Troubleshooting guide

Cinematronics Vector Monitor Repair Guide v.1.0
Page 46 of 53
Appendix B: Replacement Parts
While the majority of the Cinematronics monitors are comprised of TTL and other discrete
components, there are a few items that are difficult to find or exceedingly expensive to replace.
Hopefully the following list of replacements will give you some options.
LF13331 Replacement
By Rodger Boots
Yup, it’s an obsolete part. It’s getting hard to find. How about making your own? If I had any
ambition I’d be making these myself and selling them to anyone that wants them. But someone else
can do that, not me.
You will need an IC socket and a not-the-best analog switch IC such as a DG212, DG202, or
MAX332. (Something with a similar on-resistance to the LF13331 and can handle the power
supply voltage).
Put the IC UPSIDE DOWN on the IC socket. Pin 1 of the IC socket will be pin 8 of the IC and vice
versa. Solder it to the socket. Trim off the extra pin length. Flipping it puts the power supply pins in
the right places. ALL the parts have all the switches open with the control pins low.
Now plug it into the game. Pin 1 of the SOCKET plugs in to the pin 1 position of the game (you
might want to paint a dot on the IC (pin 1 of socket, pin 8 of IC).
The disable pin of the LF13331 no longer works on this retrofit, but according to Cinematronics
schematics it isn’t used anyway.
One last thing, the reason your LF13331 died in the first place is probably because of the power up
sequence. If -15V supply arrives before the +15V, then device will be knocked out. To prevent this,
add a diode between pins 4 and 5 of the socket for the analog switch. The cathode (banded end)
goes to pin 4, and the tail/anode goes to pin 5. Just about any diode will work, but a 1N914 is
recommended; I think I used a 1N1418. I added the diode to the bottom side of the PCB.
The pinout for the two devices are as follows:
LF13331 DG201
Control1 1 16 Control4 Control1 1 16 Control4
source1 2 15 Drain4 source1 2 15 Drain4
drain1 3 14 Source4 drain1 3 14 Source4
Vr (GND) 4 13 Disable (*) V- (-15V) 4 13 V+ (+15V)
V- (-15V) 5 12 Vcc (+15V) GND 5 12 Not connected/used
source2 6 11 source3 source2 6 11 source3
drain2 7 10 drain3 drain2 7 10 drain3
Control2 8 9 Control3 Control2 8 9 Control3