Fisher 201 Receiver Restoration

Unit: AM/FM Stereo Receiver

Manufacturer: Fisher

Model: 201

SN: 73398

Another classic stereo receiver made by Fisher Corp came on my bench for restoration. The Fisher 201 "Futura Series" was introduced in 1972 and produces 20 watts per channel into 8 ohms with less than 1% total harmonic distortion. The optional walnut veneer cabinet for this model is 21-UW. The list price in 1972 was $249.95 (Ref. High Fidelity Magazine, April 1972).

Power Supply Board

The power supply board provides +15.5V DC for the tuner section, +31.5V DC for the pre-amplifier and control amplifier, and +53V DC for the power amplifier. This board has three aluminum electrolytic capacitors: C01, C02, and C03. I replaced them with low-impedance Nichicon UPW caps. The original e-caps were tested with an Atlas ESR70 capacitance meter and the results are below. All original capacitors still have very low ESR, but the capacitance tolerance is outside the factory specification.

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

C01: rated capacitance – 47uF, measured – 57uF, ESR – 0.11Ω, deviation: +21%

C02: rated capacitance – 47uF, measured – 61uF, ESR – 0.08Ω, deviation: +30%

C03: rated capacitance – 100uF, measured – 131uF, ESR – 0.14Ω, deviation: +31%

The regulating transistor Q01 mounted on the heat sink is a 2SC1226 transistor. In my experience with restoring Fisher 201/202 receivers, the intermittent or unstable operation of the tuner section is often caused by the aging of this transistor. I replaced it with a new Fairchild MJE15032G transistor.

Power supply board - before and after

Power Amplifier Board

Similar to the Fisher 202, each channel in the Fisher 201 has a separate driver board inserted vertically into the slot. This makes the servicing of these boards very easy.

Each driver board has four aluminum electrolytic capacitors: C01, C02, C03, and C04. I replaced the e-cap C01 installed in the signal path with a high-quality film polyester WIMA cap. The remaining aluminum capacitors were replaced with low-impedance Nichicon UPW caps.

Test results on original capacitors removed from the power amplifier boards:

Left channel:

C01: rated capacitance – 1uF, measured – 1.6uF, ESR – 5.2Ω, deviation: +60%

C02: rated capacitance – 47uF, measured – 48uF, ESR – 0.42Ω, deviation: +2%

C03: rated capacitance – 100uF, measured – 141uF, ESR – 0.74Ω, deviation: +41%

C04: rated capacitance – 47uF, measured – 69uF, ESR – 0.18Ω, deviation: +47%

Right channel:

C01: rated capacitance – 1uF, measured – 1.8uF, ESR – 4.4Ω, deviation: +80%

C02: rated capacitance – 47uF, measured – 59uF, ESR – 0.22Ω, deviation: +26%

C03: rated capacitance – 100uF, measured – 142uF, ESR – 0.62Ω, deviation: +42%

C04: rated capacitance – 47uF, measured – 66uF, ESR – 0.87Ω, deviation: +40%

The capacitance tolerance of all original capacitors (except C02 from the left channel) is outside the factory specifications.

Driver boards - before and after

Power Transistors

The original Hitachi 2SC1030 power transistors were removed, cleaned, and tested with Atlas DCA55 semiconductor analyzer. The measured DC current gain on all transistors met the specifications in the datasheet. Each pair of transistors was also very well matched within ~4%. Not too bad for 50+ old vintage gear! I mounted all the transistors back on the heat sink and applied fresh thermal paste. The old thermal pads were also replaced with new Mica ones.

Original power transistors with new Mica pads and fresh thermal paste

Pre-Amplifier Board

The pre-amplifier board has seven aluminum electrolytic capacitors: C01, C02, C11, C12, C13, C14, and C19. Four of them (C01, C02, C13, C14) are installed in the signal path. I replaced these capacitors with modern low-leakage Nichicon UKL caps to improve the signal-to-noise ratio. The remaining capacitors were replaced with low-impedance Nichicon UPW caps. Note that the filtering e-cap C19 is soldered on the foil side of the PCB.

