Not bored with the Boards.



  • edited March 14
    Some satisfaction if not success

    I suppose I get some feeling of success if I do not blow up my Smart Card v2 and get back to a "starting position" .

    This is what happened . I had perhaps wrongly taken a risk with the capacitors on a faulty but "better " Issue 3b to get some tracking info to help repair another (hopeless) 3b with tracking damage (i gave up on this one) . It meant that I had to replace the capacitors on the "better" one . This was tricky as extacting the capacitors had not been easy as they had snapped off and they had left "stubble" on the pcb as they broke on removal . I solved the problem by changing the soldering iron tip to get a more precise point of contact . I also used the kitchen table as a sort of "make do" vice to help extracting the stubble . When I had cleared a resulting short from one of the caps , I had back to where I started . My Smart Card v2 had not blown up because of the short and once the short was corrected , it started buzzing away merrily with some upper RAM errors like it had had before . . This is how it was when I got this Speccy on Ebay (so I have not made it worse!) .

    I have not yet replaced the faulty upper RAM chip . I have the turned pin and the correct chip . So the next thing is to see if I can get away with replacing just one chip.

    This is what it says now

    Uper Ram "Value is Unstable"

    Bad bits 76543210 Xp SFF (or something like this)

    Suspect IC21

    I inserted a turned pin socket where I had previously extracted the old chip (I did a quick solder in job on it) . I inserted the replacement chip and got this result :-

    Lower RAM error at $7FFF
    Bad bits 76543210 XP:$00 AD: $40
    Upper RAM error at $FFFF
    Bad Bits 76543210 XP: $00 AD : $40
    Cannot proceed further both upper and lower ram is bad .

    Suspect ICs IC12 IC21

    So I wonder why the lower RAM has suddenly "gone bad". Maybe I need to do a better job at soldering in the turned pin .
    Post edited by harriusherbartio on
  • edited March 14
    So next I think I will try an solder in the turned pin socket , this time using flux . It surprised me how tricky they can be to get solder onto . I will take the chip out before I try this though.

    Learning points so far:-

    1) Remember flux and similar products ( I think I have some fancy wire somewhere that does a similar thing)

    2) The use of a vice or something similar to hold a PCB steady whilst being "pulled at" . (a crack in an expandable kitchen table will suffice) . This is useful when working both sides of the board and at time putting movement on the PCB from both sides . It is a kind of "steadying 3rd hand".

    3) I am always in too much of a rush . I need to remember to check work before moving on to the next stage. Luckily this time I appear to have "got away with it".

    4) Soldering irons have "moved on" since the 1980s . Although the packs of additional soldering iron tips are a bit of a marginal product as far as the sellers are concerned , they are well worth tracking down . Often sellers will say whether additional packs of these tips are available - that is how I got mine . But having them is one thing ,and using them is another . I think they can make all the difference in getting the right amount of heat to the right pin point . There are You Tube videos on stuff like this . I will try and re acquaint myself on the uses of the various type of soldering iron tip.

    Post edited by harriusherbartio on
  • edited March 15
    I knew I had tested the Speccy prematurely as the turned pin socket had not been soldered in properly . Here are the pics from my first go at soldering it in:-





    I dont think any any shorted but some are probably not connected . I am surprised this maybe caused the lower ram error but maybe soldering the pin in properly will sort out the fault .The main problem was in getting the solder to "take" properly . I have not found a You Tube video on this but I think Rosin flux maybe part of the answer

    Post edited by harriusherbartio on

  • I have not quite got the courage to go back to the previous project . Instead I decided to look my "dead boards" . I came across an Issue 2 (lower Ram only) and managed to tune in to "Sinclair" logo . (So how did this one slip through as dead I ask myself?)
    The Smart Card V2 says "No upper RAM detected" and Suspect ICs :- IC7, IC8 , IC10 ,IC11 , IC12 and IC3,IC4

    And lower RAM ERROR at $7FFB.

