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Maggie 9303: suddenly very low volume and distorted

Moonwatcher

Moonwatcher

Active Member
This Magnavox 9303 console pull has been sounding amazing and with Wharfedale 60s was providing an immersive, magical sense of depth and "being there" I've never heard from any of my solid state stuff.

Expert AK members recently helped with a no-sound issue, and I was advised to replace the rectifier tube, which completely solved the problem. Thank you!

But yesterday, after it had been on (but idle for a few hours), the sound was suddenly very low and a little distorted. I'm pretty sure I'm not getting the volume or power I should be. All tubes are lit, and because I have backup tubes I was able to trade them all out (except the rectifier), and it still has the problem.

I don't think it's the preamp, because I plugged the line out from my computer directly into the Maggie inputs, bypassing the preamp (original to the console), and still had pretty low volume.

Any advice on where to go from here would be greatly appreciated. There used to be a guy in my town who worked on tubes, but he has moved on (to NASA, I think!).

Thanks, and happy New Year!

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Sorry I cannot give you technical direction on this,...

but I must commend you on your description of "immersive magic" with your tube gear...I really have the same experience, and it still surprises me...every song seems to take on a new sense of detail and space...like you, I cannot remember ever experiencing that with solid state ...

Good luck on the new troubleshooting --
 
Sweet looking Maggie there. I picked up a 9301 some months back and just lost the rectifier and one of the 6BQ5's Waiting on replacements. Have been using 90db.
speakers with mine and have the same beautiful sound you describe. More than once have stopped what I was doing and looked around thinking someone was in the room with me. Good luck with getting it fixed and happy new year.
 
have the caps been replaced? If that can is original, I'd really suspect its done for. Could have taken out the rectifier tube too. Problems in both channels tells me its common to both, which basically leaves power supply and the cathode capacitor, all of which live inside that can.
 
kappclark said:
Sorry I cannot give you technical direction on this,...

but I must commend you on your description of "immersive magic" with your tube gear...I really have the same experience, and it still surprises me...every song seems to take on a new sense of detail and space...like you, I cannot remember ever experiencing that with solid state ...

Good luck on the new troubleshooting --
Click to expand...

Yeah, I think it is partly the Wharfedales, which underwhelmed me the last time I tried them but although not too powerful in the bass department really provide that presence. Glad you're enjoying your tube stuff too.
 
gadget73 said:
have the caps been replaced? If that can is original, I'd really suspect its done for. Could have taken out the rectifier tube too. Problems in both channels tells me its common to both, which basically leaves power supply and the cathode capacitor, all of which live inside that can.
Click to expand...

I think that can was replaced, but I'll check into that. The rectifier is pretty "new'' so I sort of doubt it's that, and it does light up. But maybe it was a bad tube. I replaced it about two months ago. Thanks!
 
6DZ7 said:
Check the value of the large common cathode resistor to see if it went high from overcurrent. Does it look brown in the middle?
Click to expand...

So that would be under the "can," right? I can easily look at the connections underneath, but does that can pry off or is that necessary? I'm such a novice that I don't even have the meter to check that resistor value, but there's no time like the present to get one and learn how to do this basic stuff. Thanks.
 
68db. said:
Sweet looking Maggie there. I picked up a 9301 some months back and just lost the rectifier and one of the 6BQ5's Waiting on replacements. Have been using 90db.
speakers with mine and have the same beautiful sound you describe. More than once have stopped what I was doing and looked around thinking someone was in the room with me. Good luck with getting it fixed and happy new year.
Click to expand...

Glad you're getting good results too. Could I ask what kind of 90db speakers you are using? Thanks.
 
So far have used Paradigm 3se mini, 5se, Mini MK-3 and a pair of Norman labs model 8's, db. unknown. Surprisingly for me anyway don't need gazillion watts
to enjoy music. For some reason low watt amps have always seemed to be sweeter at music. YMMV.
Edit.
I like the 3se mini and the Mini MK3 best, I think they seem to just seem to load more easily.
also depends on mood as which speakers are used.
 
Moonwatcher.

I think the reason I lost the rectifier and then a 6BQ5 was the power to house went off and came back on very quickly, after that happened I noticed the rectifier
making a spark. Within days had the meltdown. Hoping that was the cause. Cause being new to tubes, it would be an easy fix if nothing else was damaged.
When I figure what battery back up is needed will purchase.

If incorrect am open to suggestions.
 
68db. said:
Moonwatcher.

I think the reason I lost the rectifier and then a 6BQ5 was the power to house went off and came back on very quickly, after that happened I noticed the rectifier
making a spark. Within days had the meltdown. Hoping that was the cause. Cause being new to tubes, it would be an easy fix if nothing else was damaged.
When I figure what battery back up is needed will purchase.

If incorrect am open to suggestions.
Click to expand...

One way you can protect your amp is by adding a plug in GFCI adapter into the receptacle. Has intervened to protect my amps from hot cycling due to a momentary power outage on more then one occasion.
 
Moonwatcher said:
So that would be under the "can," right? I can easily look at the connections underneath, but does that can pry off or is that necessary? I'm such a novice that I don't even have the meter to check that resistor value, but there's no time like the present to get one and learn how to do this basic stuff. Thanks.
Click to expand...
The resistors connected between the can cap terminals are the power supply dropping resistors, not the cathode resistor. The cathode resistor is a 100 ohm 5w. It's a rectangular "cement" resistor and it will have the value printed on it. Seen as R12 in the Sams, which I have attached. It's in pdf which can be enlarged to show detail.

The original cans use twist lock mounts but will also have one of the twist tabs soldered to the chassis to ensure that the body of the can is well grounded. If you post pics of the can, showing the markings on the side and the bottom connections, it should be easy to tell if it has been replaced already.
 

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Moonwatcher said:
The rectifier is pretty "new'' so I sort of doubt it's that, and it does light up.
Click to expand...

what I was getting at is that if the can was bad, it may have taken out the original rectifier. A 5U4 when used like it is in a 9300 should last just about forever, though sometimes things do just go bad.
 
Legrace said:
One way you can protect your amp is by adding a plug in GFCI adapter into the receptacle. Has intervened to protect my amps from hot cycling due to a momentary power outage on more then one occasion.
Click to expand...

Thank you so much. That will be so much cheaper than the route I was headed. Do you have a suggestion on the amperage of the GFCI I see 20 amp? on Amazon.
 
FlaCharlie said:
If you post pics of the can, showing the markings on the side and the bottom connections, it should be easy to tell if it has been replaced already.
Click to expand...

Here are photos showing the rectifier lit and the underside of the can. How would you suggest I proceed? IMG_6214.jpg IMG_6223.jpg
 
The roasted resistor on the bottom of the can is a pretty big clue to me that something went wrong. Looks original to me. I'd say its due for replacement, either with a new can or individual caps on a terminal strip. This thing has lots of real estate, so a terminal strip would be my vote.
 
Yeah, the power supply needs all new caps and resistors at least.

Post pics showing all the parts underneath. There may be more damage.

Did you install the Edcor OTs yourself? Has this had any previous electrical restoration?
 
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