Bowmar MX70 PM907 401A

RSABear·Bowmar_MX70_PM907_401A·KiCAD/MX70_PM907-401A_CLEAN.kicad_sch

This repository ships a schematic but no board layout.

About the Bowmar MX70 PM907 401A PCB

Bowmar MX70 PM907 401A is an open source PCB design by RSABear, published on GitHub under the Unlicense license. It is a board, with 65 components from 31 distinct parts.

Other key parts include the B6179 and B6178. By type, the board carries 19 diodes, 18 resistors, 6 transistors, 6 capacitors, 5 ICs and 4 connectors.

It belongs with the retro computing designs in this gallery.

From the project

Information and files for the vintage 1973 Bowmar MX70 Model 9075

Status: Restoration halted / original calculator IC non-functional

This repository documents an attempt to restore and reverse-engineer a rare Bowmar MX70 (Model 90701) calculator using its original PM907-401/A PCB.

The project became a detailed reverse-engineering exercise covering PCB tracing, component identification, KiCad schematic reconstruction, power and battery restoration, and reverse engineering of the LED display interface.

Main components on the Bowmar MX70 PM907 401A

B6179B6178

Bowmar MX70 PM907 401A bill of materials (BOM)

65 components, 31 distinct parts.

Qty	Part	Footprint	Refs
1	—		U1
2	B6179		U2, U3
2	B6178		U4, U5
2	BC337	TO-92_Inline	Q1, Q2
2	2N2222	TO-92_HandSolder	Q3, Q4
1	2N3904	TO-92_Inline	Q5
1	2N3906	TO-92_Inline	Q6
1	17-PIN LED Display connector		J1
1	Conn_01x04		J2
1	Conn_01x05		J3
1	AC Adapter Socker		J4
3	V1.2		BT1, BT2, BT3
1	ON/OFF	SW_Slide-03_Wuerth-WS-SLTV_10x2.5x6.4_P2.54mm	SW1
1	A/M	SW_Slide-03_Wuerth-WS-SLTV_10x2.5x6.4_P2.54mm	SW2
1	PW-0046		TR1
1	6.1V	D_DO-15_P12.70mm_Horizontal	ZD1
1	1N4001	D_DO-41_SOD81_P10.16mm_Horizontal	D1
18	1N4148	D_DO-35_SOD27_P7.62mm_Horizontal	D2, D3, D4, D5, D6, D7, D8, D9 +10
3	6.8uF		C1, C2, C3
1	6.8uF	C_0603_1608Metric_Polar	C4

Show 11 more

Qty	Part	Footprint	Refs
1	120pF	C_0402_1005Metric	C5
1	10nF	C_0402_1005Metric	C6
2	27R		R1, R2
1	10K		R3
8	39		R4, R5, R6, R7, R8, R9, R10, R11
2	43K		R12, R18
1	12K		R13
1	1K5		R14
1	750R		R15
1	1K2		R16
1	1K		R17

Bowmar MX70 PM907 401A design files

The KiCad project lives in the RSABear/Bowmar_MX70_PM907_401A repository on GitHub; these links point at the commit this page was built from.

SchematicKiCAD/MX70_PM907-401A_CLEAN.kicad_sch

Bowmar MX70 PM907 401A: common questions

How many components are on the Bowmar MX70 PM907 401A?

65 components, from 31 distinct parts. The full bill of materials is listed on this page.

Where can I download the Bowmar MX70 PM907 401A design files?

From the RSABear/Bowmar_MX70_PM907_401A repository on GitHub, which has the schematic; the links under Design files point to each one.

Can I use the Bowmar MX70 PM907 401A design in my own project?

Yes, under the terms of its Unlicense license, which RSABear chose for the repository.

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