Recent content by Jon1982

Just to give closure, I replaced the Q13 / Q15 pair and the problem hasn't recurred - been fine for a couple of months now so I think I've nailed it. If anyone else HAS to change TC0 on the FM Front end, a 3-10pF vario cap gave me the correct adjustment. IIRC the problems all started when I...

Got an issue whereby tuner will suddenly drop out - a station tuned to say 106mhz then re-appears at 104.5mhz. Just tapping TC0 with a plastic trim tool remedies it. I <think> at some point I absent mindedly adjusted TC0 when I was trying to follow the APC setup procedure... clumsy of me and...

Thank you Mark, I believe you may well be correct. I'll get some new trimmers on order. While I'm at it, does anyone know what value the 'TCO' trimmer should be on the FM front end? I definitely have an issue there

Thanks for the info regarding the auto reset. Might be getting warmer, taken a voltage reading at D6 which I believe to be a bias diode that sits on the heatsinks on flying leads, about -1.7V which would appear normal, when the 'thud' occurs this shoots all over the place up to 30 odd volts if...

Bit more background from a couple of months back which I forgot to add The amp was at the point where it would reliably cut out with the 'thud' after a few minutes (as it is again now) I thought I would check around the rectifier / filter caps, I found a couple of connections I wasn't happy...

Just checked and it looks like I replaced that cap when I did the recap a couple of years ago (for another electro) still worth swapping out for the film cap as you suggested?

Confirm 'thud' occurs with no input signal DC offset drifted up to about 35mV before thud Will change that cap, thanks

Re-soldered pretty much everything but to no avail. The 'thud' seems to be cyclical, about once per second, and seems to be accompanied with a loss of source signal, until there is a big enough 'thud' to cut the speaker protection in. Thought that may give a clue as to where I should look next...

Thanks very much for the suggestions guys The prob doesn't seem to be the molex connectors, given them a good shine up and problem still apparent. I don't remember changing any tx's on the power amp boards. I take it there's some which are failure prone? I rechecked the bias & DC offset as...

Wonder if one of the gurus could help me track down an intermittent fault on my 1980 which is somewhere in the output stages I have checked it is not to do with the pre-amp stage by using a separate power amp via the pre-outputs Unit has been re-capped, power supply mod done and has worked...

Zebulon, I'm glad I allowed you to indulge yourself :) I must say Idunno, that unit looks in fantastic condition. I couple of my grill slats have been pushed in, although I suppose I could take them off and straighten them. Although, if they're worth that much, I might take them off and sell...

Just me being curious, this one.. My 1980 has what I would describe as grilles which cover the heatsinks. Looking at pictures of other 1980's I'm struggling to find another one that has these. Its clearly factory, but I can't see them in the service manual. My unit is a European 220 / 240V...

Thankyou for taking the time to reply zebulon, your endorsement of the chemicon caps is useful. I've ordered some 27000 uf / 100V ones which look to be the same diameter as original but a little shorter. Ordered from mouser although look to be on back-order. I read about your recent bereavement...

Could also go for 160V / 27000 uF.

Hi folks, Going to open the SX-1980 back up and change the filter caps, as my meter suggests they're starting to degrade, and they're the only electrolytics I haven't changed. I'd ideally like to keep the same can diameter (3"). I have found some Vishay caps 100V / 22000 uf as per original, I...