logo Welcome, Guest. Please Login or Register.
September 23, 2019, 01:56PM
Home Help Search Login Register
News: Visit a member's site: http://www.chessbox.de/ (Sumerian)

  Chess Computer Community
  General Category
  Discussions about Chess Computers
(Moderators: Endspielgott, Overtom, bobosse)
  Problem with Leonardo
previous next
Pages: [1] Reply Notify of replies Send the topic Print 
   Author  Topic: Problem with Leonardo  (Read 818 times)
tony
Full Member
***

Offline

Posts: 225

I love Boardnation!

View Profile E-Mail
Re:Problem with Leonardo
« on: October 30, 2008, 08:23AM »
Reply with quote

actually the 2 pads which led to seperate circuits were completly soldered over to look like 1 pad. I caught it by shining a bright light behind the board which let me see where the circuits connected to the components. the only components on these large boards are the reeds and diodes. sharp eyes,lots of luck, and the forumn pointing me saved the day. I bought this computer with the defect known to me. $300 US and taking a chance I could fix it. it is is in excellent condition and came aith the maestro 6MHz module. I think i got a good deal.
tony
Report to moderator Logged
sderyke2002
Full Member
***

Offline

Posts: 164



I love Boardnation!

View Profile
Re:Problem with Leonardo
« Reply #1 on: October 29, 2008, 12:25PM »
Reply with quote

Great to hear it is working. 

I would agree that the problem was probably lurking ever since the unit came from the factory.  I suspect either heat caused some excess flux (that was not cleaned up from the manufacture process) to run and conduct small amounts of voltage or there was a break down of something which had up to now insulated the two pads from each other - and that is why it only started flaking out now.  Whatever caused it - it's good to know it is now solved.
Report to moderator Logged
hondo
Jr. Member
**

Offline

Posts: 79

I love Boardnation!

View Profile
Re:Problem with Leonardo
« Reply #2 on: October 28, 2008, 09:26AM »
Reply with quote

Hi Tony...thats GREAT..... so glad to hear its working again...  about testing diodes in circuit > usually the easiest way is to cut one leg of the diode free of the circuitry leaving the other leg attached and test that way. That prevents loading the circuit and allows you to read just that diode...hope that helps future testing scenario's. Enjoy playing and regards....  Hondo
Report to moderator Logged
tony
Full Member
***

Offline

Posts: 225

I love Boardnation!

View Profile E-Mail
Re:Problem with Leonardo
« Reply #3 on: October 28, 2008, 07:26AM »
Reply with quote

hondo, i should have explained a lttle clearer. checking the switches in circuit will give a slight reading depending on how you place your probes. a ohmeter puts out a small current to take a reading and a liitle feedback will occur through the diodes in the surrounding circuitry. that said you guys put me on the right track. DIODES!!!!!  I put a strong light behind the board so i could see the circuitry where the diodes connect. the reeds and diodes are on opposite side of the printed circuit. I notced 2 diodes soldered to the same pad at each end even though one of the pads split to 2 paths, looked like factory joints but i removed the solder anyway. there were actually 2 seperate pads under the solder, cleaned and resoldered and BINGO the problem is solved. I think the leonardo had this problem right out of the factory. thankyou forum guys for putting me on right trouble shooting path.
best regards, Tony
Report to moderator Logged
hondo
Jr. Member
**

Offline

Posts: 79

I love Boardnation!

View Profile
Re:Problem with Leonardo
« Reply #4 on: October 27, 2008, 09:52AM »
Reply with quote

Hi Tony....Please forgive me for not fully understanding how you have explained the testing procedure but with what I think I comprehend I will suggest that you replace the reed switches that seem questionable. Since you said you have an understnding of electronics you know reed switches should either test open or closed ! If you are testing a majority in circuit and they are testing either OPEN or CLOSED without any power to the unit.... the reed switches that test DIFFERENTLY would certainly in my mind be suspect! I would make sure that you try to get the exact  replacement reed switches from an electronic parts store by using the mfg. pt. # or if thats not an option ... you may have to try to match specifications from the ones in circuit to the ones you are getting. I would also observe the exact location/proximity to the boards surface so that they function correctly. I am sure that reed switches don't last forever and if this does solve your problem (hope so ) then you may want to consider stocking up on the switches that worked in anticipation of future issues. As before....good luck .....    Hondo
Report to moderator Logged
tony
Full Member
***

Offline

Posts: 225

I love Boardnation!

