Concept 11.0

I have been on the fence of getting my malfunctioning Concept 5.5 done over or not. I will have to remember this thread in case I do decide. It will probably be the malfunctioning Sansui Model 8 that will go out first. At this point I am paying for the new lenses that were put in my eyes. Medicare pays for some but not all types of lenses and they are expensive. I could have bought a couple of SX-1250s instead. :rolleyes:
Maybe Jeff and Tinman can help you out with t
Those are great units.

My bet is a blown amp. Last owner blew the fuse. I'm betting you blew a new fuse.

If you don't set up a dim bulb tester and use it, you are just going to keep blowing fuses.

Since you don't know the things I just listed, I recommend you either find a vintage tech to work on it or sell it as is.

If we knew where you are, we may know someone capable of working on it.

I work on them but not I do not know if any of the other techs or fixers here do. They are sort of rare.
Blown amp? Would it NOT power up with a blown amp? This thing has no pulse. No lights, no fuzzy hum, nothing. I put a 3A fuse in to see if power was coming through the cord and the it fried.
 
A shorted output transistor or one that behaves that way because the driver is shorted or the pre-driver is shorted or etcetera acts like a dead short and blows the fuse as soon as power is applied.

Thus, whole unit appears dead all the time. No power can ever get used before the fuse burns out.

Any thing wrong with stuff if commonly called "blown" as in blown up as in broken.
Its just slang.

Bad output transistors are the most common problem when the fuse is burned out.
There are a few other common things that can do it but the odds drop fast that its one of those.
Bridge rectifier failure, main filter capacitor failure, bad transformer.

The odds of broken amp, bad bridge, bad cap, bad transformer are common, possible, rarely, almost never.
 
A shorted output transistor or one that behaves that way because the driver is shorted or the pre-driver is shorted or etcetera acts like a dead short and blows the fuse as soon as power is applied.

Thus, whole unit appears dead all the time. No power can ever get used before the fuse burns out.

Any thing wrong with stuff if commonly called "blown" as in blown up as in broken.
Its just slang.

Bad output transistors are the most common problem when the fuse is burned out.
There are a few other common things that can do it but the odds drop fast that its one of those.
Bridge rectifier failure, main filter capacitor failure, bad transformer.

The odds of broken amp, bad bridge, bad cap, bad transformer are common, possible, rarely, almost never.
The specified 8 amp fuse does NOT burn out. I put a lower amp fuse in and it fried as I assume it would if the unit worked. Boy your last sentence is a head scratcher...
 
So, an 8 amp fuse is what should be there and it does not burn out but there is no life in the unit.

A smaller fuse burns out.

So power gets through the switch and fuse but then we don't know what happens.

It could still be any of the things I listed but now the problem is less common.
I now suspect a bad power supply.
Transformer, bridge rectifier and main filter caps are more suspect now.
But it could be a not-so-dead short in an amp.

The missing fuse cap and fuse from the owner made me think the fuse was burning out.
My mistake.
 
Oh, and they won't power up with a blown amp if its a dead short. That will blow the fuse.
Blowing a 3 amp fuse in place of an 8 amp is meaningless except it tells us the switch works.
Maybe.
 
Nothing against Tom BUT there are a couple other very strong techs in SoCal for Concept pieces - Jeff, who runs the tapeheads.net forum (goes by Pacific Stereo and was the manager of the Pacific Stereo repair center in a previous life - Concept was developed for that company) and Tinman who you can reach thru AK or TH. Both are extremely solid techs and very familiar with the 11.0.

John

I have a long track record with Tom. I have tried numerous others and none come close. Jeff at pacificstereo.net does some fine work judging by the photos on his website. He is located in Apple Valley, IIRC. Not exactly metro L.A. but worth the drive if you want a recap restoration.
 
And the plot thickens...

How do you know the fuse does not blow? As before visual inspection is not always the best. The transformer has multiple secondaries of which one directly powers the various bulbs. That means even if your power supply to the amp was bad, your bulbs should light up. The preamp section also looks to be on a separate secondary so it should technically work if it was only the amp power section that was bad. These all have separate internal fuses that need to be check.