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

C01: rated capacitance – 10uF, measured – 17uF, ESR – 1.73Ω, deviation: +70%

C02: rated capacitance – 10uF, measured – 16uF, ESR – 2.41Ω, deviation: +60%

C11: rated capacitance – 100uF, measured – 149uF, ESR – 0.44Ω, deviation: +49%

C12: rated capacitance – 100uF, measured – 145uF, ESR – 0.52Ω, deviation: +45%

C13: rated capacitance – 10uF, measured – 15uF, ESR – 0.78Ω, deviation: +50%

C14: rated capacitance – 10uF, measured – 16uF, ESR – 0.74Ω, deviation: +60%

C19: rated capacitance – 47uF, measured – 74uF, ESR – 0.33Ω, deviation: +57%

Again, the capacitance tolerance of all original capacitors from this board is outside the factory specifications.

Filtering e-cap C19 is soldered on the foil side of the PCB

Pre-amplifier board - before and after

Control Amplifier Board

The control amplifier board has nine aluminum electrolytic capacitors: C503, C504, C511, C512, C513, C514, C517, C518, and C525. The e-caps installed in the signal path (C513, C514, C517, and C518) were replaced with film polyester WIMA caps. The other four e-caps installed in the signal path (C503, C504, C511, and C512) were replaced with modern low-leakage Nichicon UKL caps. And the remaining filtering capacitor C525 was replaced with a low-impedance Nichicon UPW cap.

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

C503: rated capacitance – 10uF, measured – 15uF, ESR – 3.1Ω, deviation: +50%

C504: rated capacitance – 10uF, measured – 15uF, ESR – 3.0Ω, deviation: +50%

C511: rated capacitance – 4.7uF, measured – 9.6uF, ESR – 5.2Ω, deviation: +104%

C512: rated capacitance – 4.7uF, measured – 9.7uF, ESR – 2.2Ω, deviation: +106%

C513: rated capacitance – 1uF, measured – 1.3uF, ESR – 4.1Ω, deviation: ++30%

C514: rated capacitance – 1uF, measured – 1.4uF, ESR – 3.7Ω, deviation: +40%

C517: rated capacitance – 1uF, measured – 1.4uF, ESR – 3.6Ω, deviation: +40%

C518: rated capacitance – 1uF, measured – 1.3uF, ESR – 4.1Ω, deviation: +30%

C525: rated capacitance – 220uF, measured – 311uF, ESR – 0.05Ω, deviation: +41%

As expected, the capacitance tolerance of all original capacitors from this board is outside the factory specifications. The measured capacitance of the two e-caps (C511 & C512) is almost double their nominal capacitance! Yeah, everything ages and electronic components are no exception.

The 2SC458 NPN transistors installed on this board are prone to failure. A typical failure mode of 2SC458 is noise and/or static. I replaced every 2SC458 transistor with a modern low-noise Fairchild KSC1845. Keep an eye on the pinout of the replaced transistors when servicing this board. The original transistor is BCE and the new one is ECB.

All controls on this board were cleaned and lubricated with DeoxIT FaderLube 5% spray.

Control amplifier board - before and after

Dial, Meter, and Stereo Indicator Lamps

To replace the dial lamps in Fisher 201 just unscrew two small screws on the top of the dial scale. Then slide the dial lamp bracket to the rear and drop the bracket to get to the lamps. I replaced the original incandescent bulbs with warm white LED lamps to maintain the original look and decrease heat.

Old incandescent dial lamps

New warm white LED lamps

The meter and stereo indicator lamps in this receiver burned out. I replaced them with new incandescent lamps.

Two original meter lamps

New meter lamps are installed

Two original stereo indicator lamps

New stereo indicator lamps are installed

Center Voltage Test

The driver boards in the Fisher 201 do not have trimmers to adjust the center voltage. The service manual simply recommends doing a center voltage test to make sure the amplifier works properly. The test is very simple. First of all, the supply voltage should be measured between pin #3 and the ground. In this unit, the measured supply voltage was ~51.8V. Then, the center voltage should be measured on each board between pin #5 and the ground. This voltage should be half of the supply voltage within +/- 2V. As can be seen from the pictures below, the measured voltage on the left and right channel driver boards were 25.12V and 24.86V, respectively. So, it is approximately half of the supply voltage within +/- 1V. The unit passed the center voltage test, and both channels work properly.

