Videokarma.org

Go Back   Videokarma.org TV - Video - Vintage Television & Radio Forums > Solid State CRT Televisions

We appreciate your help

in keeping this site going.
Reply
 
Thread Tools Display Modes
  #1  
Old 10-11-2017, 08:22 PM
lnx64's Avatar
lnx64 lnx64 is offline
VideoKarma Member
 
Join Date: Jan 2012
Location: New Port Richey, FL
Posts: 1,787
Tandy CRT swap

Not a television, but couldn't decide which section to put this in. Asking for a friend.

He's trying to swap out the CRT to a Tandy 80 model 4, but he can't get an image on it. He has the heaters lighting up, but there's nothing on the screen.

The CRT in the Tandy 80 model 4 is usually a 12VCMP31

The CRT's he's tried are:
1. MN1215H8AU - CPJ310N1U (Two numbers on the same CRT)
2. MP1433H8AU - CPJB340AHE (Two numbers on the same CRT)
3. 310KLMA

He has found that if he puts the Tandy's monitor in where the replacement CRT's are pulled, it produces an image that's far too bright. I was thinking maybe a G2 control on the Tandy's flyback could help? But he says there's no G2 control.

Hopefully anyone can help! Thanks in advance.

Last edited by lnx64; 10-11-2017 at 08:26 PM.
Reply With Quote
  #2  
Old 10-12-2017, 08:55 AM
zeno's Avatar
zeno zeno is offline
VideoKarma Member
 
Join Date: Mar 2013
Location: New Hampshire
Posts: 4,672
Is it a monochrome set ? If so no G-2 control. Most CRT's
probably use the same basing & apx voltage. Start with the
original tube & write down the voltages. Then do the same
with a new one. IIRC the Tandys used a modified RCA B&W
Get some nudies & maybe we can figure out the chassis or see
if its got a KCS### stamped on the chassis.

73 Zeno
LFOD !
Reply With Quote
  #3  
Old 10-12-2017, 09:54 AM
tom.j.fla tom.j.fla is offline
VideoKarma Member
 
Join Date: Aug 2014
Location: Dover,Fl
Posts: 250
Zeno, that was true for TRS-80 model 1. That monitor was a moded KCS201. The model 3 & 4 had a custom monitor made by RCA still based on the KCS201, 12 volt only setup and hor. and vert. sweep. Had ttl video. By the by still have 6 model 4s' in use for our farm operations. Who says we yanks didn't know how to make good stuff. All the best,Tom.J
Reply With Quote
  #4  
Old 10-12-2017, 10:46 AM
Jon A.'s Avatar
Jon A. Jon A. is offline
Don't mess with Esther.
 
Join Date: Jun 2013
Location: Canada
Posts: 4,267
Quote:
Originally Posted by tom.j.fla View Post
Who says we yanks didn't know how to make good stuff. All the best,Tom.J
I've never heard anyone say such a thing. I'm knocking myself out all the time trying to get stuff made in the US or Canada, and sometimes Japan.

By the way, what are the model 4's used for?

I used to have the TV the model 1 monitor was based on, it was made in 1977. It would be nice to get hold of another.
Reply With Quote
  #5  
Old 10-12-2017, 11:35 AM
Electronic M's Avatar
Electronic M Electronic M is offline
M is for Memory
 
Join Date: Jan 2011
Location: Pewaukee/Delafield Wi
Posts: 14,758
The brightness and sub-brightness (a service adjustment) may have been cranked to get the most from the old weak CRT, and may need to be backed down with a healthy one installed.
__________________
Tom C.

Zenith: The quality stays in EVEN after the name falls off!
What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4
Reply With Quote
Audiokarma
  #6  
Old 10-12-2017, 12:09 PM
tom.j.fla tom.j.fla is offline
VideoKarma Member
 
Join Date: Aug 2014
Location: Dover,Fl
Posts: 250
Jon A., Our 4's are used for bookkeeping, crop and live stock records and inventory control for material for the up keep of equipment and buildings. Yes we have the latest wiz-bang 'puters for the web and streaming but the 4's do records keeping a heck of a lot better then the new stuff. All the best, Tom.J
Reply With Quote
  #7  
Old 10-12-2017, 01:26 PM
lnx64's Avatar
lnx64 lnx64 is offline
VideoKarma Member
 
Join Date: Jan 2012
Location: New Port Richey, FL
Posts: 1,787
Quote:
Originally Posted by zeno View Post
Is it a monochrome set ? If so no G-2 control. Most CRT's
probably use the same basing & apx voltage. Start with the
original tube & write down the voltages. Then do the same
with a new one. IIRC the Tandys used a modified RCA B&W
Get some nudies & maybe we can figure out the chassis or see
if its got a KCS### stamped on the chassis.

73 Zeno
LFOD !
I'll see if I can get some pics of the board from him. I tried to Google it but oddly can't find anything, but yea, it's a Monochrome set.

He wanted to change it from a green phosphor CRT to amber.
Reply With Quote
  #8  
Old 10-12-2017, 04:42 PM
CoogarXR's Avatar
CoogarXR CoogarXR is offline
VideoKarma Member
 
Join Date: Feb 2011
Posts: 641
I had a TRS-80 Model 4 shipped to me a while back. It arrived smashed. I took pictures, maybe these will help identify the CRT specs?:
Attached Images
File Type: jpg RIMG0099.jpg (87.1 KB, 44 views)
File Type: jpg RIMG0302.jpg (55.9 KB, 32 views)
File Type: jpg RIMG0303.jpg (56.3 KB, 40 views)
Reply With Quote
  #9  
Old 10-12-2017, 07:37 PM
MIPS's Avatar
MIPS MIPS is offline
VideoKarma Member
 
Join Date: Jun 2014
Location: West Canadia
Posts: 1,006
Quote:
Originally Posted by CoogarXR View Post
I had a TRS-80 Model 4 shipped to me a while back. It arrived smashed. I took pictures, maybe these will help identify the CRT specs?:
Ugh, I can tell you first hand that the model III and model 4 are the biggest pains in the asses to economically shit. You pretty much have to remove the CRT and box it separately because as you found out as well their mounts don't hold up to modern logistics.
Reply With Quote
  #10  
Old 10-13-2017, 01:36 AM
Jon A.'s Avatar
Jon A. Jon A. is offline
Don't mess with Esther.
 
Join Date: Jun 2013
Location: Canada
Posts: 4,267
Quote:
Originally Posted by tom.j.fla View Post
Jon A., Our 4's are used for bookkeeping, crop and live stock records and inventory control for material for the up keep of equipment and buildings. Yes we have the latest wiz-bang 'puters for the web and streaming but the 4's do records keeping a heck of a lot better then the new stuff. All the best, Tom.J
That's awesome, keeps things interesting as well as keeping costs down. The only reason I use relatively recent computer technology is to keep up with the demands of the internet.
Reply With Quote
Audiokarma
  #11  
Old 10-17-2017, 04:44 PM
lnx64's Avatar
lnx64 lnx64 is offline
VideoKarma Member
 
Join Date: Jan 2012
Location: New Port Richey, FL
Posts: 1,787
I still haven't heard from him in a while to either relay him information here, or get information, sorry about the delay.
Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -5. The time now is 04:11 AM.



Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
©Copyright 2012 VideoKarma.org, All rights reserved.