Summary

Standard consumer-level trinitron from the early 90s. OSD runs separate from jungle, jungle has no analog RGB inputs. Unamplified RGB injection is not possible. S-Video mod is possible (see below).

Literature

• Service Manual
• Owner's Manual

Notes

The following models all share the same service/user manuals: 13TR14, 13TR24, 13TR27, 1427R, 13EXR90, 13EXR91

S-Video Mod

Note 1: Although an attempt is made in this mod to couple the input chroma ground to the CRT chassis ground, there is still potential for a ground loop to occur from thr CRT to the connected device, allowing for some AC noise (humbars) to scroll up the screen. This is because we do not have the chroma signal integrated into the optocoupler isolation the chassis uses for composite. The odds of seeing noise depend entirely on the design of the input device and the only way to fully prevent it is to plug the CRT into an Isolation Transformer such as the Tripp-Lite IS250 or similar. In my testing the current design was good enough to avoid noise on all of my game consoles but other devices such as LaserDisc players still had noise issues. Using an isolation transformer to power the CRT would be the only way to avoid seeing noise in that .

Note 2: This mod will disable the composite and RF inputs (once R326 is lifted/cut). Sony made the odd decision to process all of the stock video signals as Y/C-separated before the Jungle, so in order to tap in your own Y/C signals you will be destroying the existing signal paths, having to choose between doing this mod and thereby cutting off the chroma signal of the stock inputs, or somehow designing a multi-switch circuit to retain both your Y/C and the stock Y/C. I decided against the switching idea because I have a strong feeling it will add too much noise to an already bad/noisy video processing circuit and not be worth the trouble.

Step 1: Connect luma signal to the input pad for the composite video jack. You can find this by following the wires behind the inputs to where they connect to a plug on the main board. On the under-side of the board the pad labeled "V" is where you want to solder your luma input. Either of the "E" pads can be used for ground. We use the V-pad for Luma input because it will feed to the composite video signal chain which conveniently already handles many of the things you need like 1) 75ohm terminating our input signal, 2) decoupling it to DC, and 3) even go through an RLC noise filter before reaching the jungle. Saves us work.

Step 2: Lift (or cut) resistor R326 to prevent existing chroma buffer circuit from interfering. Solder a 0.1uf capacitor leg to the R326 pad that leads to pin 46 (C-In) of the IC301 jungle chip. Solder the other leg to your chroma input wire.

Step 3: Connect a wire from the ground of the jungle chip area to the ground near the video input pins you already soldered to. put a 0.1uF film capacitor (or smaller) on either end of the wire in series. This will couple the isolated ground to the jungle ground, eliminating any 60Hz AC humbars from entering our signals.

I suggest also disabling Dynamic Color so that the chroma signal (and composite) isn't being processed so heavily - you can do this by lifting (or cutting) a leg of R366. NOTE: It has been reported that a silkscreen printing error is present on the PCB and the service manual, and the names of these resistors are swapped on one side of the PCB and in part of the service manual. Be careful to identify the right resistor by referencing the parts list in the service manual and using an measurement from a multimeter before cutting. I think its the solder side of the PCB that has the wrong resistor names printed. The component side (top side) of the PCB is labeled correctly to match the parts list in the service manual.

Stereo Audio Input Mod

If you want to be able to hear both channels of audio from your game console coming out of the single mono speaker in this CRT, you can do a "stereo to mono mixdown" circuit. This is as simple as taking the second channel's audio input and attaching it to the existing one with a series resistor that is an exact impedance match to any one series resistor early in the original circuit.

For this TV, you can attach your second audio channel input to the capacitor side of R415 via a 1K series resistor. This will match the 1K impedance of the existing audio input and cause them to mix equally into a single audio channel. It is important to attach directly parallel to the existing 1K resistor to get an exact split with no audio clipping. Don't attach it randomly somewhere else in the circuit, it won't work. There is a simple diagram attached below to aid in your understanding.