MC2205 Love

[Gregory]

Originally Posted by Sproink

Ah!--those parallel strips of wood on the bench--that's what I do whilst working on one of my amps or pres when the glass and chassis is off! Well...and then there's the ribbon connectors...the...ribbon...connectors

Looking good Gregory!

Thanks.. what you're seeing are four, 2" square blocks of solid oak, 3/4" think. That table is actually the microwave cart. It has casters on the legs. The workbench for this project is on the island in the kitchen where the lighting is good, with three windows facing south.


-Gregory

[Gregory]

Originally Posted by dewickt

Don't forget to set the bias, this meter does the job real well. Bought mine at Harbor Tool.

Oh yeah.. the P3 Killawatt.. have one right here adding up KWHs used by the PC.


P3 digital Kill A Watt meter connected to the UPS box feeding computer system.


Now if I could just find the bias procedure.*


*Found it on the last page of the service manual. Thanks to Ryan at AudioClassics for sending the appropriate 2205 Service Manual at no charge.

-Gregory

McIntosh owner for over 30 years.

[Gregory]

End of Part-1

This will be the end of MC2205 Love Part-1. Today the old panel lamps were tested for continuity and only ONE of the four Power Guard bulbs was functional (wasn't open circuit). It was reported in other posts and forums that the Power Guard has "never come on" while here in Virginia. Those red lamps are flashing now.

The photo below is of the 2205 on a microwave cart connected to the system.


Bare essentials 2205 set up for operational tests after servicing.


As one of the guys pointed out, the amplifier is sitting on oak blocks in order for air to get underneath and up through the heat sink `chimneys.´


2205 on oak blocks for air flow under the chassis.


Heat Sink Dissipation Tests

Late in the afternoon a temperature probe was placed into the right heat sink and Temperature monitored while operating the MC2205. Yesterday the heats sinks were getting quite HOT to the touch. The following is a view of the temperature probe position.


Location of temperature probe for heat dissipation test.


The session started off with the live Lynyrd Skynyrd CD "One More From The Road".. getting warmed up with "Tuesday's Gone," "Whiskey Rock-A-Roller," and "Gimme Three Steps." It wasn't until the end of "Call Me The Breeze" that the right heat sink reached a temperature of 140.9°F (60.5°C). Not sure of the the heatsink Cutoff Switch spec, but the 2205 has never shut down due to overheating in 20 years.


Temperature at the end of "Call Me The Breeze." Top of heat sinks too hot to hold hands on.


The general rule is that at 50°C you can hold a metallic part, but at 55°C you cannot hold your hand on it. Both Left and Right sides were TOO HOT to hold palms on the top surface!!


Wrap-up

The 2205 is working as it should, however without tests for power output and distortion. There are no speaker cutouts or static in the right channel (speaker relay) as before, or dead lamps. Even the Speakers On-Off switch turns much easier than before. It should be noted that all of the front panel pot and rotary switch shaft nuts were tightened with the 1/2" deep well driver in the Xcelite Service Master tool set. Remember to snug your front panel hardware in this way, as one ring-nut was rather loose, and three others needed tightening.


XceLite 1/2" deep well nut-driver used to tighten front pot and rotary switch ring nuts.


McIntosh Wall Sign

Almost forgot.. the following illuminated sign indicates high sound pressure level tests underway!!


Illuminated McIntosh wall sign near the LEFT speaker.


On to Part-2 in a couple weeks.

-Gregory

[Gregory]

Originally Posted by deafbykhorns

Do yourself a favor and change out the small caps on preamp board along with the smaller power supply caps. The zeners might also save you some trouble down the road

Thanks for the input. Can you be more specific on what caps? Do you mean the Power Output PC boards? There are Zeners on the Power Supply PC board that drive the meters. I'm getting a parts list together for the next phase of the project.

-Gregory

[Gregory]

Originally Posted by Vintage Pete

Gregory,

Looking good!!
And I assume that the normal/limit lights (and all the rest) are functioning properly? When I did mine, it was recommended that I replace the two diodes located between the two large caps, to be on the safe side. I like to see a 2205 getting this type of TLC.. it's a sweet amp, and well worth the effort.. keep up the good work!

Pete

Yes Pete.. NORMAL/LIMIT lamps are all functioning normally. Turns out that only one green lamp was working. I wondered why Power Guard never activated, although the amp had been in storage (in Mc carton) for years before moving to Virginia.

As for diodes, I need to get another parts order together, but waiting on service manuals for other Mc units now. There are still 2205 service questions which will be addressed in MC2205 Love - Part 2.


