fix record
remove the two Alan screws at the sides of the front display
on the right side youll see Q4 transistor this is track enable enable switching ..
ie it enables the common for all the track's enable record .... switches
signal 'bypass' routes to pin15 each R/P card set
its a 2sc1815 and they are easily switched also and very often fail
check at its collector center pin for zero ~+_ 0 volts with all track enable switches on the main unit out
when one or more switches latched if the transistor is faulty its collector will 'float' around +18v even though the base pin is at +5v {pin 20 remote port}
this transistor supplies switching to enable all the onboard track switches even monitor track
and provide the signals "BYPASS" to each R/P card
this signal when you lock on a track enable switch its routed to pin 15 of
each of the track RP units plugged into the channel cards slots on the base pcb
you can get too the top pcb and etc via the back top panel
check pin 15 on a given track youll see the legend on the board for 'bypass' if its 18volts
all the time could not be switched on or not
then that track is in bypass mode and will not record
this bypass pin 15 should be pulled down by the press lock enable track switch
and its common too all the switches is transistor Q4...
pulls all the switches common to ground so letting BYPASS fall too low
for each enabled track
you can also test the enable disable internal switches if you had plugged in the remote head......1
pin 20 on the connector at the back for remote so pin one is here looking at it :::::::::::::::::::: <
will show 5 v if this signal is low 0v then the internal switches on the front wont work
and is connected too Q4 base via a pull up resistor to 5v and a 10k to the base of Q4
so it will and should show 5v
if pin 20 isnt showing 5v without the remote head connected this is a different story
hi on pin 20 will equal low on the collector of Q4 and enable the tracks switches on the machine
by pass on the tracks will fall on press at each track enable switch 'bypass' input pin 15 on the R.P cards
this is the only thing 'signal group' that affects every track record
only two other signals can like the bias osc block
but easy to test and confirm
and record will work again hurray!!!!
give it a try
remove the two Alan screws at the sides of the front display
on the right side youll see Q4 transistor this is track enable enable switching ..
ie it enables the common for all the track's enable record .... switches
signal 'bypass' routes to pin15 each R/P card set
its a 2sc1815 and they are easily switched also and very often fail
check at its collector center pin for zero ~+_ 0 volts with all track enable switches on the main unit out
when one or more switches latched if the transistor is faulty its collector will 'float' around +18v even though the base pin is at +5v {pin 20 remote port}
this transistor supplies switching to enable all the onboard track switches even monitor track
and provide the signals "BYPASS" to each R/P card
this signal when you lock on a track enable switch its routed to pin 15 of
each of the track RP units plugged into the channel cards slots on the base pcb
you can get too the top pcb and etc via the back top panel
check pin 15 on a given track youll see the legend on the board for 'bypass' if its 18volts
all the time could not be switched on or not
then that track is in bypass mode and will not record
this bypass pin 15 should be pulled down by the press lock enable track switch
and its common too all the switches is transistor Q4...
pulls all the switches common to ground so letting BYPASS fall too low
for each enabled track
you can also test the enable disable internal switches if you had plugged in the remote head......1
pin 20 on the connector at the back for remote so pin one is here looking at it :::::::::::::::::::: <
will show 5 v if this signal is low 0v then the internal switches on the front wont work
and is connected too Q4 base via a pull up resistor to 5v and a 10k to the base of Q4
so it will and should show 5v
if pin 20 isnt showing 5v without the remote head connected this is a different story
hi on pin 20 will equal low on the collector of Q4 and enable the tracks switches on the machine
by pass on the tracks will fall on press at each track enable switch 'bypass' input pin 15 on the R.P cards
this is the only thing 'signal group' that affects every track record
only two other signals can like the bias osc block
but easy to test and confirm
and record will work again hurray!!!!
give it a try
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