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Marantz 10B Tuner

PatA

PatA

Super Member
Hey all, just picked it up yesterday, I haven't taken any pics yet. I found it in a used furniture store that I go into from time to time, I almost fell over when I saw it! According to the store owner, it was being used on a daily basis, I brought up slowly, just be safe. I tested the tubes and set it up for listening. Stereo signal is flaky, it fades in and out, but more importantly, the left channel audio level drops considerably when stereo signal is lost. If I play with the tuner, I can get it back, but it will eventually fade again. I want to do a basic service, (I have no business messing with this tuner), including; cleaning all the front panel selector switches, clean tube sockets and blow out the tuner. What I need to know is, should I attempt to clean pots with Deoxit? There are two scope centering pots on the front panel, I'm not to worried about those. I am a bit concerned about cleaning the pots under the deck. These are; muting threshold, vertical gain, horizontal gain, focus, intensity, L & R output and stereo threshold. Sorry to be so long winded, any help greatly appreciated!
 
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There are 3 photocell / LDR units that fail in those. There is a guy on ebay that makes those parts. They are better than the originals.
 
If it kinda works and you want to flip it. I'd leave it as is.

There are some LDR's (Light Dependent Resistors) in there that are custom. They are tube driven Neon lamp type. They fail a lot and I haven't found a good way to repair these. It was very hard to find a good source for the CDS cells in the righ value, and it was hard to get enough light on them so they switched properly. I'm sure it could be done. On the one's that I modified, I ended up making a doubler circuit from the heater supply and driving relays through a buffered tube output signal. This works well and should last a long time and not have the flaky noise issuesthat the CDS cells have.

The other thing that can drive technicians not familiar with the 10B is the IF strip. There are no ceramic filters or anything else that bounds the IF bandwidth, so it's easy to get lost adjusting these. It's best to have a 10.7MHz chirp oscillator and a spectrum analyzer and/or a scope with a sweep generator so you can optimise the IF bandpass shape.

The tuning meter/tube can get burned phosphor spots on them from people turning them too bright.

IMO, these are not for monkeying around with. It's easy to make an unworkable mess out of them. It'd be a shame if that happened.
 
pete1729 said:
Did you sweat much as you were handing the man money for the 10b?
Click to expand...

Yeah, did sweat a little, (the 90 deg. FL heat had very little to do with it). It's been tough sledding down here for a year or two, I borrowed the cash from my father in law, (hate being in hock to that guy), I'm tempted to pay him back and keep it, but it would be forever till I could get it sent out and serviced.
 
Jon_Logan said:
If it kinda works and you want to flip it. I'd leave it as is.

There are some LDR's (Light Dependent Resistors) in there that are custom. They are tube driven Neon lamp type. They fail a lot and I haven't found a good way to repair these. It was very hard to find a good source for the CDS cells in the righ value, and it was hard to get enough light on them so they switched properly. I'm sure it could be done. On the one's that I modified, I ended up making a doubler circuit from the heater supply and driving relays through a buffered tube output signal. This works well and should last a long time and not have the flaky noise issuesthat the CDS cells have.

The other thing that can drive technicians not familiar with the 10B is the IF strip. There are no ceramic filters or anything else that bounds the IF bandwidth, so it's easy to get lost adjusting these. It's best to have a 10.7MHz chirp oscillator and a spectrum analyzer and/or a scope with a sweep generator so you can optimise the IF bandpass shape.

The tuning meter/tube can get burned phosphor spots on them from people turning them too bright.

IMO, these are not for monkeying around with. It's easy to make an unworkable mess out of them. It'd be a shame if that happened.
Click to expand...

What you say makes sense, I have located the LDR's but it is an issue that I will not try to address myself. I was hoping a good cleaning might help out, should I try to service the pots under the chassis deck?
 
Jon_Logan said:
If it kinda works and you want to flip it. I'd leave it as is.

There are some LDR's (Light Dependent Resistors) in there that are custom. They are tube driven Neon lamp type. They fail a lot and I haven't found a good way to repair these. It was very hard to find a good source for the CDS cells in the righ value, and it was hard to get enough light on them so they switched properly. I'm sure it could be done. On the one's that I modified, I ended up making a doubler circuit from the heater supply and driving relays through a buffered tube output signal. This works well and should last a long time and not have the flaky noise issuesthat the CDS cells have.

The other thing that can drive technicians not familiar with the 10B is the IF strip. There are no ceramic filters or anything else that bounds the IF bandwidth, so it's easy to get lost adjusting these. It's best to have a 10.7MHz chirp oscillator and a spectrum analyzer and/or a scope with a sweep generator so you can optimise the IF bandpass shape.

The tuning meter/tube can get burned phosphor spots on them from people turning them too bright.

IMO, these are not for monkeying around with. It's easy to make an unworkable mess out of them. It'd be a shame if that happened.
Click to expand...


Don't even touch it..

I had mine "gone through" by a so called vintage hi fi expert here in the Chicago area "Deltronics" . They almost ruined it.. Send it to the guy that Sid Smith from Marantz recommended, Mike Zuccaro in San Diego. (google him)THEN you will simply have the best tuner on the planet!
 
Be extremely careful about cleaning the dial scale glass in this model. The lettering tends to fall off, given the slightest provocation.

You have a genuine treasure. Don't let any amateurs work on it.
 
BinaryMike said:
Be extremely careful about cleaning the dial scale glass in this model. The lettering tends to fall off, given the slightest provocation.

You have a genuine treasure. Don't let any amateurs work on it.
Click to expand...

That is so funny that you mention that. That happened to me. I guess I was being overly zealous or looked at it wrong and I screwed up the lettering on the low side of the dial glass. I think it had that old hazy film that I just couldn't sit still about. Well, I screwed it up and it was a customer's unit.

What to do? Order the replacement glass..... .... yeah right. Fortunately, we went to the California College of the Arts and Crafts in Oakland and got the help of a female artist who perfectly restored the damaged lettering. I mean PERFECT. The font style, size, shape, color: perfect.

I'm never doing that again. What's that Southwest Airlines commercial? "You want to get away?". Man, I sure did.
 
Jon_Logan said:
What to do? Order the replacement glass..... .... yeah right. Fortunately, we went to the California College of the Arts and Crafts in Oakland and got the help of a female artist who perfectly restored the damaged lettering. I mean PERFECT. The font style, size, shape, color: perfect.
Click to expand...

That is ingenious, I'll have to remember that one if I ever screw up dial glass lettering. :yes:
 
I'm going to second the "keep it and wait till you find the right tech" sentiment. You are unlikely to stumble on another one.
 
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