used their Mad-1 switch as my main source for this guide.

Mad-1 Switch:
Image

Extracted from the Rom Labratory's switch, we see that:

Code:
Mad-1 pin 15 connects to Cartridge Slot Connector Pin 40
Mad-1 pin 14 connects to Cartridge Slot Connector Pin 45 + Eprom A19
Mad-1 pin 13 connects to Cartridge Slot Connector Pin 46 + Eprom A20
Mad-1 pin 12 connects to Cartridge Slot Connector Pin 47 + Eprom A21
Mad-1 pin 10 connects to Ground
Eprom pin A15 Connects to Cartridge Slot Connector Pin 41
Eprom pin A16 Connects to Cartridge Slot Connector Pin 42
Eprom pin A17 Connects to Cartridge Slot Connector Pin 43
Eprom pin A18 Connects to Cartridge Slot Connector Pin 44
Eprom pin A22 Connects to Cartridge Slot Connector Pin 48


I then used a TSOP to DIP 36 Adapter #3 from https://www.buyicnow.com/ to mount my 29F033C (same as 29F032) flash chip, burned my rom with a GQ-4X programmer. Then removed pins A15, A16, A17, A18, A19, A20, A21 & A22.

Here is an image depicting the pin layout:
Image

Here is my prepared adapter:
Image
Image

I then desoldered the Mad-1 chip completely, bent up pins 10, 12, 13, 14 & 15, then resoldered back in place. Then I began wiring up the connections as listed above.

Here are images of the first stage of wiring:
Image
Image

*Note: I used Kynar wire for this project. Also, Only the wire to the A15 pin hole in the MaskRom socket is soldered to the socket, all other wires just feed up through the MaskRom socket holes and then connect to the corresponding TSOP adapter pins.

Stage 2 of Wiring:
Image
Image

Stage 3: Attaching TSOP Adapter
Image
Image
Image

Viola! You should now having a working 1J3M LoRom board capable of using a TSOP 40 to DIP 36 Adapter.

Hope others find this useful.

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