When it comes to vintage computers, one of the first pieces of advice is “replace the capacitors.” And for many older computers, this is good advice.
The Timex/Sinclair 2068 has only a few capacitors that you could potentially be concerned about. And, as it turns out, most are still ok and don’t require replacement.
In February 2025, Carl Miles measured the values of these capacitors in the T/S 2068. The data are below.
PCB REV.: 335-850001-03A Serial# P06-67P2
| Capacitor Designation | Value uF | Voltage | Diameter | Lead Spacing | Freq @120Hz Actual Value uF | Actual D @120Hz | Actual Q @120Hz | Actual ESR @120Hz | Actual Theta @120Hz | Manufacturer | Date Code | Series | Temp °C | Capacitor Purpose |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| C3 | 470.00 | 25V | 13 x 31 | Axial | 461.40 | 0.062 | 16.02 | 0.1 | -86.4 | SAMYOUNG | CE02W | SL | 85 | DC Input Filter |
| C21 | 1.00 | 50V | 5 x 13,5 | Axial | 1.04 | 0.025 | 39.5 | 32.2 | -88.5 | SAMYOUNG | SM | 85 | RESET Filter | |
| C40 | 1000.00 | 25V | 16 x 31 | Axial | 957.10 | 0.063 | 15.58 | 0 | -86.2 | SAMYOUNG | CE02W | SL | 85 | Power Supply Filter +5V |
| C41 | 47.00 | 16V | 6,5 x 14 | Axial | 37.82 | 0.09 | 11 | 3.1 | -84.7 | SAMYOUNG | SM | 85 | Power Supply Filter +12V | |
| C58 | 100.00 | 16V | 6,5 x 18 | Axial | 88.72 | 0.072 | 13.79 | 1 | -85.8 | SAMYOUNG | SM | 85 | Composite Video | |
| C60 | 100.00 | 16V | 6,5 x 18 | Axial | 81.71 | 0.096 | 10.35 | 1.5 | -84.4 | SAMYOUNG | SM | 85 | SCLD Power Filter |
So are these capacitors good or bad?
| Capacitor Designation | Value uF | Freq @120Hz Actual Value uF | Percent Difference (Less than +/-20% Considered Good) | D Factor (<0.100 Considered Good) Actual D@120Hz | Q Factor (>10 Considered Good) Actual Q@120Hz | Actual ESR@120Hz | Theta > (-80 Considered Good) Actual Theta@120Hz | Percent Difference (< -10% Difference Considered Good) |
|---|---|---|---|---|---|---|---|---|
| C3 | 470uF | 461.4uF | -1.829787234 | 0.062 | 16.02 | 0.1 | -86.4 | -4 |
| C21 | 1uF | 1.0375uF | 3.75 | 0.025 | 39.5 | 32.2 | -88.5 | -1.666666667 |
| C40 | 1000uF | 957.1uF | -4.29 | 0.063 | 15.58 | 0 | -86.2 | -4.222222222 |
| C41 | 47uF | 37.82uF | -19.53191489 | 0.09 | 11 | 3.1 | -84.7 | -5.888888889 |
| C58 | 100uF | 88.72uF | -11.28 | 0.072 | 13.79 | 1 | -85.8 | -4.666666667 |
| C60 | 100uF | 81.71uF | -18.29 | 0.096 | 10.35 | 1.5 | -84.4 | -6.222222222 |
All the capacitors are realistically good. The 47uF (used for the +12V Supply filter cap) and 100uF cap for the SCLD Filter arguably could be considered for a replacement (the measured capacitance values for these capacitors are getting close to -20% and their Q factor is getting close to 10). There certainly are no BAD caps here.