Author Topic: Dead GE Super Base.  (Read 1603 times)

0 Members and 1 Guest are viewing this topic.

Offline Mikes Radio Repair

  • Newbie
  • *
  • Posts: 12
  • Karma: +0/-0
    • View Profile
Dead GE Super Base.
« on: December 26, 2015, 03:09:02 AM »
Got in a customers recent ebay purchased GE Superbase 3-5875A.  He purchased it knowing it had no rec or xmt.  I was hoping the varactor diode in the epoxy sealed vfo box was bad.  I have chipped the epoxy out of more of these than I can shake a stick at and have just gotten to the point that I replace that diode whether it works or not when I restore these radios.  Well, I wasn't that lucky.  Did a quick check for 10.240 on the PLL and it was missing.  Checked the 10.240 oscillator transistor and no voltage.  Checked and had main supply voltage to pin 12 of connector N2 and voltage out of the regulator transistor, hmmmm.  Time to pull the board and sure enough someone had been in it before.  They "tried" to undo a channel mod and didn't get a jumper wire connected and there are also some broken circuit traces that will need repaired.   All that no biggie and easy to fix.  The big problem is the last picture.  A cracked transformer core with a piece of the alignment tool broken off in it, grrrrrrrr.  To make matters worse it is not a standard core.  Its the one for the VFO that has a square hole and is almost impossible to find.  My stockpile of them is getting smaller and smaller.  Keeping my fingers crossed i can get the mangled core out.  The lesson here is if you don't know what your doing and don't have the correct tools don't touch it.  You could turn your what would have been a easily repaired radio into a nice looking brick.

Mike

Online Radio Tech

  • Administrator
  • Hero Member
  • *****
  • Posts: 5976
  • Karma: +318/-2
    • View Profile
Re: Dead GE Super Base.
« Reply #1 on: December 26, 2015, 07:51:14 AM »
I have yet to find a decent replacement for those cores.
Don't know how many I have seen over the years that were broken by folks.
The "average tweaknician" have no clue why the little slug sometimes do not turn when they are using the wrong tool.

I have had vintage radios in where I had to rebuild the dual IF coils because folks did not understand the core had a small drop of glue on them. So when they try and turn the core they tear the paper form to bits. A little heat and lubricant is your friend here.

Been a while since I have seen a suberbase like that one. Is there a hole in the pcb under the core?
Buddy kc4umo

Offline Mikes Radio Repair

  • Newbie
  • *
  • Posts: 12
  • Karma: +0/-0
    • View Profile
Re: Dead GE Super Base.
« Reply #2 on: December 26, 2015, 02:04:00 PM »
No hole in the bottom.  Pictured below Is one I worked on about a while ago. It is a separate circuit board potted in epoxy inside of a metal shielding can then covered with the plastic snap on cover.  Luckily if the varactor diode goes bad it is mounted on the edge of the board and the potting epoxy is the hard brittle type and can be chipped away at and it can be replaced if your really careful.   A NTE 612 is a good replacement varactor diode.  Cybernet made two types of these, a small one (this one) and a larger one.  If the transformer/coil goes bad good luck getting it out.  Its mounted in the center.  On the bright side there is a guy in the UK that makes replacement modules for these.  Apparently there were a lot of different radios in the UK that used them unlike here in the US where we only had a handfull of radios with them.

Offline Mikes Radio Repair

  • Newbie
  • *
  • Posts: 12
  • Karma: +0/-0
    • View Profile
Re: Dead GE Super Base.
« Reply #3 on: December 27, 2015, 05:51:13 PM »
Up and running.  Noticed several things That did not quite look right on this radio compared to all others I've ever worked on before. I soon realized they were changes made by General Electric when this radio was sent back to them for service at some point. The changes updated this radio to its common configuration. The main difference I noted was the main RF shield that separates the two circuit boards was missing. It only had a small RF shielding plate soldered directly to the underside of the top board. I soon realized Why this radio looked as older they did at least circuit wise. The serial number is 62.  From a collectors standpoint that's one of those oh my god moments.

https://m.youtube.com/watch?v=ianagoOcs_Q&feature=youtu.be



Online Radio Tech

  • Administrator
  • Hero Member
  • *****
  • Posts: 5976
  • Karma: +318/-2
    • View Profile
Re: Dead GE Super Base.
« Reply #4 on: September 10, 2016, 10:50:20 PM »
Mike, this post just showed up for me lol. Glad you got it going.
Buddy kc4umo

Offline nightstalker

  • Newbie
  • *
  • Posts: 1
  • Karma: +0/-0
    • View Profile
Re: Dead GE Super Base.
« Reply #5 on: February 03, 2017, 11:25:55 AM »
If anyone knows of a good contact method for Mike's Radio Repair

Please contact me at doberus69@yahoo.com

thanks

Offline k7rmj

  • Jr. Member
  • **
  • Posts: 68
  • Karma: +4/-0
    • View Profile
Re: Dead GE Super Base.
« Reply #6 on: February 03, 2017, 10:03:56 PM »
Greetings nightstalker.
Here is Mike's email
mikesradiorepair@gmail.com

Regards,

Frank

Online Radio Tech

  • Administrator
  • Hero Member
  • *****
  • Posts: 5976
  • Karma: +318/-2
    • View Profile
Re: Dead GE Super Base.
« Reply #7 on: February 04, 2017, 06:56:18 AM »
Mike Is a very busy person. 
I also know he is cutting back on what comes in till he can get caught up.
Buddy kc4umo