Basically, this means that if indeed the fuse is fine and nothing is working then I would be very concerned about the transformer unless every internal fuse has blow also.

You really need a multimeter. I don't know if I missed it but did you say you had one? You need to confirm the fuse is working. If you don't have one, the fuse is hefty enough that you could put it in something else to confirm continuity. You could also open the receiver and listen for transformer hum. At the same time you could check the status of the other fuses
 
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Once you get the fuse/power supply stuff squared away, another nice thing you can do is pull the jumpers off the rca plugs in the back and check the preamp and amp separately. Really helpful in narrowing down other problems.
 
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And the plot thickens...

How do you know the fuse does not blow? As before visual inspection is not always the best. The transformer has multiple secondaries of which one directly powers the various bulbs. That means even if your power supply to the amp was bad, your bulbs should light up. The preamp section also looks to be on a separate secondary so it should technically work if it was only the amp power section that was bad. These all have separate internal fuses that need to be check.

Basically, this means that if indeed the fuse is fine and nothing is working then I would be very concerned about the transformer unless every internal fuse has blow also.

You really need a multimeter. I don't know if I missed it but did you say you had one? You need to confirm the fuse is working. If you don't have one, the fuse is hefty enough that you could put it in something else to confirm continuity. You could also open the receiver and listen for transformer hum. At the same time you could check the status of the other fuses
 
Well,I tried several fuses and none showed any signs of burnout. I do have a multimeter and plan on getting/building a dbt. All this info from you guys is priceless to me. In a perfect world I'd ballpark diagnose the problem and then find a solid repair guy to fix it. I'm just trying to scratch the surface of knowledge that you fellas possess...
 
Schematic I'm looking at shows 4 internal fuses- amp section, preamp, lamps, and I think the am/fm section (not totally sure as I'm away from computer right now.

If you have multimeter check to see if it has a continuity tester. If that fuse is still intact it will give us a good direction on where to go next.
 
Jeff gets the inside edge on Concept for me on the strength of his extensive knowledge of the Concept product line and access to original parts and information. Marc is also a Concept owner that's rebuilt most of the models in this series (16.5, 11.0, 6.5, 5.5 etc.) and I've had so much hands-on with pieces he's done that he makes the short list of techs I'd ever refer others to or have work on my own gear. He's north LA, for reference.

Sounds like Tom meets that same standard for you, so all in all this would be three highly qualified leads. :thumbsup:

John

I have a long track record with Tom. I have tried numerous others and none come close. Jeff at pacificstereo.net does some fine work judging by the photos on his website. He is located in Apple Valley, IIRC. Not exactly metro L.A. but worth the drive if you want a recap restoration.
 
Jeff gets the inside edge on Concept for me on the strength of his extensive knowledge of the Concept product line and access to original parts and information. Marc is also a Concept owner that's rebuilt most of the models in this series (16.5, 11.0, 6.5, 5.5 etc.) and I've had so much hands-on with pieces he's done that he makes the short list of techs I'd ever refer others to or have work on my own gear. He's north LA, for reference.

Sounds like Tom meets that same standard for you, so all in all this would be three highly qualified leads. :thumbsup:

John

Yes, all true. Tom used to be a circuit designer with Onkyo and Marantz USA back in the day. He is also the factory authorized McIntosh tech for north L.A. area. Tom's strength is fast diagnosis, accurate repair estimate, and fast turnaround. This is the triple crown of tech service. There has never been a "stump the tech" job that was my experience with every other shop I visited in the L.A. area. It is well within Tom's capability to do a recap restoration but I always got the feeling he would rather knock out 10 repairs than un-solder and re-solder caps. It must be the challenge of problem solving that appeals to him. Interestingly, Tom doesn't like Concepts although he is more than capable of repairing one. It must have been his background in major brands...
 
Here's some pics of what seems to be a very clean unit.
 

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