PhilA
Active Member
A sickly SR840 (any help appreciated).
All,
Recently came by this receiver whilst purchasing another one- guy and I got chatting about stuff and he mentioned he had it as "it didn't work very well and hey, you can have it if you think you want to fix it".
Sure, why not?
20131123_224711_Fernandez St by renault9gta, on Flickr
Got it home, it's cosmetically a little untidy but all the knobs and buttons and stuff that gets knocked/falls off seems to be present.
Cracked the front off and gave it a little bit of a clean up. The chromed plastic bits have corroded- I didn't do any more than scrub with an old tooth brush and some dishwashing detergent. They've pitted and pocked like an old faucet. Still, better than it was.
20131124_001537_W 25th St by renault9gta, on Flickr
Brought it up gently on the variac. No excess current draw, no nasty surprises. Yup, cleaning the front panel didn't fix it! On the up-side, I don't feel like I need to wash my hands after touching it any more.
The front panel buttons all work, and according to the display, they all seem to be trying to tell the various boards inside what they are supposed to be doing. Sorta.
It's dusty-ish inside but not horrible. Looks like it's been stored in a garage, from the light corrosion. Nothing major, that'll happen to anything ferrous left outside here in a day or so. Batteries have leaked but damage is minimal, to the zinc coating on the chassis only. No boards affected by the leak.
20131125_170145_W 25th St by renault9gta, on Flickr
Selecting AM or FM brings the tuner display to life and it scans the display through the scale over and over, picking up nothing (though, that being said, I don't have an antenna hooked up. Still, there's one very strong local FM station that'll pick up over a long piece of wire, a diode and a loudspeaker) and even selecting that station brings in nothing even with FM mute/squelch off.
Pushing the volume buttons causes an audible but very faint pop with each discrete volume level. The volume LED's count up and down as appropriate.
Connecting a source to the CD (or any other input apart from Phono, didn't try that) creates a low volume output on both loudspeakers which has all the audio qualities of a transistor radio whose batteries are dying.
Selecting the input button you are using makes it go quiet. It's present on all other inputs, including AM/FM.
Pushing tape monitor causes a coil-driver blowing POP which quietens with each successive push. Leave it a half minute and the POP-pop-pop-clik-snap-...-..... returns. No improvement of sound.
I bypassed the preamp/mixer stage and hooked up directly to the power amp stage. Audio from both channels loud and clear.
Re-seated all the ribbon cables I could get to. No change.
Lifted the board out that's under the AM/FM (?) board. It has all the low-level inputs on the back. There's a couple D1406 transistors mounted to moderately large heat-sinks that evidently run hotter than the surface of the sun, judging by the dust/carbon/soot/muck accumulated on the chassis next to the heat-sinks and on the base of the AM/FM board above. (Cleaned since the photo).
20131125_185515_W 25th St by renault9gta, on Flickr
I've reached an impasse with it though. I don't have (or can't find for free on google) a service manual. There's nothing inside to indicate what voltages should be present from the standby or the main power circuits.
Anyone able to help with some insight? From what I read it doesn't have all the usual foibles (working, but one channel out etc) these receivers seem to present.
Thanks in advance, and sorry for the ramble
--Phil
All,
Recently came by this receiver whilst purchasing another one- guy and I got chatting about stuff and he mentioned he had it as "it didn't work very well and hey, you can have it if you think you want to fix it".
Sure, why not?
20131123_224711_Fernandez St by renault9gta, on Flickr
Got it home, it's cosmetically a little untidy but all the knobs and buttons and stuff that gets knocked/falls off seems to be present.
Cracked the front off and gave it a little bit of a clean up. The chromed plastic bits have corroded- I didn't do any more than scrub with an old tooth brush and some dishwashing detergent. They've pitted and pocked like an old faucet. Still, better than it was.
20131124_001537_W 25th St by renault9gta, on Flickr
Brought it up gently on the variac. No excess current draw, no nasty surprises. Yup, cleaning the front panel didn't fix it! On the up-side, I don't feel like I need to wash my hands after touching it any more.
The front panel buttons all work, and according to the display, they all seem to be trying to tell the various boards inside what they are supposed to be doing. Sorta.
It's dusty-ish inside but not horrible. Looks like it's been stored in a garage, from the light corrosion. Nothing major, that'll happen to anything ferrous left outside here in a day or so. Batteries have leaked but damage is minimal, to the zinc coating on the chassis only. No boards affected by the leak.
20131125_170145_W 25th St by renault9gta, on Flickr
Selecting AM or FM brings the tuner display to life and it scans the display through the scale over and over, picking up nothing (though, that being said, I don't have an antenna hooked up. Still, there's one very strong local FM station that'll pick up over a long piece of wire, a diode and a loudspeaker) and even selecting that station brings in nothing even with FM mute/squelch off.
Pushing the volume buttons causes an audible but very faint pop with each discrete volume level. The volume LED's count up and down as appropriate.
Connecting a source to the CD (or any other input apart from Phono, didn't try that) creates a low volume output on both loudspeakers which has all the audio qualities of a transistor radio whose batteries are dying.
Selecting the input button you are using makes it go quiet. It's present on all other inputs, including AM/FM.
Pushing tape monitor causes a coil-driver blowing POP which quietens with each successive push. Leave it a half minute and the POP-pop-pop-clik-snap-...-..... returns. No improvement of sound.
I bypassed the preamp/mixer stage and hooked up directly to the power amp stage. Audio from both channels loud and clear.
Re-seated all the ribbon cables I could get to. No change.
Lifted the board out that's under the AM/FM (?) board. It has all the low-level inputs on the back. There's a couple D1406 transistors mounted to moderately large heat-sinks that evidently run hotter than the surface of the sun, judging by the dust/carbon/soot/muck accumulated on the chassis next to the heat-sinks and on the base of the AM/FM board above. (Cleaned since the photo).
20131125_185515_W 25th St by renault9gta, on Flickr
I've reached an impasse with it though. I don't have (or can't find for free on google) a service manual. There's nothing inside to indicate what voltages should be present from the standby or the main power circuits.
Anyone able to help with some insight? From what I read it doesn't have all the usual foibles (working, but one channel out etc) these receivers seem to present.
Thanks in advance, and sorry for the ramble
--Phil
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