Table of Contents

Kenwood TS-450S

Issues

Phones Jack

Cuts speaker audio, but does not carry any audio itself. Ext Spk jack on rear works correctly.

Have not yet put the output of the jack on a scope to see if there's low signal or no signal.

PLL Unlock

Intermittent behavior, first noticed on 24-1-7. Rig displayed dots across the digits and played “UL” in morse when changing bands.

Some info here: https://www.qsl.net/wb4kdi/Kenwood/TS-450S/TS-450_HELP.html

May be broken or improperly adjusted TC-1 causing the loss of heterodyne xo VCO2 (board X58-3390), 64.22MHz. TC-1 is P/N C05-0331-05, 25pF.

Audio Distortion

https://www.youtube.com/watch?v=Y2A_LeiSieI

May be issues with C99 & C101, both in the audio chain near C104. (On IF Board X48-3090)

More likely tied directly to the PLL unlock issue.

Repair History

C104

Like all other TS-450Ss, C104 on this unit had begun leaking and there was considerably corrosion on the board underneath it. Audio was very low, and leaky, both telltale signs. Was able to remove it without damage, and clean all of the goo from the board. Some solder mask around it had been eaten through, but the copper seems to still be in good shape. Installed a new (questionable quality) 16v 470uF part from stock at the makerspace. Due to the age of this rig I think a full recap would be a good idea.

Here's a good option for a replacement kit:

https://klondikemikescapkits.com/products/kenwood-ts-450s-690s-electrolytic-capacitor-kit

D11

Surge protection device (gas discharge tube arrestor) D11 took a major hit at one point in the past. Failed open. Glass is smoky and cracked, the PCB is scorched underneath and the relay next to it is also very slightly melted. I've removed D11 but will be replacing it as well.

VCO2

Potential Upgrades