Test & Measurement Equipment Used to Conduct Testing, Design, and Evaluation
HP/Agilent, Bruel & Kjaer, Tektronix, GenRad and
other equipment traceable to NIST are used for testing, design, and evaluation. Voltage, frequency, current, R, L, C, & Z, noise,
THD, IM, H and S-parameters, network, spectral and FFT analysis, RF power, signal-to-noise ratio, noise figure, RFI, EMI, VSWR, SPL,
vibration, wow and flutter, stereo separation, free field acoustical measurements, modulation, temperature, dimensional measurements,
torque and weight can be accurately measured in house.
Typical Problems Due to Component Degradation
Specific to Marantz
16 and 16B
Most of the typical problems that occur with the Marantz 16 and the Marantz 16B amps are due to component degradation.
The speaker relay goes into protection prematurely, long before it should or at lower power levels. Upon turn-on, the relay energizes
early or late. Other problems are: poor frequency response, high IM and THD, noise, early clip, high offset, parasitic oscillations,
insufficient bias, bias fluctuations, and insufficient cooling due to dirt build-up.
Open and leaky capacitors are often found, as
well as, zener diode failure, out of tolerance resistors (as much as 100% or more), and loss of chassis grounds. This ground loss
is due to anodizing of the screw holes from the factory. So far, I've never seen a Marantz 16 or 16B without some of the carbon composition
resistors out of tolerance.
Other common problems are: dirty pots, excessive build-up of dirt around the predrivers (these transistors
are running close to their maximum dissipation), dirty relay contacts (silver sulfate), and solder connections that have become weak
due to the high temperature of a few resistors on the TO-3 boards. Rarely are the silver micas, polyester, or mylar caps found to
be defective. However, these will be checked, and replaced if found defective. A few 16s have had loose transformer bolts. And, in
one case where the nuts actually fell off.
Marantz 16 and 16B Work Performed
The amplifier is tested first to determine
the amplifier’s performance and definitive problems. All components are checked to ensure that the adjacent components, transistors,
etc. were not stressed and consequently prone to future failure. All of the electrolytic capacitors, including the large filter capacitors,
are replaced (no generics are used). There are a total of 16 capacitors in the model 16, 17 capacitors in the model 16B. High temp
capacitors for critical areas are tested and matched prior to installation. Capacitors used for the restoration are low ESR, low leakage,
and long life components. Sprague, Mallory, BC Components, and Panasonic capacitors are used for restoration. (If you want to supply
"designer " audio caps for your restoration, that’s fine, however the performance and/or reliability of the amp cannot be guaranteed.)
To prevent future problems and reduce noise, resistors in two critical areas of the amp are replaced with low noise, carbon-film resistors,
regardless of the condition of existing resistors. All out of tolerance resistors are replaced.
The relay is of very good quality
with normally very low contact resistance. There is high silver content in the contacts, they are prone to sulfate, then pitting.
The relay will be dissassembled in place and contacts resurfaced, not just cleaned. A three-step process is used to clean the bias
and offset pots. Zener regulation of the op-amp supply will change on occasion. If this is found, the zener diodes will be replaced
with higher power, mil spec, matched pairs. The heat sinks and all frame members will be cleaned inside and out. RCA input jacks will
be replaced if necessary. Power, frequency response, distortion and noise, bias, relay function, etc. and power transformer condition
and insulation resistance will be measured.
Great care is taken so there will be no lifted traces, overheating of board connections,
or excessive bending of wires. Careful attention will be paid so as not to scratch, marr, or ding the amp. These are functional amps
and collector’s items. They will be treated accordingly.
Purchasing parts, even in large quantities is expensive, especially when
parts need to be tested and selected. Some parts are rejected. Only the better grades of the manufacturers parts are purchased and
selected. Sometimes there is a long lead-time when suppliers are out of stock. If one value of a component is on back order, that
slows down the entire process. Sometimes a manufacturer discontinues a component, and a search for suitable replacements must be done.
Work on these amps is time consuming, in order to complete a fine job. For example, just warming up the amp while monitoring the bias
takes time. Even though automated test equipment is used, running specs on the amp still takes a considerable amount of time.
Conditions
for Marantz 16 / 16B Restoration
In order to restore your amp at the flat rate fee, all of the transistors must be in good condition.
A few defective transistors may be replaced as part of the standard restoration fee. Any repairs that require major transistor replacement
will have to be quoted on an individual basis. Individual defective transistors can be replaced while maintaining the original parameters.
Optionally, full complements of semiconductors can be replaced which will yield improved specifications and reliability. Transistors
are replaced with either the original equipment semiconductors when stocked, or carefully matched substitutes and upgrades. Repair
service (without complete restoration) is also available.
