MIJ_Pioneer
Super Member
Good research , also thanks frown - yeah I'm not sure what's going on there. Any good info from the schematic?
SX-636 no longer working properly after using DBT
- Thread starter voxswain
- Start date
petehall347
the brandy coffee man
looks like someone wired the switch as a bodge . if you are lucky the parts are still inside the switch and can be used again after a good clean .as for the pin you might be able to solder it back on .
so I guess this would put it permanently in Playback mode?
Luckily there is still a Tape2. Might not be that bad to do without Tape1, just a thought. If anyone even uses Tape Monitor these days.
petehall347
the brandy coffee man
me too . it should come apart to clean it properly if all the parts are still inside
Oh!
If that's a common switch on many SX-x3x models maybe you can find one. In the mean time you could go ahead with your restoration. I wonder if it clicks and stays in place when you press it. I've had some switches that did not stay in, until I cleaned them, then they were fine. I've seen threads on here about taking somewhat similar Marantz switches apart and cleaning them. If you can get the switch to work you could make a jumper to fix that broken pin.
Here's the Marantz switch thread:
https://audiokarma.org/forums/index...itches-for-better-cleaning-de-oxiting.266269/
https://audiokarma.org/forums/index...itches-for-better-cleaning-de-oxiting.266269/
I'm done! Finished the preamp board and finally got the new filter caps installed. Funnily enough, the new caps, the last thing I did, were what fixed my problem with the headphone out. I'm just glad it's fixed now 
Too busy listening to music on her right now, but I'll make sure to post some pics when she's all back together in my setup. Still have to test her out with speakers too, but I assume those work OK since everything else is. About the Tape 1 switch, it does press in and stay properly, but I think that it's being bypassed or something. Input from other sources will cut out when I depress Tape 2, as expected, but continues to play when I depress Tape 1. I'm going to search around for some replacement switches, but I'll save the actual repair for when I get my hands on a tape deck. I had so much fun with this repair, I think I'm gonna find a nice deck for repair and fix it up 
Thank you to everyone for your warm welcome and assistance! I think I've found my new favorite site 
Too busy listening to music on her right now, but I'll make sure to post some pics when she's all back together in my setup. Still have to test her out with speakers too, but I assume those work OK since everything else is. About the Tape 1 switch, it does press in and stay properly, but I think that it's being bypassed or something. Input from other sources will cut out when I depress Tape 2, as expected, but continues to play when I depress Tape 1. I'm going to search around for some replacement switches, but I'll save the actual repair for when I get my hands on a tape deck. I had so much fun with this repair, I think I'm gonna find a nice deck for repair and fix it up Thank you to everyone for your warm welcome and assistance! I think I've found my new favorite site
MIJ_Pioneer
Super Member
Very cool, great job! Welcome to the club
Take what you learned and apply it to another project!
Take what you learned and apply it to another project!
wow that was fast!
How does it sound?
I'm curious if you replaced the output transistors or left originals. Sorry that Tape1 switch is bypassed and in perpetual play back mode.
My SX-636 is also done except the tuner board (I'm thinking of replacing the 5 CSSA caps and the 2 2SC945s only - it seems to work well and FM sounds good as-is) Are you planning to do anything on that board? I'm curious what others think of that.
I've also been putting off replacing the dial pointer bulb - looks challenging and easy to break!
I really love my SX-636. It's got a very warm sound but the top end is still crystal clear and clean. I think it's a great "70's" sound. I listen with headphones a lot too but it will drive my Cerwin Vega's fine as well. It's a great receiver. I like how it doesn't have a relay to worry about; nice and simple.
I've thought it would be nice to have a really good cassette deck - maybe someday. I've been restoring a turntable which is also fun, very different from working on a receiver! Mostly I feed Amazon Prime Music HD to my SX-636 and it sounds so good and it's so convenient, that's just what I'm stuck on.
Really glad you got it all fixed up except the switch!
How does it sound?
I'm curious if you replaced the output transistors or left originals. Sorry that Tape1 switch is bypassed and in perpetual play back mode.
My SX-636 is also done except the tuner board (I'm thinking of replacing the 5 CSSA caps and the 2 2SC945s only - it seems to work well and FM sounds good as-is) Are you planning to do anything on that board? I'm curious what others think of that.
I've also been putting off replacing the dial pointer bulb - looks challenging and easy to break!
I really love my SX-636. It's got a very warm sound but the top end is still crystal clear and clean. I think it's a great "70's" sound. I listen with headphones a lot too but it will drive my Cerwin Vega's fine as well. It's a great receiver. I like how it doesn't have a relay to worry about; nice and simple.
I've thought it would be nice to have a really good cassette deck - maybe someday. I've been restoring a turntable which is also fun, very different from working on a receiver! Mostly I feed Amazon Prime Music HD to my SX-636 and it sounds so good and it's so convenient, that's just what I'm stuck on.
Really glad you got it all fixed up except the switch!
Was that fast? Guess I got excited. It sounds great, although I am by no means an audiophile (nor are my speakers very good). The biggest difference I notice from before the rebuild was the loudness switch. Before, there was an audible difference but not a huge one, and now there’s a definite oomph that wasn’t there before. I did leave the original output transistors, but I may replace them in the future - is there a benefit to doing so?
