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 Post subject: MOTOROLA 9L1
PostPosted: Nov Wed 07, 2018 4:22 pm 
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Joined: Sep Tue 08, 2009 5:37 pm
Posts: 269
Location: Southington, ct
I just acquired a nice 9L1, which has an 8 inch tube with the porthole face. I know the CRT has filament continuity, but want to test it better before working on the recapping. Is it safe to plug this into one of my 7JP4 sockets as I believe the pins are the same. That way I can see how good the tube projects. I was told they are the same, but the 8 inch is just a larger tube. Thanks for commenting.


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 Post subject: Re: MOTOROLA 9L1
PostPosted: Nov Wed 07, 2018 5:11 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 713
Location: Crystal Bay, NV
Yes, electrically it is the same as a 7JP4.
------
Ron


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 Post subject: Re: MOTOROLA 9L1
PostPosted: Nov Wed 07, 2018 5:42 pm 
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Joined: Feb Thu 17, 2011 11:27 pm
Posts: 11674
Location: Long Island, N.Y.
That was as big as electrostatic CRT's got in the late '40's-early '50's. It's a hard to find tube and one that it often found bad. I got a 9T1 a while back and was disappointed to learn the CRT was shot. I had to buy a donor set from a friend just to get another CRT, and that one is just passable. I've actually seen 7JP4's in these sets with large masks! Even those are getting much harder to find.
Good luck with your set.


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 Post subject: Re: MOTOROLA 9L1
PostPosted: Nov Thu 08, 2018 11:37 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Elkhorn,Wisconsin,United States
There were a few post war sets using the electrostatic 10HP4 crt too. I suspect quite a rarity.
Ed


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 Post subject: Re: MOTOROLA 9L1
PostPosted: Nov Fri 09, 2018 12:23 am 
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Ed Kozak wrote:
There were a few post war sets using the electrostatic 10HP4 crt too. I suspect quite a rarity.
Ed

I would be interested to know what set/s that was. I've had a focus on vintage TV's for many years and never heard of it.


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 Post subject: Re: MOTOROLA 9L1
PostPosted: Nov Fri 09, 2018 12:57 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Crystal Bay, NV
I don't know where they were used, but here's more large electrostatic tubes:
10GP4, 14AP4, and 20AP4.
I think Dumont used one of these pre-war.
=====
Ron


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 Post subject: Re: MOTOROLA 9L1
PostPosted: Nov Fri 09, 2018 1:17 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 713
Location: Crystal Bay, NV
Incidentally, I have a spare 8Bp4 if somebody is desperately looking for one. I'd haven't even tested it, but it's probably good.
And, yes, it was Dumont who made the 14AP4 (1939) and 20AP4 (1940).


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 Post subject: Re: MOTOROLA 9L1
PostPosted: Nov Fri 09, 2018 9:23 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 312
Location: Elkhorn,Wisconsin,United States
decojoe67 wrote:
Ed Kozak wrote:
There were a few post war sets using the electrostatic 10HP4 crt too. I suspect quite a rarity.
Ed

I would be interested to know what set/s that was. I've had a focus on vintage TV's for many years and never heard of it.


Hi decojoe67,
I had to go digging a little through the Rider's. I thought I had seen a schematic with a 10HP4 crt in an early set and I found one so far . I think there are a few more that may have been sold too. The set that is supposed to come with a 10 inch electrostatic crt is the " Belmont 22AX22 ". It has a published picture size of 8.25 x 6.25 inches. This set is listed in Riders television 1- 25 thru 1-45 for the early Belmont sets. There are some parts variations in the schematic on 1- 433,44 for the 10" crt version versus the more common 7JP4, 7" crt. When I find some other sets I'll post them.


Another schematic using a 10HP4 is a Certified Radio Labs model 48-10. It's published in Riders volume 1- 13,14 for Certified Radio Labs. This may have been a kit set, its' schematic looks like a pre-war set. I've never seen one.

