Website and contents
property of John Warren
of North Reading Engineering, North Reading, MA 01864 USA. No part of the
above may be copied and published, in part or in total, without permission.
© 2017 John Warren
© 2017 John Warren
LISTENING TESTS, BURN-IN
After servicing the amplifier, it's used for a few days to ensure it's stable and operating as expected. During this time, components are periodically measured for excessive temperature using either hand-held IR thermometers or contact thermocouples placed at specific locations within the amplifier.
SHIPPING
A FEDEX Shipping Center is about a mile from my location. When you ship an amp to us, please ship by FEDEX to that location and held for our pick-up (inquire).
Packing the amplifier properly to ship to our location is your responsibility. It should be double boxed and packed tight so as not to jostle around when handled. If you have the McIntosh double box shipping carton use it. If you need shipping cartons contact McIntosh Parts Department at 800 538 6576. Otherwise use strong, double-walled cartons. Note also, when I ship back to you I will not re-use your shipping carton if I consider it inadequate. Should I have to supply boxes, you will be charged an additional fee so use McIntosh shipping cartons or good quality boxes and double box. Print out your contact information and place it with the amplifier before you pack it up.
Do not ship the amplifier in the decorative wooden case. Remove the knobs from amps that have glass front panels otherwise we could be looking for replacement glass too.
CUSTOMERS IN THE GREATER BOSTON, NEW ENGLAND AREA
I can meet you at a mutually convenient location about an hours drive from the greater Boston area to receive and return your hardware after servicing saving you all sorts of trouble with shipping. A pick-up/drop-off fee of will be applied. I can also delivery and set the amplifier up in your home.
WARRANTY
North Reading Engineering warrants labor and parts installed by us for a period of 30 days. The 30 day period begins when the equipment is received by you from our location. Hardware returned for warranty service will be subject to inspection for alterations, signs of tampering and abuse.
INVOICING
At completion of servicing, you will be provided with an invoice by email. Payment is required prior to ship.
IF YOU WISH TO SEND YOUR AMPLIFIER TO US
Please send an email describing the hardware and what you would like done. I'll then provide contact information and determine if it makes sense to have the amplifier shipped for service.
After servicing the amplifier, it's used for a few days to ensure it's stable and operating as expected. During this time, components are periodically measured for excessive temperature using either hand-held IR thermometers or contact thermocouples placed at specific locations within the amplifier.
SHIPPING
A FEDEX Shipping Center is about a mile from my location. When you ship an amp to us, please ship by FEDEX to that location and held for our pick-up (inquire).
Packing the amplifier properly to ship to our location is your responsibility. It should be double boxed and packed tight so as not to jostle around when handled. If you have the McIntosh double box shipping carton use it. If you need shipping cartons contact McIntosh Parts Department at 800 538 6576. Otherwise use strong, double-walled cartons. Note also, when I ship back to you I will not re-use your shipping carton if I consider it inadequate. Should I have to supply boxes, you will be charged an additional fee so use McIntosh shipping cartons or good quality boxes and double box. Print out your contact information and place it with the amplifier before you pack it up.
Do not ship the amplifier in the decorative wooden case. Remove the knobs from amps that have glass front panels otherwise we could be looking for replacement glass too.
CUSTOMERS IN THE GREATER BOSTON, NEW ENGLAND AREA
I can meet you at a mutually convenient location about an hours drive from the greater Boston area to receive and return your hardware after servicing saving you all sorts of trouble with shipping. A pick-up/drop-off fee of will be applied. I can also delivery and set the amplifier up in your home.
WARRANTY
North Reading Engineering warrants labor and parts installed by us for a period of 30 days. The 30 day period begins when the equipment is received by you from our location. Hardware returned for warranty service will be subject to inspection for alterations, signs of tampering and abuse.
INVOICING
At completion of servicing, you will be provided with an invoice by email. Payment is required prior to ship.
IF YOU WISH TO SEND YOUR AMPLIFIER TO US
Please send an email describing the hardware and what you would like done. I'll then provide contact information and determine if it makes sense to have the amplifier shipped for service.
