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Mc2155 Output Driver Help

Q414= 132196 (NPN , NSD-U07)
Q407= 132194 (PNP , NSD-U57)

These ones are proving quite difficult to find, the TO-202 package is not that common any more.....
Perhaps Patrice may have some idea on this one.

I can find subs, but they may have a different pinout, which is a pain....
 
funkenaround said:
solid state is a pain

think I'll stick to valves in the future
Click to expand...

Well, tubes let you know there's a problem with plenty of warning.....but SS, it just goes POOF!! and you have a handful of blown components in a millisecond.....
So you have to be on your game......

This amp will be great once you have it running....

The transistor we need is a Class A voltage amplifier, so it needs to be the right one.....
 
See I like this kind/vintage of gear. Sure it is more complex than tube gear, but at the same time it isn't as integrated as modern gear. It is much easier to troubleshoot individual components vs when an IC fails or a capacitor is only a few mm across at best and surface mounted.
 
Hello !

Q414= 132196 (NPN , NSD-U07)
Q407= 132194 (PNP , NSD-U57)

These ones are proving quite difficult to find, the TO-202 package is not that common any more.....
Perhaps Patrice may have some idea on this one.

YES !
Mouser have : 610-CEN-U07 and 610-CEN-U57 but minimum order qty is 500 pieces :nono:
Why don't you buy them from the factory ? Or from any MCINTOSH dealer ?
It is a non sense for me to supply all what you need from here in regards of shipping charges and delivery time ...
Keep me informed
MOUSER has also 132090 ...See at : 610-MPSA14
 
Just got in, long day and finally got all what I think I need

In regards to the NSD U57, I picked up a couple of TIP 32C on a 220 chassis, but the pin arrangment is not correct, I neglected to check that, althought the operational specs were similar, I will retest the ones in circuit and if ok will forgo those for the time being

In regards to the
MJ15003G
MJ15004G
MPSA55G
MPSA05
mpsa12 I'm good to go

would have completed the operation this afternoon, but was busy installing a DC power inverter in my sailboat

hopefully good news will be coming in the next 24 hours on the Mac

one again I appreciate all the help

and I do agree, this solid state era is not overly complex, kind of like and inbetweener ,

and I'm sure it's going to sound beautiful
 

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Hello !

MPSA12 ? no MPSA12 in power output section in MC2155 .....
I watch the datasheet of MPSA12 and see that it is not a substitute but it draw more collector current
 
my bad, MPSA 14, like I said , it was a long day....

still like to know of an available sub for the NSDu57

these are the specs

Material of transistor: Si

Polarity: PNP

Maximum collector power dissipation (Pc), W: 1

Maximum collector-base voltage |Ucb|, V: 100

Maximum collector-emitter voltage |Uce|, V: 100

Maximum emitter-base voltage |Ueb|, V: 4

Maximum collector current |Ic max|, A: 2

Maximum junction temperature (Tj), °C: 135

Transition frequency (ft), MHz: 50

Collector capacitance (Cc), pF:

Forward current transfer ratio (hFE), min: 60
 
I am sorry but I don't understand why you "run" after "sub" ..To go faster ..?
Buying original components from the factory will avoid you mistake and you will be sure to go back to normal function ..at the first switch on
One pair of MPSU-07 or MPSU-57 will cost you probably 15 $
:scratch2:
 
its not a rocket ship,

simple switches with differnet names, same operating parameters, why not?

$15.00 is $15.00 added to the last $15.00 and whatever came before and may come next

for me it's not just aural, it'e economics

anyhow, got it all back together, well mostly until I needed to shake loose a heat sink screw gone on the run only to have 3 I don't knows fall onto the carpet

picture below

anybody? this sucks!

I hate extra parts
 

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nevermind, I figured it out

driver board spacers

they hide under the thin cardboard

will fire it up later today or this evening

cant find my phillips screwdriver, and its difficult to snug down the heatsinks without a good one,

funny thing is, I know I've got at least 3 on the boat!
 
funkenaround said:
its not a rocket ship,

simple switches with differnet names, same operating parameters, why not?

$15.00 is $15.00 added to the last $15.00 and whatever came before and may come next

for me it's not just aural, it'e economics

anyhow, got it all back together, well mostly until I needed to shake loose a heat sink screw gone on the run only to have 3 I don't knows fall onto the carpet

picture below

anybody? this sucks!

