View Full Version : Marantz 4400 CRT replacement by 2bp1


novanec
01-22-2013, 09:27 AM
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

http://medisoft.site40.net/2bp1.JPG
http://medisoft.site40.net/mar1.jpg
http://medisoft.site40.net/mar2.jpg
http://medisoft.site40.net/mar3.jpg
http://medisoft.site40.net/mar4.jpg
http://medisoft.site40.net/mar5.jpg
http://medisoft.site40.net/mar6.jpg

skibjr
01-22-2013, 11:25 AM
:tresbon: Wow - awesome tip!! There are quite a few of us 4400 owners out there with some pretty good burn-in on our scopes. For $30-40 bucks and some minor rewiring we'd be back in business.

Thank you!

(PS>> Possible to fix your picture links so we can have a look?)

jstang
01-22-2013, 12:07 PM
Very cool....Thanks....

I have two Russian replacements.... But the RCA is cheaper and easier to get....

Johnk

69sixpackbee
01-22-2013, 04:21 PM
Would the 2AP1 CRT work as well?
Thanx,
Bud

novanec
01-22-2013, 06:45 PM
hi..
possible, I compare the 2bp1 and have similar characteristics, but smaller diameter, attached the schematic below.

http://www.tubebooks.org/tubedata/Sylvania/1959/PT_2AP1-12KP4.pdf

Sandy G
01-22-2013, 07:08 PM
Fair Radio Sales in Lima, Ohio USED to have a pretty good supply of 2BP1s. I haven't seen a catalog of theirs in a long time, but I'd bet they still have 'em. They catered to the ham/Burgeoning Mad Scientist crowd.. The Audiophools kinda looked down their noses at 'em, but they never knew what they were missing, IMHO..

mech986
01-22-2013, 08:17 PM
This would be good news to those who need it, maybe also works in the similar 2110 and 2130 tuners with scopes?

Jailtime
01-23-2013, 02:17 AM
This would be good news to those who need it, maybe also works in the similar 2110 and 2130 tuners with scopes?

Don't see why it wouldn't work. My 2110 used the 50TB1. And the 4400 is packed much tighter, so space shouldn't be an issue either.

Sam Cogley
01-23-2013, 04:00 PM
Damn...you guys are making me want a Marantz with a scope. :D

jstang
01-23-2013, 07:19 PM
You gots to have a scope....

bktheking
01-23-2013, 07:29 PM
Scope's the shit!

http://imageshack.us/a/img593/9895/img2012052400019.jpg

Camman
01-24-2013, 04:25 PM
Updated mine but, used seperate filament transformer since the amperage requirement is much higher.
camman

Zillandia
02-28-2013, 03:29 PM
> Updated mine but, used seperate filament transformer since the amperage
> requirement is much higher.

Camman: Was this reference to the 2BP1 tube Novanec refers to ?

Has anyone else tried this substitution ?

Camman
02-28-2013, 03:58 PM
I believe the 50TB1 has a 160ma heater rating vs. 600ma rating for the 2BP1.
Haven't heard of anyone smoking the stock transformer heater winding but, I decided to just be safe and add seperate 6.3v 1 amp transformer.
camman

Zillandia
03-01-2013, 10:00 AM
Camman,
Thank you for shooting over that response so quickly !
I have 4 questions....

1. How did you know the current requirement of the 50TB1 Filament ?

2. Did you find the 50TB1 Pinout Specs somewhere ??
If so, will you share the source?

3. I assume you used Novanec's pin out modification illustration ?

4. Now that you have done the modification, how does it compare to the original performance wise ?

Camman
03-01-2013, 10:20 AM
I looked at my files but, can't find where I saw the heater spec.
The pinout is contained in the 4400 schematic.
No, my conversion was been done 2-3 years ago.
Changed my green crt to a "russian" blue phosphor crt. Works fine but, not quite as bright.
Please no worry about questions, glad to help!
camman

novanec
03-02-2013, 07:17 PM
HI..

these documents are of 50TB1 and 2BP1,

2BP1 = http://medisoft.site40.net/2BP1.pdf

50TB1 = http://medisoft.site40.net/50TB1Specs.gif


currently this modification, it works perfect, without modifying filament voltages, brightness is good, and I use the same power supply. I hope to serve the documents.

novanec
03-02-2013, 07:22 PM
Hi

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

Bye

Zillandia
03-06-2013, 07:39 PM
Hey Guys,
Sorry for the delay getting back to you both.
I didn't realize that there was a second page !!

