McIntosh - Hints and Kinks

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CircleStereo.com has some good advice on the MAC-1700, which shoul apply to other units as well. Check out http://www.circlestereo.com/info/brands/mcintosh/?content=mac1700
It reads:
McIntosh Mac-1700 Receiver
This is a receiver of the early '70's which has the distinction of being a hybrid. The tuner is tube while the preamp and power amp are solid state. It is not large, weighing in at 45 watts rms/channel but will power relatively efficient speakers very well. These will require all of the usual cleanups of controls, tube sockets, tuning capacitor, and switches. The tuner will often require tubes and alignment. They have rather large capacitors for positive and negative power supply and these often go bad, causing hum or distortion in both channels. There are other supply caps which are prone to failure. MAC1700's have been known to occasionally pop their supply fuses, (located in the fuse block underneath) and they will sometimes damage speakers due to an intermittent dc offset problem (dc appears at the speaker terminals). This is caused by the differential amp transistors on the small driver boards underneath. These must be replaced on every machine, regardless of what other repairs are needed. After all this is done, do the cosmetic to make it beautiful and enjoy.
 
MR80 - quirks

The MR80 is the best of the analog tuners, immune to overload, selective, lots of separation, and good sound. It does have some quirks, especially with the capacitive touch controls for the tuning. If your MR80 behaves strange when you use the manual tune - will not go into stereo - hangs the preset tunes - or just acts strange when you touch a control on the panel, it may have a very simple fix. Unplug the tuner, rotate the plug 180 degrees, plug it back in, good bet your problems are solved !!
 
Greetings Everyone:

Iam looking to put external meters on my MC2200 amp. Does anyone know if the blue bulb is a McIntosh proprietary (sp) color or locally available at Radio Shack? And has anyone made/purchased a meter kit that will accomplish this goal?

Thanks
 
The McIntosh blue meters are made blue by using blue filter material between the lamp and the meter and to keep the blue look when turned off it is also between the meter and the glass front.
I use blue vinyl window tint material to achieve the effect.
 
MC-30 bias much the same as MC-40?

dewickt said:
I have 2 MC40's to do this to waiting on the shelf, the resistor will be in series with the diode and the lead from the transformer. The value should be about 470 Ohms, you may have to adjust it slightly to get -52V on pin 5 of the 6L6 with the voltage on pin 3 at 470V. I use a variac to make sure the plate voltage on pin 3 is at 470 before I measure pin 5.
Posting here mainly because I have not found this answer elsewhere - even after extensive searching.

On the MC-30s, what is the bias voltage value and where is it best measured?

I believe it should be -52 volts at the grids of the 12AX7 used to drive the 6L6s. Correct, Terry?

Reason I ask is that there are minor differences in the bias circuit topology:

* One version of the A-116/MC-30's power transformer uses a separate winding to drive the bias circuit.
- The power transformer's label indicates that its a M-152-D

* Another version of the A-116/MC-30 derives its bias voltage from the high-voltage winding of the power transfomer
- power transformer on mine is labeled a M-152-B
- I note that the schematic I have includes drawings for an M-152-C which also shows bias being derived from the high-voltage windings.

Figures I have one of each to restore doesn't it?

So, Terry, any help you can provide on this detail is greatly appreciated.

Cheers,

David
 
All three of my MC-30's have the 152B transformer so no help on the other one. Pin 2 of the second 12AX7 should be -42v. This from the "Instruction Manual" for MC-30, Type A-116B.

My MC-30's, well, 2 of them, show about -40V here, IIRC, with 117v input.

Murray
 
440V on the plate and -42V on the grid of the 6L6, power transformer type is of no consiquence, replace the selenium and change the value of the resistor in series with it to set the bias, about 9.1K should get you close, a value either way may be needed to get it right on. I find anywhere from -42 to -43 is good when plate is at 440V..
 