Another set , Republic model TL-10. Published in Riders 1-7,8. The set uses a 10HP4 and post war FM sound. The schematic is dated 2-7-1948.
Ed


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 Post subject: Re: MOTOROLA 9L1
PostPosted: Nov Fri 09, 2018 11:25 am 
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Joined: Feb Thu 17, 2011 11:27 pm
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Location: Long Island, N.Y.
Ed Kozak wrote:
decojoe67 wrote:
Ed Kozak wrote:
There were a few post war sets using the electrostatic 10HP4 crt too. I suspect quite a rarity.
Ed

I would be interested to know what set/s that was. I've had a focus on vintage TV's for many years and never heard of it.


Hi decojoe67,
I had to go digging a little through the Rider's. I thought I had seen a schematic with a 10HP4 crt in an early set and I found one so far . I think there are a few more that may have been sold too. The set that is supposed to come with a 10 inch electrostatic crt is the " Belmont 22AX22 ". It has a published picture size of 8.25 x 6.25 inches. This set is listed in Riders television 1- 25 thru 1-45 for the early Belmont sets. There are some parts variations in the schematic on 1- 433,44 for the 10" crt version versus the more common 7JP4, 7" crt. When I find some other sets I'll post them.


Another schematic using a 10HP4 is a Certified Radio Labs model 48-10. It's published in Riders volume 1- 13,14 for Certified Radio Labs. This may have been a kit set, its' schematic looks like a pre-war set. I've never seen one.

Another set , Republic model TL-10. Published in Riders 1-7,8. The set uses a 10HP4 and post war FM sound. The schematic is dated 2-7-1948.
Ed

Very interesting Ed. That puts a little change in my thinking about early TV's. Even a friend I have who's been collecting and restoring vintage TV's since the '60's always mentioned that the 8" was the biggest. I would like to see what those sets looked like. They must be very uncommon. One thing for sure, it would be basically be impossible to find a replacement tube for one.


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 Post subject: Re: MOTOROLA 9L1
PostPosted: Nov Fri 09, 2018 2:57 pm 
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Joined: Sep Tue 08, 2009 5:37 pm
Posts: 269
Location: Southington, ct
Connected the CTR to my Sentinel 7 inch set and it works great!, the chassis looks untouched, all the big bulky wax Motorola caoacitors in place. Is this an easer set to try to restore? I have done some radios, but not Tv's. I would like to give it a try. Thanks for all the comments. Now on to testing the tubes.


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 Post subject: Re: MOTOROLA 9L1
PostPosted: Nov Fri 09, 2018 3:17 pm 
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Joined: Feb Thu 17, 2011 11:27 pm
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Location: Long Island, N.Y.
davidff wrote:
Connected the CTR to my Sentinel 7 inch set and it works great!, the chassis looks untouched, all the big bulky wax Motorola caoacitors in place. Is this an easer set to try to restore? I have done some radios, but not Tv's. I would like to give it a try. Thanks for all the comments. Now on to testing the tubes.

Excellent! You're lucky with your CRT. Maybe others can chime in with technicalities, but from my experience in dealing with repairman, the Motorola's are not a particularly difficult chassis to restore. The one common issue with them, and I've had several over the years, is arcing problems. This can cause "pie-crusting" of the picture and/or audio interference.


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 Post subject: Re: MOTOROLA 9L1
PostPosted: Nov Fri 09, 2018 4:29 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 713
Location: Crystal Bay, NV
The bleeder resistors in the HV section (typically 2.2 Meg or so) usually need to be replaced since their values are off by more than 20%.

You have picked a great set to start on. The Motorola chassis was way ahead of the competition in terms of engineering. I like it for the styling of their cabinets too, especially the 7" bakelite models.
====
Ron


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 Post subject: Re: MOTOROLA 9L1
PostPosted: Nov Fri 09, 2018 8:16 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 312
Location: Elkhorn,Wisconsin,United States
davidff wrote:
Connected the CTR to my Sentinel 7 inch set and it works great!, the chassis looks untouched, all the big bulky wax Motorola caoacitors in place. Is this an easer set to try to restore? I have done some radios, but not Tv's. I would like to give it a try. Thanks for all the comments. Now on to testing the tubes.

Hi Daviff,
Glad your 8JP4 is usable. If your chassis is a TS-18 or TS-18a then you have a hot chassis set. Also you may want to check the condition of the ballast tube for this model. If it is not a glass tube version, then you will have to most likely make up a modern substitute.
Ed


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