Magnavox 14MS2331/17

Matt Ross
April 20, 2024, 6:22 pm

Summary

Compact 14" flat CRT, made by Philips and sold under the Magnavox brand. Includes stereo A/V and RF inputs, but can be modified to accept S-Video and Component.

Literature

User Manual

Chassis Service Manual

Sales Brochure

L03.2U Chassis Notes

This model features an hour counter that can be seen at the top left of the service menu. It can be accessed by pressing the sequence "0 6 2 5 9 6 Menu" on the remote.

Like many Philips TVs, this model is capable of syncing to 50hz. Pal video will still display in black and white, unless the TV has been modified for component input.

Late model Philips TVs have a circuit that automatically compensates for variations in G2 voltage. When adjusting the screen pot on these TVs, it is best to disable "AKB" in the service menu. This feature can cause streaking on the image if G2 and brightness are not adjusted properly.

Several Philips TVs, including this model, are prone to oxidized microswitches on the front panel. This causes the buttons to perform the wrong function when pressed. This can be fixed by replacing the switches, or avoided by using the remote instead.

Component & S-Video mod

Written by Matt Ross (6tanks)

This chassis, like most Philips sets from this time, uses a 1-chip jungle design with integrated OSD and cannot accept an external RGB signal. However, many of these TVs can be modified to accept component and S-Video directly. Unlike some manufacturers, Philips did not use any edge enhancement or artificial sharpness filters on their component inputs, so the video quality is excellent. Thanks to user "Stonesipping" for first documenting this on the Shmups forum RGB mod thread.

This guide is applicable for some TVs with the L03.2U chassis: 14MS2331, 20MS2331, and 20MS1336. Unfortunately, mono sound TVs with this chassis, such as the MT1331/17, have a different firmware version that does not work with this mod. A similar procedure can be used for other Philips & Magnavox models, although the pinout for the jungle chip may be different.

On this TV, Component and S-Video inputs can be enabled by changing the option bits in the service menu. These settings determine what features are active or disabled. Use an original remote to enter the service menu by pressing "0 6 2 5 9 6 Menu". Now, select "Options" by pressing right. Cycle to OP 5 with the down button, select it by pressing right, and enter "204" using the number keys. Press "menu" to return to the service menu, power off the TV, and unplug it for at least ten seconds. This will write the changes to memory. Now, when you power on the TV, two new inputs labeled "SVHS" and "CVI" will be available. For a detailed explanation of how the option bits work, refer to page 30 of the service manual.

The TDA9377 jungle chip has input pins for Y, Pb, Pr, and S-Video Chroma, as well as an input select pin:

TDA%20pinout%20side

To enable component input, pin 45 of the jungle chip (INSSW2) must be connected to a +8v power supply through a 1000 ohm resistor. This can be done by populating position 3232 on the bottom of the PCB:

L03.2U%20PCB%202

The Y, Pb, Pr, and Chroma signals each require a 75 ohm terminating resistor to ground, and an inline coupling capacitor (0.1 uF works well) before connecting to the jungle chip. S-Video Luma should be connected directly to the front composite input, with no additional components needed. The inputs can be wired as follows:

L03.2U%20Schematic

I used 26 gauge ribbon cable, attached to the bottom side of the jungle chip pins and front RCA jack:

L03.2u%20wires%201 L03.2u%20wires%202

To route the wires to the top of the board, I enlarged a hole in the PCB near the tuner and ran the wires straight back from the jungle chip:

L03.2u%20hole L03.2u%20wires%203

I secured the wires to the top of the PCB with a bead of hot glue, to keep them away from the RF jack. It's a good idea to use quick connects so that the back case can be easily removed:

L03.2u%20wires4

RCA jacks for YPbPr and audio and a mini DIN for S-Video were installed in the back of the case. Terminating resistors and coupling capacitors were wired directly to the input connectors:

L03.2u%20jacks%201 L03.2u%20jacks%202

With the mod finished, the TV will display a very clean picture through component or s-video when the proper input is selected.

Gallery

Magnavox 14MS2331/17 Magnavox 14MS2331/17 Magnavox 14MS2331/17