One last bit of TLC

For the past week I search for a pocket oiler pen, or some lube for the front pot and switch shafts but could find nothing. 3-in-1 oil was too heavy, sewing machine oil was too watery and there was no fan-motor oil at the store. Finally I used Paper Shredder Lubricant that was here on the shelf, filling up the little Omega oiler. It was just the right viscosity and a very fine golden color:


Omega oiler with hypo-needle filled with paper shredder lubricant.

Now all the front controls are velvety smooth.. with Deoxit 100 on the inside and a few drops of oil on the exterior shafts. Wow.. beautiful!!


-Gregory

McIntosh owner for over 30 years.

[Gregory]

Amplifier Reassembled

The MC 2205 is back together again, as no comments were made on adding insulation material to the lamp housing. It was decided NOT to put the two original input caps back in the driver (Power Output) boards. The one open task is ordering and replacement of the BIG power supply cans. Those are easy to change out, and I'll likely go another year or two with the existing caps.


Foam tape

Here is a view of the 3/8" Frost King Rubber Foam tape applied to the meter chassis assembly.


Black rubber foam tape applied to the MC 2205 face.


Front Panel

The front panel went on with only minor alignment difficulty. A small diameter drift pin (punch) was used to quickly align the side holes. There was a GAP between the glass and the LEFT side bracket as seen in the photo (yellow arrow) below. The gap reveals a slight flaw in the glass edge, but that should be covered when the panel is aligned properly.


Front panel reinstalled. There's a gap in the left side (mainly lower corner) of the front panel.


The end caps might need to be loosened to close up the gap, or get the glass seated against the left bracket. The end cap screws however are VERY tight, and the correct screw driver is needed to avoid damage to both the screw slots and end caps.


Cosmetic Issues

The usual cosmetic issues for 30 to 40 year old McIntosh amps are bubbles in the glass, where the paint or rear coating has separated. This isn't a problem on the UUT (unit under test - or treatment) but there is definitely some gold paint missing from the NOMENCLATURE on the center-front. Notice the wording below.

There is also a tiny nick in the rectangular trim just above the left meter .002 area. That is something that I cannot always see and it's not bothersome.


In this view the GOLD lettering has lost its reflective paint in the center of the amp.


The front panel will have to come off one more time since I discovered a white `crumb´ clinging to the right-most vertical tape strip. Also I forgot to add the clear plexi-strip that ducts panel lamp illumination to the control nomenclature.

The front panel also has a strip on foam tape on its back side which has deteriorated, but not to the extent of the WIDE tape on the chassis.


Wrap up

That's about it for the MC 2205 Love project. It's right at the 1 month point since the amp was dis-assembled, but it was well worth the investment in time and parts. A new front glass assembly would really put the finishing touches on this old classic!!


Some 2205 info

Just for historical sake, here is a link to Roger Russell's 2205 blurb: McIntosh Amplifiers Part 2

And to Berners site: ttp://www.berners.ch/McIntosh/de/MC2205.htm

Do you guys remember this literature? http://www.berners.ch/McIntosh/Downloads/MC2205_bro.pdf


-Gregory

McIntosh owner for over thirty years.

[dasagu]

Hi Gregory,

May I ask.. Why the increase from 16v to 40v for the 2,200uf caps on the power board? I'm sure you have a good reason for buying these instead of the Vishay 2,200uf 16v 20% (MAL211815222E3)

Thanks!

[Gregory]

Originally Posted by dasagu

Why the increase from 16v to 40v for the 2,200uf caps on the power board? I'm sure you have a.. reason for buying these instead of the Vishay 2,200uf 16v 20% (MAL211815222E3)

Good observation!

I remember being frustrated, and unable to find a suitable part at first. Then went ahead with the Vishays combined with another order.

Thinking now.. it's about time to get back in there, make a few more tweaks, and replace those caps with Nich VX..

http://www.nichicon.co.jp/english/pr.../pdfs/e-vx.pdf


..which is what I put in the MR80 power supply. That project is easy to find by searching "Gregory MR80 power supply".

An inspection and tuneup every 5 years is about right, huh? Lol

Yeah.. winter's coming, and that's a good time for Tech projects.


Gotta agree with JW. The 2205 is a wicked-powerful amp! and solidly in the heavy, auto-transformer coupled, Power Guard equipped McIntosh amplifier category.

[Gregory]

Originally Posted by Gregory

One last bit of TLC

I used Paper Shredder Lubricant that was here on the shelf, filling up the little Omega oiler.


Omega oiler with hypo-needle filled with paper shredder lubricant.

Now all the front controls are velvety smooth..

-Gregory

WARNING

Do NOT use paper shredder oil for electronic equipment!

It is vegetable oil (not mineral oil) and will gum-up your controls!!


Use a grade of sewing machine oil or similar.