|
|
Post by elorens on Nov 7, 2022 8:34:01 GMT 12
This arrived in poor condition, having served time as a rats’ toilet. There is evidence of a lot of corrosion and most of the wire insulation is shot. The back end, IF onwards, now goes, but the frequency changer refuses to cooperate. It looks as if the coils may be shorted to ground. Has anyone worked on this model, please? Any suggestions? Thanks!
|
|
|
|
Post by Peter Walsham on Nov 7, 2022 9:22:54 GMT 12
A couple of checks I can suggest before condemning the coil(s). Check the oscillator padder capacitor (C21 & C28) for leakage/shorting to earth, & correct capacitance (disconnect them from the circuit before testing). Also check capacitors C9, C10, C13, & C14 for leakage & correct capacitance. Also check resistors R6 & R8 as well. If my memory serves me right, I have found at least one Philips wire wound trimmer capacitor go short circuit (the very stable, but horrible things that they are!).
Peter W
|
|
|
|
Post by elorens on Nov 7, 2022 19:07:20 GMT 12
A couple of checks I can suggest before condemning the coil(s). Check the oscillator padder capacitor (C21 & C28) for leakage/shorting to earth, & correct capacitance (disconnect them from the circuit before testing). Also check capacitors C9, C10, C13, & C14 for leakage & correct capacitance. Also check resistors R6 & R8 as well. If my memory serves me right, I have found at least one Philips wire wound trimmer capacitor go short circuit (the very stable, but horrible things that they are!). Peter W Great, thanks Peter, will check those points. L |
|
|
|
Post by Philconut on Nov 7, 2022 20:51:08 GMT 12
I concur with Peter. I had a Philips 652 which drove me around the bend - almost, till I checked the padder trimmer. It had a 4k resistance across the terminals. It all came right after cleaning. I have never struck this before but will be wary next time. The most annoying thing was that the radio worked perfectly intermittently. THis particular trimmer was of the interleaved metal/mica variety.
|
|
