The voltage drop on 5v1 Zener of positive ccs is only 0.9V
Unfortunately I don't have spare 5v1...
Unfortunately I don't have spare 5v1...
My next suggestion is to start with a new PCB populating only the VAS zone and check for its output to be near zero V. Unless you are able to desolder all components beyond the VAS without damaging the PCB, leaving all the holes open.
Dear,
I was so delicate when de/soldering, pcb survived.
The second channel works fine, but consumes 440mA.
Output offset of the second channel set to 2 +-15mV, varies telatively fast. I think I have to lower the idle, because measured voltage per rail is 66VDC!🫣
Ordered 5v1 will arrive at Tuesday
Thank you for nursing!
I was so delicate when de/soldering, pcb survived.
The second channel works fine, but consumes 440mA.
Output offset of the second channel set to 2 +-15mV, varies telatively fast. I think I have to lower the idle, because measured voltage per rail is 66VDC!🫣
Ordered 5v1 will arrive at Tuesday
Thank you for nursing!
440mA is more or less the expected current draw, the CCSs by themselves draw around 140mA.
My midpoint, without a servo nor DC feedback, was 1mV varying slightly with the temperature. The midpoint must be fixed with a DC feedback or a servo.
My midpoint, without a servo nor DC feedback, was 1mV varying slightly with the temperature. The midpoint must be fixed with a DC feedback or a servo.
I changed Zener, and got 0,9V drop on it again, I changed CCS 15033 and didn't helped, I checked the cap and 6k8 res, and is ok...
Steering 15033 measures well...
please advice what can be broken?
BTW Marigno, you scared me, I started to solder series zener + mosfet power supply to get +/- 55VDC on it.
Steering 15033 measures well...
please advice what can be broken?
BTW Marigno, you scared me, I started to solder series zener + mosfet power supply to get +/- 55VDC on it.
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I fixed it.
There was no connection on pcb between the colector of ccs transistor and the emiter of steering diamond.
So guys be careful with this pcb.I am not sure if it was broken as new or I destroyed it with careful soldering.
Power supply +/-55.3V.
A radiator becomes a little hot, I can touch it but not hold too long after 20 minutes.
The offset is a horror, it varies +/-1V so I will connect my main speakers Magnepans 1.5 via large capacitors.
The sound on my test speakers is vg even before burning in.
Is there in the thread a block schematic how to connect the grounds, I would like avoid the noise.
Thank you in advance for dropping the link.
Regards
P
There was no connection on pcb between the colector of ccs transistor and the emiter of steering diamond.
So guys be careful with this pcb.I am not sure if it was broken as new or I destroyed it with careful soldering.
Power supply +/-55.3V.
A radiator becomes a little hot, I can touch it but not hold too long after 20 minutes.
The offset is a horror, it varies +/-1V so I will connect my main speakers Magnepans 1.5 via large capacitors.
The sound on my test speakers is vg even before burning in.
Is there in the thread a block schematic how to connect the grounds, I would like avoid the noise.
Thank you in advance for dropping the link.
Regards
P
witam. problem z uruchomieniem nhb-108 zmontowanego na oryginalnym schemacie z serwerem. podłączony razem z żarówką zasilacz 50vdc po włączeniu i ustawieniu offsetu napięcie na szynie wynosi 35vdc? żarówka nadal świeci. nie wykryłem żadnych zwarć, oryginalne tranzystory, wartości rezystorów ok. ten sam objaw na dwóch różnych płytkach. włączałem bez bezpiecznika po 2 sekundach spalił się rezystor R16 36r po stronie minusowej płytki. czy ktoś może pomóc?
hello. problem with starting nhb-108 assembled on the original diagram with server. connected together with the bulb 50vdc power supply after switching on and setting the offset is voltage on the rail 35vdc? the bulb still lights. I did not detect any short circuits, original transistors, resistor values ok. same symptom on two different boards. switched on without fuse after 2 seconds resistor R16 36r burned on the minus side of the board. can anyone help?
English please.
Hugo
Moderation team
My remark was directed towards the translation.
Obviously supply voltage will be lower with bulb
resistor in series.
You will find help if you describe your problem
hinting at the schematic used, it is in post .. ?
Obviously supply voltage will be lower with bulb
resistor in series.
You will find help if you describe your problem
hinting at the schematic used, it is in post .. ?
You describe that you use a bulb to limit the current to the dc supply.
Is the bulb in the ac mains circuit or in the dc path ? Which kind of bulb ?
The dc supply is symmetric, so you would need two bulbs in order to limit
the current if in dc path. Do I understand correctly that you see the full rail
voltage as amplifer output offset?
This and burnout of R36 is indication of a short in your soldering or wiring
or broken part. If you have fuses in the supply lines you can insert resistors
(or bulbs) instead, say 20 ohms 5 watts. If these get hot during switch on,
quickly disconnect power and have a look for the fault condition.
Is the bulb in the ac mains circuit or in the dc path ? Which kind of bulb ?
The dc supply is symmetric, so you would need two bulbs in order to limit
the current if in dc path. Do I understand correctly that you see the full rail
voltage as amplifer output offset?
This and burnout of R36 is indication of a short in your soldering or wiring
or broken part. If you have fuses in the supply lines you can insert resistors
(or bulbs) instead, say 20 ohms 5 watts. If these get hot during switch on,
quickly disconnect power and have a look for the fault condition.
This thread has more than 2200 posts. Probably your bulb supply is described somewhere,
but I will certainly not search for it. I guess there are many hundred people on this forum
who can help you, but all relevant information must be there, otherwise it will not happen.
Clear pictures can sometimes be useful also.
but I will certainly not search for it. I guess there are many hundred people on this forum
who can help you, but all relevant information must be there, otherwise it will not happen.
Clear pictures can sometimes be useful also.