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G8MNY  > TECH     19.02.24 09:52l 65 Lines 2914 Bytes #999 (0) @ WW
BID : 1750_GB7CIP
Read: GUEST
Subj: IC 735 Lamps Mod
Path: IW8PGT<I3XTY<I0OJJ<GB7CIP
Sent: 240219/0747Z @:GB7CIP.#32.GBR.EURO #:1750 [Caterham Surrey GBR] $:1750_GB
From: G8MNY@GB7CIP.#32.GBR.EURO
To  : TECH@WW

By G8MNY                            (Updated Oct 23)
(8 Bit ASCII graphics use code page 437 or 850, Terminal Font)
 ________________________________________________________
³         ÚÄÄÄÄÄÄÄÄ¿ ÚÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄ¿  ==  ==  == ³
³ ßßßß == ³  \     ³ ³ Rx 14.273.5 vfo A 12³    _    _   ³
³ /~\     ÀÄÄÄÄÄÄÄÄÙ ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ   (_)  (_)  ³
³ \_/                          ____  IC-735              ³
³      ßßß ~~~~~~""""""~~~   /'    `\    ßßß   /"~"\  [] ³
³  0   ÜÜÜ                  |(~)     |   ÜÜÜ  |     |    ³
³           Þ Þ Þ Þ Þ Þ    ³  ~       ³        \._./  [] ³
³ /~~\ ßßß  Þ Þ Þ Þ Þ Þ     |        |   ßßß  ==  ==  == ³
³ \__/ ÜÜÜ  # # # # # #  []  \.____./    ÜÜÜ  [___] [___]³
ÀÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÄÙ
I now have 3 of these old triple convertion HF PLL rigs, a heavily used one for
/P use, club events, & training courses etc. a spare one, and a cleaner one in
the shack.

SYMPTOMS
There are 4 of these lamps illuminating the meter & the LCD panel, brillinace
is set but an accessable pot on the mic side of the rig. So the odd blown lamp
it is not to bad to use the rig. The lamps are grain of wheat 12V wire ended &
run on about 10V. They have a green cover over each bulb. Unlike LEDs the light
goes 360deg around to illuminate large areas.

PREPING REPLACEMENTS  
Having a box of tiny screw 6V SMD white lamps, I set about using them as 
replacements....
        oÄÄ¿
      :~ ~:6         They needed a series 68R so they did not blow up,
      :   :8         which is soldered from the tip & lead wired towards 
  ____:   :R  +10V   the bulb & then bent sideways. The earth wire is
Gnd   øÄÄÄ´ÀÄÄÄ      soldered to the case solder point.
     ³³   ³³Green
Glass³³   ³³Cover
 Bulb \\_// 
       ~~~
FIXING IT
Access is fairly straight forward, but a few screws!
 1/ Remove power lead, remove top and bottom covers, including the 4 anti
    rattle screws around the LS.
 2/ Unscrew the 2 front panel Locking screws, and tilt the panel down to access
    the wire ended lamps (in PCB holes) and unsolder the blown ones.
 3/ If needed for more access, unscrew the 4 screws for PA unit, remove
    external Phono Rx patch lead, release the LS lead, RF drive lead from
    underside PCB & 2 other connectors to the upper PA unit.
 4/ Carefully remove the dud lamps green covers, and put them on the new bulbs.
 5/ Cut the new lamp wires to length & tin them. Solder in with the lamps case
    on the earth side if possible. 
 6/ Now put everything on its side, and make power safe, power up the rig and
    check for correct lamp function.
 7/ Power down and reassemble.


Also see tech buls "IC 735 No RF Output Fault", "IC 735 No PA Bias Fault",
"PA instability in ICOM IC735", "Autocaller with old Maplin kit" & "CW/SSB Rig
Frequency".


Why don't U send an interesting bul?

73 de John G8MNY @ GB7CIP


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