sx-727 lamp replacement
- Thread starter rmunson
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IIRC, and it's been a LOOOOOOOOONNNNNGGG Time since I've done lamps on a x2x series, so it could very well be wrong, but it looks very similar to my 737. So take it as a general guide, with a grain of salt. 1st off, the White panel they sit in comes off the top of the DIAL lighting panel. They have a rubber grommet or sleeve that shims the bulb in the hole. They will either come out the front after cutting the wires(look at the back and see if there is 2 holes for just the wires or a bigger hole for the bulb) or out the back. The rubber will have heated up and literally welded itself to both the bulb and or the panel hole.
Patience is your #1 friend with these. Go slow, and work it out on paper or in your mind 1st. Then try the least destructive way 1st. a small sleeve or pick can be used to free the rubber from the panel. Once you get it free, pull it out, replace the bulb. Try to keep the rubber intact to re-use. You can use multiple layers of heatshrink tubing (short pieces and heat each and let cool before the next layer) if the rubber has gone bust. Don't sleeve until they are tight to get back in. Leave a little slack.
Installation is reverse.
Patience is your #1 friend with these. Go slow, and work it out on paper or in your mind 1st. Then try the least destructive way 1st. a small sleeve or pick can be used to free the rubber from the panel. Once you get it free, pull it out, replace the bulb. Try to keep the rubber intact to re-use. You can use multiple layers of heatshrink tubing (short pieces and heat each and let cool before the next layer) if the rubber has gone bust. Don't sleeve until they are tight to get back in. Leave a little slack.
Installation is reverse.
Jerry's TV
Active Member
The function lamps should pull out (gently) from the rear and be replaced by lamps that look like the picture below 4.12mm 8V 40 mA. I get mine from Dgwojo here on AK. He will have a kit for all the lamps needed.
I did a 727 with light blue LEDs for dial lights that look really good. Picture below, top unit is with blue LEDs in dial,bottom picture is original lamps. Independent 727 picture is with the light blue LED lamps.
You will also notice the early build 727 on the bottom has a different annodize color on the faceplate aluminum. more bronze color. It is Janury 1972 build, where the other is more silver as an August 1973 build. (by serial number digit date)
I did a 727 with light blue LEDs for dial lights that look really good. Picture below, top unit is with blue LEDs in dial,bottom picture is original lamps. Independent 727 picture is with the light blue LED lamps.
You will also notice the early build 727 on the bottom has a different annodize color on the faceplate aluminum. more bronze color. It is Janury 1972 build, where the other is more silver as an August 1973 build. (by serial number digit date)
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rmunson
Well-Known Member
Hi guys -
my 2 meters are smudged with greasy thumbprints - is it advisable to touch the blue enamel? Is there any way to clean the meter faces or will I risk damaging the paint or lettering?
the designers/engineers did not make it easy to get to those lamps behind the meters... I trust I'm ok with gently lifting and separating the meters up and above the lamp housing?
my 2 meters are smudged with greasy thumbprints - is it advisable to touch the blue enamel? Is there any way to clean the meter faces or will I risk damaging the paint or lettering?
the designers/engineers did not make it easy to get to those lamps behind the meters... I trust I'm ok with gently lifting and separating the meters up and above the lamp housing?
Jerry's TV
Active Member
dish soap in water should be fine. the dial lamps go in from the back. there should be a couple small scews which lifts the lid off the light box for the meters.
rmunson
Well-Known Member
Thanks for all of the advice - I'm making progress --
Today I am looking at the power and speaker selector switch.
Should I shoot deoxit into the power switch section of this selector? Or just focus on the speaker selector wafer?
I'm a little nervous at shooting dexit into the power switch --
Today I am looking at the power and speaker selector switch.
Should I shoot deoxit into the power switch section of this selector? Or just focus on the speaker selector wafer?
I'm a little nervous at shooting dexit into the power switch --
Attachments
Jerry's TV
Active Member
Focus on cleaning the speaker control section. Getting detoxit in the power contacts is fine, but if not needed, don't intentionally spray it.
rmunson
Well-Known Member
ok - I've replaced a couple function bulbs, installed the faceplate and meter LEDs and now onto deoxiting the controls...
the bulbs seemed to be epoxy'd in so I dug in with an xacto and freed them --
LEDs shining bright! I purchased Wojo's Pioneer kit - super fast excellent service!
the bulbs seemed to be epoxy'd in so I dug in with an xacto and freed them --
LEDs shining bright! I purchased Wojo's Pioneer kit - super fast excellent service!
rmunson
Well-Known Member
hmm.... well I didn't expect that to happen!
after putting in the new lamps, I deoxit'd the controls -
system does not come up --
upon power, I can tell that the system is pulling power - but no lamps turn on, no functions come up --
I checked the fuses - they are all ok - I record 120V at the power switch when at OFF position when system is plugged into power -
upon turning the system power switch to ON, voltage reads 0 -- readings at the AC switched/unswitched plugins at back of system read 120V, so it's pulling in power --
I'm not hearing the protection relay circuit ping -
should I go in there and see what state the protection relay is in? Coming from a cold powered off state, should the relay be open or closed?