Thank you both for the replies! They answered many questions.
Novanec: The pdf and gif images were GREAT and will be a great help
:thmbsp:

Camman: Yes, I have the 4400 schematic but I don't remember the pinout specs being there. Novanec's pdf helped out in this regard.

Also Camman:
How did you find a blue 2BP1 ????
I thought they were only available in green....

If you guys ever need help trouble shooting the 4400 or a 4300 I have outlined quite a number of issues on the schematic. I bought them new in 1976 and have serviced them many times over the years. If you plan to keep the receiver for the long haul, I can be reached directly: NetcomD(at)aol.com

Camman
03-06-2013, 08:41 PM
Zillandia,
The pinout spec's I thought you referred to was the pin# and internal connection.
The blue phosphor CRT is a Russian tube 5LO38M. Very difficult to locate these days. Found mine after an arduous Internet search. :boring:
camman

Zillandia
03-07-2013, 11:02 AM
Camman,
Now I'm more confused than I was before!
You used a 5LO38M blue in a 4400.
Did you also use a 2BP1 in another 4400 ?
:no:

Camman
03-07-2013, 11:07 AM
I have never installed a 2BP1 in a 4400.
The "M" is the code for blue phosphor.
camman

Zillandia
03-07-2013, 01:03 PM
oooooh!
Thanks for the clarification.

CIR Engineer
01-03-2015, 04:23 PM
Zillandia,
The pinout spec's I thought you referred to was the pin# and internal connection.
The blue phosphor CRT is a Russian tube 5LO38M. Very difficult to locate these days. Found mine after an arduous Internet search. :boring:
camman
Could you please provide the pinout for this tube (5LO38M)? I have one and would like to use it.

Thank you,
craigr

CIR Engineer
01-03-2015, 04:24 PM
Also, does anyone know if there is a RED phosphor tube that would work? I have been unable to find one. I think red could look really cool in my 2110 especially since there is the blue filter in front of it (should make magenta).

Does anyone know of any other blue phosphor scope tubes off hand? They are so much harder to come across than green!

craigr

Camman
01-03-2015, 05:37 PM
Here is a link.......
www.tubehobby.com/datasheets/5lo38.pdf
camman

CIR Engineer
01-03-2015, 05:44 PM
Sweet thanks!

It may take me some time to sort that all out, but it should suffice.

Best regards,
craigr

Camman
01-03-2015, 06:06 PM
I just used its pinout and compared it to a standard CRT like a 2ap1.

CIR Engineer
01-06-2015, 11:20 AM
Got it thanks.

Really not bad at all.

craigr

CIR Engineer
02-07-2015, 11:20 AM
I just used its pinout and compared it to a standard CRT like a 2ap1.
Could you please tell me what socket the 5LO38M (and also the 2AP1) use? Radiomuseam says "11-pim magnal base," but I am still not sure what base that is...

http://www.radiomuseum.org/tubes/tube_cv790.html

Are these the right ones?
http://www.ebay.com/itm/370695558647?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

Or these?
http://www.ebay.com/itm/261597269329?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT

I really would like to permanently mount the tube the right way with a socket, but I just want to be sure I get the correct one. I have heard they are difficult to find.

Thanks!
craigr

CIR Engineer
02-07-2015, 11:37 AM
...and what's the difference between a "Sub Magnal" and "Magnal" base? I know a lot about solid state, but little about tubes so I am somewhat out of my element here.

Thanks again,
craigr

Camman
02-07-2015, 12:15 PM
Craigr,
Those are not the correct sockets.
I found the correct one РШ19 (RSH19), U11, Magnal, B11-1, B11-33, and B11-66 or IN-1 @
http://www.gstube.com
Not in stock although :(

Camman

CIR Engineer
02-07-2015, 12:43 PM
Craigr,
Those are the correct sockets.
This one would be appropriate and will allow better clearance with metal ring removed.
http://www.ebay.com/itm/261597269329?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT&afsrc=1&rmvSB=true
THANK YOU THANK YOU THANK YOU!!!

