Author Topic: Com Ser Laboratories tear down possible repair  (Read 3257 times)

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Offline The Radio Shop

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Com Ser Laboratories tear down possible repair
« on: February 23, 2014, 09:16:34 AM »
When I quit the commercial 2 way radio business (EF Johnson) I started doing more radio repair at home in the early 90ís. I was in need of a service monitor to generate and receive signals from and to the radio under test. I found this service monitor local and purchased it. The range is 0 to 999 MHz.  Just what I needed.  And with the scope and trouble tracer add on I was able to check CTCSS by watching the Lissajous patterns on the scope.

After a couple of years the magic smoke rolled out of the scope unit.  A quick tear down revealed one of the PIO caps had exploded.  0.1uf @ 2kv. Being so busy at the time I simply unplugged the unit and continued to work.  I think it was 7 years later the unit started showing its age.  The signal out became distorted and had low output.  This was time to start trying to obtain info on this unit.  So off on the internet I went only to find nothing.  Google search would not return anything on this unit.  The only name branded part in the machine was the RF attenuator made by WaveTek. So I looked them up and ordered the precision resistors that were in the unit.  The guy I talked to said that Com Ser Laboratories was sort of a fly by Night Company and was bought out by another company.  Never did find out who that was. 

Later in December of 2007 a friend of mine that travels found a guy out west that had the same unit less the scope attachment.  He was able to scan the schematics to Adobe and emailed them to me. These looked like they had already been scanned many times and really did not have much info on them.  No part numbers or part locations. So if anyone has any other info on this please let me know.
I have placed the files on my website back then for download:
http://gokarters.com/smf/index.php?topic=1736.new#new

The monitor as it looks:


Cover removed showing the rear of the unit. Here we can see the card tray that holds the boards. These use old style card edge connectors



This is a view from the top showing card tray and between the tray and front panel is the mother board.
The first card is the 10 MHz crystal oscillator board.



Here we have the card tray lifted up. It is hinged along with the mother board also.
On the bottom of the chassis you can see the power supply.  This supplies:
5VDC
-5VDC
10 VDC
15VDC
-28VDC



Here is a closer look at the power supply board



This image shows how the card tray pivots to allow service to the bottom of the chassis.
Also in the bottom lef you can see the bras cylinder. this is the WaveTek RF attenuator.



I am afraid this may be a problem. The display shows the digits, although it has no power applied.  If I can fix the unit I will have to come up with a new display.



This is the scope unit. It mounts on top of the generator.  I am guessing the engineering department knew nothing of heat transfer back then.  The main scope board mounts component side down.  So a lot of heat has been transferred to the circuit board and has chard the board.



Just a closer image of the scope board.


This will most likely be a tough repair, so will be working on it in spare time. First thing I want to do is check out the power supply and make sure everything there is up to spec.

Thought I share a bit here.
Buddy kc4umo

Offline The Radio Shop

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Re: Com Ser Laboratories tear down possible repair
« Reply #1 on: February 24, 2014, 05:04:12 PM »
Here is the scope CRT. was hoping to find some match on the internet but google returns only a few.
Buddy kc4umo

Offline The Radio Shop

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Re: Com Ser Laboratories tear down possible repair
« Reply #2 on: September 12, 2015, 09:36:20 AM »
So if you have the scope trouble tracer unit on your Com Ser generator you will find there is no material as in schematics or whatever on this unit. After many months of crass reference to the tube "Hitachi 75AVB31" you will find that the "Beckman BK 1405" scope is the same scope used in this unit.

I have attached the schematic at the bottom of this post.
Enjoy
Buddy kc4umo

Offline The Radio Shop

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Re: Com Ser Laboratories tear down possible repair
« Reply #3 on: September 20, 2015, 01:50:11 PM »
I am going to start trouble shooting this piece of test gear in the near future.
Plan is:
*Repair scope unit. Need some macron 104k @ 2KV and 3 @1kv oil filled caps. I tried heavy ceramics but cannot get voltage up.
*Check power supply rails.
*Check signals on all card boards.
*Find what caused the display LCD to go bad and locate a replacement. Bad driver chip perhaps.
*Re-draw schematics with voltage measurements and component locations.
*Photograph boards to label components.

I will be posting an over view of this unit on YouTube shortly.
Buddy kc4umo

Offline buildstoys

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Re: Com Ser Laboratories tear down possible repair
« Reply #4 on: February 17, 2018, 11:02:11 PM »
Buddy,

Curious if you ever made any headway in your restoration work on your ComSer?  I also own one in need of TLC, but sadly have no additional information to share.  Seems like your photos and schematics have been the only thing we've got to go on.

Offline The Radio Shop

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Re: Com Ser Laboratories tear down possible repair
« Reply #5 on: February 19, 2018, 11:43:26 AM »
Hi and welcome.
Mine is in very bad shape. I have basically gave up on it. The information I have here is about all that can be found.
Was hoping to find another one of these one day and use mine as parts to get one up and running.
Buddy kc4umo

Offline buildstoys

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Re: Com Ser Laboratories tear down possible repair
« Reply #6 on: February 19, 2018, 11:59:27 AM »
Buddy,

Good to hear you still have it!

I'll get mine out this week and assess it's current status and post some photos here.

Hopefully between the two of us we can at least get one functioning - if not for anything other than the challenge and nostalgic purposes :)

Offline Wheld

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Re: Com Ser Laboratories tear down possible repair
« Reply #7 on: March 23, 2019, 05:58:46 PM »
I have a Com Ser Labs BR 1000 A with Com-Ser  CSL UD 100 updater both in working condition when stored 2 years ago.  They are for sale if anyone is interested.

Offline The Radio Shop

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Re: Com Ser Laboratories tear down possible repair
« Reply #8 on: March 24, 2019, 07:42:02 AM »
Price?
Buddy kc4umo

Offline KE4EST

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Re: Com Ser Laboratories tear down possible repair
« Reply #9 on: March 26, 2019, 07:01:01 AM »
That is what I am wondering..... Price?
Michael, KE4EST