Nick_the_'Nole
Super Member
Heh, quite the unholy royal bitch, wasn't it? 
So you have the thing working now?
So you have the thing working now?
have a lead on an SX-750, but...
- Thread starter Nick_the_'Nole
- Start date
Nick_the_'Nole said:Heh, quite the unholy royal bitch, wasn't it?
So you have the thing working now?
Definitely a pain.
And apparently I didn't clean it well enough, it's beyond hope? Now it does the flickering at power-up, but then I hear a click, and then it stabilizes. There doesn't seem to be a repeatable length of wait between when I turn it from "Off" to an output. Is this normal? There is no loud static noise on the outputs, like there was before.
I suppose I could go back in and attempt to clean it again?
vwap said:
Did you burnish the contacts until they were bright? Deoxit won't cut burned material.
edit: also make sure there is enough tension to exert a closing force on the contacts.
Thanks!
Thanks Mark and all for the info in here!
Did my 450 switch yesterday and it's perfect now. Snaps on immediately with no crackle, light dimming or anything else. Wish I hadn't seen the condition of those contacts on the actual PCB part of it though. The wiper things are looking pretty old, but I guess they'll hold up. I cleaned all that stuff too and cleaned the old goo from the rotating plastic part inside the power switch and re-lubed with some lithium grease.
The thread might use some info on how you guys went about cleaning/burnishing the burnt contacts though. I sort of guessed at that and hit them with a fine grinding wheel in a Dremel, then switched to some sort of rubber buffing wheel after the crud had been scraped down.
BTW, my SX-450 switch appears to be assembled backwards compared to the 550 pictures here (the switch box is mounted on the back side of the PCB). Luckily, it also didn't have anything holding it together, other than the two bolts.
Take Care,
George
PS- Ditto the comments on the PITA of taking this thing out.
Seems like parts of these things were just not designed for easy replacement, but I guess 25 or 30 years is a decent length of time for its first service call. The 5800 I just did had one lousy capacitor sitting on the tail end of the mainboard which barely protruded over the power supply board. I had to disassemble ten things just to desolder that one last cap. If they had moved it about a half inch over, I could have hit it from the bottom like all the rest of them.
Thanks Mark and all for the info in here!
Did my 450 switch yesterday and it's perfect now. Snaps on immediately with no crackle, light dimming or anything else. Wish I hadn't seen the condition of those contacts on the actual PCB part of it though. The wiper things are looking pretty old, but I guess they'll hold up. I cleaned all that stuff too and cleaned the old goo from the rotating plastic part inside the power switch and re-lubed with some lithium grease.
The thread might use some info on how you guys went about cleaning/burnishing the burnt contacts though. I sort of guessed at that and hit them with a fine grinding wheel in a Dremel, then switched to some sort of rubber buffing wheel after the crud had been scraped down.
BTW, my SX-450 switch appears to be assembled backwards compared to the 550 pictures here (the switch box is mounted on the back side of the PCB). Luckily, it also didn't have anything holding it together, other than the two bolts.
Take Care,
George
PS- Ditto the comments on the PITA of taking this thing out.
Seems like parts of these things were just not designed for easy replacement, but I guess 25 or 30 years is a decent length of time for its first service call. The 5800 I just did had one lousy capacitor sitting on the tail end of the mainboard which barely protruded over the power supply board. I had to disassemble ten things just to desolder that one last cap. If they had moved it about a half inch over, I could have hit it from the bottom like all the rest of them.Attachments
whaleoil
Member
SX450 Switch cleanup
I agree with the PITA statement, the disassembly is tedious at best. I am trying to do this with the wafer still attached. It's pretty tight in there. The contacts were really awful. I haven't burnished them yet, wondering if there is a cleaner way than working it with a dremel, etc...
I agree with the PITA statement, the disassembly is tedious at best. I am trying to do this with the wafer still attached. It's pretty tight in there. The contacts were really awful. I haven't burnished them yet, wondering if there is a cleaner way than working it with a dremel, etc...
Attachments
Don't remember specifics, but I think I had it outside of the chassis somehow - look out for that tuner string!!
Those are pretty bad contacts...
1500 grit folded paper dragged between the closed contacts between my fingers? Doing both sides at one time?
sorry - you caught me signing out for the nite...
Those are pretty bad contacts...
1500 grit folded paper dragged between the closed contacts between my fingers? Doing both sides at one time?
sorry - you caught me signing out for the nite...
Common problem on those pioneers. Pustelniakr has done this repair before and deoxit wont cut through burned contacts in the alps switch that is used.
They are REAL contacts that can be disassembled (pita to get to tho) and burnished for like new performance for years to come.
I had a picture up, then took it down, of an sx-550 switch disassembled to show the contacts...
this is a link to the after action report on Rabbi Rich's work on that sx-450.
here is the picture again. I pulled it to save space here.
Yes yes, and I have done this many times, but some (a lot) have ANOTHER unused set of contacts. on the bottom, all we ever did was take it apart and move the unused contacts to the top.
Then things changed and they stopped putting in the other pair of contacts, big let down.
Better yet - clean the contacts and run both pairs in parallel - Significantly increases switch life YMMV
I know this is an old thread (but referenced hundreds of times). I just did the SX-550 power switch and thought I'd show a broader view of removal without desoldering the speaker wafer.
The contacts had the typical carbon formation and pitting, and the burnishing board cleanup was completely successful.
The contacts had the typical carbon formation and pitting, and the burnishing board cleanup was completely successful.
