Marantz Model 150 CRT Scope.

[Mark R]

Found a CRT on Line. My CRT part Number is 85DB1/ 6H3....The one on line is 85DB1/7J3.... I guess they would be the same maybe? Don't know what the slash number means.

Also mine has a deflection Coil glued to the glass tube in the front. with a lead wire going to the deflection circuit. Any one ever removed that coil? What would you advise to loosen that glue. It appears only to have a small amount around the front of the coil tape.

NOS Toshiba 85DB1 / 7J3 CRT Cathode Ray Tube for Marantz Tuners Free Shipping | eBay

Up for sale is a Toshiba 85DB1 / 7J3 CRT. You will receive ONE NOS Tube.

www.ebay.com

Above is the link to the CRT...Waiting for a response from the seller in regards to the Part Numbers.

Thanks:

 

[audiotemp]

This is mostly in Japanese but has some English too. You might also try feeding it, or parts of it, to googly translate. It shows 85db1 but I do not know if it explains the /7J3.

http://segalandassociates.com/Docum...--Cathode-ray-tube-catalog-B4-71-48-pages.pdf

 

[Mark R]

Ok.. Closed the deal. Paid less then the asking price. CRT is on the way. Now I have to figure out a method for removal of that Deflection coil.

I'm sure We have an Expert here who can advise me. That's why this is the Best Audio Forum and why I am a Subscriber.

Thanks Guys...

 

[Mark R]

Thanks "Audiotemp"

I tried the link but it went nowhere. Would not load . Anyway I appreciate the effort.
Thanks Mark R

EDIT: I tried the link again.... This time it said site cannot be reached ...than split second later it went to Japan ...L.OL Thanks... Now all I have to do is try and decode it. I wish I had some Japanese Friends ..Save me some time translating. But the seller assured me this CRT is the same and will work.

Next step... Get that coil lose... Gotta hit the Shop Manual . Thanks again Audiotemp.

Regards: Mark R

 

[audiotemp]

Thanks "Audiotemp"

I tried the link but it went nowhere. Would not load . Anyway I appreciate the effort.
Thanks Mark R

Works for me. Did you click on it, or copy and paste it?

 

[Mark R]

See post #4..Bold text.. It Hic-Copped and them went thru on the second try..Thanks...

 

[zenith2134]

Hi,

I have never worked on one of these Marantz before.

Bonded yokes are difficult to remove since they were integral to the tube itself and considered permanent. Attempting to remove one is a risk both in terms of implosion and damage to the parts.

These are XY vector type tubes, much different than raster scan video. They're rather like an oscilloscope tube. (identical really).

It'd help if you could perhaps provide photos of the old tube in order to determine the best course of action.

I see that both that Toshiba datasheet and the the ebay listing show a tube without specifying deflection yoke. I don't recognize that tube at all other than the part designation denoting it a green phosphor and the size in millimeters.

 

[Mark R]

The coil must have been slipped on as the CRT was inserted into the unit. The adhesive looks like was added ONLY in the front around the edges. I did manage to break lose a small amount of the adhesive in the front. Since I ordered the tube I'll waite till it arrives before going any further. The coil is listed as a separate Part Number .. Coil designation "L001" and Marantz Part Number "LD0004001" in the service manual. So I don't think it was made by the CRT Mfg.

Also I have years of experience with handling Old Large CRT TV's. I know how dangerous they can be. I had a special Discharge probe I used to insert into the HV feed socket on the Glass CRT to discharge them. And even then.. I would double check for voltage. Here's some pic's of the CRT. I drew a Black line on the rear to help locate the new one .That's not glue. It's only on the front in mostly on the corners.

 

[zenith2134]

As long as you can reuse that sleeve, all should be fine.

It's going to be great once you have a bright new tube in there! (off topic but I once put a brand new old stock 11" inline CRT in my '66 GE portacolor. Looked like new!)