    But at least this board is not totally dead!
  • edited March 22

    I have not quite got the courage to go back to the previous project . Instead I decided to look my "dead boards" . I came across an Issue 2 (lower Ram only) and managed to tune in to "Sinclair" logo . (So how did this one slip through as dead I ask myself?)
    The Smart Card V2 says "No upper RAM detected" and Suspect ICs :- IC7, IC8 , IC10 ,IC11 , IC12 and IC3,IC4

    And lower RAM ERROR at $7FFB.

    But at least this board is not totally dead![/quote]

    Post edited by harriusherbartio on
  • edited March 23
    The ISSUE 3B as per the above pics

    I summoned up the motivation needed to finish off the Issue3b as per the pics above . I had rushed the solder effort with the turned pin socket at IC21 ,which had been a mistake . The first thing was to remove the inserted chip at IC21 from the turned pin socket and retest with Smart Card v2 again . This time ,the lower Rom tested OK so basically I appeared to be back where I started , as the lower RAM failure shown with the IC21 chip inserted had gone away . It was "back to square one" so to speak with just the upper Ram problem.

    This time I made the effort to find some flux and re-solder it and clean up the turned pin socket at IC21 . When it was retested it shower upper ram failure at IC15 ,IC16 ,IC17 ,IC19 ,IC22 ,IC25,IC26 ,but not at IC21 ,the one I had just replaced . So basically it is a 16k Spectrum . I will reassemble it back into an old case and carry out further tests as a 16k machine . I do not think it worth the effort cutting out all those remaining upper RAM chips . If it is OK as a 16k I will be able to use it for testing the likes of Cheetah RAM packs etc I has been good practice using flux : it does make it a lot easier to do a better cleaner job.

    Feeling enthused by the usefulness of the Smart Card v2 I decided to try one last test on an Issue2 that I had previously given up on but which earlier today I found had come up with the Sinclair logo . The Smart card did its stuff again and detected no upper RAM and suspect ICs in the lower RAM at IC7 , IC10 ,IC3 , and IC4 . So something had caused lower RAM failure this time What a useful gadget this Smart Card is.
    Post edited by harriusherbartio on
  • edited July 28
    Stonechip has come up on this thread before but this is something different .This bit is about " The Stonchip Programmable Joystick Interface ": I bought one of these recently on Ebay . The box and instructions looked like they were about to disintegrate so I laminated them straight away . The Red light comes on when attached to a Speccy (as it should) . The Ebay seller said it had not been tested as it was part of a collection and therefore it was deemed to have been tested by the previous owner ( or similar) . So I accepted this and bought it anyway .

    It got me back into using a proper Speccy again . I had to reremember some things to do on my slightly "modern" but still "old style" set up . My modern "laptop" type power supply for the old style Spectrum had to be "pushed together" (like a laptop power supply ) where the mains cable joins the supply (otherwise it does not power up!!) . And with my hand set I had to remember to press the Menu button several times to get the full range of options to tune the "more modern" type but still " old style" TV in . This was where I found that this Stonechip interface red light came on as it should but having a working Spectrum with "red light on Inteface" did not mean that I had actually tested it . Well that was as far as I got . I did not have time at that point for further testing .

    But this Interface has come up before:-

    So this guy wanted to test it but did not have the instructions and I had the instructions but lacked the willpower! I was more interested to see if the chips had had their IDs sanded off . But again I was defeated on this as the case appears to have been glued together so no easy way in

    There are 3 settings on the switch 1) Normal 2) Program 3)Play.

    Before using it you are meant to clear data by setting it to PROGRAM and pressing FIRE in all possible diections .It is then ready to be PROGRAMMED after switching the switch to PROGRAM . An example short program is then LISTED in these instructions . This prog is for moving a BLOCK around the screen. The rest of the instructions appear to relate to programming the diagonals and similar stuff . So quite a lot to do just to test it ( that was why I gave up and was happy just to get a RED light - just like the Ebay seller it seems!)
    Post edited by harriusherbartio on
  • edited July 28

    Post edited by harriusherbartio on
  • edited July 28
    It turned out that the case was not glued together - it was a "push fit". This board is Issue 3
    Post edited by harriusherbartio on
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