I hate extra parts
Click to expand...

Just get the right transistors, those ones are difficult to sub because of the pinout/performance. You can easily find a TO220 to do the job but many of them have a lower transition frequency (ft) and the Collector will be on the centre pin which is different to the original.
Its a class A voltage amplifier, and it needs to right to maintain the amplifiers correct gain, performance and stability.
So in this case for intents and purposes, it is a rocket ship.

If you sub something else in there which is not right, it may end up costing you more when the amplifier fails because of incorrect parts...

If were me I would suck it up and get the right one.....
 
I fully understand, just can't help being a yesterday guy

anyhow, I just had the time to button everything up and as they say

"hope for the best and expect the worst"

well I got the latter

no change in the operation, Left channel is still out, just get low marble distortion,

the meter is still out too

obviously I need to look closer, the obvious failures are obviously not the everything

I'll make a more thorough investigation tomorrow

time for a shot!
 
just had a stroke of genius and thought I would swap left driver board right(good one) for driver board left (in question) and see what I get

well here is what I got

with good driver board in affected left channel

1-no meter operating
2-humm only and no audio

with reconditioned driver board in right channel

1-meter operational
2-degraded audio quality


my coclusion

left meter may be toast
left driver board has additional issues I need to discover
more failures in the left channel exist outside of the driver board

output transformer? I hope not

I never did change the 132203 or 204's I swear they tested out fine

as well with the NSD's

back to the drawing board I guess,

any thoughts where to look?
 
funkenaround said:
I fully understand, just can't help being a yesterday guy

anyhow, I just had the time to button everything up and as they say

"hope for the best and expect the worst"

well I got the latter

no change in the operation, Left channel is still out, just get low marble distortion,

the meter is still out too

obviously I need to look closer, the obvious failures are obviously not the everything

I'll make a more thorough investigation tomorrow

time for a shot!
Click to expand...

Did you check the emitter resistors? You are sure to find a few open circuit.

Did you get the correct class voltage amplifier (you said that one had failed?)

Did you methodically go through and check everything before you turned it on? IE; check EVERYTHING with you meter?
Did you set the bias?

I'm sorry to say, it doesn't seem to me like you are being very procedural about the way you are approaching this.

Transistors are either fine or they are not, there's no "I swear they were OK" , it just doesn't work like that.

I can help you if you stop. Go back, tell us what you have done, what you have checked, step by step.....then we can tell where you are.

You ask "any ideas", yes I do, but its only as good as what you are telling us. I would not have fired it up. You have multiple problems here.
There are meter circuit problems as well as amplifier issues.
I could probably get this amp going in about an hour, but I am on the other side of the world and relying on you to tell me/others exactly what is happening.

It wont the the Autoformer, they are not like output transformers on Tube amps, they are a grounded coil, the output taps are physically connected to the amplifier, any fault like excessive DC goes straight to ground through the coil.
I have never heard of a Autoformer failing.
Get the amplifier going first, don't worry about the meters, once the amp is working then you can work back form there.
 
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funkenaround said:
emitter resistors???

nope, I fast tracked this one

one step forward, two steps back

my way of life..lol
Click to expand...

The only way to fix this efficiently is to slow down so you only go though everything once. Then it will be one foot in front of the other and no steps back.
Otherwise you will be going all over the place clutching at straws....and become frustrated because you aren't getting anywhere....
 
couldn't get the inoperable meter out of my mind last night

pulled the face plate off

merely a poor plug connection, carefully bent the tabs a couple of times and voila, meter working just fine

while i'm on the topic of the meter, I might as well note, this amp had an accidental drop on the left corner, not by me, but some previous handler

in the drop, the glass sustained a crack and I suspect the meter and it's connection sustained a shock to discombobulate

I have wondered as to whether this mishandling could be responsible for the the channel issue

gonna make the big dig later on

as for the glass, where can I get a "quality" replacement for this?? its hardly noticeable from a 1/2 foot, the crack is located all the way the the left, so the main screen is pristine, no bubbling at all, was perfect...lol
 
Glass: Mcintosh, Audio Classics or Tom Manley (who works with Terry Dewick).
 
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