MC2300 Versions

MC2300 was produced in 4 basic production runs that can be identified by the first 2 parts of the serial number.
1Y--- , first run, no themostats on fans (noisy), red power switch.
2Y--- , Had thermostat controlled fans, red power switch.
3Y---, and 4Y---, had Had thermostat controlled fans, white power switch (some 3Y had red).

There were also several possible variations within a run that were special ordered, like the MC2300C that has a 64 ohm output and no .5 ohm it uses a standard MC2300 top cover and front panel with a new rear panel showing the changes.
 
Terry:

Please let me know if you can help me on my MC30 problem.
I read that some months ago you received a question about high red glowing (and therefore high sound distortion) in a 6L6 tube, is there a solution out of the shelf since it is a repetitive problem? I would apreciate your advice.

Regards. Maquico.
 
Need to check the bias on the tube, possibly replace the bias rectifier and filter, check the answers above about the bias update, if bias is OK you may have a transformer problem.
No off the shelf parts kits that I know of to do the update.
 
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Thanks a lot for your answer.
In fact while waiting for help I changed the whole tube set for the MC30 for a new one and the result was that one of the 6L6 (metal) went well over heated, (the other one not) and the sound distortion become a terrible noice just for blowing up the speaker, is your diagnosis the same with these sintoms?

Maquico.
 
Same problem different tubes, start checking voltages or get it to a tube man for a check up.
 
Production history

McIntosh Electronics Production History (1949 to 1999)
T=Tube, SS=Solid State, W=Watts, AF=Autoformer, PG=Power Guard, DC=Direct Coupled, SL=Slim Line

