The observant who are familiar with compressors will have already noted the unusual build of this compressor. it is a direct drive oil free unit but it does not have the usual 'black box' and associated plumbing sat outside the motor cover. Such black boxes contain the pressure switch and contactor assembly. In its absence I expected to find a smaller pressure switch, as seen on airbrush compressors, and I was not disappointed
I removed the cover after unscrewing the four self tapping retaining screws. All was revealed......
The STANLEY branded compressor is also available under the Einhell (Germany) brand and I had already obtained the parts schematic. The schematic matched my unit so they are one and the same unit. Einhell make some decent kit and happily provide spare parts, so things were looking up.
An exploded parts view of the STANLEY compressor is to be found here:
http://www.mtmc.co.uk/Stanley-Compressors/Stanley-8216035SCR011-Type-Rev-A-Compressor-Spare-Parts__p-12734901-94723.aspxThe Einell exploded parts view is here:
https://www.isc-gmbh.info/isc_de_en/tools/einhell-blue/stationary-tools/compressed-air-technology/bt-ac-200-24-of-3/The compressor comprises the following significant parts....
1. The Air reservoir tank.
2. The electric motor and compressor cylinder module
3. An AC 250V 16A rated DPST illuminated rocker switch providing the power control to the compressor electrical systems.
4. A small pressure switch samples the air pressure in the reservoir tank and opens its contacts at 116PSI. Contacts close again at 90PSI.
The pressure switch is wired in series with the motor neutral supply line.
5. A self-resetting over-temperature thermal cut-out is attached to the static windings of the motor and wired in series with its supply line.
6. An air regulator and associated pressure gauge are connected to the reservoir tank output.
So its a pretty simple beast with only a few likely causes of failure.....
1. On/Off switch faulty
2. Air pressure switch faulty and stuck open
3. Motor over-heat protector faulty and stuck open
4. Motor faulty, burnt out.
The quickest test was to bypass the on/off switch........ the compressor burst into life and began pressurizing the reservoir tank. Whoopee! an easy fix
I was not finished though. I needed to inspect all electrical parts of the compressor to see if anything else looked amiss with it.
I found the following not to my liking.....
1. The Lucar spade connectors on the pressure switch are not a tight enough fit and arcing as occurred due to the >5A current passing through them. The pressure switch is still working OK but I have my doubts about its likely life span.
2. The wiring from the motor to the pressure switch and cable connectors is messy and needs tidying a little.
3. One motor supply cable was being crushed under the motor cover due to poor placement. An easy fix as it just needed moving.
4. The use of a cheap 250V 16A DPST rocker switch was just asking for trouble on a compressor. Its contacts were badly burnt and the moving contact had welded itself to the pivot in the open position !
I shall be rectifying these issues as part of the repair. A better quality rocker switch will be tried and if that fails, a high current solenoid will be fitted.
The STANLEY/Einhell compressor is a neat and light weight little unit suitable for my humble needs, but the use of a simple pressure switch and a DPST rocker switch indicates that it is budget product built down to a price. The original owner paid £140 for it so it is not exactly cheap. General build quality is fine though. The motor/compressor cylinder module is neat and well made.
The unit will likely be fine with my light use but I expect issues with the pressure switch at some point in the future. A new one is 18 Euros from Einhell.
I attach the picture that I took of the unit with its covers removed.
Fraser