Supply voltage measured between pin #3 and the ground

Center voltage measured between pin #5 and the ground (left channel)

Center voltage measured between pin #5 and the ground (right channel)

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 10.69 VRMS (left channel) and 10.60 VRMS (right channel). It corresponds to the output power of 14.3W on the left channel and 14.0W on the right channel.

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. Please watch a short demo video at the end of this post. Thank you for reading.

Fisher 201 - after restoration

Demo video after repair & restoration

Fisher 202 Receiver Restoration

Unit: AM/FM Stereo Receiver

Manufacturer: Fisher

Model: 202

SN: 22247

Another Fisher receiver (Futura series, model 202) came in for restoration. I restored exactly the same model a few months ago and one can read the restoration process in detail here: Fisher 202 receiver restoration. So, this post will be shorter than usual but I want to document what was done on this unit for future references. I hope it will be a good addition to my previous post about the Fisher 202 restoration.

Before I powered up this little receiver I checked the fuses on the back side to make sure that all of them have a correct rated current. There are three fuses on the back side: the main 2A slow blow fuse to protect the unit and two 2.5A slow blow fuses to protect the left and right channels. The fuse protecting the left channel was blown but someone bypassed it with a small piece of aluminum foil (!). Well, I was not surprised since you never know what can be found in these old units... Anyway, I replaced the blown fuse with a new one and powered the receiver up using my Dim Bulb Tester (DBT). The light bulb flashed for a second on bright and then dimmed out almost completely. So, this unit has no short circuit.

Blown fuse - bypassed with a small piece of aluminum foil

Power Amplifier Board

The Fisher 202 has two driver boards. These boards are very easy to service once removed from the slot. I didn't find any signs of overheating on these boards. All transistors and diodes have been tested and no bad components were found. So, I replaced only electrolytic capacitors. The original e-cap C01 installed in the signal path has a relatively high equivalent series resistance (ESR) of 2.6Ω (left channel) and 2.2Ω (right channel). I replaced it with a low leakage Nichicon UKL cap. The ESR of a new e-cap is only 1.5Ω which is lower in comparison to the original one. The lower ESR is always better, especially for e-caps installed in the signal path. The remaining three e-caps C02, C03, and C04 were replaced with low impedance and high-reliability Nichicon UPW capacitors. All original e-caps removed from the power amplifier board were tested with Atlas ESR70 capacitance meter and the results are below.

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

C01-L: rated capacitance – 1uF, measured – 1.44uF, ESR – 2.6Ω, deviation: +44%

C01-R: rated capacitance – 1uF, measured – 1.36uF, ESR – 2.2Ω, deviation: +36%

C02-L: rated capacitance – 100uF, measured – 131uF, ESR – 0.05Ω, deviation: +31%

C02-R: rated capacitance – 100uF, measured – 131uF, ESR – 0.06Ω, deviation: +31%

C03-L: rated capacitance – 220uF, measured – 266uF, ESR – 0.15Ω, deviation: +21%

C03-R: rated capacitance – 220uF, measured – 270uF, ESR – 0.15Ω, deviation: +23%

C04-L: rated capacitance – 47uF, measured – 85uF, ESR – 0.19Ω, deviation: +81%

C04-R: rated capacitance – 47uF, measured – 77uF, ESR – 0.22Ω, deviation: +64%

Left and right driver boards - after servicing

Power Transistors

The original Hitachi power transistors 2SC1030 were removed, cleaned, and tested with Atlas DCA55 semiconductor analyzer. According to the datasheet, the DC current gain measured in each transistor was in spec. However, it should be noted that Atlas DCA55 semiconductor analyzer provides the accurate reading for DC current gain only on low-power transistors. A high-power transistor requires a much higher collector current and collector-emitter voltage to accurately measure its current gain. However, it is still a very useful device for comparing transistors of a similar type for the purposes of gain matching or fault-finding.

I replaced the old thermal pads with new Mica ones and refreshed the thermal compound.

Original power transistors with new pads and thermal compound

Power Supply Board

The power supply board has three electrolytic capacitors C01, C02, and C03. These were replaced with low impedance Nichicon UPW caps. The new e-caps have a maximum operating temperature of +105C which is a beneficiary in power supply circuits. The original e-caps installed in vintage gears from the 70's have a maximum operating temperature of +85C. All original e-caps removed from the power supply board were tested and the results are below. The ESR of the original e-cap C03 is elevated. The new e-cap installed instead of C03 has a lower ESR of 0.15Ω.