Model Product Type Description Years Price
15W-1 Power Amplifier T 15W 1949 (1 year) $149.50
50W-1 Power Amplifier T 50W 1949-1950 $249.50
20W-2 Power Amplifier T 20W 1951-1954 $149.50
50W-2 Power Amplifier T 50W 1951-1955 $249.50
A-116 Power Amplifier T 30W 1953-1954 $143.50
MC-30 Power Amplifier T 30W 1954-1962 $153.50
MC-30A Power Amplifier T 30W-with DK-30-60 damping kit 1954-1962
MC-60 Power Amplifier T 60W 1955-1961 $219.00
MC-60A Power Amplifier T 60W- aith DK-30-60 damping kit 1955-1961
MC240 Power Amplifier T 40-40W 1960-1969 $288.00
MK30 Power Amplifier T 30W Kit 1960-1961 $120.00
MC225 Power Amplifier T 25-25W 1961-1967 $198.00
MC75 Power Amplifier T 75W 1961-1970 $229.00
MC275 Power Amplifier T 75-75W 1961-1970 $444.00
MC40 Power Amplifier T 40W 1962-1979 $159.00
MC250 Power Amplifier SS 50-50W-AF 1961-1971 $429.00
MC2505 Power Amplifier SS 50-50W-AF-Meters 1967-1977 $549.00
MC2105 Power Amplifier SS 105-105W-AF-Meters 1967-1977 $799.00
MC3500 Power Amplifier T 350W-Meter 1968-1971 $1,099.00
MC2100 Power Amplifier SS 105-105W-AF 1969-1977 $599.00
MC50 Power Amplifier SS 50W-AF 1969-1970 $199.00
MC100 Power Amplifier SS 105W-AF 1970-1973 $299.00
MC2300 Power Amplifier SS 300-300W-AF-Meters 1971-1980 $1,799.00
MC2205 Power Amplifier SS 200-200W-PG-AF-Meters 1975-1979 $1,649.00
MC2120 Power Amplifier SS 120-120W-PG-AF 1976-1982 $999.00
MC2125 Power Amplifier SS 120-120W-PF-AF-Meters 1976-1981 $1,199.00
MC2200 Power Amplifier SS 200-200W-PG-AF 1976-1982 $1,199.00
MC502 Power Amplifier SS 50-50W-PG-DC-Slimline 1978-1989 $1,200.00
MC2500 Power Amplifier SS 500-500W-PG-AF-Meters 1980-1990 $3,800.00
MC2255 Power Amplifier SS 250-250W-PG-AF-Meters 1981-1986 $2,995.00
MC2155 Power Amplifier SS 150-150W-PG-AF-Meters 1981-1986 $2,295.00
MC2250 Power Amplifier SS 250-250W-PG-AF 1982-1987 $2,495.00
MC2150 Power Amplifier SS 150-150W-PG-AF 1982-1987 $1,925.00
MC2002 Power Amplifier SS 200-200W-PG-DC-Meters 1984-1988 $1,850.00
MC752 Power Amplifier SS 75-75W-PG-DC 1985-1988 $895.00
MC7270 Power Amplifier SS 270-270W-PG-AF--Meters 1985-1991 $2,499.00
MC754 Power Amplifier SS 100-100W-PG-DC 1988-1992 $895.00
MC7200 Power Amplifier SS 200-200W-PG-DC-Meters 1989-1993 $2,779.00
MC2600 Power Amplifier SS 600-600W-PG-AF-Meters 1990-1995 $6,000.00
MC7150 Power Amplifier SS 150-150W-PG-AF-Meters 1991-1994 $2,400.00
MC7300 Power Amplifier SS 300-300W-PG-AF-Meters 1991-1995 $3,400.00
MC7100 Power Amplifier SS 100-100W-PG-DC-Slimline 1992-1997 $1,400.00
MC1000 Power Amplifier SS 1000W-Mono-PG-AF-Meter 1992- $6,500.00
MC7106 Power Amplifier SS 160W x 6 @ 4 Ohms-PG-DC 1992- $3,500.00
MC275 Power Amplifier T 75-75W-Commemoritive 1993-1996 $4,000.00
MC500 Power Amplifier SS 500-500W-PG-AF-Meters 1994- $7,000.00
MC7108 Power Amplifier SS 50W x 8 @ 4 Ohms-PG-DC 1994- $2,500.00
MC7104 Power Amplifier SS 100W x 4 @ 4 Ohms-PG-DC 1995-1997 $2,750.00
MC150 Power Amplifier SS 150-150W-PG-AF-Meters 1995-1997 $3,000.00
MC300 Power Amplifier SS 300-300W-PG-AF-Meters 1995-1998 $3,750.00
MC352 Power Amplifier SS 350-350W-PG-AF-Meters 1998- $4,500.00
MC7205 Power Amplifier SS 200W x 5 @ 4 Ohms-PG-DC 1998-
MC2000 Power Amplifier T 130-130W-Meters-50th Anniversary 1999- $15,000.00





McIntosh Electronics Production History (1949 to 1999)
T=Tube, SS=Solid State, W=Watts, AF=Autoformer, PG=Power Guard, DC=Direct Coupled, SL=Slim Line

