MC2205 Love

[Gregory]

MC2205 Love - Part 1

I think it's time to start the MC2205 Love web page. Today I opened up the 2205, took off the front panel, replaced the speaker relay, changed out the lower panel lamps, and lubed ALL the controls and switches with Deoxit.

Here are some important questions in order to proceed.

Question 1: How does one go about replacing the Power Guard and Meter indicator lamps? Unsolder in place? remove ribbon and board?


It looks like four of the lamps were replaced before.



Does this diode look crisp to you?


Question 2: To access the eight meter lamps, does the meter cover have to come off? Or do they pop out from the top?


What's the standard way to pop-out these meter lamps?


Now for some difficulties. The NEW speaker relay is a Potter & Brumfield but the lugs are 0.186 wide instead of 0.206 and since the quick disconnect female terminals are 0.225 wide (inside) they do not fit on the relay lugs well. I think the lugs aren't as thick either. Should I replace ALL of the non-insulated quick disconnect terminals to fit the NEW relay or just squeeze them with pliers to grip better?

It's in such FINE shape, and will be almost like NEW.


-Gregory

MR80, MCD7007, C33, MC2205, Thiel CS3.5

[Vintage Pete]

Originally Posted by Gregory

MC2205 Love - Part 1

I think it's time to start the MC2205 Love web page. Today I opened up the 2205, took off the front panel, replaced the speaker relay, changed out the lower panel lamps, and lubed ALL the controls and switches with Deoxit.

Here are some important questions in order to proceed.

Question 1: How does one go about replacing the Power Guard and Meter indicator lamps? Unsolder in place? remove ribbon and board?


It looks like four lamps were replaced before.



Does this diode look crisp to you? I have some 1N4004 replacements. Are those ok?


Question 2: To access the eight meter lamps, does the meter cover have to come off? Or do they pop out from the top?


What's the standard way to pop-out these meter lamps?


Now for some difficulties. The NEW speaker relay is a Potter & Brumfield but the lugs are 0.183 wide instead of 0.208 and since the push-on terminals are 0.225 wide (inside) they do not fit on the relay lugs well. I think the lugs are of a narrower thickness too. Should I replace ALL of the push-on terminals to fit the NEW relay or just squeeze them with pliers?

It's in such FINE shape, and will be almost like NEW.


-Gregory


MR80, MCD7007, C33, MC2205, Thiel CS3.5

Question #1-I haven't had to replace the lamps in my 2205 yet...the lamps didn't work when I got the amp, but the problem turned out to be aged diodes and caps on the power supply board. To perform the repair, I removed that board. If you DO need to replace the lamps, I think I would disconnect the ribbon cable and remove the board to perform the task. The Normal & limit lamps are type 7382 peanut style lamps; the Hold, db and watts lamps are type 7381. You may be able to find these at a local electronics supply store.

That diode does look crisp, and I'd be suspicious of it. I don't know the value, my service manual identifies it as D120, with only a McIntosh part number to identify it: 070-031. I would contact McIntosh or Audio Classics to be on the safe side.

Question #2-The meter illumination lamps simply pop out from the top. Very simple to replace-a type 1866 bayonet style lamp. You should be able to get these at a local supply house. I think I just gently pried the lamp holders up and out with a small flat bladed screwdriver.

I not sure I can help with your relay question...perhaps someone can chime in who's had experience with this aspect.

I hope this is of some help...


Pete

[Gregory]

Originally Posted by Vintage Pete

Question #1-I haven't had to replace the lamps in my 2205 yet...the lamps didn't work when I got the amp, but the problem turned out to be aged diodes and caps on the power supply board. To perform the repair, I removed that board. If you DO need to replace the lamps, I think I would disconnect the ribbon cable and remove the board to perform the task. The Normal & limit lamps are type 7382 peanut style lamps; the Hold, db and watts lamps are type 7381. You may be able to find these at a local electronics supply store.

That diode does look crisp, and I'd be suspicious of it. I don't know the value, my service manual identifies it as D120, with only a McIntosh part number to identify it: 070-031. I would contact McIntosh or Audio Classics to be on the safe side.

Question #2-The meter illumination lamps simply pop out from the top. Very simple to replace-a type 1866 bayonet style lamp. You should be able to get these at a local supply house. I think I just gently pried the lamp holders up and out with a small flat bladed screwdriver.

I not sure I can help with your relay question...perhaps someone can chime in who's had experience with this aspect. I hope this is of some help.

Pete

Yeah thanks.. I've ordered ALL replacement lamps several months ago. That would include 7381, 7382, and 1866. One of the eight meter lamps was out, and at least one of the green Power Guard lamps was dead. Here is a pic of the ribbon connecting the lamp PCB to the driver card.


Lamp PCB ribbon at the Power Supply board end.


Where does the ribbon disconnect? That way I could separate the front panel frame from the Amp. The last guy didn't clip the leads off or remove flux. NOT good!!


The foam tape that spaces the front panel from the frame crumbled and fell off. I had to remove the crumbs and adhesive tape, but some glue was left behind.



After the glass was removed, the foam tape crumbled and fell off in chunks.



Some adhesive remained after the tape was removed.