PERFORMANCE ANALYSIS FOR DISTORTION,
LINEARITY AND BANDWIDTH
Performance characteristics measured and plots provide plots:
Distortion- % Total Harmonic Distortion (%THD) versus output power
Linearity- A plot of signal voltage IN versus signal voltage OUT (straight line relationship to max. input level of amp expected)
Bandwidth (Swept-Sine)- A plot of output power as a function of frequency
Bandwidth (FFT)- A plot of output power that highlights troubles at specific frequencies across the amplifier bandwidth
Performance characteristics measured and plots provide plots:
Distortion- % Total Harmonic Distortion (%THD) versus output power
Linearity- A plot of signal voltage IN versus signal voltage OUT (straight line relationship to max. input level of amp expected)
Bandwidth (Swept-Sine)- A plot of output power as a function of frequency
Bandwidth (FFT)- A plot of output power that highlights troubles at specific frequencies across the amplifier bandwidth
VINTAGE McINTOSH SOLID-STATE AMPLIFIER SERVICING
Although vintage McIntosh amplifiers are a well made and durable many of the components in the circuits are life-limited, having lives that depend on hours of use and operating temperature. As parts "field-age" in service, they degrade and the symptoms of degradation manifest themselves as buzzing sounds, mains hum, noise, distortion and loose bass response.
VINTAGE MODELS SERVICED:
AMPLIFIERS
MC2105 - Overhaul package available
MC2100 - Overhaul package available
MC2300
MC2505
MC250
MC100
MC50
INTEGRATED AMPLIFIERS
MA5100
MA6100
PRE-AMPLIFIERS
Email to discuss your specific needs.
TUBE AMPLIFIERS
Email to discuss your specific needs.
VISUAL INSPECTION
Protective cages and panels are removed. PC boards, chassis wiring, passives and discrete devices are examined for trouble. Altered, replaced, distressed, damaged or missing parts are identified. The PC boards are pulled from the edge card connectors and examined individually for distress. I can, at times, perform in-circuit analysis of components on the boards to check for open circuits, damaged discrete devices and so on.
Should significant alterations or damage be discovered, I'll provided a detailed description of the trouble, some bench photos and possible ways to address it. If nothing glaring is noted, the electrical behavior of the amplifier is assessed.
UPDATING (ENHANCED RELIABILITY / LONG TERM SERVICE)
If your amplifier is functional yet hasn't been serviced after years of use, it can be "updated" to replace life-limited components. Updating an old amplifier with new components will change the sound output and, in my opinion, clearly for the better. Bass response is "tighter", noise is lower and the amp will run cool. Updated amps are just quieter.
First, I'll perform both the visual and tear-down inspections to assess the condition of the hardware and operating performance. Measurements include power supply behavior, rail voltages and output section characteristics including distortion and bandwidth . Power supply main filter caps are replaced. Aluminum electrolytic caps are replaced with Nichicon, Vishay, Panasonic brands. Film type capacitors along the signal path are replaced with WIMA, Nichicon or Panasonic brands. Performance plots, oscilloscope screen captures and photo documentation of work performed, as needed, are provided electronically to the customer.
A basic amplifier update for reliable, long term service includes:
New thermistors
New output transistors
All small signal electrolytic capacitors replaced
All input coupling capacitors replaced
Multi-section capacitor reworked
New power supply capacitors
New ceramic disc power supply snubber caps
Gain pots, rocker switches, PCB edge card holders flushed, cleaned
Input/power output/output section emitter resistors measured and replace as needed
Restore modified or rewired boards to proper condition
DISCRETE SEMICONDUCTOR DEVICES
Transistor, diodes and rectifier replacements are from the best manufacturers in the industry, sourced through authorized distributors. When an exact replacement for a discrete is specified by McIntosh, I'll use it. I do not indiscriminately replace parts without considering the design intent for the part selected. Small signal and power output board replacement transistors are first curve traced for basic V-I characteristics and when required by design, matched.
Parts sources include McIntosh, Mouser, Digi-Key and Allied Electronics.
McIntosh amps, preamps and integrated amps designed around discrete semiconductor devices are classics and deserve to be well treated. Soldering techniques used produce solder joints that are indistinguishable from those made at the factory. Part removal and installation is performed to insure PC board solder pads, solder lugs and solder tabs are stressed no more than necessary. Benches are outfitted to handle ESD sensitive devices. When a task is complete, the work is examined using precision distortion analyzers. At customer request, we will provide a package containing all parts removed from the unit.
OVERHAUL PACKAGES FOR MC2100 AND 2105 AMPLIFIERS - A NEAR NEW AMPLIFIER
This is a service package that restores the MC2100 and 2105 units to like new condition and consists of new output transistors, a complete power supply rebuild, new McIntosh supplied power output boards, a complete rebuild of the preamplifier input board, multi-cap rework, new thermistors and optional reworks including meter board rebuild and recalibration, new RCA inputs, input potentiometers, mounting feet, knobs and output terminal strips. Inquire for pricing. Here is an example of what an overhaul looks like.
