Many thanks Boydk. I have only revisited this thread after some time has passed as I thought it had already come to a natural end. I am overawed by the continued response by everybody and I am extremely thankful to everyone. I have found it interesting but as you suggest, it is way above my understanding in much of the technicalities. Your fix seems to be the good news I was hoping to find. May I ask though, I assume your term the "detector" coil is the same coil they call the discriminator?. If so the manual says it has 2x coils "202" and "204" ?.. Please see the manual page 7. Also I can't find these coils on the board layout on the manual, due to the very poor quality of the image. So I would be most grateful if you could tell me what coil/ coils I should just tweak a tiny amount. Very much obliged
Yes to your Q....... Different terms (depending on what part of the the world) for same function. Discriminator (older)/Detector (newer).
Actually........ Just follow the alignment procedure in #5 of the manual. I assume, you´re qualified to measuere DC millivolts on
the indicated points 😉
Adjust them as equally as possible.
Another not so correct way.
Can I assume, that if you activate the "FM-Mute" circuit, the tuner is silent, when showing the correct frequency, but "open"
when the display shows 50KHz step "misaligned"??
If so, activate FM-mute and manually tune to the correct frequency. Then carefully turn the "202" 1 mm CV or CCW (mark the position before you begin).
If suddenly sound, then done.
If no result, the return the "202" to where it was and do the same with "204" instead. This should give you sound with correct
frequency indicated, Second test: Do some auto tuning, and make sure, it now "locks" correctly.
But still....... First suggestion in manual #5 is the correct one. Tune to your preferred frequency and
measure and adjust as close to 0 volt as possible on the 2 indicated positions.
OR........ even better........ live with it, if your CDO (OCD in alphabetical order) 🤣 allows it.
Actually........ Just follow the alignment procedure in #5 of the manual. I assume, you´re qualified to measuere DC millivolts on
the indicated points 😉
Adjust them as equally as possible.
Another not so correct way.
Can I assume, that if you activate the "FM-Mute" circuit, the tuner is silent, when showing the correct frequency, but "open"
when the display shows 50KHz step "misaligned"??
If so, activate FM-mute and manually tune to the correct frequency. Then carefully turn the "202" 1 mm CV or CCW (mark the position before you begin).
If suddenly sound, then done.
If no result, the return the "202" to where it was and do the same with "204" instead. This should give you sound with correct
frequency indicated, Second test: Do some auto tuning, and make sure, it now "locks" correctly.
But still....... First suggestion in manual #5 is the correct one. Tune to your preferred frequency and
measure and adjust as close to 0 volt as possible on the 2 indicated positions.
OR........ even better........ live with it, if your CDO (OCD in alphabetical order) 🤣 allows it.
Last edited:
Thank you very much Boydk. I really appreciate your help on this. Yes, I'm OK with electronic construction, measuring and testing. It's mostly just the problem identifying where certain parts are located in a tuner. They are so much more complicated than an amplifier or similar. You are correct as regards the FM-mute action and the display misalignment. Your detailed step-by-step instruction is what I wanted. I now have confidence to try the adjustment. Hopefully if I spend more time in studying the manual I will confidently locate the positions of the 2x coils! . I will report back as soon as I have tried it, maybe in a weeks time whatever. I'm very much obliged. Thanks again 🙂
Thanks very much sgrossklass. After zooming in and magnifying the component image from the manual I have spotted them: Once I get the time, it should be easy to locate them on the board. I also need some nylon trimmer tools too:
If so, I might use the trusty soldering iron on the metal can for a bit of persuasion if need be... 50-80°C should help things along. (In which case everything should be allowed to cool back down to ambient before going for the adjustment in earnest.)
In my much younger decades, as service manager/ grease monkey at two A/V retail biz's, my recommendation is to measure twice, cut once. If you're bound and determined to do this, (and that's y'own biz), prop up a camera on a tripod and record where you started from and how far you've experimented. Like evolution, most changes are potentially fatal. In areas where we have inherently limited information, we should err on the side of conservatism. In areas where we cannot verify information, we are blind.
I'm currently working on the restoration of a Marantz 18 receiver, very fancy in its day, built-in 1" oscilloscope and such, late 1960s. The owner has provided a spare parts unit with better cosmetics as an organ donor. I spent two days removing and cleaning the better dial glass, whose half century old painted-on-glass numbers and marking were only a breath away from gone. It mostly survived, but it reinforced in me a clearer division between what can be done and what should be done. Member anatech has a sig that sums that up pretty concisely. The factory service manual actually says to return the IF module to the factory for alignment, but has an emergency procedure including procuring a duplicate IF strip cover and crafting an RF "Y" into the cover. The rest isn't that great either.