I’d like to have done the tuner board too but I don’t have any of the required equipment to realign the tuner afterwards, so I’m leaving that as-is for now. I don’t use the radio too much anyways, so not a huge loss.
Next project for me is disassembling and re-greasing my BIC 960 turntable, which has a broken autoplay, and then I’m gonna start looking at some of the wooden Pioneer tape decks. I’ve seen a couple nice ones online for semi-reasonable prices, and the price gets better if you buy one with a messed-up veneer, which I might do anyway to learn how to re-veneer. Once I do that, I’ve found some fairly cheap replacements for the Tape 1 switch, so that shouldn’t be a problem. Thank you for the kind words, and best of luck with your receiver!
And the promised glamour shot, of course:
I’d like to have done the tuner board too but I don’t have any of the required equipment to realign the tuner afterwards, so I’m leaving that as-is for now. I don’t use the radio too much anyways, so not a huge loss.
Next project for me is disassembling and re-greasing my BIC 960 turntable, which has a broken autoplay, and then I’m gonna start looking at some of the wooden Pioneer tape decks. I’ve seen a couple nice ones online for semi-reasonable prices, and the price gets better if you buy one with a messed-up veneer, which I might do anyway to learn how to re-veneer. Once I do that, I’ve found some fairly cheap replacements for the Tape 1 switch, so that shouldn’t be a problem. Thank you for the kind words, and best of luck with your receiver!
And the promised glamour shot, of course:
Not that I know of unless there's a problem. (relatively expensive too) I did on mine but I don't think I needed to.
Looks great!
Your dial pointer light might be out, like mine is . . . I guess that's common with these. BIC 960 - that's a coincidence! I have one too and a 940 I've been working on and still messing with.
Yeah, I just noticed the pointer light is out too. Maybe I’ll do that when I fix the switch. Have you done any work on the BICs yet? If so, I’d appreciate it if you have any advice. It looks a bit tricky, and the service manual isn’t much help. I also have to figure out what should be lubed and what shouldn’t be.
dly66
Addicted Member
A number of vintage receivers I have put new caps on a tuner board did not seem to affect the tuner performance.
Be careful. The SX-535 was my learning piece be careful with the pointer. I think its acrylic and can snap like balsa wood. Snapped the 535 one twice and glued it back together and used some black RTV to cover the repair at the base. Otherwise it was glowing at both the tip and at the repair. Taught me to be careful working on one without a face on it and have not damaged another since. It is delicate surgery have replaced dead pointer bulbs in a couple of models, including the SX-1500TD. Actually an LED is lighting that one up now.
Usually you have to figure out how to get it loose to be able to work on it. Usually requires taking the front panel off, may have to loosen some other parts. Usually have to free up a section of the tuner string by taking it off some of the pulleys to make the pointer easier to work on.. Then you have to put it back the way it was. May take some experimentation, it can be like solving a puzzle.
Keep in mind these guys are around 45 years old. My SX-1500TD recently hit 50. My SX-636 serial number indicates it was built in 1975. Incandescent bulbs don't last forever.
Be careful. The SX-535 was my learning piece be careful with the pointer. I think its acrylic and can snap like balsa wood. Snapped the 535 one twice and glued it back together and used some black RTV to cover the repair at the base. Otherwise it was glowing at both the tip and at the repair. Taught me to be careful working on one without a face on it and have not damaged another since. It is delicate surgery have replaced dead pointer bulbs in a couple of models, including the SX-1500TD. Actually an LED is lighting that one up now.
Usually you have to figure out how to get it loose to be able to work on it. Usually requires taking the front panel off, may have to loosen some other parts. Usually have to free up a section of the tuner string by taking it off some of the pulleys to make the pointer easier to work on.. Then you have to put it back the way it was. May take some experimentation, it can be like solving a puzzle.
Keep in mind these guys are around 45 years old. My SX-1500TD recently hit 50. My SX-636 serial number indicates it was built in 1975. Incandescent bulbs don't last forever.
Thanks dly, I appreciate the advice! I'm definitely going to tackle it at some point.
Aren't these cool turntables? I think they are anyway! Actually I had a 960 in high school and remember saving up for it.
I took the 940 completely apart and got all the old lube out of it and it works really well, still messing with the cue damping adjustment screw and refinishing the walnut base, but I'm almost done. The original lube becomes glue essentially so it's important to get it all cleaned out.
Here is one thread:
https://audiokarma.org/forums/index.php?threads/bic-940-repair-a-thon.908743/
I also used those "Jordan Pier" videos on youTube. Here's Part 1:
We're lucky those videos are there, he walks you through all the steps - it's great.
Anyway I hope that helps!
Aren't these cool turntables? I think they are anyway! Actually I had a 960 in high school and remember saving up for it.
I took the 940 completely apart and got all the old lube out of it and it works really well, still messing with the cue damping adjustment screw and refinishing the walnut base, but I'm almost done. The original lube becomes glue essentially so it's important to get it all cleaned out.
Here is one thread:
https://audiokarma.org/forums/index.php?threads/bic-940-repair-a-thon.908743/
I also used those "Jordan Pier" videos on youTube. Here's Part 1:
Anyway I hope that helps!
Thanks, that's quite helpful! Those videos seem like a great step-by-step guide. I'll start tonight!