DT9205A Multimeter R7 994 SMD Resistor—What Is the Value of R8 SMD Resistor?

User question

In dt9205a multimeter r7 is 994 smd resistor what is the value of r8 smd resistor

Artificial Intelligence Response

Direct answer to the question

• If your DT9205A has R7 marked “994” (i.e., 990 kΩ), the companion R8 is typically “103”, which is 10 kΩ. (elektroda.com)
• A few board variants use “993” (99 kΩ) in that position; verify on your specific PCB before replacing. (elektroda.com)

Key points

• “994” SMD code = 990 kΩ; “103” = 10 kΩ; “993” = 99 kΩ.
• R7 and R8 are part of the d.c.-voltage input divider feeding a 200 mV full-scale ADC.
• The 990 kΩ + 10 kΩ pair yields a 100:1 division used for the 20 V range. (elektroda.com)

Detailed problem analysis

• Function in the meter:
  • DT9205A-type meters use an ICL7106/FS9922-family ADC with ~200 mV full-scale. To measure higher voltages, the input is scaled by a resistive ladder. With R7 = 990 kΩ and R8 = 10 kΩ, the ratio (R7+R8)/R8 = 100, giving a 100:1 divider for the 20 V range. (elektroda.com)
  • Some production manuals describe a 1 MΩ section of the divider for these ranges; if R7 is 990 kΩ, the remaining leg has to be 10 kΩ to sum to ~1 MΩ, consistent with R8 = “103”. (Design inference from the manual’s stated divider total.) (manuals.plus)
• Why not 10 MΩ or “shunt” values?
  • A 10 MΩ R8 (“106”) would not produce the required ratios and is not used at that node.
  • Very low-ohmic values (e.g., 9 Ω/90 Ω) are current-shunt parts for the mA ranges on some boards. If your R7 truly reads “994”, it is not in the shunt chain; it is the high-value divider leg, so R8 belongs to the high-value divider as above. (elektroda.com)
• Board-to-board variation:
  • DT9205A is a family designation used by several contract manufacturers. While “R8 = 10 kΩ” is by far the most common pairing with “R7 = 994”, a smaller subset substitutes “993” (99 kΩ) and adjusts the tapping scheme accordingly. Always check your specific PCB. (elektroda.com)

Current information and trends

• Recent online repair notes and summaries continue to show the 990 kΩ + 10 kΩ combination as the dominant build for the divider around R7/R8, with occasional 99 kΩ sightings on clone boards since ~2023. (elektroda.com)
• Vendor manuals for DT9205A variants still describe a 1 MΩ divider section for the d.c.-voltage ranges, aligning with 990 kΩ + 10 kΩ in the standard topology. (manuals.plus)

Supporting explanations and details

• SMD code refresher:
  • 994 → 99 × 10^4 = 990 kΩ
  • 103 → 10 × 10^3 = 10 kΩ
  • 993 → 99 × 10^3 = 99 kΩ
• Divider math example (20 V range):
  • With R7 = 990 kΩ and R8 = 10 kΩ, an applied 20.00 V produces 0.200 V at the ADC input: 20.00 V × [10 kΩ / (990 kΩ + 10 kΩ)] = 0.200 V.
• Relation to input impedance claims:
  • Some manuals state “10 MΩ input impedance” generically for DCV; the effective input impedance can depend on which ladder section is in-circuit on each range. The 1 MΩ sub-ladder (≈990 kΩ + 10 kΩ) is commonly selected for the 20 V range tap, while other ranges may include additional series elements to raise the seen impedance. (Design inference from typical 7106-based DMMs and the cited manual.) (manuals.plus)

Ethical and legal aspects

• Using an incorrect R8 value alters measurement ratios and can compromise accuracy and the stated CAT II/1000 V safety margin. Replace like-for-like and test after repair. (elektroda.com)

Practical guidelines

• Identification:
  • Inspect R8’s top mark under magnification; if legible, “103” confirms 10 kΩ. If unreadable, lift one end and measure with a known-good meter. (elektroda.com)
• Replacement part spec:
  • Value: 10 kΩ (most common) or 99 kΩ on some variants—match your board.
  • Tolerance: 1% (or better).
  • Package/power: match original footprint (usually 0805/1206) and equal-or-higher power rating.
  • TCR: ≤100 ppm/°C preferred for stability.
• Post-repair checks:
  • Verify DC accuracy on 2 V, 20 V, and 200 V with a trusted source; readings should scale correctly if the divider is right. (elektroda.com)

Possible disclaimers or additional notes

• The DT9205A label covers multiple board revisions; designators may shift (R8 could be silkscreened as R10/R11 on some versions). Confirm by tracing from the V/Ω jack to the divider chain and the rotary-switch taps. (elektroda.com)

Suggestions for further research

• Cross-check with your unit’s service/assembly manual if available; some public manuals describe the divider as ~1 MΩ for the low-voltage ranges. (manuals.plus)
• If you want a second opinion, photograph the divider area around R7 and R8 and share it; board photos are often decisive.

Brief summary

• With R7 marked “994” (990 kΩ), R8 in a DT9205A is almost always “103” (10 kΩ), forming the 100:1 divider needed for the 20 V range. A minority of clone boards use “993” (99 kΩ); verify on your PCB or by measurement before ordering parts. (elektroda.com)

If you can share a clear photo of the R7/R8 area or your PCB code, I can confirm which variant you have and specify an exact replacement.

Disclaimer: The responses provided by artificial intelligence (language model) may be inaccurate and misleading. Elektroda is not responsible for the accuracy, reliability, or completeness of the presented information. All responses should be verified by the user.