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

C01: rated capacitance – 100uF, measured – 134uF, ESR – 0.09Ω, deviation: +34%

C02: rated capacitance – 100uF, measured – 132uF, ESR – 0.07Ω, deviation: +32%

C03: rated capacitance – 220uF, measured – 368uF, ESR – 0.32Ω, deviation: +67%

Power supply board - before and after

Pre-amplifier Board

I replaced all electrolytic capacitors on this board. The e-caps C1 and C2 installed in the signal path were replaced with low leakage Nichicon UKL caps. The original e-cap C1 installed in the right channel has a very high ESR in comparison to C2 in the left channel. The ESR of the Nichicon UKL capacitor is about 1.80Ω. The low ESR is critical for e-caps installed in the signal path. The remaining e-caps were replaced with low impedance Nichicon UPW/UPM caps.

Test results on original capacitors removed from Pre-amplifier board:

C1: rated capacitance – 10uF, measured – 12uF, ESR – 11.6Ω, deviation: +20%

C2: rated capacitance – 10uF, measured – 15uF, ESR – 1.84Ω, deviation: +50%

C9: rated capacitance – 100uF, measured – 152uF, ESR – 0.50Ω, deviation: +52%

C10: rated capacitance – 100uF, measured – 148uF, ESR – 0.46Ω, deviation: +48%

C16: rated capacitance – 100uF, measured – 154uF, ESR – 0.04Ω, deviation: +54%

Pre-amplifier board - before and after

Control Amplifier Board

All electrolytic capacitors on this board are installed in the signal path. The exception is only the e-cap C525.  I replaced e-caps C503/C504, C511 thru C514, and C517/C518 with low leakage Nichicon UKL caps. The e-cap C525 was replaced with a low impedance Nichicon UPW cap. 

This board also has four noisy 2SC458LG transistors and I replaced them with modern low noise Fairchild KSC1845. The new transistors were carefully matched by current gain and base-emitter voltage within 1%. Watch the pinout on replacement transistors. The original transistor is BCE and the new one is ECB.

I tested all original 2SC458LG transistors from this board with Atlas DCA55 semiconductor analyzer. One transistor TR501 from the left channel was found leaky. The measured collector leakage current was 0.026mA which is substantial for Si transistor. A leakage current is expected to be less than 0.001mA for the Si transistor.

Test results on original capacitors removed from Control amplifier board:

C503: rated capacitance – 10uF, measured – 19uF, ESR – 2.5Ω, deviation: +90%

C504: rated capacitance – 10uF, measured – 17uF, ESR – 2.6Ω, deviation: +70%

C511: rated capacitance – 4.7uF, measured – 6.9uF, ESR – 2.2Ω, deviation: +47%

C512: rated capacitance – 4.7uF, measured – 6.9uF, ESR – 2.2Ω, deviation: +47%

C513: rated capacitance – 1uF, measured – 1.7uF, ESR – 2.7Ω, deviation: +70%

C514: rated capacitance – 1uF, measured – 1.3uF, ESR – 2.2Ω, deviation: +30%

C517: rated capacitance – 1uF, measured – 1.2uF, ESR – 3.0Ω, deviation: +20%

C518: rated capacitance – 1uF, measured – 1.3uF, ESR – 2.2Ω, deviation: +30%

C525: rated capacitance – 220uF, measured – 268uF, ESR – 0.04Ω, deviation: +22%

Faulty transistor TR501 from the left channel - substantial leakage current

Control amplifier board - before and after

Dial, Dial Pointer, and Stereo Indicator Lamps

The dial pointer and two stereo indicator bulbs burned out in this unit. I replaced them with new white LED lamps. The new LED lamps will virtually last forever. I also replaced the original incandescent bulbs with cool blue LED lamps to decrease heat and improve the illumination. I found that the cool blue LED lamp makes the illumination of the dial scale more uniform in this model.

Burned original dial pointer bulb

New white LED lamp installed

Burned original stereo indicator bulbs

New white LED lamps installed

New cool blue LED lamps installed

Center Voltage Adjustment

The center voltage adjustment is a straightforward procedure and is clearly described in the service manual. The DC voltage between pin 5 of the left/right channel driver board and the ground should be adjusted to ~31V. I adjusted the center voltage at pin 5 to ~30.7V on each channel since the voltage measured at pin 3 was 61.4V. In general, the DC voltage at pin 5 should always be half of the voltage at pin 3.