Although vintage McIntosh amplifiers are a well made and durable many of the components in the circuits are life-limited, having lives that depend on hours of use and operating temperature. As parts "field-age" in service, they degrade and the symptoms of degradation manifest themselves as buzzing sounds, mains hum, noise, distortion and loose bass response.
VINTAGE MODELS SERVICED:
AMPLIFIERS
MC2105 - Overhaul package available
MC2100 - Overhaul package available
MC2300
MC2505
MC250
MC100
MC50
INTEGRATED AMPLIFIERS
MA5100
MA6100
PRE-AMPLIFIERS
Email to discuss your specific needs.
TUBE AMPLIFIERS
Email to discuss your specific needs.
VISUAL INSPECTION
Protective cages and panels are removed. PC boards, chassis wiring, passives and discrete devices are examined for trouble. Altered, replaced, distressed, damaged or missing parts are identified. The PC boards are pulled from the edge card connectors and examined individually for distress. I can, at times, perform in-circuit analysis of components on the boards to check for open circuits, damaged discrete devices and so on.
Should significant alterations or damage be discovered, I'll provided a detailed description of the trouble, some bench photos and possible ways to address it. If nothing glaring is noted, the electrical behavior of the amplifier is assessed.
UPDATING (ENHANCED RELIABILITY / LONG TERM SERVICE)
If your amplifier is functional yet hasn't been serviced after years of use, it can be "updated" to replace life-limited components. Updating an old amplifier with new components will change the sound output and, in my opinion, clearly for the better. Bass response is "tighter", noise is lower and the amp will run cool. Updated amps are just quieter.
First, I'll perform both the visual and tear-down inspections to assess the condition of the hardware and operating performance. Measurements include power supply behavior, rail voltages and output section characteristics including distortion and bandwidth . Power supply main filter caps are replaced. Aluminum electrolytic caps are replaced with Nichicon, Vishay, Panasonic brands. Film type capacitors along the signal path are replaced with WIMA, Nichicon or Panasonic brands. Performance plots, oscilloscope screen captures and photo documentation of work performed, as needed, are provided electronically to the customer.
A basic amplifier update for reliable, long term service includes:
New thermistors
New output transistors
All small signal electrolytic capacitors replaced
All input coupling capacitors replaced
Multi-section capacitor reworked
New power supply capacitors
New ceramic disc power supply snubber caps
Gain pots, rocker switches, PCB edge card holders flushed, cleaned
Input/power output/output section emitter resistors measured and replace as needed
Restore modified or rewired boards to proper condition
DISCRETE SEMICONDUCTOR DEVICES
Transistor, diodes and rectifier replacements are from the best manufacturers in the industry, sourced through authorized distributors. When an exact replacement for a discrete is specified by McIntosh, I'll use it. I do not indiscriminately replace parts without considering the design intent for the part selected. Small signal and power output board replacement transistors are first curve traced for basic V-I characteristics and when required by design, matched.
Parts sources include McIntosh, Mouser, Digi-Key and Allied Electronics.
McIntosh amps, preamps and integrated amps designed around discrete semiconductor devices are classics and deserve to be well treated. Soldering techniques used produce solder joints that are indistinguishable from those made at the factory. Part removal and installation is performed to insure PC board solder pads, solder lugs and solder tabs are stressed no more than necessary. Benches are outfitted to handle ESD sensitive devices. When a task is complete, the work is examined using precision distortion analyzers. At customer request, we will provide a package containing all parts removed from the unit.
OVERHAUL PACKAGES FOR MC2100 AND 2105 AMPLIFIERS - A NEAR NEW AMPLIFIER
This is a service package that restores the MC2100 and 2105 units to like new condition and consists of new output transistors, a complete power supply rebuild, new McIntosh supplied power output boards, a complete rebuild of the preamplifier input board, multi-cap rework, new thermistors and optional reworks including meter board rebuild and recalibration, new RCA inputs, input potentiometers, mounting feet, knobs and output terminal strips. Inquire for pricing. Here is an example of what an overhaul looks like.
NORTH READING ENGINEERING
NORTH READING, MASSACHUSETTS 01864 USA
NORTH READING, MASSACHUSETTS 01864 USA