2070-9x User’s Manual
16
MAINTENANCE
Preventative Maintenance
There is no preventative maintenance required or anything that needs to be
adjusted for the life of the product.
Trouble analysis
The model 2070-9xx is a fairly complex Modem with hundreds of parts. This makes
this Modem hard to trouble shoot for the average technician with limited experience.
It also requires special soldering tools to work with the surface mount parts. On the
other hand this modem is constructed with top quality parts and so you will not
experience many failures.
The chart on the next page will help find the problem if you decide to fix the model
400 yourself.
Trouble shooting Sequence chart
PROBLEM
CAUSE
The board is non-functioning
Power coming into the board or
could have a problem. Check
connectors
Modem is not generating Mark and
Space Freq.
No RTS or TXD coming from Host.
Check edge connector, Q8, Q7 and
U8.
Transmitter turns Off after 6
seconds
Anti-streaming is turned on and
transmissions of more that 6
seconds are being used.
No Receive Data
RXD and CD LEDS off
Check edge connector, U1, U2, and
U3..
No Receive Data
no LEDs
Check output of input filter U1 pin8,
you should have a strong signal at
this point.
No Receive Data
CD LED on
Check Demodulator section. UU6.8,
U6.14, and U5.14 should be close to
+12v.
PRELIMINARY
