Huntron Support Forum

Go to Huntron web site

The Forum recently experienced a database failure with user and post information being lost.
Visit the Technical Support Announcements board for details.

640 switcher problems

640 switcher problems
« on: July 13, 2014, 11:01:43 am »
Greetings All,
    I recently purchased a 640 switcher, as-is, from E-***.  It came with the users manual and cables.  When I set it up with my  2000B, it blew the power fuse for the 2000.  The 640 led's flickered a few times before the 2000 fuse blew.(correct fuse was in my 2000)
I know this equipment is no longer factory serviced and repair information is scarce. Can anyone suggest a plan.  Does anyone know if the Huntron CD would provide enough
information for me to attempt a repair of the 640.
thank you,
mike

Re: 640 switcher problems
« Reply #1 on: July 13, 2014, 02:11:58 pm »
Just a further note-I disassembled the units circuit boards...I probed around the board with the printer jack...c-7,c-41,c-42 all show short between terminals...also u-23 shows short between the left and center terminals. i believe the part # MC 79L05acp is a -5 volt regulator.  does one remove the component and test out of circuit for final test??
thanks
mike

admin

  • Huntronian
  • 400
    • HUNTRON.COM
    • Email
Re: 640 switcher problems
« Reply #2 on: July 14, 2014, 07:18:02 am »
It sounds like the regulator is causing the problem. The best test would be to check the regulator out of circuit to be sure that it is shorted. With it removed also test the pins on the PCB to see if there is still a short indication. Use the Low Tracker range at 60Hz since there might be large filter caps that would show a short indication at a higher range setting. I will see if schematics are available. Stay tuned...
Thanks.

Admin
The most important troubleshooting tool is your eyes.

Re: 640 switcher problems
« Reply #3 on: July 14, 2014, 02:31:18 pm »
pulled u-23, checked ok...found problem was shorted input c-7 cap (10 of 25 v talantum)...replaced cap (correct polarity !) and installed new volt reg.  hooked up switcher to 2000 and about 1 min later the "magic smoke" came forth from talantum cap c-3 on the relay board.  the cap is completely disintegrated.  without a parts list/schematic I fear I will not be able to tread further.
thanks
mike

Re: 640 switcher problems
« Reply #4 on: July 15, 2014, 09:24:21 am »
just a thought (rambling)
   since the power/clock input is coming in from the 2000B, and this is the second cap to fail catastrophically at the power input of the respective board,  at some point I have to assume the  voltage  being provided by my 2000B must be "a little high".   I have a 4 wire cable connecting the 2 units together...anyone know pin layout and voltage output??
thanks
mike

admin

  • Huntronian
  • 400
    • HUNTRON.COM
    • Email
Re: 640 switcher problems
« Reply #5 on: July 15, 2014, 09:26:12 am »
Can you provide the "06-XXXX" part numbers from the PCBs? Information on the 640 is proving hard to locate.
Thanks.

Admin
The most important troubleshooting tool is your eyes.

Re: 640 switcher problems
« Reply #6 on: July 15, 2014, 10:35:53 am »
Greetings and Thanks,
  my top board with sounder is 07-7721 rev. A 1991
middle board (printer?)        is 07-7720  rev. A 1991
bottom (relays/bad c-3)       is 07-7719  rev. A 1991
front panel                          is 07-7710  rev. A 1991

thanks for the help!!
mike

admin

  • Huntronian
  • 400
    • HUNTRON.COM
    • Email
Re: 640 switcher problems
« Reply #7 on: July 15, 2014, 12:21:56 pm »
The accessory power/clock jack on the 2000 is:
pin 1, +12V; pin 2,-12V; pin 3, ground; pin 4, clock from rate control circuit

The closest schematic I have located that is in digital form is the DSI700 Scanner board. It was very similar so it could help.
http://www.huntron.com/privatesales/technical/dsi700-scanner-pcb.pdf
The most important troubleshooting tool is your eyes.

Re: 640 switcher problems
« Reply #8 on: July 15, 2014, 06:18:42 pm »
Thank you for all the information....I think I may actually have a chance of getting it back to working again....I did check the output voltage from my 2000b and it shows
-15.5 volts for the -12 v line  and 14.55 v for the +12 line at the accessory cable, probably just too much for  23 year old inlet caps(although first cap replaced was rated 25 v)  do you see any problem just running the switcher with a homebuilt power supply +- 12 volts regulated, and fused, clock signal supplied by 2000B.
thanks for all your help
mike

admin

  • Huntronian
  • 400
    • HUNTRON.COM
    • Email
Re: 640 switcher problems
« Reply #9 on: July 16, 2014, 02:37:57 pm »
It could be the caps are old as you suggested. There are regulators in the circuit so it should be able to handle the slightly higher voltage. Anyhow, using an external power supply should be okay if you want to go that way.
The most important troubleshooting tool is your eyes.