Cautions for Some Marantz 16 Amplifiers
CAUTION: Although rare,
a few of the Marantz 16 amplifiers should NOT be turned up slowly on a variac. The 16Bs are the exception to this. These few Marantz
16 amplifiers will oscillate when turned up slowly with a variac, and will continue to oscillate at a high frequency when turned up
to the terminal line voltage. These few Marantz 16 amplifiers have to be turned on quickly. You must observe the slow turn on process
with a line wattmeter. You will notice that the wattmeter will continue to rise indicating power well past the bias requirement.
Marantz
16 & 16B Shipping and Packaging
You should remove and keep your faceplate. It's not necassary to restore your amp. Removing the
faceplate is optional, but recommended so that it doesn't undergo any possible shipping damage. Needless to say, it is easily removed
with four ¼-20 bolts. Be careul not to scratch the faceplate when removing these bolts. Time and time again … someone takes pliers,
crescent wrench, or sockets that scratch, etc. to remove these bolts. Use the appropriate socket and be careful not to let the socket
hit the faceplate or use a piece of plastic such as saran wrap over the bolt then push on the socket. Do not overtighten these bolts.
They are not that tight to begin with. Pull out the two bi-pin lamps, they are on sockets.
Remove and keep your fuse caps and fuses.
If improperly packed, on occasion they are cracked off in shipping. It is not necessary to ship them … keep them aside. Wrap both
power cords in sufficient bubble wrap, paper, etc. so that the plugs do not scratch the amp. Tape a piece of paper or index card type
material over the top and bottom caution labels. Do not use masking tape or duct tape. Use the minimum amount of cellophane tape to
hold the paper in place. Do not apply the tape to the labels themselves. Packing material often catches the corner of these labels
and damages them.
The amp should be packaged in stiff, thick, rubber foam that surrounds the amp and conforms to the inside the box.
Amplifiers wrapped in multiple layers of bubble wrap have been known to survive the trip well. Of course, there are other ways to
pack the amp. Thick rubber foam is highly recommended. Multiple layers of carpet padding also work well. It is your responsibility
to pack the amp properly so it arrives in good shape. Your packaging should be adequate to safely ship both ways. If your packaging
is insufficient, there may be an additional charge for packing material.
You pay shipping both ways. Shipping should be insured both
ways. I am not responsible for shipping damage. If you are in the Chicagoland area, and want to hand deliver the amp, we can make
arrangements to avoid shipping. (I’d be willing to travel a little bit to save you a few miles.)
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Resources for electronic, test & measurement, laboratory, and acoustic equipment
Marantz 7T, 14, 15, 16, 16B, 18, 19
Repair & Restoration Service
Marantz Model Sixteen
All Marantz 16 and Marantz 16B amplifiers need attention due to component degradation.
Marantz 16 can be restored to new specifications
or better for a flat rate fee of $260* per stereo amp
Marantz 16B can be restored to new specifications or better for a flat rate
fee of $270* per stereo amp
*As of January 1, 2012, the flat rate fees no longer apply to services on the above amplifiers. Parts
costs from suppliers have risen dramatically. Quotes will be provided at the time of inquiry.
(See Conditions for Marantz 16 / 16B
Restoration below.) Above prices include all parts and labor. Shipping is additional. Repair service (without complete restoration)
is also available and will be quoted on an individual basis.
I have designed, redesigned, modified, and repaired amplifiers for over
50 years, and now specialize in Marantz 14, 15, 16, 16M, 16B, 18, and 19. Shown in the pictures below are a few of the Marantz 15s
(3 versions), 16s, and 16Bs that have been restored and/or modified. Also shown is a 15 and 16, specifically used to test new types
of components. These are a few from my collection.
Quality components have been specifically selected for the Marantz 14, 15, 16,
16B, and 16M. After years of conducting comprehensive testing, manufacturers and their types of components that work best with these
amplifiers have been chosen. These components meet or exceed the original component specifications of the amplifiers and will not
change the characteristics of your amplifier.
Modifications such as drilling holes or extending leads are not required to install
these components. Only the highest quality soldering, desoldering, and reflow equipment is used in an antistatic environment. Specialized
fixtures to hold assemblies in place and solder masks are used to replace components. This prevents stress on interconnecting wires
and expedites component replacement. All components are time tested, graded, and matched. High temperature, 105ºC capacitors are used
in critical areas. These have a life expectancy of over 200,000 hours. All resistors used for restoration are carbon-film, low noise.
Marantz 16 and Marantz 16B Electrical Repair / Restoration
