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Monarch SA-614

davros

davros

Active Member
I recently aquired a Monarch SA-614 Stereo amplifier, it is in need of some TLC and a recap job. It looks entirly original, and it'll need a full recap and cleaning before I dare to plug it in. I have found nothing about this amp online, and I was hoping someone might have some info, or a schematic.

It appears to have 2 6BQ5's, 1 12AT7, and an Unidentified rectifier tube. Seperate Tone and volume controls, and a Phone-Tuner-Aux control. I'll post pics later today to see if anyone recognizes it.

Thanks for the help!

Marc
 
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The rectifier is exactly the same shape and size as the 6BQ5's the only difference is the internal's.

I know I saw someone else post about having a SA-614, but for the life of me I can't find it.
 
After quite a bit of scrubbing, I found faint traces of the tube stamps in the chassis, they are 6CA4, 6BQ5, and 12AX7.

Man this thing is dirty, I've found grass, bits of leaves, and the thickest layer of dust ever.

Tom, you nailed the tube lineup!
 
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I swear I put pics on this the first day? In fact I know I did! I wonder what happened?
 

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I do believe that is a generic 'tube amp'. :D Probably made in Japan in the early to mid 1960s. Perhaps it was a kit?
It looks a lot like a lot of SE 6bq5/6bm8 amps you see on ebay, sold under various brand names.
Realistic/Radio Shack?
Perhaps Olsen or Calrad?
A similar looking one just sold on ebay, labeled 'Philmore'.

Is one input labeled 'xtal'?
 
The inputs on the back read Aux, Tuner, Phono. The speaker connections are COM,4,8,16.

I included some closeups of the interior. This is my first "rebuild" of a tube amp, and I thought I would start with something "average". Seems like this one is a start.

Any Idea what the orange componant is? It's labled "foil" with no value that I can tell. There is one conected to each channels tone control.
 

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It's a cool little amp and a good place to start. You could pretty easily draw the circuit yourself. I think there is an Olsen equivalent of this amp, I'll try to find it.
 
Thanks PatA, I probably will draw out a schematic if I can't find one. Just too useful to have around. I've got to finish 2 other projects before I start this one, but I like to be prepared when I do start.

I'm in the Military overseas, and there's nothing worse than ordering parts, waiting 3 weeks, and realizing you missed something! I've learned to look twice and order once!
 
Well the Recap is complete, and after fixing some poor looking conections, and cleaning the daylights out of itI was ready to turn it on.

After a good cleaning I found that all of the tube sockets were marked. The 12AX7 Socket had a bad 12AU7 in it, and I replaced it with a 12AX7. I put the 6CA4, and the 6BQ5's back in and slowly powered it up.

At about 75V I started getting sound (I had it hooked up to an old Sony Diskman and some crappy speakers) By 90V it sounded pretty good, and at a full 120V it was actually pretty loud.

After letting it run for about 20 Minutes I made these observations.

With no input (CD Paused) there was a small amount of hum, nothing you could hear with music playing, but whenever there was a break in the music you could here it (softly). The hum is not affected by the volume.

There is also a small amount of static, about the same level as the hum. I didn't notice it at first, only after the amp ran for a little while. The next time I turned it on it was still there. (not affected by turning any of the volume or tone knobs)

The 12AX7 is New (TAD Brand)
The 6BQ5's are original and old (Ten brand?)
The 6CA4 is original (Tube is not marked at all)

This is a "Generic" tube amp, my purpose in rebuilding it is to get some practical experience repairing and troubleshooting tube amps.

So, suggestions for the hum/Static?

Marc
 
davros said:
Well the Recap is complete, and after fixing some poor looking conections, and cleaning the daylights out of itI was ready to turn it on.

After a good cleaning I found that all of the tube sockets were marked. The 12AX7 Socket had a bad 12AU7 in it, and I replaced it with a 12AX7. I put the 6CA4, and the 6BQ5's back in and slowly powered it up.

At about 75V I started getting sound (I had it hooked up to an old Sony Diskman and some crappy speakers) By 90V it sounded pretty good, and at a full 120V it was actually pretty loud.

After letting it run for about 20 Minutes I made these observations.

With no input (CD Paused) there was a small amount of hum, nothing you could hear with music playing, but whenever there was a break in the music you could here it (softly). The hum is not affected by the volume.

There is also a small amount of static, about the same level as the hum. I didn't notice it at first, only after the amp ran for a little while. The next time I turned it on it was still there. (not affected by turning any of the volume or tone knobs)

The 12AX7 is New (TAD Brand)
The 6BQ5's are original and old (Ten brand?)
The 6CA4 is original (Tube is not marked at all)

This is a "Generic" tube amp, my purpose in rebuilding it is to get some practical experience repairing and troubleshooting tube amps.

So, suggestions for the hum/Static?

Marc
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Hi! Do you have a cap list or a schematic? I found a 614 recently and someone gave it a bad cap job and screwed everything up.
 
Sorry I don't.
I just replaced the caps like for like, with a little increase in voltage where possible.

I traded this off back in 2012, good luck on yours!
 
Tom Bavis said:
Rectifier is probably 6CA4/EZ81 - if it's not as tall as the 6BQ5s, then probably 6V4/EZ80. Pretty simple circuit I'm sure - you could probably draw it out, print this one and mark the differences: http://www.audiophool.cjb.net/amp-pcb.gif
Click to expand...

Hey tom, do you have a copy to the schematic?

IMG_2676.jpegIMG_2671.jpegIMG_5041.jpegIMG_5042.jpeg


I had a copy I can’t seem to find, and need to know what the it values are.

Any help would be greatly appreciated!!
 
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