old mc275
New Member
Dear Mcintosh friends,
This is my first post and I need some advice on an original MC275 I recently bought please.
If Clint Eastwood saw me there in that second hand store and would have asked me “Ask yourself, punk, is this your lucky day” my answer would have been “Yes, Yes, Yes, Mr. Harry !!! “
The chance of finding this amp here in Holland is kind of slim.
The chance to buy it for the price of a dinner for two even slimmer.
The amp was in a very average cosmetic state, lots of dust, dead insects etc. , but after some brushing ,vacuuming and mild cleaning turned out to be quite acceptable.
While carefully cleaning up the chrome I stumbled upon the top serial number which turned out to be 27510041 !!!!!! (see pic 3 and 5)
After that I stopped, according to some of the articles on this forum the first MC275 ever built had sn 27510001.
Did that mean I had the 40th MC275 ever made in front of me ? ( oops 41th :stupid:thank you Rodeodave )
This was the time I decided to join this forum and ask for some advice because it is very hard to get some reliable information here in the Netherlands.
The amp has been to the clinic for the last time in 1973 according to the stickers, the insides look fine and original but has not seen some voltage for a long time, so until now I only did visual inspections read a lot of articles on this forum and used a multimeter on a powerless amp.
These are my first findings :
As far as I can tell all the transformers are ok.
3 out of the 4 220 ohm 5W resistors are blown.
The thermistor is gone.
The rectifier diodes seem ok.
L2 has been very hot but still conducts.
A KT88 socket has once been replaced
No cracked or damaged capacitors except maybe 2 out of the 4 big power supply caps look suspect, paper parts and brownish stuff visible through the holes.
One of the two 330pf caps in the feedback circuit, C2 C13, the ones that look like resistors, has a very matte surface, it looks like it has been hot.
R65 according to the schematics should be 500 ohm 5W but is a 1/2W 1K.
C31 on V1-A and C32 on V1-B both 1.8pf are missing, looks they were never there.
So far no severe problems as far as I can tell.
I have got a step down transformer 220-110V 9A and a variac at home.
My questions are these :
I know that these amps are collectable, does this low serial number add value ?
Should I leave it alone and sell it to a rich asian guy and retire?
If this is not the case how should I proceed, even if I replace all of the dead parts, all the kt88’s are suspect and I am not even thinking of firing the amp up with the variac with these tubes in place so I can do voltage readings.
I hope some members of this forum can help me out on this.
Thanks in advance.
Robert.
P.S. English is not my native language so please forgive any wrongdoings.
This is my first post and I need some advice on an original MC275 I recently bought please.
If Clint Eastwood saw me there in that second hand store and would have asked me “Ask yourself, punk, is this your lucky day” my answer would have been “Yes, Yes, Yes, Mr. Harry !!! “
The chance of finding this amp here in Holland is kind of slim.
The chance to buy it for the price of a dinner for two even slimmer.
The amp was in a very average cosmetic state, lots of dust, dead insects etc. , but after some brushing ,vacuuming and mild cleaning turned out to be quite acceptable.
While carefully cleaning up the chrome I stumbled upon the top serial number which turned out to be 27510041 !!!!!! (see pic 3 and 5)
After that I stopped, according to some of the articles on this forum the first MC275 ever built had sn 27510001.
Did that mean I had the 40th MC275 ever made in front of me ? ( oops 41th :stupid:thank you Rodeodave )
This was the time I decided to join this forum and ask for some advice because it is very hard to get some reliable information here in the Netherlands.
The amp has been to the clinic for the last time in 1973 according to the stickers, the insides look fine and original but has not seen some voltage for a long time, so until now I only did visual inspections read a lot of articles on this forum and used a multimeter on a powerless amp.
These are my first findings :
As far as I can tell all the transformers are ok.
3 out of the 4 220 ohm 5W resistors are blown.
The thermistor is gone.
The rectifier diodes seem ok.
L2 has been very hot but still conducts.
A KT88 socket has once been replaced
No cracked or damaged capacitors except maybe 2 out of the 4 big power supply caps look suspect, paper parts and brownish stuff visible through the holes.
One of the two 330pf caps in the feedback circuit, C2 C13, the ones that look like resistors, has a very matte surface, it looks like it has been hot.
R65 according to the schematics should be 500 ohm 5W but is a 1/2W 1K.
C31 on V1-A and C32 on V1-B both 1.8pf are missing, looks they were never there.
So far no severe problems as far as I can tell.
I have got a step down transformer 220-110V 9A and a variac at home.
My questions are these :
I know that these amps are collectable, does this low serial number add value ?
Should I leave it alone and sell it to a rich asian guy and retire?
If this is not the case how should I proceed, even if I replace all of the dead parts, all the kt88’s are suspect and I am not even thinking of firing the amp up with the variac with these tubes in place so I can do voltage readings.
I hope some members of this forum can help me out on this.
Thanks in advance.
Robert.
P.S. English is not my native language so please forgive any wrongdoings.
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