 

[Mark R]

Yeah ..The Sleave looks well made and rigid. Just have to be careful I don't crush the windings under that ISO tape. The Heater does glow in the dark .. and the is -970 Volts on Each end of the leads. Also the Brightness Pot on the rear tracks ok. . Just requires you to take your time getting it lose. Looks like it will have to come out the front which means taking the front plate off and dealing with the hold down in front.

 

[Mark R]

Ok So I got the New CRT's in. Got a nice deal on Both. I have another 150 Marantz out Getting an FM Alignment with the Famous Sencore SG-80. The Sencore SG 80 is in such high demand and none to be found. Still used by Techs today. I'm sure there are other types of FM alignment gear on the market, but for some reason techs that are dong vintage gear Love this unit. It's all over YouTube in use by people like "XRAY TONY B" and others.

Why Sencore got out of that end of the business I have no clue. Anyway, The CRT that was in the M-150 is weak. I used a small brush and some Acetone to soak the glue area and prodded the junction of the deflection coil and glass with one of flat my Plastic IF tuning tools. After a few minutes the Glue gave way and the deflection coil slid back.

The CRT comes out of the front after removing the 4 Faceplate bolts and the CRT adjusting knobs. Removed the metal shield around the CRT and the hold down clamp at the rear and slid the old CRT out and the new one in. Put it all back together and did a few adjustments on the brightness and rotation and I'm good to go..

Thanks for all of your input.

Mark R

 

[PCMALO]

Hi Mark. I just read your posts with interest because I am considering getting a new tube to replace the dim one in my 120B tuner. But what had me stumped was how to remove the deflection coil without destroying it or the tube or myself! So it was great to read how you used Acetone to dissolve the glue.

So I have two questions. (1) what did you use to re-glue the coil onto the new tube? I would think it might need to be high-temp but then I don't really know if the tube gets hot or not in operation.

(2) there is a variable resistor (R013 on the 120B) attached to the coil. What does it actually do and did you have to adjust it after installing the coil on the new tube?

Thanks in advance for any info.

 

[Mark R]

Hi PCALMO

Question #1.. I used dabs of Hot Glue from a standard Hot Glue Gun. Just small 1/8th inch dabs across the top maybe three .. and then along the outside using 3 dabs as well. The right inboard side I could not safely get into that area . So I just let it be. The coil stops on its own when you push it up towards the front of the CRT. It's basically in the same spot as it was when it came out. Seems tight and doesn't move.

Keep in mind that that Hot glue is very hot and can burn you badly. So I used a small amount keeping the tape wrapped around that coil in mind. I didn't want to melt it...L.O.L.

Question #2: I have no variable resistor at the coil. There might be somewhere in the 150 circuit. However.... When I fired up the 150 it was hardly off. Just a Minor adjustment on the side of the chassis and that was it. I have a 120 that needs alignment and the scope is good. It's sitting here waiting it's turn. I might just sell it as is. It does receive stations and was re capped completely. I think when I recapped it in doing the FM section I must have wacked that part out . It just has problems locking on stereo station in stereo. It does seem to tune ok but not sure after the recapp.

It was on ebay for a while but I pulled it off. I was going to send it to a Friend who has a Sencore SG80 Alignment unit. Most Vintage guys use that and they are like the holy Grail and hard to find if not impossible,

Hope I answered some of your questions,:

Mark R

 

[PCMALO]

Hi PCALMO

Question #1.. I used dabs of Hot Glue from a standard Hot Glue Gun. Just small 1/8th inch dabs across the top maybe three .. and then along the outside using 3 dabs as well. The right inboard side I could not safely get into that area . So I just let it be. The coil stops on its own when you push it up towards the front of the CRT. It's basically in the same spot as it was when it came out. Seems tight and doesn't move.

Keep in mind that that Hot glue is very hot and can burn you badly. So I used a small amount keeping the tape wrapped around that coil in mind. I didn't want to melt it...L.O.L.

