DigiLite Hardware Updates-keep checking here
Posted: Wed Sep 28, 2011 5:22 pm
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ASK QUESTIONS ON OTHER DIGILITE POSTS..KEEP THIS CLEAR TO ENABLE EASY LOOKUP FOR OTHER MEMBERS.
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There is now a page at http://www.g8ajn.tv/dlother4.html for corrections and modifications to the hardware.
1/ To help ease the initial shortage of pcbs protoype boards v5.6 were issued, but there was a track between IC3 pin 7 and pin2 of IC4. It should go to the junction of R20/R21 (bottom side of pcb) not directly to pin2..To correct this cut the track that goes beneath R20 and join it instead to the junction of R20/R21 instead. The modulator still works but with limited adjustment. This is be corrected in version 5.7.
There is a picture of the change on the DigiLite website under OTHER/CORRECTIONS menu.
2/ On the 5.6 version pcbs C20(0.1)decoupling near U2 should be connected to the ground plane.
3/ The part numbers for the Nyquist filter coils L1,L3 (5.6uH) are RS 191-0453 (Farnell 509-929) and L2,L4 (6.8uH)are RS 191-0469 (Farnell 164-4263).
4/ As a precaution add a 0.3 decoupling capacitor on the input pin of the 8v regulator, on the DC IN socket is a convenient place. It will be added to v5.7 boards. Rob M0DTS reports some parasitic oscillations have been modulating the ht line without it. The effect may vary with different regulator manufacturers.
5/ Some of the part numbers for the tantalum capacitors appear to be wrong size types.The published corrections to tantalum cap part numbers on the Digilite corrections page incorrectly states that the original parts were too big. This is not the case, they were in-fact too small! Correct size to fit pcb footprint should be 2312/case C. Suggest 165-8557 for the 10uF and 301-8490 for the 100uF. The 220uF was correct in original parts list and can remain 165-8711 as per original parts list and not as corrected.(Thanks to Dave G0MXW for sorting it out!)
There's more that Clive G3GJA has found;a low ESR C1 should be 170-2721and L5, 1uH, is listed as a 0805 size but is 0603 on the board. Part no. for the 0603 size part is 165-3742. All part numbers Farnell.
Latest updated parts list is available at http://www.g8ajn.tv/dlhardware1.html
6/ Early overlay plans show the tantalum capacitor C1 reversed polarity. Negative side should go to ground plane.The screen print on the pcb is correct.
7/ Some diagrams show an extra connector PL2 and R42. These were intended to be part of the SD card reader option and were not included in the v5.7 layout and can be ignored. I will produce a separate article about the SD card option at a later date when Brian is happy with the software etc.
The tracking corrections above only apply to the v5.6 boards and have been corrected in the current v5.7 boards.
ASK QUESTIONS ON OTHER DIGILITE POSTS..KEEP THIS CLEAR TO ENABLE EASY LOOKUP FOR OTHER MEMBERS.
______________________________________________________________________________________________
There is now a page at http://www.g8ajn.tv/dlother4.html for corrections and modifications to the hardware.
1/ To help ease the initial shortage of pcbs protoype boards v5.6 were issued, but there was a track between IC3 pin 7 and pin2 of IC4. It should go to the junction of R20/R21 (bottom side of pcb) not directly to pin2..To correct this cut the track that goes beneath R20 and join it instead to the junction of R20/R21 instead. The modulator still works but with limited adjustment. This is be corrected in version 5.7.
There is a picture of the change on the DigiLite website under OTHER/CORRECTIONS menu.
2/ On the 5.6 version pcbs C20(0.1)decoupling near U2 should be connected to the ground plane.
3/ The part numbers for the Nyquist filter coils L1,L3 (5.6uH) are RS 191-0453 (Farnell 509-929) and L2,L4 (6.8uH)are RS 191-0469 (Farnell 164-4263).
4/ As a precaution add a 0.3 decoupling capacitor on the input pin of the 8v regulator, on the DC IN socket is a convenient place. It will be added to v5.7 boards. Rob M0DTS reports some parasitic oscillations have been modulating the ht line without it. The effect may vary with different regulator manufacturers.
5/ Some of the part numbers for the tantalum capacitors appear to be wrong size types.The published corrections to tantalum cap part numbers on the Digilite corrections page incorrectly states that the original parts were too big. This is not the case, they were in-fact too small! Correct size to fit pcb footprint should be 2312/case C. Suggest 165-8557 for the 10uF and 301-8490 for the 100uF. The 220uF was correct in original parts list and can remain 165-8711 as per original parts list and not as corrected.(Thanks to Dave G0MXW for sorting it out!)
There's more that Clive G3GJA has found;a low ESR C1 should be 170-2721and L5, 1uH, is listed as a 0805 size but is 0603 on the board. Part no. for the 0603 size part is 165-3742. All part numbers Farnell.
Latest updated parts list is available at http://www.g8ajn.tv/dlhardware1.html
6/ Early overlay plans show the tantalum capacitor C1 reversed polarity. Negative side should go to ground plane.The screen print on the pcb is correct.
7/ Some diagrams show an extra connector PL2 and R42. These were intended to be part of the SD card reader option and were not included in the v5.7 layout and can be ignored. I will produce a separate article about the SD card option at a later date when Brian is happy with the software etc.
The tracking corrections above only apply to the v5.6 boards and have been corrected in the current v5.7 boards.