This webpage chronicles the repair of a Kenwood TS-440/SAT ham radio.
These are fairly complex radios, 160 thru 10 meters, with full PLL tuning, All-Mode operation, and built in automatic antenna tuner.
There is a type of glue the factory used in certain sections of the radio circuit board to keep vibration to a minimum.
For reference purposes here we will call the stuff "evil brown glue" or 'EBG'.
This glue material conducts electricity more and more as it ages, eventually disabling the radio altogether.
Removal of this glue, and the thorough cleaning of the circuitboard areas and their parts is important.
Parts can be cleaned and reused when not available, if carefully removed from the circuitboard.
Replacement of diodes and transistors is usually required to do a thorough job.
Its a good practice to replace anything that came in contact with the glue, if the replacement parts are available.
Heres the repair method I used during the restoration of one of these fine radios.
Kenwood TS-440/SAT ham radio, showing a serious fault, 7 dots across the frequency display.
This indicates the PLL circuit has gone out of range and "unlocked". Nothing works in this state.
Kenwood TS-440/SAT with its top cover removed.
Kenwood TS-440/SAT RF board exposed, showing its SSB and CW filters installed.
RF board tray hinges at the front of the radio chassis, lift and swing open.
Tilt the RF board tray back to expose the PLL board.
Location of the VCO-5 section, its shroud and cover in place.
VCO-5 circuit shown with its cover removed.
Evil brown glue (EBG) in VCO-5 must be removed when it ages like this.
The stuff becomes very conductive when it gets old and crispy.
VCO-5 is an oscillator that mixes with 4 independent oscillators in VCO-1.
When this circuit faults out, PLL unit unlocks and all bands fail, showing dots on the front display.
PLL board exposed for removal.
PLL board removed.
View of VCO-5 on the PLL board.
Removal of VCO-5 shroud.
VCO-5 with shroud removed, showing Evil Brown Glue.
Capacitor in VCO-5 that is pretty much destroyed and 'Sploded.
VCO-5 after glue removal, before stripping and cleaning.
The exploded capacitor has already been removed.
VCO-5 section stripped and holes cleaned.
In process of cleaning board surface in VCO-5.
Removal of every trace of the remaining conductive "film" is important.
The largest amount of this crap in the whole radio is located here in VCO-1.
There are 4 adjustable oscillators for multiband operation.
Faults in this circuit can be on any or all bands.
This area is usually at fault when dots only show on some bands but not all of them.
Red lines outline the area of remaining contamination after glue removal, that must be cleaned from the board.
In the process of stripping and cleaning the VCO-1 section. Its half stripped in this photo.
Intense cleaning of the board surface must take place next to remove all traces of the Evil brown glue (EBG).
As you can see, the board surface is filthy with the conductive film-like remains of the removed glue.
And I have finally found the rare and critical tidbits that eluded me for over a month!
Im going to promote my supplier here (East Coast Electronics in NY) for being
the only source found for several of the most critical replacements.
In particular, the Varactor Diode and two of the transistors in VCO-5 being
the rarest. Looks like about 60 bucks so far to buy all these board-level
parts, and about 10 solid hours burned in the cleanup and repair.
More updates when the parts all get here.
~ resource ~
03/18/2010 - Parts are here! Im starting reassembly tonite.
I will install everything Ive got and anything left out will get
mouser or fry's parts as they are not specific.
Im keeping an extra D-14 (VCO-5) varactor diode since I ordered 2.
They are so rare, I had to get one extra in case some one wants to buy it from me.
It will cost you $30, but you wont have to wait 6 weeks or longer( or much much longer) to get one.
The parts inventory that came this week.
The super-rare varactor diodes, I only needed one but as hard as they are to obtain, I ordered a spare while I could.
These parts weren't even manufactured in February yet, after ordering them in January.
Close up shot of these rare jewels! ... its like electronic porn...
Preparing to start reinstalling available parts
VCO-1 stripped and cleaned. EBG film has been cleaned from the board surface in this photo.
Close up of cleaned and stripped VCO-1, ready for re-assembly.
VCO-5 re-assembled with new parts, shroud soldered back in place too.
Close up of VCO-5, note the shiny new varactor diode (D-14)... oh yea...
11 components were replaced in the VCO-5 rebuild, everything else cleansed squeaky-clean.
Tomorrow night VCO-1 gets this same treatment ~stay tuned!
VCO-1 is almost complete. I need 4 MA858 diodes, or their equivelent.
It looks so much better, and will post pics tomorrow. No goop or crud anywhere in the radio now.
I need those diodes and some QC inspection of the rebuild, and it will be time to put some power to it.
VCO-1 de-gooped, cleaned, and re-assembled with new capacitors and diodes.
Shroud is not installed yet.
RF board and VCO-1 Almost ready , just lacking 4 MA858 diodes here (D45,D47,D49,D51), and one more in a different circuit.
Im in the inspection phase, re-rechecking and re-re-rechecking the solder side and component side looking
for any stray solder, or missing solder...missing parts, stray parts... you know, any bad stuff.
Updates when the diodes are in my hand...
the quest continues ...