Model Product Type Description Years Price
AE-2 Preamplifier T Mono 1950-1952 $79.50
C-104 Preamplifier T Mono 1950-1954 $59.50
C-108 Preamplifier T Mono 1954-1955 $86.50
C-4 Preamplifier T Mono 1954-1959 $64.50
C-8 Preamplifier T Mono 1955-1959 $88.50
C-8S Preamplifier T Mono-Stereo Controls 1958-1960 $99.00
C20 Preamplifier T Stereo 1959-1963 $269.00
C11 Preamplifier T Stereo 1961-1963 $209.00
C22 Preamplifier T Stereo 1963-1968 $279.00
C24 Preamplifier SS Stereo 1964-1968 $249.00
C26 Preamplifier SS Stereo 1968-1978 $449.00
C28 Preamplifier SS Stereo 1970-1978 $649.00
C27 Preamplifier SS Stereo 1977-1983 $749.00
C32 Preamplifier SS Stereo 1977-1981 $1,649.00
C29 Preamplifier SS Stereo 1978-1985 $1,399.00
C504 Preamplifier SS Stereo-SL 1980-1988 $1,090.00
C33 Preamplifier SS Stereo 1981-1985 $2,450.00
C30 Preamplifier SS Stereo 1985-1987 $1,649.00
C34V Preamplifier SS Stereo 1985-1992 $2,499.00
C31V Preamplifier SS Stereo-Remote Control 1987-1989 $1,895.00
C35 Preamplifier SS Stereo-Remote Control 1989-1992 $1,995.00
C37 Preamplifier SS Stereo-Remote Control 1991-1992 $2,399.00
C100 Preamplifier SS Stereo-Remote Control-2 Chassis 1997- $6,500.00
C15 Preamplifier SS Stereo-Remote Control 1998- $1,500.00
C36 Audio Control Center SS Stereo 1992-1995 $1,700.00
C38 System Control Center SS Stereo-Remote Control 1992- $2,500.00
C712 System Control Center SS Stereo-Remote Control-SL 1993-1997 $1,500.00
C39 A/V Control Center SS 6 CH-Remote-Dolby-PL 1993-1998 $4,000.00
C40 Audio Control Center SS Stereo 1992-1998 $3,500.00
MX130 A/V Tuner Control Center SS 6 CH-Remote-Dolby-PL 1993- $4,800.00
MX132 A/V Tuner Control Center SS 6 CH-Remote-Dolby-AC3-PL-DTS 1998-
THX-M THX Add-On Module SS THX PL Enhancement 1993- $500.00
MX118 A/V Tuner Control Center SS 6 CH-Remote-Dolby-PL 1994-1997 $3,000.00


McIntosh Electronics Production History (1949 to 1999)
T=Tube, SS=Solid State, W=Watts, AF=Autoformer, PG=Power Guard, DC=Direct Coupled, SL=Slim Line

Model Product Type Description Years Price
MA230 Integrated Power Amplifier T-SS 30-30W-Tube Pwr-SS Preamp 1963-1966 $349.00
MA5100 Integrated Power Amplifier SS 45-45W-DC 1966-1972 $449.00
MA6100 Integrated Power Amplifier SS 70-70W-DC 1972-1979 $699.00
MA6200 Integrated Power Amplifier SS 75-75W-DC-PG 1978-1991 $1,899.00
MA6400 Integrated Power Amplifier SS 100-100W-DC-PG-Meters 1995- $3,000.00
MA6800 Integrated Power Amplifier SS 150-150W-PG-AF-Meters 1995- $5,000.00
MA6450 Integrated Power Amplifier SS 100-100W-DC-PG-Meters 1998-
MA6850 Integrated Power Amplifier SS 150-150W-PG-AF-Meters 1998-

MAC1500 Receiver T/SS 30-30W-Tube Pwr-Tuner-SS Preamp 1965-1967 $499.00
MAC1700 Receiver T/SS 40-40W-SS Pwr- Tube Preamp-Tuner 1967-1973 $599.00
MAC1900 Receiver SS 55-55W-DC 1973-1978 $949.00
MAC4100 Receiver SS 75-75W-DC-PG-Pwr LED's 1978-1985 $1,999.00
MAC4200 Receiver SS 75-75W-DC-PG 1985-1987 $2,890.00
MAC4275 Receiver SS 75-75W-DC-PG 1988-1990 $2,099.00
MAC4280 Receiver SS 75-75W-DC-PGp\-Remote Control 1988-1991 $2,099.00
MAC4300V Receiver SS 100-100W-DC-PG-Pwr LED's-Remote 1988-1993 $2,995.00


McIntosh Electronics Production History (1949 to 1999)
T=Tube, SS=Solid State, W=Watts, AF=Autoformer, PG=Power Guard, DC=Direct Coupled, SL=Slim Line

