right now I have a bigger issue. like I mentioned I am making the PS in a separate chassis and there will be four 4-lead umbilical cords; one for each BiB board, to the other chassis where an 8-channel preamp with volume attenuator will be.
after testing the BiB boards with dummy load resistors, I removed the resistors and soldered the output wires to 4-pole connectors on the chassis. I also grounded the chassis to earth and added a separate small PS for powering up the volume control (which takes 5V reg).
then I powered it up and blew the main fuse. I thought the auxiliary PS was shorting, disconnected it and blew another fuse. Then it dawned on me that these regs may not be able to be powered with four output leads open ended? Did I fry them???
;or something else is the culprit.
p.s. if I fried them, which components are likely to need a replacement?
THX
after testing the BiB boards with dummy load resistors, I removed the resistors and soldered the output wires to 4-pole connectors on the chassis. I also grounded the chassis to earth and added a separate small PS for powering up the volume control (which takes 5V reg).
then I powered it up and blew the main fuse. I thought the auxiliary PS was shorting, disconnected it and blew another fuse. Then it dawned on me that these regs may not be able to be powered with four output leads open ended? Did I fry them???
;or something else is the culprit.p.s. if I fried them, which components are likely to need a replacement?
THX
They must not be powered when open ended in Kelvin mode. There is no control response that way. It's warned against in the guide. Put the dummies at the ends and check what outputs still work or not. If some outputs have gone weird test those sections semis. Some could have blown. Start with MOSFETs Vgs. Then BJTs Vbe.
wow, with no safeguards these are then not practical for a two chassis implementation. I wish the comment was more prominent in the guide. with no spare parts at hand it is going to take me a month to get these back on line.
how does one implement them in a regular (no sensing) mode? it takes a jumper some place?
how does one implement them in a regular (no sensing) mode? it takes a jumper some place?
The best place for a regulator is:
At the input pins of the load !
The worst place for a regulator is in some remote box.
The longer the connection between the regulator and the load, the worse the performance becomes.
Applying remote sensing is just a plaster over the cut, it has not cured the problem.
At the input pins of the load !
The worst place for a regulator is in some remote box.
The longer the connection between the regulator and the load, the worse the performance becomes.
Applying remote sensing is just a plaster over the cut, it has not cured the problem.
I thought I was taking advantage of the remote load sensing when doing two box solutions and putting the Xformer away from the preamp.
Well now that I understand the issue better: I hate the idea of putting a huge label across the PS box: "Do not power up before connecting to preamp". so I am seriously considering stacking them on top of each other and fixing them together somehow into effectively one unit. at that point instead of shortening the fancy 4-lead PS cables off the back I might as well drill through the top & the bottom and bring the wires to preamp the shortest route possible. I only have to find a way of attaching two mini galaxy chassis together without any visible straps on the outside.
but first it is time to call on my friend who is fully equipped and knows what he is doing to help me find a way out of having burnt the regs. I only hope sourcing the damaged transistors does not get into chasing particular grades from different sources. If one order from Mouser can do it that is acceptable else I will really remember this project over others.
Well now that I understand the issue better: I hate the idea of putting a huge label across the PS box: "Do not power up before connecting to preamp". so I am seriously considering stacking them on top of each other and fixing them together somehow into effectively one unit. at that point instead of shortening the fancy 4-lead PS cables off the back I might as well drill through the top & the bottom and bring the wires to preamp the shortest route possible. I only have to find a way of attaching two mini galaxy chassis together without any visible straps on the outside.
but first it is time to call on my friend who is fully equipped and knows what he is doing to help me find a way out of having burnt the regs. I only hope sourcing the damaged transistors does not get into chasing particular grades from different sources
. If one order from Mouser can do it that is acceptable else I will really remember this project over others.
You can safeguard with low consumption dummies (even in the PSU box) just to make the Kelvin circuit ends meet when no real load is attached. You should not connect or disconnect on the fly powered up PSUs of any kind to any preamp anyway. Power hot plugging is asking for trouble in general with any kind of equipment.
Its not sure they suffered damages already though, but possible. Does not require matched spare semis per se.
About two wire mode: There is a link about it in post#1 of this thread.
Two wire mode does not require remote safeguard termination.
Its not sure they suffered damages already though, but possible. Does not require matched spare semis per se.
About two wire mode: There is a link about it in post#1 of this thread.
Two wire mode does not require remote safeguard termination.
Ok, I cut off the connectors (a lot of work with miniature connectors in a crowded housing), reloaded all four boards with resistors and the regs work as before. so nothing got burnt . I am back to square one where one neg rail board is flaky (a slight press on the wires and off goes the voltage).
I decided to wait for my friend to become available to check into that board. of course I do not have a spare kit for a neg board. but I hope the other neg board which runs Ok provides some clues by means of comparison as to which component may be the culprit.
. I am back to square one where one neg rail board is flaky (a slight press on the wires and off goes the voltage).I decided to wait for my friend to become available to check into that board. of course I do not have a spare kit for a neg board
. but I hope the other neg board which runs Ok provides some clues by means of comparison as to which component may be the culprit.sorry if this was covered elsewhere but the ground is confusing me here as there is a separate ground on V- and V+ SSLV board but they are to supply bf862 preamp board which has one ground per channel (and a plus and a minus V rail). in SSLV BiB the screws are not used to connect them to chassis so they are floating I guess. in the amps I made I got used to the bipolar PS and the star ground off of the copper plate on the PS filter caps and then connecting it to earth via a bridge (or a thermistor) to break up a ground loop if any.
FIY I am using four SSLV boards (two positive and two negative) to supply eight channels of bf862 preamp. so two boards are to supply four channels like this:
http://www.diyaudio.com/forums/pass-labs/254190-best-options-making-f-5-integrated-amp.html#post3882666
what's the prevailing thought about how to best do the ground in this case? Thx.
FIY I am using four SSLV boards (two positive and two negative) to supply eight channels of bf862 preamp. so two boards are to supply four channels like this:
http://www.diyaudio.com/forums/pass-labs/254190-best-options-making-f-5-integrated-amp.html#post3882666
what's the prevailing thought about how to best do the ground in this case? Thx.
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Its they are having individual zero because they are independent regulator sections with their own full diode bridges and Tx secondary (which is a good thing)
Those points should simply be wired to the same point on the preamp's common. You can still use the thermistor or bridge (float safe) but connected at the above central point too.
Those points should simply be wired to the same point on the preamp's common. You can still use the thermistor or bridge (float safe) but connected at the above central point too.
Has nothing to do with that. Its an intrinsic property in all Mosfets. Go there see Fig. 10 chart: http://www.vishay.com/docs/91080/91080.pdf
Salas I have done just as you suggested above on my BA3 balanced pre which is dual mono with two + and two - regs. Today out of curiosity I disconnected the thermisters from the chassis connection keeping only the IEC earth connection to the chassis and I measure 9.22VAC between the 0S0F on the one reg (or preamp common) to chassis and 8.33VAC for the other reg to chassis. I verified that all four regs are outputting 24VDC as set several months ago between the FS and 0 points of the regs. Is this OK? A bit confused.
Thanks. nash
That's what I was thinking but thanks for explaining.
Would it be OK to keep it floating with only a lift bridge ie no resistor along with the bridge in parallel. The bridge would trigger a safe connection to chassis if V exceeds the forward diode V but otherwise there would be no connection. I figure this would also allow me to keep the channel signal ground reference separate utilizing a safe bridge for each channel. I'd like to incorporate the same in my DCG3 build too(but that will have the DCSTB)
nash