Pioneer SG-9800 equalizer, LED replacement and recap

[leesonic]

I did some work on my Pioneer SG-9800 equalizer today. I soldered in three new pots that I got from eBay. I also replaced the tape monitor switches and the attenuator switches with some that came from an old Sharp tape deck (motto : never throw anything away). I had to trim down the PCB pins with a Dremel, but they fitted just right after this.

I also took the chance to replace the LEDs, the three round ones behind the power, tape and overload lights, plus the 24 that light up the sliders. For these, I used Mouser part number 604-WP113SRDT, these are listed as 2mm x 5mm x 7mm. I've heard that 2mm x 4mm LEDs will fit exactly, but these ones have a light output of 80mcd. I simply shaved the long edges down with a Dremel, and then finalizing them by rubbing the edge on some sandpaper.

The three pictures below show the new LEDs on the right bank, with the old ones on the left bank. Quite a difference don't you think? Of course, the camera makes them look WAY brighter than they really are, at times the shutter speed was dropping down to 1/2 second. Plus, these were all taken with the slider knobs removed, except on one for comparison. The pictures were taken in a darkened garage, with the only light coming in from a window to the left.





This picture was taken with the slider knobs installed.



And this one with the overhead light turned on.



Lee.

 

[Skylab]

Looks great!!!! I have an SG-9800 - nice to know the LEDs can not only be replaced but upgraded

 

[CarnahanBB]

Dang! That sucker looks sweet! Nice work!

 

[1TUFSS]

Good stuff!

 

[leesonic]

Here is a picture of the re-capped board, around by the power supply area.



And here is the front. Notice the one switch in the foreground, and the two hidden under the ribbon cable, these are the ones I replaced.

 

[day67]

Great pics! Thanks Leesonic. Caps list will come in handy

 

[kevin_09]

Hi I did change my led to blue it looks cool lol
here is the video
https://www.youtube.com/watch?v=GpIjr9Oj40I

 

[Tangerine]

Lee,

Thanks fo

I did some work on my Pioneer SG-9800 equalizer today. I soldered in three new pots that I got from eBay. I also replaced the tape monitor switches and the attenuator switches with some that came from an old Sharp tape deck (motto : never throw anything away). I had to trim down the PCB pins with a Dremel, but they fitted just right after this.

I also took the chance to replace the LEDs, the three round ones behind the power, tape and overload lights, plus the 24 that light up the sliders. For these, I used Mouser part number 604-WP113SRDT, these are listed as 2mm x 5mm x 7mm. I've heard that 2mm x 4mm LEDs will fit exactly, but these ones have a light output of 80mcd. I simply shaved the long edges down with a Dremel, and then finalizing them by rubbing the edge on some sandpaper.

The three pictures below show the new LEDs on the right bank, with the old ones on the left bank. Quite a difference don't you think? Of course, the camera makes them look WAY brighter than they really are, at times the shutter speed was dropping down to 1/2 second. Plus, these were all taken with the slider knobs removed, except on one for comparison. The pictures were taken in a darkened garage, with the only light coming in from a window to the left.

This picture was taken with the slider knobs installed.

And this one with the overhead light turned on.

Lee.

r the hard work you've put in with refurbing your SG-9800. I'm keen to see the pics that were originally posted here, but they aren;t available any more. Do you still have them at hand?

Cheers,

Les.

 

[leesonic]

I'm keen to see the pics that were originally posted here, but they aren;t available any more. Do you still have them at hand?
.

Fixed broken picture links.

 

[jvinhj240]

how big sound improvement after upgrades? are they easy to replace for newbie?

 

[Mike66202]

Nice post. Thanks for the information. I have one of these and tried to replace the led's with these blue ones:
http://www.ebay.com/itm/100pcs-2x3x...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649
I saw a u-tube of a guy actually got his to work, but when I tried it...all went well for the first 4 or 5 then the led's got progressively dimmer. I kept going until all were replaced on the left side and they were BARELY visible at all.
All the sliders were cleaned with faderlube f5 then a application of faderlube f100. So, I replaced all the blues with the oroginals and they are all nice and bright again...just red. Sounds great....but no joy with the blue led's
Obviously, something is wrong here. Could anyone help with this?
The look of the blue led's are a way nicer match with my sr-303 and ct-f900.

Thanks
Mike

 

[leesonic]

I saw a u-tube of a guy actually got his to work, but when I tried it...all went well for the first 4 or 5 then the led's got progressively dimmer. I kept going until all were replaced on the left side and they were BARELY visible at all

Hi Mike,

I bet your problem is the forward voltage drop of the blue LEDs versus the red ones. Without looking at the schematic (because I don't have it to hand), I would guess the LEDs are wired in series, which is the best way to drive them, as LEDs do strange things in parallel. So, if you have 10 LEDs that have a forward voltage drop of 2v, you can connect them all in series across a 20v power supply. Now, if you try the same with blue LEDs, which typically have a voltage drop of 3v, you're going to run out of voltage pretty quick. It MAY be possible to split the single banks of 10 LEDs into two banks of five (or four banks of five if you could both channels), and use dropper resistors if necessary.

Lee.

 

[Mike66202]

Hi...yes...what you're saying makes sense to me (in my VERY limited understanding) however...not being educated enough to tackle that...I think I'd be better off leaving them red.
What i simply cannot understand, is, how kevin_09 (in this thread....see above) pulled it off by simply swapping the led's.
Here is his video...

Even I think I could tackle this.

 

[tassellic]

Hi...yes...what you're saying makes sense to me (in my VERY limited understanding) however...not being educated enough to tackle that...I think I'd be better off leaving them red.
What i simply cannot understand, is, how kevin_09 (in this thread....see above) pulled it off by simply swapping the led's.
Here is his video...

Even I think I could tackle this.

Have same trouble !!! Try to replace blue leds . Right side some leds turn on others no ! Left side no dim at all . Connected direct to a 30 v line ..same trouble . Trying replace to 2.0 v leds .

 

[Mike66202]

I could not find any 2 volt BLUE led's. I dont think they exist. If you do find them....please share.
Good luck

 

[rcs16]

Blue LED technology is not the same as reds, ambers etc, thus require a higher turn on V to operate (typ 3.5V depending on the part) . I'd have to take a look at the sch to see what is required to use blue leds. probably just a change in the V drop resistor size to allow more V for the led.

 

[tassellic]

Got it same dim in all leds ! Dismounted and cleaned each potentiomenter with isopropilic alchool . It seens dirty and dust causes a resistance in slide ..so voltages fall more than regular . now all leds light in the same bright (low)

 

[rcs16]

I just checked the schematic, i think the leds are wired in series as in 2 strings consisting of 12/string so that adds up to around 2.0*12 ~=24V
The schem i have is not the best.

 

[tassellic]

Voltage to the leds is -14.5 and +14.5 v before protection resistor..after is 9.6 v. total is almost 24v .. 2v per led

 

[Timothy Flath]

Do you need to change the Opamps on this baby if they are working good? Reason is these opamps are like $5 apiece X 22: https://ca.mouser.com/productdetail...=sGAEpiMZZMtxdzBvM0rKca1NCdcAPFSCAnhKoWBF2fA=

Are these the right replacements?