K-TRONIX ELECTRONICS REPAIR
Vintage Audio · Restoration · Service · www.ktronixrepair.com
Final Bench Report
Diagnostic Summary
Initial inspection revealed no significant visual damage or component leakage. All potentiometers and switches were cleaned thoroughly using contact-safe cleaner and lubricant. Following service, both channels produced clear, balanced audio with no distortion or noise. The previously reported right-channel muffling has been fully resolved.
Testing & Evaluation
| Test Area | Result / Observation |
|---|---|
| Low-Volume Test | Balanced stereo image, noise-free signal. |
| High-Volume Load Test | Stable performance over 60 minutes under load. |
| Thermal Monitoring | All driver transistors and regulators remained within safe temperature limits. |
| Bias / DC Offset | Stable, consistent readings — no drift observed. |
| Protection Relay | Engaged and released cleanly; no chatter or delay. |
| Power Supply Rails | Voltages steady and within design spec. |
Capacitor Health Assessment
| Parameter | Finding |
|---|---|
| ESR (Equivalent Series Resistance) | Within normal range. |
| Leakage / Swelling | None observed. |
| Drift / Value Deviation | No out-of-spec readings detected. |
| Overall Condition | Stable and reliable for continued use. |
Capacitors were evaluated for ESR, leakage, and drift. All measured values remained within tolerance and showed no signs of failure. While the existing capacitors are presently stable, a full capacitor replacement (recap) is recommended in the future to maintain long-term reliability and performance stability.
Banana Plug Retrofit (Itemized)
| Description | Time / Qty | Rate | Subtotal |
|---|---|---|---|
| Design Work — measurement & CAD modeling for rear plate | 0.25 hr | $89/hr | $22.25 |
| 3D Printing — custom rear terminal plate(s), PLA+/PETG | 1 set | — | $10.00 |
| Banana Plug Terminals — gold-plated, panel-mount | 2 sets | — | $15.00 |
| Installation Labor — removal, plate fitment, wiring, soldering | 0.50 hr | $89/hr | $44.50 |
| Estimated Total (itemized) | $91.75 |
Final Notes
The Marantz 2275 now performs cleanly across all inputs and outputs, exhibiting excellent channel balance, stable bias, and strong sonic integrity. No further issues were observed during extended bench testing. Next step: unit will be reassembled and prepared for pickup.
K-Tronix Electronics Repair · Billings / Molt, Montana
www.ktronixrepair.com