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Marantz 150 Scope queston

I don't recall a beam intensifier circuit- my kc6060 lab scope has that, the beam will actually disappear with no signal present.
 
Does the Marantz scope autoblank in FM/multipath mode with no sig?

Sent from my SM-N900V using Tapatalk
 
Here are the voltages at the scope pins, taken with a focused bright dot:

PCB 900 specified voltages with bright dot
Pin # Pin # Voltage Read with Fluke 87 III
1 J930 ===== -970 -965 6.22ACv
2 J932 ===== -960 -959
3 J931 ===== -970 -948 Bright varies -873 to -956
4 J934 ===== -840 -828 Focus varies -447 to -956
5 J929 ===== +120 +118
6 J928 ===== +120 +113
7 J927 ===== ?
11 J927 ===== +120 +119
12 J926 ===== +120 +117
13 J925 ===== +120 +116
14 J933 ===== -970 -963 6.22ACv

About the beam intensifier, The Handbook of Instructions says on the bottom of page 5 under section 3: "adjust BRIGHT so that the dot is barely visible. Automatic beam intensifier circuitry will brighten the display when trace deflecting signals are applied to the horizontal or vertical amplifiers."
 
Oh, that's just normal with any scope unit, since your maxed out on intensity I would say your scope tube is shot. So during normal daylight you can't see it, lights out in the dark you can see it but it's not bright?

I have a spare untested tube.
 
That's right, the display has to be in the dark to see any activity. I could use your spare untested tube if you want to sell it.
 
Bought a working CRT from Brad and when installed it provided a bright display when in the audio mode - so problem was the original CRT. I took the original CRT and tried to rejuvenate it and it did get a bit brighter but still showed no display in the audio mode, however, it was useable in the tuning mode. Next step is to align the 150.
 
Reviving this thread hopefully some member can provide new clue to where I can purchase a toshiba cathode ray tube 85db1/7j?

Seems like nothing online and no replacement. Did any of you guys locate a suitable aftermarket replacement CRT perhaps??
Any advise would be appreciated.
Barkai
 

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You sure your CRT is dead and not the circuit itself or possibly the transformer? What have you done to diagnose?
 
Thanks for the super quick reply!
I'm not sure but my tech thinks so. I want to purchase a CRT as a replacement either way since this tuner is a keeper :)
Would love to find a functional NOS or even another brand (other than Toshiba) which may work...
 
Haven't found anything that will sub, I had bought a parts unit that had a spare. Your tech needs to determine if it's the circuit either way.
 
Thanks bktheking I will keep my eyes open for whatever I found either one for parts or an actual CRT which are so rare.
I did just purchase a non-working Kenwood kc-6060a as a project so if I can get it restored I would play with the scope on it as well.
Split the fun I mean :)
upload_2021-2-21_10-28-10.png
 
bktheking said:
It shows -971 v dc, maybe cir engineer can explain, it was told to me once that they were cold cathode heaters.
Click to expand...
Your scope tube is a CRT it has to heat up the cathode to produce thermionic emission. Also since it's static deflection your 2nd anode is not under a rubber cap it is part of the pin socket and yes it's around 2KV, so be extra careful it will bite hard.
 
@Itchyru I ended up not needing a new CRT tube replacement after all. My tech managed to fix the issue was something else.
I keep a few alerts in ebay and Reverb for NOS CRT for the audioscopes I own.
Nothing new in a long time which means impossible to find a replacement when picture dies out :(

List of Audioscopes:
Marantz 150
Kenwood kc-6060a
Sony VT-M5
MCS VTR component TV

Barkai
Obsessed with audioscopes :)
 
There is a Pioneer SD-1100 Audioscope for sale now on ebay for crazy money.
I wish I could justify it, my holy grail...enjoy!

upload_2023-4-14_12-15-46.png

Barkai
 
Barkai said:
@Itchyru I ended up not needing a new CRT tube replacement after all. My tech managed to fix the issue was something else.
I keep a few alerts in ebay and Reverb for NOS CRT for the audioscopes I own.
Nothing new in a long time which means impossible to find a replacement when picture dies out :(

List of Audioscopes:
Marantz 150
Kenwood kc-6060a
Sony VT-M5
MCS VTR component TV

Barkai
Obsessed with audioscopes :)
Click to expand...
You know you can rejuvenate most CRT's? I have a beam builder and have done hundreds. I don't know about today, but 20 years ago CRT's were rebuilt by cutting the neck off and putting a new gun assembly in them. They were just as good as new, but 1/2 the price of a new replacement.
 
Barkai said:
@Itchyru I ended up not needing a new CRT tube replacement after all. My tech managed to fix the issue was something else.
I keep a few alerts in ebay and Reverb for NOS CRT for the audioscopes I own.
Nothing new in a long time which means impossible to find a replacement when picture dies out :(

List of Audioscopes:
Marantz 150
Kenwood kc-6060a
Sony VT-M5
MCS VTR component TV

Barkai
Obsessed with audioscopes :)
Click to expand...
What was the issue, in case mines the same
 
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