Repair of ancient monitor - Teleray model 7R circa 1988

[Steve]

I have been given the challenge to fix the above old monochrome
monitor, a Teleray model 7R made by Research inc, which is completely
dead. It consists of a tube, CRT drive circuit board, PSU board and a
big logic board (it displays only text, is not a 'picture' monitor). I
have been unable to find any service information for it , even using
web searches for the manufacturers.
It seems to have a PSU fault, again each board is long obsolete without
any info I can find on the web. Although I can do some fault finding,
the PSU is switched mode and relies on feedback from the other boards
to operate, and also needs to be loaded, so it's like finding the break
in a contionuous circle. Added to that fact is that I live in Saudi
Arabia and the monitor had been taken to a local repair shop so I can't
even guarantee the components are the correct ones without service
data. This monitor is part of a larger old test station and there are
no compatible newer monitors due to the age/programming of the rest of
the test station.

So if anyone knows of anywhere I could get such information, I would be
very grateful.

 

[Luke Siemaszko]

I have been given the challenge to fix the above old monochrome
monitor, a Teleray model 7R made by Research inc, which is completely
dead. It consists of a tube, CRT drive circuit board, PSU board and a
big logic board (it displays only text, is not a 'picture' monitor). I
have been unable to find any service information for it , even using
web searches for the manufacturers.
It seems to have a PSU fault, again each board is long obsolete without
any info I can find on the web. Although I can do some fault finding,
the PSU is switched mode and relies on feedback from the other boards
to operate, and also needs to be loaded, so it's like finding the break
in a contionuous circle. Added to that fact is that I live in Saudi
Arabia and the monitor had been taken to a local repair shop so I can't
even guarantee the components are the correct ones without service
data. This monitor is part of a larger old test station and there are
no compatible newer monitors due to the age/programming of the rest of
the test station.

So if anyone knows of anywhere I could get such information, I would be
very grateful.

I think KME in the UK do a new product designed to be replace
non-standard old monitors. ie it can be set up to accept any non
standard video signal. if you can work out the spec of what you have to
inteface to, I think this would be more reailstic than trying to get the
old monitor working. If the rest of the system is alive then you can
just scope it to get the hoizontal and vertical sync frequencies.

http://www.kme.co.uk/

 

[Bob Parker]

Hi
A document I found at
http://slackware.osuosl.org/slackware-3.5/source/a/etc/termcap-BSD
gives this information about the Teleray monitors:

#### Teleray
#
# Research Incorporated
# 6425 Flying Cloud Drive
# Eden Prairie, MN 55344
# Vox: (612)-941-3300
#
# The Teleray terminals were all discontinued in 1992-93. RI still
services
# and repairs these beasts, but no longer manufactures them. The
Teleray
# people believe that all the types listed below are very rare now
(1995).
# There was a newer line of Telerays (Model 7, Model 20, Model 30, and
# Model 100) that were ANSI-compatible.


Unfortunately I wasn't able to find any useful info about Research
Inc. The only company by that name I found makes heating systems etc.
Good luck with your challenge.

Bob

 

[budgie]

Hi
A document I found at
http://slackware.osuosl.org/slackware-3.5/source/a/etc/termcap-BSD
gives this information about the Teleray monitors:

#### Teleray
#
# Research Incorporated
# 6425 Flying Cloud Drive
# Eden Prairie, MN 55344
# Vox: (612)-941-3300
#
# The Teleray terminals were all discontinued in 1992-93. RI still
services
# and repairs these beasts, but no longer manufactures them. The
Teleray
# people believe that all the types listed below are very rare now
(1995).
# There was a newer line of Telerays (Model 7, Model 20, Model 30, and
# Model 100) that were ANSI-compatible.

Weren't they just glass teletypes aka dumb RS232 terminals?

 

[Franc Zabkar]

Weren't they just glass teletypes aka dumb RS232 terminals?

That was my experience, at least with one particular terminal. I
suspect that just about any ANSI-compatible A/N terminal should do the
trick, unless the interface is using some proprietary current loop
system.

- Franc Zabkar

 

[Steve]

Thanks for the info Luke but no one will pay for this
repair/modification, even though I'm only the user (it belongs to the
Saudi Air Force) they expect it to be repaired magically without cost.
I know what the obvious answer should be but I'd like to keep my job.
I am quite willing to repair existing equipment if I can do it
relatively cheaply for 'smartie points' at work but major
mods/replacements are a no-no. I have also contacted research
Incorporated by email but have had no response so far. Currently I am
testing individual components on the 2 VDU PCBs as they are quite
basic, the only suspect item I have found so far is the PSU chopper
transformer but I have no way of testing it as I don't know what pins
are connected to what windings.

 

[Bob Parker]

If it's got one or more high-value startup resistors, at least check
those for correct value because they often go open circuit.

Bob

 

[Steve]

Thanks, Bob

I've checked all the resistors by measurement out of circuit, all the
capacitors the same way including ESR tests on the electrolytics. Have
checked the semiconductors using a Peak Atlas semiconductor tester and
what I think is the chopper transistor by substitution.
I do have a close up photo of the PCB I'm currently working on if
anyone's interested, it's quite small but, as I said earlier, without a
circuit diagram to check out the chopper transformer or know how to
load the circuit and simulate feedback, I still don't know for sure
that it's this PCB causing the fault. I still have 3 or so 3 pin
devices to check as soon as I'm released from 'look after the baby' and
shopping duties. I have also contacted the manufacturer of the chopper
transfromer and PSU PCB with no replies so far. The only 'success' I
have had is that the primary side of the PSU is OK, ie the mains diode
bridge DC output is correct with minimal ripple.

 

[Bob Parker]

It can only help if we can have a look at one or more photos of the
board. Where can we see it/them?

Regards
Bob

 

[Steve]

Hi Bob, I have 4 pics, each 865KB but haven't seen pics posted on the
group, possibly because they use too much bandwidth. I don't exactly
know how to make them available other than posting them to someone's E
mail address. If you know how I could post them I'll do it.

Thanx

Steve