Remove collector and open base of Nikon Labophot

Maybe there is some wear at the thread where the stage fits, causing that the stage cannot hold.

Wharfedale pro bx1360sd

I have had problems with this stereo mixer amplifier which had the symptoms of no sound output from either channel .

I opened up the unit and discovered that the amplifier was correctly amplifying my input signal up to a relay which switches the output through to the speakers .

This relay did not activate at all.

When the power switch is turned ON you should hear a click approximately 2 seconds later , if no click then there is a problem with the circuitry associated with this relay .

I traced out all the connections associated with this relay and made a circuit diagram .

The relay is a 24v relay and I will explain the way that I can see that this section of the amplifier works.

It has been designed to ;

1. Create a slow start delay ( 2 seconds ) when the power is turned ON.

This it needed because otherwise there is a current surge and sparks from the relay turning on immediately.

1. Thermal cutout mounted on heatsink . If the ventilation fan fails the heatsink and transistors may get too hot and the cutout will operate and cut power to the relay by going open circuit.
2. Speaker protection from blown output transistors. There are 2 transistors q802 and q803 both 2sc1815. They are connected together emitter to emitter and collector to collector to form a differential Op amplifier I.C. If there is a blown output transistor then DC voltage will be detected by q802 and q803 and the relay will be switched OFF to protect the speakers .

Q804 turns On Q805 which turns On Q806 to activate the relay .

Voltages on transistors

Q802 and Q803 2sc1815

Base 0V Collector 12.9V Emitter 0V

Q804 2sa1015

Base 12.9V Collector 0V Emitter 15.1V

Q805 2sc1815 (driver for Q806)

Base 0V Collector 7.2V Emitter 0V

Q806 2sc1815

Base 0V at Turn ON then after 2 secs increases to 0.7V

Collector 2.8V ( transistor is activated as a switch Turned Fully ON ( saturated) to turn on the Load which is the relay .

Emitter 0V

I have replaced the following transistors to fix my amplifier q805 2sc1815 and q806 2sc1815 .If you are going to use a different type of transistor it may not work and also the lead connections of a 2sc1815 for the collector and emitter are different to those such as on a 2n2222( transposed).

It is most likely that the lenses are dirty.

Take off the dust collector , put the machine somehwere out in the open air and switch it on if the motor runs up to speed then the probelm is inside the dust collector and it is probably a blocked hepa filter

If the motor does not run clean with the dust collector removed then you need to remove the base plate and check for blockages there

you have more than likely damaged some transistors.
the resistors have burned because of excessive current.
there are 2 typesof transistors,bipolar and mosfet
a bipolar transistor has 3 pins.1) base 2)emitter 3)collector.
an NPN is tested with the + meter lead on the base , and a PNP transistor with the - lead on the base.
TESTING
base to collector should read .5 to .6 v drop in one direction and open in the other with a digital meter on the diode check function.
base to emitter about the same,but slightly higher than the collector.
if base to collector is .5v then base to emitter is .52 or so.it is always higher than the base collector number.
between emitter and collector will read open in both directions.
if there is a short on any lead combination,the transistor is blown.
npn transistors operate on the positive rail power supply,and pnp on the negative rail.
typically a 150 watt amp will run + - 65vdc.
the transistors running on the plus side are npn and on the negative pnp.
most pnp output transistors are green.,but some are black,
so we must go by the numbers on the transistors, eg.A1076 is a pnp,B755 is a pnp and all transistors that have a C or D eg. D424 are NPN transistors. all A and B numbers are PNP and all C and D numbers are NPN.
MOSFET transistors have 3 pins 1)gate 2)drain 3)source
the source goes to power like the collector does. the drain is like the emitter,and the gate switches it on like the base does.
testing a mosfet is a different procedure.
a mosfet with k then a number e.g. k135 is a positive device like npn.
a mosfet with j and a number e.g. J50 is a negative device like pnp.
a mosfet reads open source to drain both directions.
for a positive (k number device) the plus meter lead goes on the source.,the black meter lead on the drain. on the diode test function.
jump a wire from the source to the gate for 1/2 second and remove the jumper while leaving the other two meter leads connected to the source and drain.The mosfet should switch on and the meter should show a short.that means the mosfet switched on.About 5 seconds later,the resistance from drain to source should go open.
for a p channel mosfet,it checks the same,except that the black meter lead goes on the source and gate .
a mosfet will stay switched on longer than the voltage applied to the gate,if it is driving a high impedance device such as a meter.
a bipolar transistor will not stay on when voltage is removed from the base lead.
i hope this has been of some help.

Are you talking about the LV power supply or the HV power supply? The terminology your using is related to the horiz drive circuit. Have you checked the B+ off the regulator which should be about 120v or, it will on the pc bd for the correct voltage. Do you have sound? If you do then you will have to use use your scope to see if you have proper drive at the base of the Horizontal Output Transistor. Then we can go from there. Oh, by the way I can tell by the voltage readings you stated both of those transistors of turned off.

HI,
IS THE BASE OF THE WASTE BIN ATTACHED OR HAS IT SNAPPED OFF?THE BASE OF THE WASTE BIN JUST CLIPS BACK ON THE ONE END SO THAT IT CAN SWING.IF HOWEVER THE BASE IS ATTACHED BUT WONT STAY SHUT OR LOCK THEN ITS POSSIBLE THE LATCH INSIDE THE CYCLONE HAS SNAPPED OFF.IF ANY " DIRT CHEAP " ( EXCUSE THE PUNN )SPARE PARTS AR REQUIRED THEN PLEASE FEEL FREE TO EMAIL ME DIRECT: [email protected]

The Nikon Optiphot 2 tube length is 160 mm DIN finite. It is a 1990 vintage microscope. Any objective lens with the standard RMS thread, -160 engraved on it will work. It will not work with other brnads with the infinity symbol engraved on it or infinity tube length Nikon 200 mm, CFI60 objectives for 2000 vintage to present microscopes. - Lawsen Lew

You should start by changing the bulb, even though it looks ok chances are that it's no longer working. Do the same with the fuse if the new bulb doesn't work.

Test that power is reaching the socket with a voltmeter or a multimeter so ensure the wiring is ok with the new fuse. If no power is reaching the bulb socket, then you will need to check the wiring every step of the way.

There is problem in sound IC. First check it