But I digress. First, do no harm (that you can't back out of). Second, be able to back out. Third, do no harm.
All good fortune,
Chris
I'm currently working on the restoration of a Marantz 18 receiver, very fancy in its day, built-in 1" oscilloscope and such, late 1960s. The owner has provided a spare parts unit with better cosmetics as an organ donor. I spent two days removing and cleaning the better dial glass, whose half century old painted-on-glass numbers and marking were only a breath away from gone. It mostly survived, but it reinforced in me a clearer division between what can be done and what should be done. Member anatech has a sig that sums that up pretty concisely. The factory service manual actually says to return the IF module to the factory for alignment, but has an emergency procedure including procuring a duplicate IF strip cover and crafting an RF "Y" into the cover. The rest isn't that great either.
But I digress. First, do no harm (that you can't back out of). Second, be able to back out. Third, do no harm.
All good fortune,
Chris
Hi Chris,
Agreed!
I've rebuilt a few Marantz 18 receivers. Nice units, construction is very different from what most would be familiar with. The alignment isn't terrible, most shops did not have the required equipment back then, so "return to factory" was a wise policy. Even a decade later, some Marantz products were factory service only. I was one of the shops designated to repair those under warranty, so warranty station "B".
Careful and slow. Think about things before doing them. I have a dead Marantz 18 here as well. A victim of some shop that didn't think before acting.
Labeling on all glass is temporary at best. Any force can remove it (even dry). I try to carefully dab the glass between characters with water on a Q-Tip, or very carefully and gently blot with paper towels (flat). Working on old radios id good training. I wonder, these days you could take some detailed pictures and have the glass reprinted. It might work for broken dials too.
Agreed!
I've rebuilt a few Marantz 18 receivers. Nice units, construction is very different from what most would be familiar with. The alignment isn't terrible, most shops did not have the required equipment back then, so "return to factory" was a wise policy. Even a decade later, some Marantz products were factory service only. I was one of the shops designated to repair those under warranty, so warranty station "B".
Careful and slow. Think about things before doing them. I have a dead Marantz 18 here as well. A victim of some shop that didn't think before acting.
Labeling on all glass is temporary at best. Any force can remove it (even dry). I try to carefully dab the glass between characters with water on a Q-Tip, or very carefully and gently blot with paper towels (flat). Working on old radios id good training. I wonder, these days you could take some detailed pictures and have the glass reprinted. It might work for broken dials too.
If you need a really complete number "1" for a model 18, I'll try to rescue it from the bench top. Just about broke my heart to see it leave, at the very end of a lot of trying hard. "As women go, she went" - some great poet
I swear that I didn't even look at it cross-eyed, and certainly didn't touch it even within a millimeter, but those dial glasses are way beyond fragile. Maybe it's only a special issue here in the swampy American South, but really, you can't breath on 'em.
Love your idea of restoration glass from a scan. Hopefully somebody will see this and assess a biz opportunity. A lot of tricky work to make one, but the next 19 might pay off. Same for McIntosh, and sooner than later, for the hipster 1970s Japanese receivers.
Always good fortune,
Chris
I swear that I didn't even look at it cross-eyed, and certainly didn't touch it even within a millimeter, but those dial glasses are way beyond fragile. Maybe it's only a special issue here in the swampy American South, but really, you can't breath on 'em.
Love your idea of restoration glass from a scan. Hopefully somebody will see this and assess a biz opportunity. A lot of tricky work to make one, but the next 19 might pay off. Same for McIntosh, and sooner than later, for the hipster 1970s Japanese receivers.
Always good fortune,
Chris
Hi Chris,
Yeah, that's an option. Thanks.
The one I have stored is pretty darned rough. Dial glass was broken before it came in. The previous "tech" threw the glass out instead of trying to save any part of it. I get McIntosh with broken face plates as well. Admittedly you have to be careful with these, given they are glass it should be self apparent!
It always breaks my heart when I see what some folks do to things. I even get old great tube amps where every wire has been replaced with Teflon wire - not run in the same path and total circuit changes. Always some self-proclaimed expert. They generally don't work after this treatment.
Yeah, that's an option. Thanks.
