Tuner Board ICs have corrosion

Stevescivic

Active Member
this is what is inside one of my SX-1050 receivers. I don't dare to power it up for fear I will fry something. Looks like the previous owner didn't know there was some sleep that water damage. All three IC's in the tuner have corroded legs and there are a couple of disc caps and jumper wires and a few resistors that have rust on them. What ICs are these and can replacements be purchased ? Lastly can I just give the board a good cleaning with board cleaning spray and not replace anything? Previous owner prior to shipping to me wasn't even aware of this issue and was using the unit previously with no ill effects.
 

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I would not worry about the corrosion on those IC legs, all of them have it. it is normal since they were originally silver plated and this is silver oxide which is not a problem. They are still working after how many years(2017-1978) :)
Some rust on the inductor lead is okay as well.
 
really?? they look like water got onto them or something crazy like that yet the PCB board is completely dry. Admittedly I know the unit was stored in higher humidity conditions as I have 2 SX-1050's brought home at the same time. One from eastern canada has the speckled chassis (signs of condensation) and the west coast unit is shiny and perfectly clean. Since I am doing a full rebuild on both units can I use PCB or plastic safe contact cleaning spray and clean the corrosion off so that at least it doesn't look like it's all rusted out?

Thanks,
 
Sure it is a high humidity environment that causes the rusted leads. The HA1137/HA1138 IC's do look more rusted than the usual silver oxide as mine have. The problem with cleaning solution/rust remover is that you have to be very careful not to get solution into areas where you do not want it to go or be left behind say under ICs, inside transformers etc where it could continue to be active and cause issues later.
I do not like to offer advice to find out later that there is a failure because it was not done properly. For the rusted legs you could try "CLR/rust remover" using a q-tip then after it has removed the rust, thoroughly neutralize with potable water, then blow out the remaining, let dry/use a hair dryer to completely remove water before any power is applied. I have used some rust remover solution for car body work that removes rust and then leaves a sort of oxide as a barrier against further oxidization but have never tried it on IC leads, so user beware.
 
hi RCS16. What I ended up doing yesterday was using an old toothbrush to brush off the loose rust, then used 99.99% anhydrous electronics grade cleaning alcohol and brushed the areas that were rusty (it was oddly just the legs of the IC's and the odd resistor/cap leg that was a bit rusty).

In the end the physical brushing helped remove the buildup of loose rust and then I followed up with a toothpick to pick off any chunks of rust I could get to. In the end it was as good as I could get it which was much better than before I started. I followed up with a thorough spraying with compressed air to make sure everything was dry and then I went and took a QTip saturated in alcohol to "mop" up the tuner board area that I was cleaning and all looks half decent now.

Are those tuner IC's available should they fail? One looks like one made by Hitachi and the other 2 look Pioneer specific.

Personally I'd like to replace the ICs but I know that if I mess with the tuner board by recapping and swapping components that there is a good chance I will misalign the tuner.

Thanks,
 
Good to hear that IPA was all that was necessary to rermove some of the rust.
Those parts are all available as Hitachi branded, near impossible to find NOS of the Pioneer branded, unless you scavenge from old gear. Changing of HA1137,HA1138,HA1196 all would require some alignment. If you change HA1137, you will have to re adj the quad coil for AFC center and also adjust for linearity which usually means having a low THD RF sig gen and THD analyzer to do a proper job of it. The PLL IC HA1196 need the VCO to be adjusted by measuring the VCO freq. For the AM IC HA1138, need to do adj per the procedure so I recommend to leave as is until they fail if that ever happens
 
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