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Q

quan

Member
Joined 2007
Hi Jason, i found out today that the ebay OPS BJT were dud ie Qnjw 0302 was NPN and hfe was 18, Qnjw 0281 was NPN ,hfe only measured 20 as well. So all this time the driver Qnjw 0320 was NPN all along. I took out all drivers and pre-drivers and measured again . Those mje340 and 350 all ok, my originals Qnjw were blown so had to be replaced. Lesson learnt from ebay fakes!!!. I have messaged them, interesting to hear their response. Anyway fired up again with all new drivers/predrivers/OPS-one pair only for now with bulb limiter. I was able to adjust current output through the 0.22R resistor. The current measured through 0.22RE was 50mA.The flash sink is hardly warm, good sign but the main problem i find is DC offset measured at 140mV. The bulb is only dim so i hope so far so good.
Quan
 
jkuetemann

jkuetemann

Member
Joined 2010
quan said:
Hi Jason, i found out today that the ebay OPS BJT were dud ie Qnjw 0302 was NPN and hfe was 18, Qnjw 0281 was NPN ,hfe only measured 20 as well. So all this time the driver Qnjw 0320 was NPN all along. I took out all drivers and pre-drivers and measured again . Those mje340 and 350 all ok, my originals Qnjw were blown so had to be replaced. Lesson learnt from ebay fakes!!!. I have messaged them, interesting to hear their response. Anyway fired up again with all new drivers/predrivers/OPS-one pair only for now with bulb limiter. I was able to adjust current output through the 0.22R resistor. The current measured through 0.22RE was 50mA.The flash sink is hardly warm, good sign but the main problem i find is DC offset measured at 140mV. The bulb is only dim so i hope so far so good.
Quan
Click to expand...

The offset could be a slight difference in the resistors used to simulate the IPS and 140mV is fine. Remember the testing phase for the OPS had no correction from feedback. Once an IPS in installed the feedback will drive the offset lower.

And semis off ebay... It costs more but I suggest using a reputable vendor known to buy direct from the manufacturer.
 
Q

quan

Member
Joined 2007
jkuetemann said:
The offset could be a slight difference in the resistors used to simulate the IPS and 140mV is fine. Remember the testing phase for the OPS had no correction from feedback. Once an IPS in installed the feedback will drive the offset lower.

And semis off ebay... It costs more but I suggest using a reputable vendor known to buy direct from the manufacturer.
Click to expand...

Thanks Jason. I will try with IPS later then report.
Quan
 
mrsavage

mrsavage

Member
Joined 2011
Bill of Materials, Schematic, etc. for each PCB

Is there a final Bill of Materials, Schematics, and other documentation for
each of the PCB's? Or point me to each thread and thread number for this information. Maybe I could help compile all the possible BOM's for each PCB's. Example PCB's are: (1) IPS (CFA-XH), IPS (Symasui), 2P OPS, 5P OPS, etc.
Take care.:confused:
 
jkuetemann

jkuetemann

Member
Joined 2010
mrsavage said:
Is there a final Bill of Materials, Schematics, and other documentation for
each of the PCB's? Or point me to each thread and thread number for this information. Maybe I could help compile all the possible BOM's for each PCB's. Example PCB's are: (1) IPS (CFA-XH), IPS (Symasui), 2P OPS, 5P OPS, etc.
Take care.:confused:
Click to expand...

No one has yet done any 'official' BOMs to the best of my knowledge. I do keep intending to sit down with the Mouser site and put something down but somehow it hasn't happened yet. I should at least do up a spreadsheet for the versions I have re-spun.

The main SlewMaster thread has all the schematics in their various iterations and lots of banter about parts and implementation. I would like to see OS rejoin us sooner rather than later for his input if possible.
 
Q

quan

Member
Joined 2007
Hi Jason, i have test iPS/OPS. One chanel DC offset is 1mV but the other channel DC offset is 195mV. I am able to adjust bias through 0.22R and measure 16.5mV(about 75mA). I did match the input pair of IPS pretty closely. Where should i be looking at?. TIA.
Quan
 
jkuetemann

jkuetemann

Member
Joined 2010
quan said:
Hi Jason, i have test iPS/OPS. One chanel DC offset is 1mV but the other channel DC offset is 195mV. I am able to adjust bias through 0.22R and measure 16.5mV(about 75mA). I did match the input pair of IPS pretty closely. Where should i be looking at?. TIA.
Quan
Click to expand...

Remind me which IPS we are talking about. Are you using the CFA-XH or the Symasui? Does the problem follow the IPS if you swap them?
 
Q

quan

Member
Joined 2007
jkuetemann said:
Remind me which IPS we are talking about. Are you using the CFA-XH or the Symasui? Does the problem follow the IPS if you swap them?
Click to expand...

Hi Jason, i am using CFA-XH atthe moment. The OPS boards seem to be ok as DC offset is good when i swapped the other board in. I suspect one of IPS is not functioning as expected.When i adjusted the bias current i find it is difficult to match the current flow through the vas resistors.
Quan
 
jkuetemann

jkuetemann

Member
Joined 2010
quan said:
Hi Jason, i am using CFA-XH atthe moment. The OPS boards seem to be ok as DC offset is good when i swapped the other board in. I suspect one of IPS is not functioning as expected.When i adjusted the bias current i find it is difficult to match the current flow through the vas resistors.
Quan
Click to expand...

Generally I just start off with the adjusters centred and the OPS bias set low, use the adjusters to get the offset as close to 0 as possible, set up the bias in the OPS and test it. The current range is limited on the IPS adjusters and it will be close to correct anyway. You may use each adjuster a smaller amount rather than one adjuster on its own.
 
Q

quan

Member
Joined 2007
jkuetemann said:
Generally I just start off with the adjusters centred and the OPS bias set low, use the adjusters to get the offset as close to 0 as possible, set up the bias in the OPS and test it. The current range is limited on the IPS adjusters and it will be close to correct anyway. You may use each adjuster a smaller amount rather than one adjuster on its own.
Click to expand...

Thanks Jason, so should i set the OPS bias lower say at 11mV ie 50mA across the 0.22 R first?. Currently i set IPS by measuring 2V across each 470R connecting across FB/ND/PD, OPS- connect 8K resistor across V/PD, -V/ND then adjust across 0.22R for 16.5mV.
Quan
 
jkuetemann

jkuetemann

Member
Joined 2010
Bring the OPS to 10mA or the minimum you can get if it doesn't go that low when connecting the IPS for the first time. On the CFA-XH, centre the adjusters as a preset. Use the adjusters to get minimal offset and then adjust the OPS bias. The actual VAS current has a limited range and will be in the ballpark with the adjusters centred. Try that and see how it goes.

The testing procedures for checking the sections individually is just for verification, when joined together they should be setup together.
 
Q

quan

Member
Joined 2007
jkuetemann said:
Bring the OPS to 10mA or the minimum you can get if it doesn't go that low when connecting the IPS for the first time. On the CFA-XH, centre the adjusters as a preset. Use the adjusters to get minimal offset and then adjust the OPS bias. The actual VAS current has a limited range and will be in the ballpark with the adjusters centred. Try that and see how it goes.

The testing procedures for checking the sections individually is just for verification, when joined together they should be setup together.
Click to expand...

Thanks Jason, will try that later - at work now-and report back.
Quan
 
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