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Marantz 4400 CRT replacement by 2bp1

bktheking said:
If a magnet were close it would certainly move the beam. Try without a magnet beside the tube.
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:scratch2: ya think?

:D

I put this project on hold for a couple days because I was busy and I wanted to just wait for the sockets to make my temporary connections more secure. I think I will have time to try again today or perhaps this evening… if not than tomorrow as I have most of the day off.

I'll report back once I have tested.

craigr
 
So it turns out I had two factors working against me.

1) My 2AP1 tube is dead and nonfunctional.

2) The speaker that was next to my test tubes was also pulling the beam off the face of the tube. When I hooked the 5LO38M away from the speaker on my work bench the phosphor lit right up.

Unfortunately, the NOS 5LO38M that I have here is VERY dim. I suspect that it is leaky so hopefully my alternate 5LO38M that is coming will be brighter. I know the pure blue phosphor tubes are dimmer, but the 5LO38M that I have here is too dim to be useful for anything.

So when the new 5LO38M gets here I will try again. The blue color of the phosphor is magnificent and matches the dial nearly perfectly (maybe slightly too blue even). Here is a video showing the tube lit up with the brightness all the way up in a nearly dark room. Unlike the OEM tube that shows up very blue in photos, but is actually more turquoise in color, this tube is pure blue and the color you see in the video is the actual color of the tube in real life.

http://www.cir-engineering.com/bin/bluescope.MOV

Funny how often the very simple projects turn into really long and drawn out projects due to silly variables.

Oh well, thanks to all.

craigr
 
I have a Sencore CR7000 here. I did rejuvenate my 50TB31 with success. I'd be willing to try any tube you want me to as long as you send me a printout with the tube pinout along with so I don't have to dig up the info.

You can PM me, but someone said they PM'ed me here and I didn't get the message (I have gotten others). Feel free to email if you want.

craigr
 
novanec said:
Heater current

Hi

I forget, the heater current for 50TB1 is 6.3v 0.3 amp and for 2BP1 6.3 v 0.6 amp..

Bye
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Do you have to change the fuse to a higher Amperage for the 2BPI? I’m trying to use a 2BPI in my 4400 but it keeps blowing fuse #1 0.5A
 
I did conversion to 2bp1 tube and everything works fine. Just needed to change fuse 1 to 800mA one and everything is fine now. I have one question, there is 2bp11 tube which is blue one. Has anyone tried to use that one? In manual, everything is same as 2bp1 except Persistence (don't even know what does it mean in tubes) 2bp1 (medium) 2bp11 (short). Other question is are those 2bp11 easy to find there in States? Because here in Europe they are also very rare to find.
 
any chance someone may know where to find a replacement tube for the 4400? mine has a dead center burnout spot, and it keeps deflecting beams across the screen
 
james may said:
any chance someone may know where to find a replacement tube for the 4400? mine has a dead center burnout spot, and it keeps deflecting beams across the screen
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You are not going to be able to find one, they are unobtanium (50tb1 tube) except if you buy for example faulty Marantz 2110 Tuner with working tube and use that one. This forum is about people who had same problem and did swap from 50tb1 to 2bp1 tube. 2bp1 is still around.
 
it may be a little petty for me to want to spiff up the old birds beak, but god those screens are fun to look at. most of the unit is rebuilt, maybe a few things here and there to get it finished, and itl never be mint. i would still love to fix up the o-scope.
 
novanec said:
Hi

I have a marantz 4400, the CRT is damaged, is the 50tb1, but I could be replaced using the RCA crt 2bp1, works perfect, without modifying the circuit or voltages, only changing the connector pins, attached diagram. This is achieved crt on ebay at a price of 30 dlls, is very easy to get, unlike the original which cost 300 dlls, and is very difficult to achieve, is 2 inches in diameter by 6 long. I hope to serve.

http://medisoft.site40.net/2bp1marantz.html

2bp1.JPG

mar1.jpg

mar2.jpg

mar3.jpg

mar4.jpg

mar5.jpg

mar6.jpg
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Hello,
Will this work as a replacement for the Scope of the 4400?
General Electric 2BP1 (CV3678) NOS CRT Tube
Thanks!
 
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