SL200 modulation valve

[Robert Hilton]

I've got a TK SL200 that has a defective modulation circuit
When it kicks in the valve cycles rapidly (buzzing) and the suction pressure drops.
Any ideas?

[clivemtk]

yeah turnoff modulation

[wilt]

great answer clive typical of you!

[Robert Hilton]

Indeed, that was the quick and easy solution for the owner/driver, but I was interested if anyone else had come across this before.

[clivemtk]

dont suppose you have it on hubbards youd turn it off anyway

[MRW]

The modulation valve still operates on unit start up,
there was a problem a few years back ,where the piston ,which is in 2 halfs unwinds on its thread,
does the valve operate ok but just makes a noise when modulating?

[Robert Hilton]

It operates okay if you connect it directly to 12v supply. It gives code 34 when in operation