View Profile E-Mail
Re:Problem with Leonardo
« Reply #5 on: October 27, 2008, 09:33AM »
Reply with quote

well i checked every diode on the reed boards and the foward and reverse bias is the same on all. resoldered them all and rechecked bias which didn't change.did this for all 64. one thing i did notice that on the lower board (1st 4 rows) the reading across the reed switches is open which seems normal. on the upper board the reed switches all have slight reading on the ohmmeter. no power at all to unit. tried it again and occuping the E5&F5 causes A6+A7 and E1-F1 lights to blink together. doing it in setup mode they will blink in red. moving the pieces to the squares and it will blink in orange. I now now stand at a dead end. any more ideas????
tony
Report to moderator Logged
tony
Full Member
***

Offline

Posts: 225

I love Boardnation!

View Profile E-Mail
Re:Problem with Leonardo
« Reply #6 on: October 26, 2008, 05:53PM »
Reply with quote

thanks guys, I have checked and double checked every solder joint i could find. i also did an ACL with power and without power. every function works perfectly until both those squares are occupied. it will play start to finish without a hitch. checking those diodes sounds like a good idea which i will start on. if there are pararlell resistors they must be located on a different board. the 2 boards with the reed switches and diodes have no other components on them and are connected to anotherboard with ribbon cable. I have a few yrs. electronics work under my belt so i should be able to check those E5&F5 diodes with no problem. if it is a diode i hope they have a number on them or some ID. working without a schematic is really tough.  thanks again, tony 
Report to moderator Logged
sderyke2002
Full Member
***

Offline

Posts: 164



I love Boardnation!

View Profile
Re:Problem with Leonardo
« Reply #7 on: October 26, 2008, 11:15AM »
Reply with quote

My Saitek President wood autosensory board had a square go bad on it that didn't affect the game until it was activate as well, and it was resolved by replacing the diode associated with the square. 

It had not failed open or closed it simply had aged and the reverse bias on it had weakened.  So I agree with the other poster that you should not over look this item.  Since it is sometime difficult to test a diode in circuit (because of all the alternative paths available) it might be simplest to simply remove the diode and replace it.
Report to moderator Logged
hondo
Jr. Member
**

Offline

Posts: 79

I love Boardnation!

View Profile
Re:Problem with Leonardo
« Reply #8 on: October 26, 2008, 10:26AM »
Reply with quote

Hi Tony....  Just a cpl. of things to try BEFORE you trash it.  First.....if your game has an ACL reset button I would first do a HARD reset w/out the power being connected ... this means no batteries in circuit and not plugged into AC. Second...if you do have it apart and you know how to use a VOM meter and know how to check a diode in circuit I would do that next. I also suspect that the diode has a resistor in parallel with it. I would check the forward and reverse bias of the surrounding diodes and make sure they are all about the same. Then I would check that the resistors all are close to specs. and pretty much all are about the same ohms as the ones next to each other. Also check for cold or questionable solder connections as that is a major concern with older PC boards! Be careful working around IC's as they can sometimes be a bit sensitive to static charges and go POOF when you accidently put tools or fingers where they don't belong. Good luck and remember things usually aren't as bad as they FIRST appear to be.  Regards    Hondo
Report to moderator Logged
tony
Full Member
***

Offline

Posts: 225

I love Boardnation!

View Profile E-Mail
Problem with Leonardo
« Reply #9 on: October 26, 2008, 07:28AM »
Reply with quote

This is driving me nuts and I'me ready to throw it out the window. The computer operates fine unless you reach a position where the E5 & F5 squares will be occupied at the same time. when a piece is moved to either of these squares and the other is occupied, the computer will freeze and blink 2file and 2 row leds. the only way around this is to take back the move and go to another square and then continue the game. in games where these 2 squares are not occupied at the same time, it plays perfectly. all the reed switches are good. it is now completly apart and i notice there are diodes with each reed switch. is this a pssible cause, i have checked everything else i can think of. this glitch happens wheather or not the module is in. it also doesn't matter which of the 2 squares is occupied 1st or last. (at my wits end) any thoughts or ideas would be greatly appreciated. I would hate to have to junk it.
regards, Tony
Report to moderator Logged
Pages: [1] Reply Notify of replies Send the topic Print 
previous next
Jump to:  

Login with username, password and session length

Chess Computer Community
Get your Ad Free Message Board at Boardnation!   © 2013 Boardnation  Web hosting by Nubis