I believe the normal sound I hear on power up is the relay magnetically snapping closed, right?
The only non standard thing I can think of, is I used a 6V battery to test the lamps as I was installing them into the system - did this cause damage?
Bewitched, bothered, and bewildered am I
after putting in the new lamps, I deoxit'd the controls -
system does not come up --
upon power, I can tell that the system is pulling power - but no lamps turn on, no functions come up --
I checked the fuses - they are all ok - I record 120V at the power switch when at OFF position when system is plugged into power -
upon turning the system power switch to ON, voltage reads 0 -- readings at the AC switched/unswitched plugins at back of system read 120V, so it's pulling in power --
I'm not hearing the protection relay circuit ping -
should I go in there and see what state the protection relay is in? Coming from a cold powered off state, should the relay be open or closed?
I believe the normal sound I hear on power up is the relay magnetically snapping closed, right?
The only non standard thing I can think of, is I used a 6V battery to test the lamps as I was installing them into the system - did this cause damage?
Bewitched, bothered, and bewildered am I
Jerry's TV
Active Member
Hi - sorry to hear but hopefully something easy.
Have you downloaded the Service Manual from Hifi Engine? It is free - just create a log in and download.
https://www.hifiengine.com/manual_library/pioneer/sx-727.shtml
A portion of the schematic is inserted below.
Test for ~ 8V AC on the dial lamps and confirm Fuse 2 is Ok
Find the power supply board AWR-011 - access from the bottom, center of the unit.
Meaure the wire wrap pins on the power supply card, as numbered in the schematic and shown below.
You might want to bolt the unit back together somewhat so you don't have too many moving parts as you are handling it.
View attachment 1064680
Have you downloaded the Service Manual from Hifi Engine? It is free - just create a log in and download.
https://www.hifiengine.com/manual_library/pioneer/sx-727.shtml
A portion of the schematic is inserted below.
Test for ~ 8V AC on the dial lamps and confirm Fuse 2 is Ok
Find the power supply board AWR-011 - access from the bottom, center of the unit.
Meaure the wire wrap pins on the power supply card, as numbered in the schematic and shown below.
You might want to bolt the unit back together somewhat so you don't have too many moving parts as you are handling it.
View attachment 1064680
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Jerry's TV
Active Member
Hi - drawing attached - red circle shows two fuses, the fuse a the back of the chassis inside is F5, there is also a fuse in the black plastic holder which is accessible from the back outside of the unit, this is F1. Both are 3 amp. The green circles on the schematic show where the other fuses on the mid-chassis terminal strip are wired,
the fuses are common to older autos and electronics so should be easy to source. F5 has wires soldered to it which will be harder to find, but can be ordered.
https://www.digikey.ca/product-detail/en/littelfuse-inc/0318003.HXP/F2610-ND/777326
https://www.digikey.ca/product-detail/en/littelfuse-inc/0312003.HXP/F2510-ND/777226
Since you are having power problems you should build yourself a simple "dim bulb tester" (DBT) to keep from blowing more fuses while you sort out the reason the inital fuses failed. Search the forums for DBT and you will find lots of references. The DBT gadget is a simple light bulb in series with the power going to the receiver so the lamp resistance limits the current below the 3Amp fuse and shows with light how much current the receiver is drawing. I used a power bar, opened the cord, cut the black connector and wired a lamp socket in series. A 40w to 60 watt standard light bulb is good for the 727. When connected to the DBT, and you turn on the receiver, the lamp should glow bright for 1 or 2 seconds while it charges the main power supply caps, then only slightly lite glow after that. If the lamp glows bright, you have a short which will blow a fuse again if plugged directly into main power. This simple gadget will save you a bunch of grief.
the fuses are common to older autos and electronics so should be easy to source. F5 has wires soldered to it which will be harder to find, but can be ordered.
https://www.digikey.ca/product-detail/en/littelfuse-inc/0318003.HXP/F2610-ND/777326
https://www.digikey.ca/product-detail/en/littelfuse-inc/0312003.HXP/F2510-ND/777226
Since you are having power problems you should build yourself a simple "dim bulb tester" (DBT) to keep from blowing more fuses while you sort out the reason the inital fuses failed. Search the forums for DBT and you will find lots of references. The DBT gadget is a simple light bulb in series with the power going to the receiver so the lamp resistance limits the current below the 3Amp fuse and shows with light how much current the receiver is drawing. I used a power bar, opened the cord, cut the black connector and wired a lamp socket in series. A 40w to 60 watt standard light bulb is good for the 727. When connected to the DBT, and you turn on the receiver, the lamp should glow bright for 1 or 2 seconds while it charges the main power supply caps, then only slightly lite glow after that. If the lamp glows bright, you have a short which will blow a fuse again if plugged directly into main power. This simple gadget will save you a bunch of grief.