I'll need to get some foam tape for the proper spacing? and to seal any light leaks? BTW.. already have many of the electrolytic caps including the two LARGE ones on the driver board, and four 1N4004 diodes. No power supply components. Did you replace the rectifier diodes?


-Gregory

[tony-w]

Had one back in the late 70's and loved it.

[Vintage Pete]

Originally Posted by Gregory

Yeah thanks.. I've ordered ALL replacement lamps several months ago. That would include 7381, 7382, and 1866. One of the eight meter lamps was out, and at least one of the green Power Guard lamps was dead. Here is a pic of the ribbon connecting the lamp PCB to the driver card.


Lamp PCB ribbon at driver board end.


Where does the ribbon disconnect? That way I could separate the front panel frame from the Amp. The last guy didn't clip the leads off or remove flux. NOT good!!


The foam tape that spaces the front panel from the frame crumbled and fell off. I had to remove the crumbs and adhesive tape, but some glue was left behind.



After the glass was removed, the foam tape crumbled and fell off in chunks.



Some adhesive remained after the adhesive tape was removed.

I'll need to get some foam tape for the proper spacing? and to seal any light leaks? BTW.. already have many of the electrolytic caps including the two LARGE ones on the driver board, and four 1N4004 diodes. No power supply components. Did you replace the rectifier diodes?


-Gregory

Hi Greg,

I replaced the two large caps on the power supply board C307, C308 (McIntosh part no. 066-247) and two diodes D302 and D303 (McIntosh Part No. 070-031).

To disconnect the ribbon cable from the power supply board, simply grasp the cable with your fingers and gently rock it back and forth while pulling outward. Use the same method in reverse to reconnect it. Be careful not to bend the pins; but you'll find that the cable and its pins are actually pretty sturdy.

Replacing the foam light seals is a simple deal. I've done this quite a few times with my vintage mac gear-MR77, MR78, MC2205 etc. If you can salvage a sample chunk of the deteriorated foam, take it to a local hardware store or Home Depot and get yourself a roll of Open Cell grey foam weatherstrip. It is self-adhesive with a peel off strip. You'll probably want 3/16" thick x 3/8" wide, but if you can, take a sample to be sure. This is used mainly for light seals in the units. You'll want to clean off the old glue from the unit prior to installing the new. Use Goo-gone or a similar product.

I suggest you send a PM to AA member Terry Dewick to discuss your relay contact pin issue. Terry specializes in repairing these vintage units and is the best. Many members will attest to Terry's expertise. He has helped me out with several issues.

Good luck-the MC2205 is a great amp and is worth the effort. Mine is in my Florida Room system and I love it!

You're starting to get me motivated to do my long overdue MR78 cleaning....


Good luck!

Pete

[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

[Gregory]

Today was the end of Part-1

A lot was accomplished in the past two days. The meter chassis assembly came off fairly easily. Here is a photo of the meter assembly and Lamp PC Board prepped and ready for component replacement:


Power meter chassis assembly disattached and Lamp PC Board removed.


The following are the activities and accomplishments in Part-1

1) New Speaker Relay installed.
2) Four new 1866 lamps installed in lower front chassis.
3) Eight new 1866 lamps installed in meter compartment.
4) Seven new Power Guard / power indicator lamps installed.
5) Replaced two 2200uF caps on the Power Supply PC board.
6) Chassis and interior decontaminated.. dust, surface film, oxidation (and a small cobweb) removed.
7) Front pot and rotary switch shaft ring-nuts tightened.
8) All pots and switches thoroughly treated with Deoxit.


The first PWB serviced was the front Lamp PC Board. Here are photos of the prepped trace side, and with lamps inserted and soldered.


Lamp PC Board with old lamps removed, desoldered and defluxed. Some of the copper foil pads started to peel up.



New lamps inserted and soldered.. board almost ready to reattach.


Looking PDG (pretty darn good) for thirty years old. Here's the reworked lamp / power indicator board. That diode wasn't burnt, it simply hand some crud on the lead(s).


Completed Lamp PC Board front side with new bulbs installed.


Next the Power Supply PC board was cleaned up and the 2200uF, 16v caps replaced with Vishay 118 AHT, 40v caps. I need to order some additional parts. Already have a complete set of small electrolytic caps for the 2205. These are the first two installed. The following are views of the before and after Power Supply PC board component side.


Power Supply board with original 2200uF, 16v electrolytic caps (large gold).



Power Supply board with new Vishay 118 AHT, 2200uF, 40v electrolytic caps installed.


There was enough time left in the afternoon to attach the bottom cover, hook-up the MC2205 and test it out. Various CDs were cranked to check Power Guard lamp function and warm the heat sinks to 40-50°C. It was giving off it's familiar HOT aromas.


Getting a workout after Part-1 of MC2205 Love complete. Heat sinks 40-50°C. Power Guard working ok.


More parts are needed such as diodes and signal path caps, but the trusty old 2205 is looking and feeling a LOT younger today.


-Gregory

McIntosh owner for over 30 years.
--

[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

[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!

[dewickt]

Don't forget to set the bias, this meter does the job real well.

http://p3international.com/products/.../P4400-CE.html
Bought mine at Harbor Tool.