Date: 13 Jan 89 19:24:00 GMT
Subject: R7000 Display/Sensitivity Problem
If you are having trouble with you Icom R7000 display being flaky
and then a sudden decress in sensitivity try the following:
PROBLEM: ICOM R7000 radios that are used 24 hours a day for a long time
(2 years ) when shut off the display will become flaky and it
is also possible for a lost in overall gain (3 to 40 db).
SOLUTIONS:Officially there is ICOM ECO SB# 9288-004, attached below.
Unofficially from Tech who repairs R7000
The ECO does help the display problem, but most likely
it is not the problem. *
* note repairing your own radio my void you warranty and only
allow a qualified technician to do the job, otherwise damage
could happen to your R7000. If the VCO does not track then a
major alignment would have to be done after. Check the
ICOM IC-R7000 Service Manual for more details before starting
this repair, and to make sure I have not made any typeing errors
you should get a copy of the ECO from ICOM !
1st SOLUTION:
Replace on the DC to DC Board the following capacitor.
Check the noise with an oscilloscope on both sides of
R3, if the noise is not way down on one side then
replace C2 a 33uf 16V capacitor. Noise feedback
can decress the overall sensitivity of the R7000.
Replace on the Display Board
C19 and C20 a 10 uf 16VDC capacitor
I found that on my R7000 C19 & C20 were the cause of my
display problems. They are 10 uf eletrolytics capacitors
that are lemmon yellow pc mounted units, when they go bad
the base of the yellow caps change to a brown color.
I put in the following ECO first but it did not help. If
you look at the service manual you will see that the ECO
values are on the schematic but my unit had the old values.
I suggest that you check the above first, it is a lot easier
to do, C19/C20 can be done in 10-15 min while the ECO will
take about a hour.
2nd SOLUTION: The ECO
ICOM America, INc
2380-116th Ave, N.E.
Bellevue, Washington 98004
206-454-7619
SERVICE BULLETIN
UNIT MODEL R7000
SB# 9288-004
EFFECTIVE DATE 4/1/88
SERIAL # AFFECTED: ALL
PRODUCT GROUP: Amateur
BACKGROUND INFORMATION:
Display failure do to weak components
TECHNICAL INFORMATION:
Improvement in DC to DC converter and display power supply.
PARTS AFFECTED BOARD TYPE CHANGE TO NEW PART NUMBER
Q1/Q2 2SC 1214 DC to DC Board 2SC 2655 906-00385
R1/R2 3.3 KOHM DC to DC Board 5.16 K 915-01173
C3/C4 PF DC to DC Board 0.001 MF 50V 918-01500
ceramic cap
Q11/Q12 Display Board 2SC2655 906-00385
R31/R32 3.3KOHM Display 5.16k Ohm 915-01173
C13/C16 Display 0.001 MF 918-01500
DETAIL PROCEDURE:
1. Remove top and bottom cover.
2. Remove front panel sub-assembly from main chassis of radio
3. Remove the DC to DC board and replace components as listed
4. Reinstall DC to DC board.
5. Replace front panel sub-assembly onto main chassis of radio
6. Replace top and bottom covers.
ESTIMATE TIME TO COMPLETE IS 1 hour
Page 2 of the ECO has a new schematic but no information
--------------end of ECO--------------
SOURCE: The QRZ Windows Ham Radio CDROM |