Jerry's TV
Active Member
HI - i just re-read you recent post and noticed you said the left most fuse on the terminal strip --- this is circled in blue below and will be F2. Confirm this as it should have blue wire from the transformer connected (not green) and live side of the fuse should measure ~ 8VAC to ground.
It is a 3 amp fuse and connected to the dial lights. this explains your dial lights going out, This fuse only effects the dial lights.
Sorry for confusion above, but I left it posted as it maybe helpful in other ways
It is a 3 amp fuse and connected to the dial lights. this explains your dial lights going out, This fuse only effects the dial lights.
Sorry for confusion above, but I left it posted as it maybe helpful in other ways
rmunson
Well-Known Member
Thanks Jerry - re: the dim bulb tester yes - I was just thinking the same thing -
Thanks for your help with the schem as well --
has anyone seen this before - the fuses seem to be enclosed in clear plastic tubing
not sure why my image link isn't working - I'm using imgBB --
https://ibb.co/d4sA9m
yes - thanks for that clarification it is the fuse at the bottom of the 3 in my image - it has a cap connected to it
attaching pic as well -
Thanks for your help with the schem as well --
has anyone seen this before - the fuses seem to be enclosed in clear plastic tubing
not sure why my image link isn't working - I'm using imgBB --
https://ibb.co/d4sA9m
yes - thanks for that clarification it is the fuse at the bottom of the 3 in my image - it has a cap connected to it
attaching pic as well -
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Jerry's TV
Active Member
Hi - the plastic tube is there to protect the fuse, you can try and slide the old fuse out or cut open and re-wrap.
rmunson
Well-Known Member
yes - interesting - I was just wondering if this was factory, or if this might have been done by a service tech at some point -
another interesting thing I noticed was the version I have doesn't have a 2nd fuse by the fuse holder - but a .001 cap instead -
On my system the 3 fuses (f2, f3 and f4 if I'm reading my schem correctly) by the terminal strip are soldered in - was that common? I would have thought they would have just used clips?
Jerry's TV
Active Member
Soldered in fuses was common in early 70's. And not unusual for Pioneer to make small changes, like dropping or adding a second fuse, over the production run.
rmunson
Well-Known Member
put together a dim bulb tester tonight -
tested on other devices in the house and normal operation was similar to above -
results inconclusive - pretty sure that fuse is blown though -- will be replacing that next --
No power to the front end - is that a deal breaker for any signal coming through the system?
results inconclusive - pretty sure that fuse is blown though -- will be replacing that next --
No power to the front end - is that a deal breaker for any signal coming through the system?
With the power off, un-connect from the line, place your DMM in ohms mode across the AC plug pins, close the power switch, you should read a few ohms, if the primary ckt is intact.
if not it is either a open fuse, switch or transformer primary winding.
with power off you can measure the transformer winding resistances. also measure continuity through all the fuses etc.
No need to power on the unit to do a lot of troubleshooting with the ohmmeter. if the lamps do not light and they are good lamps showing continuity it is fairly easy to find the cause.
if not it is either a open fuse, switch or transformer primary winding.
with power off you can measure the transformer winding resistances. also measure continuity through all the fuses etc.
No need to power on the unit to do a lot of troubleshooting with the ohmmeter. if the lamps do not light and they are good lamps showing continuity it is fairly easy to find the cause.
Jerry's TV
Active Member
Hi the DBT lamp action is about what i would expect with the dial lamp fuse blown. The initial flash is the main power supply caps charging up. the light goes dim because you have no other current draw in the receiver, though the DBT lamp. Do you hear the protection relay click in after about 5 or 10 sec of power on? It may or may not with the DBT connected, depends on tolerances of the protection circuit given the lower voltage of the DBT.
Do you notice on the video that the DBT lamp flashes less on the second power up? That would indicate the caps have some "power" left in them when you turn it back on. Which makes me think things are working as they should.
Replace the dial lamp fuse you found blown and try the DBT again.
With LED lamps in the receiver drawing really low current, the DBT lamp will start bright like you show now, then barey glow steady, but you'll see it. I have a sx727 with LED I'll send you a video of it on DBT when I get a minute in the next couple days.
Do you notice on the video that the DBT lamp flashes less on the second power up? That would indicate the caps have some "power" left in them when you turn it back on. Which makes me think things are working as they should.
Replace the dial lamp fuse you found blown and try the DBT again.
With LED lamps in the receiver drawing really low current, the DBT lamp will start bright like you show now, then barey glow steady, but you'll see it. I have a sx727 with LED I'll send you a video of it on DBT when I get a minute in the next couple days.
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