Recreation of VGA module PCB for Loewe TVs with Q2500M chassis.
Project based on work done by Oelii from circuit-board.de/forum
Schematic recreated from the scratch in KiCad. PCB based on Oelii's layout and verified with Desing/Electrical Rules Checker tools.
Components footprints replaced with KiCad standard ones.
Unverified, obtained from post by djcalle on circuit-board.de/forum:
- Q23, Q24, Q25 can accept VGA cards.
- Q25 and Q24 use the same VGA card (only 2 differences: cable length and 150R termination on RGB lines.)
- Q25 seems to be inconsistent with VGA card compatibility.
- Q24 seems consistent with vga card compatibility.
- Q23 uses its own different card.
Original schematic from Loewe Q2500-M chassis service manual
Recreated schematic and PCB
| Reference | Value | Footprint | Qty |
|---|---|---|---|
| C811,C817,C826,C828,C829 | 100n | 0805 | 5 |
| C813,C814,C821,C827 | 10p | 0805 | 4 |
| C816 | 10u | 0805 | 1 |
| C818 | 22n | 0805 | 1 |
| C822 | 100p | 0805 | 1 |
| L816,L826 | 1210(3225) | 4.7uH | 2 |
| R814,R819,R821,R823,R828,R829 | 100R | 0805 | 6 |
| R817 | 10k | 0805 | 1 |
| R818 | 1k | 0805 | 1 |
| R827 | 47k | 0805 | 1 |
| R836,R837,R838 | 150R | 0805 | 3 |
| I811 | 74HCT86 | SO-14 | 1 |
| W801 | VGA DSUB-15 Edge pin offset 8.35mm Mounting holes offset 10.89mm |
1 | |
| W831 | JST XH 2.54 12 Pin | 1 |
Send "gerbers" folder content packed to zip archive.
L816 and L826 SMD 1210(3225) inductors value are unknown; 4.7uH in Q2300 VGA module schematic; can be replaced with 0R resistor.
W831 connector originally is Molex 22-23-2121. Probably can be replaced with XH 2.54 12 pin connectors / cables, note pins step 2.5/254 mm. Pay attention on cable connectors type: same direction or reverse direction. Most cable are up to 30 cm, sometimes 50 cm. Measure what you need before ordering.
Double-check ground and VCC connection on VGA module PCB and TV chassis before soldering 12-pin W831 connector and power on.
Q2400 chassis:
Q2500 chassis:
Mods information provided by @neonname.
Combined VGA adapter board output and TV input termination/load resistance for RGB lines should be ~75 Ohm.
TV Signal Board schematic:
Q2400 signal board already have 75 Ohm termination resistors on RGB lines.
150 Ohm RGB termination resistors on adapter board should be removed.
TV Signal Board schematic:
PCB components side:
PCB solder side:
PCB missing W1011 VGA connector and RGB input resistors, RGB input connected to ground with 0R load resistors.
Suggested changes, needs to check on real board:
- Replaсe R2641, R2643, R2646 (0R) with 27R, add missing R1016, R1017, R1018 47R resistors (like Q2500-M) (probably incorrect termination)
- Or replaсe R2641, R2643, R2646 (0R) with 150R; add missing R1016, R1017, R1018 (0R) (like Q2500-H). Note: R2512, R2513, R2514.
TV Signal Board schematic:
PCB components side:
PCB solder side:
Recommended changes:
- Replaсe R2641, R2643, R2646 (68R) with 150R; R1016, R1017, R1018 (10R) with 0R; R2512, R2513, R2514 (0R) with 47R; remove C1016, C1017, C1018.
TV Signal Board schematic:
PCB components side:
PCB solder side:
Suggested changes, needs to check on real board:
- Replaсe R2641, R2643, R2646 (47R) with 150R; R1016, R1017, R1018 (27R) with 0R; remove C1016, C1017, C1018. Note: R2512, R2513, R2514.