Question #2: I have no variable resistor at the coil. There might be somewhere in the 150 circuit. However.... When I fired up the 150 it was hardly off. Just a Minor adjustment on the side of the chassis and that was it. I have a 120 that needs alignment and the scope is good. It's sitting here waiting it's turn. I might just sell it as is. It does receive stations and was re capped completely. I think when I recapped it in doing the FM section I must have wacked that part out . It just has problems locking on stereo station in stereo. It does seem to tune ok but not sure after the recapp.

It was on ebay for a while but I pulled it off. I was going to send it to a Friend who has a Sencore SG80 Alignment unit. Most Vintage guys use that and they are like the holy Grail and hard to find if not impossible,

Hope I answered some of your questions,:

Mark R

Thanks Mark. That helps a lot!

Yeah, on the 120B there are two wires coming off the coil. One connects to chassis ground. The other wire goes to a VR next to the CRT where two wires come off and connect to the tuner's power supply PCB (P800). I have highlighted the coil in this section of the schematic. I just don't know electronics enough to determine its function, however. Can you determine it?

 

[Punker X]

Thanks Mark. That helps a lot!

Yeah, on the 120B there are two wires coming off the coil. One connects to chassis ground. The other wire goes to a VR next to the CRT where two wires come off and connect to the tuner's power supply PCB (P800). I have highlighted the coil in this section of the schematic. I just don't know electronics enough to determine its function, however. Can you determine it?

View attachment 3287848

The coil is not a deflection coil. It a focus coil. The pot is a focus adjustment. Adjust for a pin point with no input.

 

[PCMALO]

The coil is not a deflection coil. It a focus coil. The pot is a focus adjustment. Adjust for a pin point with no input.

Thanks, Mike. I only referred to it as a deflection coil because that's what it's called in the Service Manual. The tuner also has a separate focus control at the back of the tuner, adjustable using a screwdriver, so I guess there are two ways to adjust for a pin point spot. So I guess as long as I have enough control using the focus adjusting screw at the back, I shouldn't need to mess with the internal VR.

 

[Mark R]

There yah go. The Old Focus coil...L.O.L. Thanks Mike for the answer. Also Remember..When your fiddling around in that High Voltage circuit.. make sure you safe. Those little scope circuits develop some Heart Stopping Voltage. Let us know how you make out.

Mark R.

 

[PCMALO]

Just to wrap up this thread... I found a NOS oscilloscope replacement - a Toshiba 85DB1 / 7J3 CRT - on eBay from seller AudioPathic Distractions (lilwing3) that worked perfectly to restore my Marantz 120B to full scope brightness! As of today, 9/17/24, he still has one available. I believe the same tube is used in the 150 tuner.

I followed the suggestion by @Mark R to loosen the deflection coil glue through patient application of acetone (and lighter fluid) and a gentle prodding with a plastic tuning tool and a small screwdriver with a thin blade. There was glue all along the front of the coil and 3/4" down the 4 "corners" of the tube. There was no glue at the rear of the coil. See attached picture.

After loosening the coil, removing the tuner's faceplate/cover (0107), the front scope cover (0507) and the rear tube bracket (1221), the tube can be slipped out the front. Then remove the metal tube shield (1225) and rubber buffer ring (1222) and reinsert them onto the new tube before inserting it back into the chassis and through the deflection coil.

I used a bead of kitchen and bath adhesive sealant along the front edge of the deflection coil to (hopefully!) affix it to the tube again.

After powering it up, I needed to adjust the deflection coil variable resistor (R013) to vertically align the scope trace better when in "tuner" mode.

Anybody looking for a nice refreshed 120B?

 

[Mark R]

Thanks For the UpDate...I'll go out and check the price. Good to hear you got your 120B rock-en again. My 120 is still in a box waiting for me to get back into it. Put it away after I recaped it and the FM alignment went out. My 120 does not have the same scope as the "B" model. It's a Marantz "120".Been busy finishing up a SENCORE SG 165 AM/FM alignment unit to Put up for sale.