Now I can stop pulling out what little hair I have left :yes:

Sub magnal is mounted beneath chassis where as magnal is mounted above chassis.

Camman
That's what I assumed, but I didn't want a simple mistake to wind up costing me. So thanks again.

I just ordered the sockets you linked me to.

craigr

Camman
02-07-2015, 01:03 PM
:D
camman

CIR Engineer
02-15-2015, 02:14 PM
Here is a link.......
www.tubehobby.com/datasheets/5lo38.pdf
camman
So I thought this would be a quick project once all the parts were here, but instead I am pulling out my hair. I have two CRT's here; the 2AP1 and the 5LO38M. Both tubes appear to have identical pinouts so I have been doing all my testing with the 2AP1 in case something goes wrong.

Well, I cannot get any illumination out of the 2AP1 I have here. I don't know if the problem is my wiring pinout or if the 2AP1 I have is defective or dead. I am afraid to test with the 5LO38M because I certainly don't want to fry that one. The only thing I am certain of is that the heater is correct because it lights up properly.

Could you please check my wiring?

2AP1 Pin 1 Heater H1 = Marantz Pin 1
2AP1 Pin 2 Cathode K = Marantz Pin 3
2AP1 Pin 3 Deflection #1 D1 = Marantz Pin 7
2AP1 Pin 4 Anode #1 A1 = Marantz Pin 4
2AP1 Pin 5 No Connection
2AP1 Pin 6 Deflection #2 D4 = Marantz Pin 12
2AP1 Pin 7 Anode #2 A2 = Marantz Pin 5
2AP1 Pin 8 Deflection #2 = Marantz Pin 9
2AP1 Pin 9 Deflection #3 = Marantz Pin 11
2AP1 Pin 10 Grid #1 = Marantz Pin 2
2AP1 Pin 11 Heater H2 = Marantz Pin 14

Is that right or what? It looks like the polarity of the deflections may be the other way, or that maybe the X-Y deflections are backwards?

This is frustrating the heck out of me because it should not be difficult!

I put my 2AP1 on my Sencore CR7000 CRT analyzer and I am not getting any emissions on the tester. However, none of these scope CRT's are in the Sencore refrence book, so I may be hooking the tube up wrong to the tester as well.

Help please :scratch2:

craigr

bktheking
02-15-2015, 02:22 PM
It should be pretty straightforward however have you confirmed x/y control voltages are adjusting and you have the required voltage to the rest of the tube?

CIR Engineer
02-15-2015, 02:40 PM
It should be pretty straightforward however have you confirmed x/y control voltages are adjusting and you have the required voltage to the rest of the tube?
I have the original 50TB1 still installed in the Marantz tuner and it works so I would expect that everything is in order.

I found a post in google groups that shows a wildly different pinout than what novanec has in his first post for the conversion to 2BP1. I don't think the info on google is correct though?

https://groups.google.com/forum/#!topic/rec.audio.tubes/etPmtNYDFfU

The poster shows this:
**Pin 1: Heater
Pin2: G1
Pin 3: K
Pin 4: P1
Pin 5: X-
Pin 6: X+
Pin 7: G2
Pin 9: G1
Pin 11: P2
Pin 12: Y+
Pin 13: Y-
Pin 14: H

Connections to P900:

Pin # PCB #
1 J930
2 J932
3 J931
4 J934
5 J929
6 J928
7 J927
11 J927
12 J926
13 J925
14 J933

That's not what my schematics for the 2110 show though either.

Thanks,
craigr

bktheking
02-15-2015, 02:48 PM
I performed the pinout conversion using novanec's conversion and it worked perfectly. What is this tuner you speak of?

CIR Engineer
02-15-2015, 02:50 PM
It should be pretty straightforward however have you confirmed x/y control voltages are adjusting and you have the required voltage to the rest of the tube?
Now you have me thinking though... I did not try the centering controls when I was testing the 2AP1. The centering controls are near the midpoint and this centers the trace on the original 50TB1. However, I wonder if it is possible that the trace needs such radically different centering offsets that perhaps my trace was not hitting the phosphor surface and just shooting off the face of the 2AP1. Do you think that is possible?

craigr

Camman
02-15-2015, 02:51 PM
Hi Craig,
Even though the connections look correct, I did not use a 2AP1 connected to my Marantz 4400.
I just used the pin layout to determine the matching connections of the 5LO38M. (They both have 11pins.)
Attached pictures of connections I used and adapter I constructed to maintain stock CRT socket.
Hope this helps.
Let me know!

