Marantz 2218 Receiver Restoration

Unit: AM/FM Stereo Receiver

Manufacturer: Marantz

Model: 2218

SN: N/A

One of my customers brought in another beautiful Marantz receiver for restoration. The unit is in great cosmetic condition and works pretty well but has some issues typical for 40-50 years old electronic equipment. Several original dial lamps burned out, both BALANCE and VOLUME pots are dirty, and most switches have oxidized contacts due to aging. So, it should be serviced to bring it back to the factory spec and extend its healthy life for another 40 years.

Marantz 2218 is a fairly rare model. It is a lower-power AM/FM stereo receiver from the classic 22XX silver face series. It was manufactured from 1978 to 1980. It produces 18 watts per channel into 8 ohms with no more than 0.08% total harmonic distortion. The optional walnut veneer cabinet for this model is WC-116.

Marantz 2218 is a service-friendly receiver because of very good access to each PCB.

Main Amplifier & Power Supply Board (P700)

The power supply and main amplifier circuits are assembled on one board (P700).

The power supply circuit has six aluminum electrolytic capacitors: C753 thru C758. All of them were replaced with low impedance Nichicon UPW/UPM caps.

Test results on original capacitors removed from the power supply circuit:

C753: rated capacitance – 330uF, measured – 349uF, ESR – 0.01Ω, deviation: +6%

C754: rated capacitance – 220uF, measured – 236uF, ESR – 0.01Ω, deviation: +7%

C755: rated capacitance – 100uF, measured – 110uF, ESR – 0.02Ω, deviation: +10%

C756: rated capacitance – 330uF, measured – 304uF, ESR – 0.01Ω, deviation: -8%

C757: rated capacitance – 220uF, measured – 185uF, ESR – 0.08Ω, deviation: -16%

C758: rated capacitance – 1000uF, measured – 1246uF, ESR – 0.01Ω, deviation: +25%

The main amplifier circuit has four low leakage e-caps (C701, C702, C705, C706) installed in the signal path and four aluminum electrolytic capacitors (C709, C710, C717, C718). The original low leakage e-caps were replaced with modern low leakage Nichicon UKL caps. And the remaining aluminum e-caps were replaced with low impedance and high-reliability Nichicon UPW/UPM caps.

Test results on original capacitors removed from the main amplifier circuit:

C701: rated capacitance – 10uF, measured – 10uF, ESR – 0.94Ω, deviation: 0%

C702: rated capacitance – 10uF, measured – 9uF, ESR – 1.23Ω, deviation: -10%

C705: rated capacitance – 47uF, measured – 48uF, ESR – 0.23Ω, deviation: +2%

C706: rated capacitance – 47uF, measured – 47uF, ESR – 0.21Ω, deviation: 0%

C709: rated capacitance – 47uF, measured – 53uF, ESR – 0.11Ω, deviation: +13%

C710: rated capacitance – 47uF, measured – 54uF, ESR – 0.11Ω, deviation: +15%

C717: rated capacitance – 100uF, measured – 90uF, ESR – 0.04Ω, deviation: -10%

C718: rated capacitance – 33uF, measured – 39uF, ESR – 0.23Ω, deviation: +18%

Two large filter capacitors (C751, C752) were tested in-circuit with Atlas ESR70 capacitance meter.  Both e-caps are still in a factory spec with minimum deviation from the rated capacitance. And both have zero ESR. So, I didn't change them. In general, the filter capacitors rarely fail in vintage gears, and I usually don't replace them unless their ESR is high or per customer request.

In-circuit test on two filter capacitors - both are still in spec

C751: rated capacitance – 6800uF, measured – 6490uF, ESR – 0Ω, deviation: -5%

C752: rated capacitance – 6800uF, measured – 6455uF, ESR – 0Ω, deviation: -5%

The original trimming resistors (R717, R718) on this board were replaced with new Bourns potentiometers.

Main amplifier & power supply board - before and after

Phono Amplifier Board (P400)

The phono amplifier board has two solid tantalum capacitors (C401, C402) installed in the input signal path, two low leakage electrolytic capacitors (C415, C416) installed in the output signal path, two filtering aluminum e-caps (C413, C417), and two DC blocking aluminum e-caps (C405, C406). Both tantalum capacitors were replaced with modern low leakage Nichicon UKL caps. The original low leakage e-caps as well as aluminum e-cap C413 were replaced with film polyester WIMA MKS2 caps. And the remaining aluminum e-caps were replaced with low impedance Nichicon UPW/UPM caps.

Test results on original capacitors removed from the phono amplifier board:

C401: rated capacitance – 3.3uF, measured – 3.5uF, ESR – 2.2Ω, deviation: +6%

C402: rated capacitance – 3.3uF, measured – 3.6uF, ESR – 2.5Ω, deviation: +9%

C405: rated capacitance – 100uF, measured – 137uF, ESR – 0.22Ω, deviation: +37%

C406: rated capacitance – 100uF, measured – 134uF, ESR – 0.21Ω, deviation: +34%

C413: rated capacitance – 1uF, measured – 1.3uF, ESR – 1.1Ω, deviation: +30%

C415: rated capacitance – 1uF, measured – 1uF, ESR – 4.1Ω, deviation: 0%

C416: rated capacitance – 1uF, measured – 1uF, ESR – 4.4Ω, deviation: 0%

C417: rated capacitance – 100uF, measured – 111uF, ESR – 0.01Ω, deviation: +11%

Phono amplifier board - before and after

Pre & Tone Amplifier Board (PE01)

The pre & tone amplifier board can be easily released from the chassis for servicing. One should remove the faceplate and then unscrew three nuts from the BASS, TREBLE, and BALANCE potentiometers. And that's it! Just compare with what you need to do to release the same board from the chassis in Marantz 2238B. Indeed, it is a service-friendly design!