Model Product Type Description Years Price
MR55 Tuner T AM-FM-Mono 1957-1959 $249.00
MR55A Tuner T AM-FM-Mono 1959-1962 $276.00
MR66 Tuner T AM/FM Simulcast, Stereo Add-On 1960-1961 $325.00
MR65 Tuner T FM-Mono 1960-1962 $225.00
MR65A Tuner T FM-Mono-Stereo Add-On 1962-1966 $284.00
MR65B Tuner T FM-Stereo 1962-1964 $329.00
MR67 Tuner T FM-Stereo 1963-1968 $299.00
MR71 Tuner T FM-Stereo 1963-1969 $399.00
MR73 Tuner SS AM-FM-Stereo 1969-1971 $549.00
MR74 Tuner SS AM-FM-Stereo 1972-1979 $849.00
MR78 Tuner SS FM-Stereo 1972-1979 $1,699.00
MR75 Tuner SS AM-FM-Stereo 1980-1985 $1,349.00
MR80 Tuner SS FM-Stereo-Digital 1980-1985 $2,499.00
MR500 Tuner SS FM-Stereo-Digital-SL 1983-1985 $1,499.00
MR510 Tuner SS FM-Stereo-Digital-SL 1986-1990 $1,699.00
MR7082 Tuner SS AM-FM-Stereo-Digital 1986-1990 $1,579.00
MR7083 Tuner SS AM-FM-Stereo-Digital 1990-1995 $1,750.00
MR7084 Tuner SS AM-FM-Stereo-Digital-SL 1996- $1,500.00

MX110 Tuner-Preamplifier T FM-Stereo 1962-1969 $399.00
MX112 Tuner-Preamplifier SS AM-FM-Stereo 1968-1971 $599.00
MX114 Tuner-Preamplifier SS FM-Stereo 1969-1971 $549.00
MX113 Tuner-Preamplifier SS AM-FM-Stereo 1971-1980 $1,099.00
MX115 Tuner-Preamplifier SS FM-Stereo 1972-1974 $599.00
MX117 Tuner-Preamplifier SS AM-FM-Stereo 1980-1984 $1,649.00

McIntosh Electronics Production History (1949 to 1999)
T=Tube, SS=Solid State, W=Watts, AF=Autoformer, PG=Power Guard, DC=Direct Coupled, SL=Slim Line

Model Product Type Description Years Price
MCD7000 CD Player SS Single Disk 1985-1987 $1,399.00
MCD7005 CD Player SS Single Disk 1987-1988 $1,599.00
MCD7007 CD Player SS Single Disk 1988-1994 $2,000.00
MCD7008 CD Player SS 7 Disk Changer 1992-1996 $2,200.00
MCD7009 CD Player SS Single Disk 1995- $2,750.00
MCD7010 CD Player SS Single Disk 1998-
MLD7020 Laser Video Disk Player SS 2 Side Auto Play- AC3 RF Out 1995- $3,200.00

MI-2 Performance Scope T Multipath Indicator 1963-1964 $219.00
MI-3 Performance Scope T Multipath Indicator 1964-1971 $249.00
MPI-4 Performance Scope SS Multipath Indicator- Audio Scope 1973-1977 $599.00
MQ101 Equalizer SS 3 Band EQ for ML Speakers 1970-1978 $250.00
MQ102 Equalizer SS Bass EQ for ML Speakers 1970-1978 $74.50
MQ104 Equalizer SS 4 Band Variable EQ 1977-1991 $500.00
MQ107 Equalizer SS 7 Band Variable EQ 1981-1993 $650.00
MQ108 Equalizer SS 7 Band Variable EQ-Balanced I/O 1994-1996 $500.00
SCR-1 Speaker Relay Switch 2 Pairs Speakers 1970-1971 $49.50
SCR-2 Speaker Relay Switch 2 Pairs Speakers-AC Switch 1971-1991 $200.00
SCR-3 Speaker Relay Switch 2 Pairs Speakers-AC Switch 1991- $219.95
MVS-1 Video Switcher Composite 1986-1992 $299.00
MVS-2 Video Switcher Composite-S Video 1991-1996 $375.00
MVS-3 Video Switcher Composite-S Video-Audio 1992- $700.00
CR10 Audio Multizone System SS 4 Zone Audio 1992-1995 $2,000.00
CR12 A/V Multizone System SS 4 Zone Audio/Video 1995- $3,300.00
MAC-3 Dolby Digital Decoader SS AC-3-Pro Logic-Remote Control 1997- $1,800.00
MSD-4 AC-3 RF Demodulator SS Accessory for MX132 1998-
 