576055
576058

CIR Engineer
02-15-2015, 02:51 PM
I performed the pinout conversion using novanec's conversion and it worked perfectly. What is this tuner you speak of?
I'm running a 2110 and it uses the same 50TB1 so it should have the same pinout as novanec's.

Thanks for your help.

craigr

bktheking
02-15-2015, 02:59 PM
2AP1 and 2bp1 are almost the same tube, they should interchange, 2bp1 being an even better performer. If you have the 50tb1 tube did you try it in the 4400 to verify the circuit works?

CIR Engineer
02-15-2015, 03:47 PM
Hi Craig,
Even though the connections look correct, I did not use a 2AP1 connected to my Marantz 4400.
I just used the pin layout to determine the matching connections of the 5LO38M. (They both have 11pins.)
Attached pictures of connections I used and adapter I constructed to maintain stock CRT socket.
Hope this helps.
Let me know!

576055

All right, we are practically the same. However, my +/-X is reversed to yours. Could this actually cause no image on the tube face though?

Thank you,
craigr

Camman
02-15-2015, 03:56 PM
No, I don't believe so.
If moving left/right, up/down and intensity pots don't show an image, I would say there is a problem with the 4400's circuitry or CRT.

CIR Engineer
02-15-2015, 03:57 PM
2AP1 and 2bp1 are almost the same tube, they should interchange, 2bp1 being an even better performer. If you have the 50tb1 tube did you try it in the 4400 to verify the circuit works?
The 50TB1 is the OEM tube and yes, it is installed in the tuner. The tuner is a Model 2110.

The 2AP1 and 2BP1 have similar specifications, but different pinouts. I am trying to test with a 2AP1 first to just get the 2AP1 working to verify the concept. The 2AP1 has an identical pinout to the 5LO38M and I want to use the 5LO38M. The 5LO38M is the Russian copy of the 2AP1, but has blue phosphor.

The 5LO38M tubes are extremely difficult to get and the 2AP1's are easy to get which is why I am testing with a 2AP1 first.

All of this is just to get a blue phosphor tube in the scope. It may be worth it in the end, but I did not expect to have this level of difficulty!

Thanks,
craigr

CIR Engineer
02-15-2015, 03:58 PM
No, I don't believe so.
If moving left/right, up/down and intensity pots don't show an image, I would say there is a problem with the 4400's circuitry or CRT.
Everything works perfectly with the OEM 50TB1 tube.

So I don't think there is anything wrong with the tuner (2110) circuitry.

craigr

Camman
02-15-2015, 04:07 PM
Hmm, Ok.
Maybe check with lights dimmed?
Otherwise, I would do a voltage comparision of each pin for both tubes.

CIR Engineer
02-15-2015, 05:20 PM
So after confirming my wiring with what Camman provided I went ahead and wired up the 2AP1 again with the same polarity on the deflection that Camman used. As expected changing the polarity had zero effect. I then tried turning brightness all the way up, moving horizontal and vertical centering all over the place, and even trying the horizontal and vertical offsets on the PCB and this also had no effect. I was in a dimly lit room as well.

So having confidence in the wiring being correct by a second set of eyes I went ahead and wired in the 5LO38M. Unfortunately, this tube also shows no illumination no matter where I set the controls :tears:

So at this point neither the 2AP1 nor the 5LO38M are working for me :no:

I put everything back together and have given up for now. I will think about it some...

Thanks to all for the help, especially you Camman.
craigr

CIR Engineer
02-15-2015, 05:24 PM
One thing I just though of... when testing these tubes I have had them sitting next to the tuner on the table and have connected them to the tuner using wire leads with alligator clips to the OEM socket. I have not removed the 50TB1 OEM tube and have not installed the electrostatic electromagnetic shield over the new tube.

Could it be possible that the shield is required for the tube to function properly? By not testing with the shield, could this be causing all my woes?

craigr

bktheking
02-15-2015, 05:37 PM
Nope, no shield, all it does is hold the tube. I've had the tube in my hand working.

CIR Engineer
02-15-2015, 05:40 PM
Nope, no shield, all it does is hold the tube. I've had the tube in my hand working.
Kind of what I thought, but I am grasping at straws now.