The one I have stored is pretty darned rough. Dial glass was broken before it came in. The previous "tech" threw the glass out instead of trying to save any part of it. I get McIntosh with broken face plates as well. Admittedly you have to be careful with these, given they are glass it should be self apparent!
It always breaks my heart when I see what some folks do to things. I even get old great tube amps where every wire has been replaced with Teflon wire - not run in the same path and total circuit changes. Always some self-proclaimed expert. They generally don't work after this treatment.
If I can persuade the (even older than me) gentleman to donate his lesser dial glass to a higher cause (and maybe the hopes of a better reproduction, down the road..) I'll send it to you. My thoughts are that anybody old enough and crazy enough and rich enough to want a pretty Marantz 18 deserves to have one. Doesn't harm anybody and good for the local economy, why not?
The glass itself is ordinary window glass, not even edge beveled (and it crumbles on the corners when trying to remove the clips holding it to its metal frame) and will try to cut the interloper, but maybe a scan could be done safely? The original glass has four locating marks in the corners, like you would imagine for multi-colour printing, and the ?paint? looks like it might have been done from a transfer from a single large (full frame) sheet. Probably obvious to someone in the printing trade, but the details are mysterious to me.
I'll retain (as opposed to the military term Strategic Transfer of Equipment to an Alternate Location) (see the Fat Electician's YouTube channel for divine enlightenment) the ridiculously stiff spring clips used to hold the glass to the metal frame, doubtlessly lost on your example. You'll need to engineer a black tape funnel between the #1847 lamps and the side faces of the glass. On the two that I have here, both are untaped areas about 3/16" beginning at the bottom of the glass, and upwards, so probably not painfully critical, but they did go to a lot of trouble to cover up the rest of the light.
All good fortune,
Chris
The glass itself is ordinary window glass, not even edge beveled (and it crumbles on the corners when trying to remove the clips holding it to its metal frame) and will try to cut the interloper, but maybe a scan could be done safely? The original glass has four locating marks in the corners, like you would imagine for multi-colour printing, and the ?paint? looks like it might have been done from a transfer from a single large (full frame) sheet. Probably obvious to someone in the printing trade, but the details are mysterious to me.
I'll retain (as opposed to the military term Strategic Transfer of Equipment to an Alternate Location) (see the Fat Electician's YouTube channel for divine enlightenment) the ridiculously stiff spring clips used to hold the glass to the metal frame, doubtlessly lost on your example. You'll need to engineer a black tape funnel between the #1847 lamps and the side faces of the glass. On the two that I have here, both are untaped areas about 3/16" beginning at the bottom of the glass, and upwards, so probably not painfully critical, but they did go to a lot of trouble to cover up the rest of the light.
All good fortune,
Chris
Is the glass opaque or translucent after printing?
The dial restoration can be done using sublimation ink jet printing (used for CD / DVD back in the day) on a new piece of float glass of the right thickness.
Color laser print on to paper, or PET / PVC film also works, and some specialists offer archival grade non fading prints.
Can attach on back side of glass.
Very simple compared to the old days, then it would have involved screen printing in multiple colors....make screen, dry one color, repeat for next color and so on, with a wastage allowance, for a one off you might waste up to ten...
The dial restoration can be done using sublimation ink jet printing (used for CD / DVD back in the day) on a new piece of float glass of the right thickness.
Color laser print on to paper, or PET / PVC film also works, and some specialists offer archival grade non fading prints.
Can attach on back side of glass.
Very simple compared to the old days, then it would have involved screen printing in multiple colors....make screen, dry one color, repeat for next color and so on, with a wastage allowance, for a one off you might waste up to ten...
Normally the printed glass is clear with a diffusion film between it and the light source (close to the light bulbs). Many times the light source shines across a rear panel and not right through the dial glass.
Some later sets, like 1970's Marantz, have the diffuser right on the back of the dial scale that is printed.
Some later sets, like 1970's Marantz, have the diffuser right on the back of the dial scale that is printed.
Yes...PET / PVC films are transparent, and the paper used for drafting maps is actually a translucent polyester film, that is found for AO size plotters.
Other options for opaque and light permitting materials also exist.
The restoration process is less difficult now than earlier methods.
Other options for opaque and light permitting materials also exist.
The restoration process is less difficult now than earlier methods.
Last edited:
Yes, I use archival grade vellum for Marantz and similar applications. It's more expensive, but does not yellow and it is more even. In the long term, it's the best.