Center voltage adjustment - left channel

Center voltage adjustment - right channel

Voltage measured between pin 3 and the ground

All the knobs and the faceplate were gently cleaned in warm water with dish soap. Also, all pots and switches 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. Please watch a short demo video at the end of this post. Thank you for reading.

Fisher 202 - after restoration

Demo video after repair & restoration

Fisher 202 Receiver Restoration

Unit: AM/FM Stereo Receiver

Manufacturer: Fisher

Model: 202

SN: 15547

Today I am showing a little Fisher 202 receiver that came in for restoration. The Fisher 202 was introduced in 1970 and was the first of the Futura series. It produces 28 watts per channel into 8 ohms with 0.5% total harmonic distortion. The receiver has one phono input, one tape input, and two Aux inputs. The list price in 1970 was $249.95. The optional walnut veneer cabinet for this model is 21-UW.

The previous owner told me that the right channel in this receiver is dead. I checked three fuses on the back side and found that one fuse protecting the right channel is blown. I replaced the blown fuse and powered up this little receiver using my Dim Bulb Tester (DBT) to check that there are no short circuits. For more information on Dim Bulb Tester refer to my previous post on Craig 5502 restoration. The receiver passed the test with DBT and I removed the cover to look inside.

Power Amplifier Board

The power amplifier in Fisher 202 is very easy to service since each channel has a separate driver board inserted in the slot. I removed both boards for inspection and immediately realized that the resistor R10 on the right channel board is severely overheated. I measured its resistance and it was 267Ω. The same resistor on the left board was 183Ω. The schematic says the resistor R10 is supposed to be 180Ω. The overheated resistor from the right channel is definitely not original. I unsoldered the resistor R10 from both boards and replaced it with a new metal film resistor 180Ω/0.5W. I also tested all other electronic components (transistors, diodes, and remaining resistors) on each driver board. No other problems with electronic components were found on those boards. I replaced the electrolytic capacitor C01 with a low leakage Nichicon UKL cap. The remaining three e-caps C02, C03, and C04 were replaced with low impedance and high-reliability Nichicon UPW capacitors.

Test results on original capacitors removed from Power Amplifier board:

C01-L: rated capacitance – 1uF, measured – 1.7uF, deviation: +70%

C01-R: rated capacitance – 1uF, measured – 1.8uF, deviation: +80%

C02-L: rated capacitance – 100uF, measured – 124uF, deviation: +24%

C02-R: rated capacitance – 100uF, measured – 165uF, deviation: +65%

C03-L: rated capacitance – 220uF, measured – 261uF, deviation: +19%

C03-R: rated capacitance – 220uF, measured – 275uF, deviation: +25%

C04-L: rated capacitance – 47uF, measured – 68uF, deviation: +45%

C04-R: rated capacitance – 47uF, measured – 66uF, deviation: +40%

Left and right driver boards - before servicing

Overheated resistor R10 on the right driver board

Resistor R10 installed on left driver board

Driver boards - after servicing

Driver boards installed

Power Transistors

The original Hitachi power transistors 2SC1030 were removed, cleaned, and tested with Atlas DCA55 semiconductor analyzer. The DC current gain was in spec according to the datasheet. Each pair was also very well matched within ~3%. It should be noted that Atlas DCA55 semiconductor analyzer provides the accurate reading for DC current gain only on low power transistors. A high-power transistor requires a much higher collector current and collector-emitter voltage to accurately measure its current gain. However, it is still a very useful device for comparing transistors of a similar type for the purposes of gain matching or fault-finding.

I applied a fresh thermal compound and also replaced the old thermal pads with new Mica ones.

Power transistors tested with Atlas DCA55 semiconductor analyzer

Old thermal pad - the thermal grease is almost completely dried out

Original power transistors with new pads and fresh thermal compound

Power Supply Board

The power supply board provides +15.5V DC for the tuner, +31.5V DC for the pre-amplifier and control amplifier, and +62V DC for a power amplifier. This board has 3 electrolytic capacitors C01, C02, and C03. I replaced all e-caps with low impedance and high-reliability Nichicon UPW/UPM caps. The test results on the original e-caps removed from this board are below. All of them are outside of the factory capacitance tolerance +/- 20%.

