Mc2155 Output Driver Help

[funkenaround]

Mc2155 Left Channel Gone

Just picked up a Mc2155

Left channel out

its in need of some transistors on the driver board (picture below)

I haven't got a schematic and am trying to build a shopping list

I've tried to pull crossreff's from the numbers on the transistors but am at a loss

I've tried Berners site, but the 2155 service manual is in password protection

Like to get this sweet thing running tonight

the one right channel sounded so nice paired with my Mx110

 

[c_dk]

I would suspect the bias transistor mounted in the heatsink pulled down the whole channel.....if you get the schematic from Mac parts many of the now obsolete generic part numbers are on the schematic

 

[clinic-audio]

Hello funkenaround

let start by the beginning :
When I send some of my original service manuals to JUERG (Berner site) we did not expect that many bad mind will copy this FREE source a good quality schematics and service manuals to make money .
Juerg spend a lot of time to scan all of these documents and some did rob them and after offer for sale on EBAY for almost nothing . As they do not care about the service we give Juerg decide to use password and he was right !
Now, go on your problem with your MC2155
I never saw any drastic damage on a small transistor !! I suspect also some power transistors are bad too !
To understand the codification of MCINTOSH transistors you have to know that every TR are named "132 and then 6 numbers "
In your picture for exemple we can see the damaged one with "143" ; This one is a 132143 like that the other is "150" so you know now it is 132150 ! easy no ?
All these transistors are available at the factory . If not come back to me .
Give us more details about every defect components on your driver board and give me the serial number of your amp because there is 3 differents drivers boards for MC2155 and I need (to be able to help you the best as possible) the serial number for this reason and this to avoid any confusion .

Waiting to know a little bit more ....:scratch2:

 

[clinic-audio]

See what happen on a MC2155 if you don't use the right spares parts !

So be very carefull if you want to do it yourself !

 

[funkenaround]

hi there,

thanks for the reply

I'm at my local lectronics shp and they
are unable to cross any of the small/blown transistors
or the power transistors

I'd send you the serial right now, but tha amp is at home

if your at your computer right now and can assist while I'm in the
store, I'd really appreciate that

ill wait on your reply

ty

 

[c_dk]

According to my schematic the toasted transistor is the negative drive limiter....there would be 32 pages to scan in this map fold schematic.....best to get from Mac.

I suspect much carnage elsewhere and would expect at least 5 hours of bench time.

Again most all these transistor's have been obsoleted and subs have been subbed many times.

 

[kevzep]

I'm at my local lectronics shp and they
are unable to cross any of the small/blown transistors
or the power transistors

All transistors substitutes are available for these amplifiers, so don't worry about that.
Clinic-audio is a legend and will see you right.......:thmbsp:

 

[funkenaround]

can you just inform me of the todays world equivlant/values for rhe power transistors and the 132143 /132150

I don't have the ability for a xomplete teardown right now

 

[c_dk]

When the burned transistor fail as the have THEY are telling you a complete tear down is needed......they are the canary in the mine shaft so to speak.

 

[kevzep]

can you just inform me of the todays world equivlant/values for rhe power transistors and the 132143 /132150

I don't have the ability for a xomplete teardown right now

If those transistors were the current limiters, as c_dk says they have had a major failure trying to do their job.
This means you have had a catastrophic failure on the output section most likely.

I could suggest some substitutes, but the other two guys posting here (c_dk and clinic-audio) can rattle the subs off the top of their head....So I will leave that to them, so we don't have any confusion or conflicting information.

I can tell you its all standard and readily available from Mouser or On-semi......

 

[c_dk]

I had to look at the schematic, not the schematic information prints...different than the full schematic, for it's correct part number.....it is 039417.

With this type of damage you really need this road map from Mac.

 

[funkenaround]

that's for the 132143

what is tge # for tge 132150? and the square black power resistors?

 

[clinic-audio]

Sorry but I was out of my computer ...

I send you a PM in a couple of minutes with every answer you are waiting for

 

[kevzep]

Sorry but I was out of my computer ...

I send you a PM in a couple of minutes with every answer you are waiting for

Patrice my friend, you are a legend.....:thmbsp:

 

[clinic-audio]

Hi Kevin

PM sent to you !

 

[clinic-audio]

Hello Funkenaround

Witch driver board is in your MC2155 ?

 

[funkenaround]

all the help is much appreciated

my aim is to see whether I keep this Mac and sell off my Fisher Sa300b, Scott MonoBlocks and or Citation V, or just move this one along after I've got her running smoothly

the single channel sounded pretty darn nice on its own, and that's what I don't like, the purchase was supposed to be strictly a buy and sell maneuver

I don't listen much these day's, just couldn't help myself

oh well, it's a wait an see condition right now

once again, many thanks to all the posters and looking forward to the information coming from Patrice

cheers !

 

[kevzep]

all the help is much appreciated

my aim is to see whether I keep this Mac and sell off my Fisher Sa300b, Scott MonoBlocks and or Citation V, or just move this one along after I've got her running smoothly

the single channel sounded pretty darn nice on its own, and that's what I don't like, the purchase was supposed to be strictly a buy and sell maneuver

I don't listen much these day's, just couldn't help myself

oh well, it's a wait an see condition right now

once again, many thanks to all the posters and looking forward to the information coming from Patrice

cheers !

He's asking you in the last post, which one of those three driver boards posted, is the one for your amp? Unless you answered in PM which we didn't see......

Once you have all the information, the repair will be pretty straight forward.
You will be surprised.....

 

[funkenaround]

my board is marked

045863

 

[kevzep]

my board is marked

045863

That doesn't seem to be any of the three posted, but perhaps print out the 045864 and see if it matches up to what your one is?

Then I have a list which I think you have as well which you can refer to and order up your new components from.....

Just let us know where you need help and I will do my best from the info I have. clinic-audio is in France, and it is sleep time over there now....