[hojomojo96]

Just stopping by to verify something - I've heard that the McIntosh 1900 has a weak power switch, so I plugged it into a switch at the outlet. Is this the right idea?
Sidenote, hopefully I'll soon be able to build my case for it.

EDIT: HELP. This just started, but the receiver has just started shutting off mid play. It wasn't on too long and doesnt feel all that hot. Where do I start?

 

[Skylab]

That's not really a good sign...the Mac 1900 doesn't have pots for adjusting DC Offset or bias...so I'm not sure what to recommend. Probably best bring it to a qualified tech.

 

[PhoenixG]

Just stopping by to verify something - I've heard that the McIntosh 1900 has a weak power switch, so I plugged it into a switch at the outlet. Is this the right idea?
Sidenote, hopefully I'll soon be able to build my case for it.

EDIT: HELP. This just started, but the receiver has just started shutting off mid play. It wasn't on too long and doesnt feel all that hot. Where do I start?

Can you give any more details on how you're using it when it goes silent? Do the lights stay on or go off? Does the unit come back up if you turn it off and on again? If you're on radio, is the muting circuit on? Can you touch your output transistors to see if they are really hot? Do all inputs go silent, or just whatever you're listening to? Have you cleaned the unit with deoxit and checked/ replaced the fuses?
 
Also, unrelated note, I'm firing up the minivanmobile tomorrow for a nice unit. Skylab and Moody, I don't remember which one of you has it's little brother, but I'll be joining your tube club (hopefully).

 

[hojomojo96]

Can you give any more details on how you're using it when it goes silent? Do the lights stay on or go off? Does the unit come back up if you turn it off and on again? If you're on radio, is the muting circuit on? Can you touch your output transistors to see if they are really hot? Do all inputs go silent, or just whatever you're listening to? Have you cleaned the unit with deoxit and checked/ replaced the fuses?

Also, unrelated note, I'm firing up the minivanmobile tomorrow for a nice unit. Skylab and Moody, I don't remember which one of you has it's little brother, but I'll be joining your tube club (hopefully).

It doesn't go silent - it turns off. Completely. And then after a while, it comes back up again, all by itself. Turning it on and off right after doesnt help either. Which sounds like a heat problem to me maybe? But its never too hot to touch. Which ones are the output resistors? I'm a nub haha, and in highschool. And no, havent gotten around to using deoxit and replacing fuses, I have exams so I was waiting.

 

[PhoenixG]

It doesn't go silent - it turns off. Completely. And then after a while, it comes back up again, all by itself. Turning it on and off right after doesnt help either. Which sounds like a heat problem to me maybe? But its never too hot to touch. Which ones are the output resistors? I'm a nub haha, and in highschool. And no, havent gotten around to using deoxit and replacing fuses, I have exams so I was waiting.

So I googled your problem. It seems like your protection circuit has been stepping in and shutting you down. 99% of the time, it's a bad protection temperature sensor, and the rest of the time it's a runaway output transistor due to bad bias voltage or bad transistors. The output transistors are the big round ones on the heat sinks in the middle of the unit. You can diagnose the problem with some electronics cooling spray. Open the unit and locate the output transistors and the protection sensors. They'll both be on the heat sinks. Maybe download the service manual to make sure of what you're looking at.
Turn the unit on and wait until it turns off. See what got hot and hit it with cooling spray. If it comes back up, go from there.Hopefully, it's the sensor, as you can just replace it. If it's the transistor, then you have to figure out why it's overheating. Good luck. This unit is worth fixing.

 

[hojomojo96]

So I googled your problem. It seems like your protection circuit has been stepping in and shutting you down. 99% of the time, it's a bad protection temperature sensor, and the rest of the time it's a runaway output transistor due to bad bias voltage or bad transistors. The output transistors are the big round ones on the heat sinks in the middle of the unit. You can diagnose the problem with some electronics cooling spray. Open the unit and locate the output transistors and the protection sensors. They'll both be on the heat sinks. Maybe download the service manual to make sure of what you're looking at.
Turn the unit on and wait until it turns off. See what got hot and hit it with cooling spray. If it comes back up, go from there.Hopefully, it's the sensor, as you can just replace it. If it's the transistor, then you have to figure out why it's overheating. Good luck. This unit is worth fixing.

If the output transistors are the big silver ones, then they're not hot at all. The boards near the heatsink/power supply are the only ones putting out heat. I'll order deoxit and cooling spray asap. Thanks so much, I'm definitely gonna try to fix it.