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

C01: rated capacitance – 100uF, measured capacitance – 161uF, deviation: +61%

C02: rated capacitance – 100uF, measured capacitance – 142uF, deviation: +42%

C03: rated capacitance – 220uF, measured capacitance – 287uF, deviation: +31%

Power Supply board - before and after

Pre-amplifier Board

The pre-amplifier board has 5 electrolytic capacitors: C1/C2, C9/C10, and C16. Two signal path capacitors C1 and C2 were replaced with low leakage Nichicon UKL caps. The remaining e-caps were replaced with low impedance and high-reliability Nichicon UPW/UPM caps. Four NPN transistors 2SC458LG installed on this board are prone to create noise or work improperly. I replaced those transistors (TR01 thru TR04) with modern low-noise Fairchild KSC1845. The new transistors were gain matched within 1%. Watch the pinout on replacement transistors if you need to service this board. The original transistor is BCE and the new one is ECB. The original electrolytic capacitors and transistors removed from the pre-amplifier board were tested to check their long-term reliability. As expected all e-caps are outside of the factory capacitance tolerance +/- 20%.

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

C1: rated capacitance – 10uF, measured – 19uF, deviation: +90%

C2: rated capacitance – 10uF, measured – 13uF, deviation: +30%

C9: rated capacitance – 100uF, measured – 158uF, deviation: +58%

C10: rated capacitance – 100uF, measured – 160uF, deviation: +60%

C16: rated capacitance – 100uF, measured – 158uF, deviation: +58%

Pre-amplifier board - before and after

Pre-amplifier board - all new Fairchild KSC1845 transistors are gain matched

Control Amplifier Board

The control amplifier board has nine aluminum electrolytic capacitors: C503, C504, C511, C512, C513, C514, C517, C518, and C525. All capacitors except the filtering cap C525 were replaced with low-leakage Nichicon UKL caps. The e-cap C525 was replaced with a low-impedance and high-reliability Nichicon UPW cap. Four noisy 2SC458LG transistors were replaced with modern low-noise Fairchild KSC1845. The new transistors were gain matched within 1%.

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

C503: rated capacitance – 10uF, measured – 19uF, deviation: +90%

C504: rated capacitance – 10uF, measured – 18uF, deviation: +80%

C511: rated capacitance – 4.7uF, measured – 6.1uF, deviation: +30%

C512: rated capacitance – 4.7uF, measured – 6.0uF, deviation: +28%

C513: rated capacitance – 1uF, measured – 1.6uF, deviation: +60%

C514: rated capacitance – 1uF, measured – 1.6uF, deviation: +60%

C517: rated capacitance – 1uF, measured – 1.6uF, deviation: +60%

C518: rated capacitance – 1uF, measured – 1.6uF, deviation: +60%

C525: rated capacitance – 220uF, measured – 282uF, deviation: +28%

Control amplifier board - before and after

Dial and Stereo Indicator Lamps

It is very easy to replace the old dial bulbs in Fisher 202. Just unscrew two small screws on the top of the dial plate and the plate holding all dial lamps would be released. I replaced the original incandescent bulbs with warm white LED lamps to maintain the original look and decrease heat.

Two stereo indicator bulbs burned out. I replaced them with new white LED lamps.

Old incandescent dial bulbs

New warm white LED lamps installed

Old stereo indicator bulbs

New white LED lamps installed

Center Voltage Adjustment

The center voltage adjustment is a straightforward procedure. The multimeter should be connected between pin 5 of the left/right channel driver board and the ground. With no signal input, the DC voltage at pin 5 should be adjusted to 31V. In general, the DC voltage at pin 5 should always be half of the voltage at pin 3. So, I adjusted the center voltage at pin 5 to ~31.5V on each channel since the voltage measured at pin 3 was 63V.

Center voltage adjustment - left channel

Center voltage adjustment - right channel

As a routine procedure on all vintage gears I restore, all the knobs and the faceplate were gently cleaned in warm water with dish soap. Also, all pots and switches 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. Thank you for reading.

Fisher 202 - before restoration

Fisher 202 - after restoration