When it is released from the chassis, it is also very easy to clean and lubricate all three controls on this board. I cleaned and lubricated them with DeoxIT FaderLube 5% spray.

This board has six low leakage e-caps (CE03, CE04, CE11, CE12, CE13, CE14) installed in the signal path, two bi-polar e-caps (CE15, CE16) installed in the output signal path, and one filtering aluminum e-cap (CE20). Four low leakage e-caps (CE03, CE04, CE11, and CE12) were replaced with film polyester WIMA MKS2 caps. The other two low leakage e-caps (CE13 and CE14) were replaced with modern low leakage Nichicon UKL caps. The original bi-polar e-caps were replaced with new bi-polar Nichicon UES caps. And the remaining filtering e-cap was replaced with a low impedance Nichicon UPM cap.

Test results on original capacitors removed from the pre & tone amplifier board:

CE03: rated capacitance – 1uF, measured – 1uF, ESR – 2.8Ω, deviation: 0%

CE04: rated capacitance – 1uF, measured – 1uF, ESR – 2.2Ω, deviation: 0%

CE11: rated capacitance – 1uF, measured – 1uF, ESR – 3.2Ω, deviation: 0%

CE12: rated capacitance – 1uF, measured – 1uF, ESR – 3.2Ω, deviation: 0%

CE13: rated capacitance – 4.7uF, measured – 4.8uF, ESR – 1.75Ω, deviation: +2%

CE14: rated capacitance – 4.7uF, measured – 5.1uF, ESR – 1.22Ω, deviation: +9%

CE15: rated capacitance – 4.7uF, measured – 5.1uF, ESR – 0.96Ω, deviation: +9%

CE16: rated capacitance – 4.7uF, measured – 5.2uF, ESR – 1.18Ω, deviation: +11%

CE20: rated capacitance – 100uF, measured – 111uF, ESR – 0.02Ω, deviation: +11%

Original and new bi-polar capacitors CE15 and CE16

Pre & tone amplifier board - before and after

Dial and Meter Lamps

The easiest way to replace the dial lamps in Marantz 2218 is to disassemble the PCB holding these lamps from the plastic holder. However, any attempts to do it will certainly result in breaking the small plastic tabs. The plastic holder becomes very brittle over time. Therefore, I always prefer to replace the old incandescent lamps from the front panel. It is also quite challenging to do because the dial scale should be removed from the chassis. The dial scale is mounted on the chassis with double-sided tape. And, it is always a risk to damage it. However, the risk is minimal if the right tools are used. And of course, some experience is also needed. I usually use an X-ACTO #2 Knife for this job and work very slowly with patience. The old incandescent lamps were replaced with warm white LED lamps to maintain the original look and decrease heat. Note, that there is no vellum paper behind the dial scale in Marantz 2218. It makes the replacement of dial lamps a little bit easier.

To replace the original incandescent lamp behind the meter in Marantz 2218, one should remove a small PCB holding the lamp. The small plastic tab will snap off for sure while trying to do it. But this is the only way to replace this lamp. Sad but true. However, I am always able to glue the small plastic tab back after the lamp is replaced. It takes some patience but is doable. I strongly recommend using a modern LED lamp (warm white or cool blue) here instead of a new incandescent lamp. The LED lamp not only substantially reduces the heat and thereby protects the vellum paper behind the meter but also will last almost forever. You wouldn't need to replace it again in the future and face the same trouble.

Dial scale removed - original incandescent dial lamps

Dial scale removed - warm white LED lamps

Bias Adjustment

The bias is measured across two emitter resistors (R731 and R733) on the left channel, and across two emitter resistors (R732 and R734) on the right channel. It should be adjusted to ~9mV with trimming resistors R719 and R720, respectively. It corresponds to the idling current of 20mA.

Bias on the left and right channels after restoration

Output Power Test

The final output power test was performed at the end of my restoration. The receiver was loaded with a low inductance 8Ω/100W dummy resistor for each channel. The oscilloscope was connected across the speaker terminals and a sine-wave signal of 1kHz was applied to the AUX jacks. The output sine-wave signal was perfectly symmetrical on both channels with no clipping up to 11.86 VRMS (left channel) and 12.21 VRMS (right channel). It corresponds to the output power of 17.6W on the left channel and 18.6W on the right channel. A very small difference (~6%) observed between the left and right channels can be attributed to the imperfection/aging of the balance potentiometer.

Output power test

As usual, all the knobs and the front panel were gently cleaned in warm water with dish soap. All controls have been cleaned with DeoxIT 5% contact cleaner and lubricated with DeoxIT FaderLube 5% spray.

The final result can be seen in the photos below. The receiver looks and sounds fantastic! Please watch a short demo video at the end of this post. Thank you for reading.

Marantz 2218 - after restoration

Demo video after repair & restoration