Rank: Member
Groups: Member
Joined: 8/22/2010(UTC) Posts: 38  Thanks: 14 times
|
Hello: I've built two identical Placid HDs PSU to target 5.25VDC at 510mA for Buffalo II with Tridents and ended up with the same (within 0.01VDC) voltages on both All 3 green LED are on. AC_IN->= 10.59VAC Out-> 5.19VDC [TP_VIN+, TP_CCS+] = 0VDC [TP_GND1, TP_VIN+] = 12.95VDC [TP_Out, TP_Shunt+]=0.00017VDC [TP_GND-TP_VREF+] = 3.95VDC Vout does not adjust above 5.19VDC with changes to VR2. Parts: - The small signal transistors are BC550C and BC560C, not 'B'.
- R12 is 2KOhm. R7 is 100KOhm. Both values are from the BOM.
- D1 is Semitec 5.6mA, and the voltage reference at 3.92VDC appears fine.
What should be checked? Are the values for R7 and R12 for 5.25VDC output correct? What am I missing?] Fluke 287 DMM is used. /Dmitry Edited by user Monday, February 24, 2014 2:30:27 AM(UTC)
| Reason: Added part values. File Attachment(s):  IMG_2334.JPG (300kb) downloaded 1 time(s). IMG_2335.JPG (327kb) downloaded 1 time(s).dsolodov attached the following image(s): IMG_2333.JPG (254kb) downloaded 20 time(s). IMG_2336b.jpg (245kb) downloaded 13 time(s).You cannot view/download attachments. Try to login or register.
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 8/22/2010(UTC) Posts: 38 Thanks: 14 times
|
Retook pictures with a different camera. File Attachment(s): IMG_3367a.JPG (322kb) downloaded 12 time(s). IMG_3368a.JPG (317kb) downloaded 6 time(s). IMG_3369a.JPG (306kb) downloaded 9 time(s). IMG_3373a.jpg (314kb) downloaded 6 time(s).You cannot view/download attachments. Try to login or register.
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 6/17/2008(UTC) Posts: 921  Thanks: 1 times
Was thanked: 70 time(s) in 69 post(s)
|
My thoughts.
AC_in = 11v, a little high for 5V out. @500mA it will get hot as ....
Are you using the stock tranny ? Are the Placids bought as full kit from TPA ?
Next up, you're not shunting any current. What happens when VR1 are turned, measure between TP_shunt and TP_out
Can you get any reading (besides 0.00017v). Remember, mV equals mA in this configuration. Put your DMM in mV mode.
|
 1 user thanked avr300 for this useful post.
|
|
|
|
Rank: Member
Groups: Member
Joined: 8/22/2010(UTC) Posts: 38 Thanks: 14 times
|
Hi Avr300: Thank you so much for the hint! I missed mVDC range completely. After switching for mVDC for measurement points, I managed to increase shunt current to 510mA, and than let the VOut to be configured for 5.25VDC as desired. Apparently the CSS was set to be very low for the initial setup, and that did not let the PSU to reach 5.25VDC out. Well, I am glad I asked first and did not burn the PSUs. Thank you again. > Are you using the stock tranny ? No, I have a custom ordered transformer with 1x9V 16VA and 2x15V 15VA each. > AC_in = 11v, a little high for 5V out. @500mA it will get hot as .... The transformer is tested to produce 10.20VAC unloaded and 9VAC at full load using 120V input. So while testing Placid without load and 124VAC home AC, the transformer output is 10.53VAC. I let the PSU run with 5W 100R resistor. The output transistors were at 48C and 51C with 2" heatsinks. Edited by user Monday, March 3, 2014 10:28:03 PM(UTC)
| Reason: Not specified
|
|
|
|
|
|
Forum Jump
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.
