Fixing a Quicktake 150 serial connector – colin@colino.net
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colin@colino.net
2026/06/21<br>About 2 minutes read
Problem with this Quicktake 150 was that it didn’t respond to the computer. It sent its Hello when DTR went down, but then did not reply to the first computer init message. I supposed it meant its RX pin was somehow disconnected. This was true.
The Quicktake is an assembly of multiple PCBs (at least 5), connecting to each other via flat flexible cables, ribbon cables, bare wires, and PCB-to-PCB connectors, either angled or stacked. It is hell to disassemble and even worse to reassemble.
The smallest one of the PCBs is the I/O ports one, which is connected to the large bottom’s PCB via two SMT connectors1. The problem lied on the connector, on the small I/O PCB. While checking every pin, I noticed that pin 2 was also disconnected. I didn’t manage to fix the connector, so I went the bodge wire route.
My two bodge wires
Here is documentation for next time I have to verify the serial port’s connectivity up to the ICs, U309 and U310.
My notes
The row of resistors on the left of U309 and U310 are alternated 0Ω and 27Ω resistors. The pins of the serial port are connected on the right side of the 27Ω resistors:
pin 1: R385
pin 2: R393
pin 3: R381
pin 4: it’s GND, not connected to any resistor
pin 5: R389
pin 6: R383
pin 7: R387
pin 8: R391
To verify the connections from the resistors to the U309 and U310 ICs, where each IC’s pin 1 is in the top right corner as follows:
8 7 6 5 4 3 2 1<br>U310<br>9 10 11 12 13 14 15 16
8 7 6 5 4 3 2 1<br>U309<br>9 10 11 12 13 14 15 16
U310 pin 1: R387 (serial port pin 7)
U310 pin 7: R389 (serial port pin 5)
U310 pin 10: R393 (serial port pin 2)
U310 pin 14: R391 (serial port pin 8)
U310 pin 15: R389 (serial port pin 5 – again – this is not a typo)
U309 pin 10: R385 (serial port pin 1)
U309 pin 14: R381 (serial port pin 3)
U309 pin 15: R383 (serial port pin 6)
This also apply to the Quicktake 100, as they’re basically the same hardware with a different firmware.
The large bottom PCB is also connected to the large top PCB via one FFC, one ribbon cable, and three straight wires. It is also connected to the LCD display PCB via a right-angle PCB-to-PCB connector. ↩︎
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