 

[Oregonian]

No, this isn't a new receiver or amp but it is an addition to my now ALL Pioneer Spec system. 
 
Picked up this Pioneer S50 turntable this morning - replaces my Yamaha P-520 which was a nice table but wanted all Pioneer in the rack.  Cerwin Vega's are staying.............
 
TT sounds very nice................
 


 
Played the Eagles - One of These Nights - my favorite song - first.  Did not disappoint. 

 

[LugBug1]

Lookin good! Matches well with the Spec 

 

[PhoenixG]

I hinted I had something coming, and here it is:

 
800c. Looks good, but one of the output tubes is red plating, so that has to be solved before I can do anything with it.

 

[MIKELAP]

  No, this isn't a new receiver or amp but it is an addition to my now ALL Pioneer Spec system. 
 
Picked up this Pioneer S50 turntable this morning - replaces my Yamaha P-520 which was a nice table but wanted all Pioneer in the rack.  Cerwin Vega's are staying.............
 
TT sounds very nice................
 


 
Played the Eagles - One of These Nights - my favorite song - first.  Did not disappoint. 

The tower of power.

 

[LugBug1]

  I hinted I had something coming, and here it is:

 
800c. Looks good, but one of the output tubes is red plating, so that has to be solved before I can do anything with it.

Cheeky 

 
 
Congrats bud

 

 

[Argybargy]

I hinted I had something coming, and here it is:



800c. Looks good, but one of the output tubes is red plating, so that has to be solved before I can do anything with it.

Lovely. I listen to mine every day. I'd be curious to hear what headphones you find to have the best synergy.
And what tubes you settle on.
All of the vintage 600ohm phones sound great, with my top pick being the Beyer dt990, the one from the late 1980s(?).

 

[PhoenixG]

Lovely. I listen to mine every day. I'd be curious to hear what headphones you find to have the best synergy.
And what tubes you settle on.
All of the vintage 600ohm phones sound great, with my top pick being the Beyer dt990, the one from the late 1980s(?).

This is the best vintage receiver thread on the internet, but despite the site name, I'm not big into headphones. I have one vintage pair of JVC's I use to test the basic functions of amps that don't have anything hooked up, but I'm otherwise headphone-less. Also, protip, I keep headphones plugged in (on vintage amps with a resistor based head amp) when I adjust the dc bias to keep cap-coupled output amps from running away. I almost exclusively use speakers, and I try to keep my musings on them at the speaker forum (which I'm going to shamelessly plug now). 
Check it out, subscribe, post. I'd like to see what everyone has and how they like it.
http://www.head-fi.org/t/552257/calling-all-vintage-speaker-owners/1230#post_10556223

 

[roadcykler]

I procured a Mitsubishi M-PF5200 Pre-amp/Tuner and a M-A4200 amp and some smaller Mission speakers today. The Mitsubishi stuff is in very good condition and looks great but I can't find much of anything on-line about either of them. Just a few random things here and there but nothing definitive. Anyway, not sure what I'm going to replace but I may have at least have an integrated for sale soon and will list the vintage Kenwood tuner as soon as I get a couple of pictures.
 
If anyone here has any info on the preamp and amp or where I could find some, I'd appreciate it. 

 

[analogsurviver]

  I procured a Mitsubishi M-PF5200 Pre-amp/Tuner and a M-A4200 amp and some smaller Mission speakers today. The Mitsubishi stuff is in very good condition and looks great but I can't find much of anything on-line about either of them. Just a few random things here and there but nothing definitive. Anyway, not sure what I'm going to replace but I may have at least have an integrated for sale soon and will list the vintage Kenwood tuner as soon as I get a couple of pictures.
 
If anyone here has any info on the preamp and amp or where I could find some, I'd appreciate it. 

Google is your friend.  http://www.analogalley.com/osccart/product_info.php?currency=GBP&products_id=299
 
This time, nothing on your Mitsubishi models on hifienhene - except pictures :
 
http://www.hifiengine.com/gallery/images/mitsubishi-m-a4200-stereo-power-amplifier.shtml
 
http://www.hifiengine.com/gallery/images/mitsubishi-m-pf5200-preamplifer-tuner.shtml
 
https://www.flickr.com/photos/36757414@N04/4601980758/in/photostream/
 
From the last pics it is clear output stage is implememented by STKs.
 
Never saw any Mitsubishi gear in flesh, but some were supposedly quite decent indeed - particularly the modular series predating your units ( around 1989) by about a decade.