First, is it actually the switch which is the culprit? A check for voltages on the switch wiring or checking with an ohm-meter will tell you that: refer to drawing attachment below. If it is the switch, then presumably, that rotary switch will mechanically click into the 4 positions, and that, in turn, implies an open-circuit contact(s) on that switch. I would remove the switch ass'y. from the receiver and have a good look at the wiper and its contacts. You may well find a fixed contact has 'opened out', so not making contact with the wiper. Or there might be mechanical damage and one (or more) fixed contacts have been displaced and pushed to one side. Most important of all is to try to establish if the cause was mechanical failure or an electrical burn-out of a switch contact. If the latter, then obviously the cause of that must be put to rights first.
I've attached a drawing of this switch function - which I hope helps.
[attachment=3817]
Unfortunately, this switch is a 'special' - as that drawing discloses. Apart from the mechanically-coupled switch for the a.c. mains supply (SW24), an analysis of the rest of the switching function (SW23) shows it could be replaced by a ganged 3-pole 4-way switch. However, if you really do conclude that a genuine replacement switch is required, all I can suggest is to generate a 'search-and-tell-me' on e-bay. Parts for AR88s are occasionally to be found there.
Al.
I've attached a drawing of this switch function - which I hope helps.
[attachment=3817]
Unfortunately, this switch is a 'special' - as that drawing discloses. Apart from the mechanically-coupled switch for the a.c. mains supply (SW24), an analysis of the rest of the switching function (SW23) shows it could be replaced by a ganged 3-pole 4-way switch. However, if you really do conclude that a genuine replacement switch is required, all I can suggest is to generate a 'search-and-tell-me' on e-bay. Parts for AR88s are occasionally to be found there.
Al.
