Rank: Member
Groups: Member
Joined: 12/7/2011(UTC)
Posts: 474
Location: Amsterdam
Thanks: 31 times
Was thanked: 4 time(s) in 3 post(s)
|
I am unable to adjust the LH HDBP properly...
The VR1 potmeters are adjustable in value, but when I try to set the 60mA Shunt current the values are jumping up and down sometimes and other times the values are stucked.
Can I assume that the both potmeters are deffective?
Altough the resistance shows smooth in- and decrease. How likely is it that two pots at the same print are bad?...
This is the same Placid as the one that was getting warm yesterday with the basic potmeter settings so there might be someting going on from the beginning.
One VR1 is stucked in the approx. 100-130mA and the other approx. 86mA shunt current
What can be wrong here?
|
|
|
|
|
|
Rank: Administration
Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 2,868
Location: Massachusetts, USA
Thanks: 2 times
Was thanked: 141 time(s) in 134 post(s)
|
99% of the time, such problems are caused by a bad solder joint(s) and/or misplaced transistors(s).
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 12/7/2011(UTC)
Posts: 474
Location: Amsterdam
Thanks: 31 times
Was thanked: 4 time(s) in 3 post(s)
|
Ok, I will check! ....all the components are heading the right direction and all the values of the resistors are the same as on the other placid... The problem could possibly be caused by one of the semiconductors.. Is there a way to meassure them? They do not all have a tekst clearly visible so they ar hard to destinguish. thx, Jordo Edited by user Thursday, March 22, 2012 5:14:16 AM(UTC)
| Reason: Not specified
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 12/7/2011(UTC)
Posts: 474
Location: Amsterdam
Thanks: 31 times
Was thanked: 4 time(s) in 3 post(s)
|
I only fail to see QP3. But all the other parts have the correct numbers 550B or 560B so I assume QP3 will be ok too. And the problem must have a similar common source because it occurs on both sides.... Can I make some measurements to pinpoint the problem? Edited by user Thursday, March 22, 2012 11:06:43 AM(UTC)
| Reason: Not specified
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 12/7/2011(UTC)
Posts: 474
Location: Amsterdam
Thanks: 31 times
Was thanked: 4 time(s) in 3 post(s)
|
I just resoldered some joints just to be sure.
I don't think this will be causing a problem...
Any suggestions still?
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 12/7/2011(UTC)
Posts: 474
Location: Amsterdam
Thanks: 31 times
Was thanked: 4 time(s) in 3 post(s)
|
V_ref has it's normal value of approx 3,8V.
So far so good.
|
|
|
|
|
|
Rank: Administration
Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 3,979
Location: Nashville, TN
Thanks: 25 times
Was thanked: 89 time(s) in 83 post(s)
|
Any chance you can post some pictures?
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 12/7/2011(UTC)
Posts: 474
Location: Amsterdam
Thanks: 31 times
Was thanked: 4 time(s) in 3 post(s)
|
Off course, pictures will be helpfull  Jordo attached the following image(s):  IMG_7353.JPG (218kb) downloaded 133 time(s). IMG_7356.JPG (222kb) downloaded 125 time(s). IMG_7357.JPG (236kb) downloaded 115 time(s).You cannot view/download attachments. Try to login or register.
|
|
|
|
|
|
Rank: Administration
Groups: Administration, Customer
Joined: 10/24/2006(UTC)
Posts: 2,868
Location: Massachusetts, USA
Thanks: 2 times
Was thanked: 141 time(s) in 134 post(s)
|
It appears there are many cold solder joints in need of flux in the first picture. They should be smooth and shiny.
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 12/7/2011(UTC)
Posts: 474
Location: Amsterdam
Thanks: 31 times
Was thanked: 4 time(s) in 3 post(s)
|
Ok, so the resistances might be too high...
I solder with lead free tin @ 370 degrees celcius.
But it's true, some are shiny.
So it is an coincidence that the others work well..
Should I suck the tin away and order some flux and re-solder it?
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 12/7/2011(UTC)
Posts: 474
Location: Amsterdam
Thanks: 31 times
Was thanked: 4 time(s) in 3 post(s)
|
Ok I see what I did wrong!  I haven't payed attention to the QP1-2, QN1-2... I prepared them on the coolers and installed them randomly... How stupid! I will correct it right away! Edited by user Tuesday, March 27, 2012 9:06:16 AM(UTC)
| Reason: Not specified
|
|
|
|
|
|
Rank: Member
Groups: Member
Joined: 12/7/2011(UTC)
Posts: 474
Location: Amsterdam
Thanks: 31 times
Was thanked: 4 time(s) in 3 post(s)
|
Yep, that did the trick! I will proceed
|
|
|
|
|
|
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.