Thanks,
craigr

bktheking
02-15-2015, 06:12 PM
Plug in the new tube, turn it on for a minute set to tuning and shut it off in the dark, you should see it center after it loses voltage.

Camman
02-15-2015, 06:16 PM
Craig,
The 50TB1 is removed from socket while the 2AP1 is connected?
Did you check that there is the same voltages directly at the 2AP1 tube pins?

Camman
02-15-2015, 06:47 PM
One other thought
Edit: Bad Info!

CIR Engineer
02-15-2015, 07:00 PM
Plug in the new tube, turn it on for a minute set to tuning and shut it off in the dark, you should see it center after it loses voltage.
Really good idea. I will try that when I regain some stamina for this simple project.

Thank you,
craigr

CIR Engineer
02-15-2015, 07:03 PM
Craig,
The 50TB1 is removed from socket while the 2AP1 is connected?
Yes, only one tube at a time is connected to the tuner.

Did you check that there is the same voltages directly at the 2AP1 tube pins?
I did not check that. I would be shocked if the 50TB31 worked if there was a voltage problem, but again I am grasping at straws so it's worth a look.

*I noticed that I have been saying 50TB1, but I actually have the "blue" 50TB31 phosphor OEM tube. Pinout is the same so this should not be any issue.

craigr

CIR Engineer
02-15-2015, 07:17 PM
One other thought,
When making the connections looking at the back of the 2AP1, pin one is on the right of the keyway 2,3,4-11 pins are then counterclockwise.
When looking at the tubes from the back the pins are number clockwise and I have been going by that. Do you think they are actually numbered backwards on the tube socket?

Left is the 5LO38M and right is the 2AP1.

http://www.cir-engineering.com/bin/tubes.jpg

Thanks,
craigr

CIR Engineer
02-15-2015, 07:25 PM
One other thing is that I am using an external power supply for the 6.3 volts on the heater. The 2110 only has a .3 amp fuse on the heater power supply and the .6 amps of the 2AP1/5LO38M cause the fuse to blow (obviously). I also don't want to double the heater load on the hard to replace transformer.

craigr

Camman
02-15-2015, 07:54 PM
Sorry,
:no:Back of socket not CRT:no:
Your 5LO38M pin diameter is larger than mine.
PM sent

CIR Engineer
02-15-2015, 08:02 PM
One thing I just though of... when testing these tubes I have had them sitting next to the tuner on the table and have connected them to the tuner using wire leads with alligator clips to the OEM socket. I have not removed the 50TB1 OEM tube and have not installed the electrostatic electromagnetic shield over the new tube.

Could it be possible that the shield is required for the tube to function properly? By not testing with the shield, could this be causing all my woes?

craigr
All right, I think this idea may have possibly lead me to the solution. I am not motivated enough to try again today, but maybe tomorrow after work.

I have been working on the new tube by laying it next to the tuner. There is about 8" of shelf and then next to that is a speaker that is shielded, but the new tube is still only about 4" from this large speaker. I think the magnets in the speaker are pulling the beam off the face of the tube!

I just took the cover back off the tuner and slid the tuner close to the speaker. The electromagnetic shield is on the installed tube, but even still, the trace went from center to nearly off the bottom of the tube and I didn't even get the tube as close to the speaker as the test tubes have been.

So it just may be that this issue has nothing to do with the tube or wiring and everything to do with an unfortunate placement of the experiment.

We'll see I guess.

craigr

CIR Engineer
02-15-2015, 08:03 PM
Sorry,
:no:Back of socket not CRT:no:
Your 5LO38M pin diameter is larger than mine.
PM sent
Darnet, so the sockets that are coming tomorrow probably won't fit.

Live and learn I guess :)

craigr

bktheking
02-15-2015, 09:45 PM
If a magnet were close it would certainly move the beam. Try without a magnet beside the tube.

CIR Engineer
02-18-2015, 07:49 AM
If a magnet were close it would certainly move the beam. Try without a magnet beside the tube.
: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

CIR Engineer
02-18-2015, 07:51 PM
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

bktheking
02-18-2015, 07:58 PM
If you figure out how to rejuvinate I'd love to send you some tubes :D.

CIR Engineer
02-19-2015, 08:14 AM
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