Attachments
Rixxx
Active Member
SX 550 switch ... or a Noble replacement ?
Picked up a SX 550.
Broken glass, and shell of 2 knobs missing.
10 euro.
Could not withstand the challenge and bought.
Powered up, on the dim bulb. making a lot of noise, but non the less.
Even played on direct AC. Went for the recap. (caps in tha house)
Checked the transistors. aw, a lot degraded.
Replaced and reordered.
Then, having checked the info here, went for the switch..
But, my switch is a noble. But dear, not only the frontplate needs to be taken off, all other sub-frontplates as well, and even that is not enough to get the F ehr darling out....
Turned out , along with all the subplates, also the dial scale has to be loosened and the power transformator kicked out...
Anyways, a little too much force and there it was... a broken wafer...
I ignored my brute force and ignorance and went on to check the power switch...
as, I noticed before, the solder contacts , both on the print and on the housing of the power switch were "worked on " insides were clean on first sight, but the buttons in the housing were black. Cleaning revealed a thin layer of some kind of lubrication... Probably not the good stuff... Here's where a lot of trouble starts. When people put in **** that lays a film on the contacts!
cleaned them mechanically.
Next step repairing the waver... Cut out a piece of plexi glass to give strength to a reassemble with glue..
Cleaned up the copper leads on the print with a proxxon (multitool) and a mini ironbrush
Glued the plexi glass part together with the glued waverparts with bison 2 components glue. First tried to glue two parts of plexi. That turned to be rock solid after 20 minutes. First attempt went haywire. While i took the time to reconnect the tracings on the waver with halfconducterleadclippings and solder, I realized the plexi was still moving. The waver itself, by now was jointed together by glue and soldering though.
Turned out that I used too much glue out of the dubble seringe. cleaned the surfaces, dried them and made a mix of the two component glue on a jar lid, and applied thin to 1 surface only and reglued.
With the nob on it I could hear the switch doing it's work.
(be sure the "driver" of the switch is before the micro handle otherwise, it will not switch the power after reassemble)
Meanwhile I discover a transistor, a cap and a tantalum, all, hidden just behind the faceplate and subfaceplate. Without this "major surgery"I would not have spotted them.
I worked from sight, and made a sketchy map with layout and directions from the transistors., so I do not have to think EBC, etc.
Ok, "repaired waver and cleaned switch" final : I admit not a beauty, but as I hope to find out soon ; functional
Tomorrow I get the ordered transistor replacements.
The outputs ; D526 seemed ok, till I searched for the D526-O
The're rated higher so, they fell below the specs...
It IS a lot easier to make a seperate switch by cutting the wires to the combiswitch and place them above the phone plug. But that might have bad side effects ? - if you do maybe take out the phono plug all together and make a power switch there.
Ok folks , thats all for now.
Picked up a SX 550.
Broken glass, and shell of 2 knobs missing.
10 euro.
Could not withstand the challenge and bought.
Powered up, on the dim bulb. making a lot of noise, but non the less.
Even played on direct AC. Went for the recap. (caps in tha house)
Checked the transistors. aw, a lot degraded.
Replaced and reordered.
Then, having checked the info here, went for the switch..
But, my switch is a noble. But dear, not only the frontplate needs to be taken off, all other sub-frontplates as well, and even that is not enough to get the F ehr darling out....
Turned out , along with all the subplates, also the dial scale has to be loosened and the power transformator kicked out...
Anyways, a little too much force and there it was... a broken wafer...
I ignored my brute force and ignorance and went on to check the power switch...
as, I noticed before, the solder contacts , both on the print and on the housing of the power switch were "worked on " insides were clean on first sight, but the buttons in the housing were black. Cleaning revealed a thin layer of some kind of lubrication... Probably not the good stuff... Here's where a lot of trouble starts. When people put in **** that lays a film on the contacts!
cleaned them mechanically.
Next step repairing the waver... Cut out a piece of plexi glass to give strength to a reassemble with glue..
Cleaned up the copper leads on the print with a proxxon (multitool) and a mini ironbrush
Glued the plexi glass part together with the glued waverparts with bison 2 components glue. First tried to glue two parts of plexi. That turned to be rock solid after 20 minutes. First attempt went haywire. While i took the time to reconnect the tracings on the waver with halfconducterleadclippings and solder, I realized the plexi was still moving. The waver itself, by now was jointed together by glue and soldering though.
Turned out that I used too much glue out of the dubble seringe. cleaned the surfaces, dried them and made a mix of the two component glue on a jar lid, and applied thin to 1 surface only and reglued.
With the nob on it I could hear the switch doing it's work.
(be sure the "driver" of the switch is before the micro handle otherwise, it will not switch the power after reassemble)
Meanwhile I discover a transistor, a cap and a tantalum, all, hidden just behind the faceplate and subfaceplate. Without this "major surgery"I would not have spotted them.
I worked from sight, and made a sketchy map with layout and directions from the transistors., so I do not have to think EBC, etc.
Ok, "repaired waver and cleaned switch" final : I admit not a beauty, but as I hope to find out soon ; functional
Tomorrow I get the ordered transistor replacements.
The outputs ; D526 seemed ok, till I searched for the D526-O
The're rated higher so, they fell below the specs...
It IS a lot easier to make a seperate switch by cutting the wires to the combiswitch and place them above the phone plug. But that might have bad side effects ? - if you do maybe take out the phono plug all together and make a power switch there.
Ok folks , thats all for now.
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