MC30 repair and update

dewickt said:
Same problem different tubes, start checking voltages or get it to a tube man for a check up.
Now at last and with great help from Terry I have compiled a great deal of information to repair my MC30 (heat on 616 and bussy noice) but before initiate de ordeal to find a tube man I found that there are several modifications (at least 30 years ago) made in the amp, the power resistors, bias cap, diode, the three horizontal caps on resistors board and most visible the can cap and amp resistors, some of these modifications recommended by Terry, but not the can cap which in this case is substituted by three huge capacitors 500vd 60pf Dubilier drilitie. Now I beg for your recommendation, should I persue only on repairing the actual status or reinstalling a new can cap and amp resistors or any other more desirable update?

Thanks in advance
 
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Cleaning chrome on MX110/6U8

You guys are insane, well at least I know where to send my MX110 preamp when it needs work. I would be afraid to change a light bullb in the thing, let alone the stuff y'all are talking about.

My question is more towards the limits of my technical know-how.

No. 1.: What do you reccomend for cleaning/preserving the chrome chassis on an MX110 that will not harm the lettering.

No. 2: What brand/equiv. tubes do you reccomend for V16 and V17 (6U8). My are the original telefunken and one of them has developed pops and noise confirmed by switching them. I have replaced the marginal tube with a NOS USA tube but it is a bit noisy. Have had a very difficult time locating 6U8 NOS Telefunkens.

Thanks in advance, and sorry these questions are so basic compared to bias voltage, bumble bee cap. color codes, etc.

Travis
 
McIntosh chrome responds nicely to a good car wax, I use Turtle wax Carnuba paste, just don't rub real hard on the lettering, and also gives the black paint a nice shine. If your chrome is getting tired with pits or hazing you can use Wenol metal polish (www.wenol.com), it can help revive the chrome to be as good as it can be. Whatever you do use a clean soft rag to do it, keep using a clean section as the dirt it picks up can scratch the chrome leaving swirls and hazing.
No real help for the 6U8 except that a 6EA8 or 6GH8 will also work, check for a previous thread on this.
 
The 6U8 is a bit of a "buggy" sort of tube.....I go through a few sometimes in certain brands before I find a linestage quality pair that will work well without shorting or microphonics.

I have had very good luck with the Seimens 6U8, as well as the RCA (but the RCA's seem better in the earlier vintages). I buy 6U8 by the sleeve, since I know that 2-3 out of 5 may not be linestage suitable.

Best advice I can give on 6U8 linestage tubes in the MX110 is that once you find a good pair that you like and work well - leave 'em. Not a spot for "roll happy" folk, based on my experiences.
 
How do I clean the laser on a Mc 7005? I posted this in another thread, but this one seems to attract the real expert (Terry D.) Thanks, I need allthe help I can get.
 
I clean the optics with a cotton swab dampened with household ammonia, be careful as the optics mount is delicate.
 
Strange things

Hi all,

I'm a newbie so please forgive me if I'm dropping this in the wrong
section. I have a C32 preamp I bought about a year ago and as of
late it's doing something very strange.

After about 15 or 20 minutes the volume will ramp up to full output!
(moving the volume knob has no effect when this happens). Is there
something I could check before I send this unit out for service?
Could it be a simple ground problem from a solder joint? And have
any of you heard of this happening with a C32?

Thanks
 
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