Replacing Technics SP-10 Mk.II strobe with LEDs - diyAudio
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Old 23rd October 2012, 12:07 AM   #1
johnm is offline johnm  United Kingdom
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Default Replacing Technics SP-10 Mk.II strobe with LEDs

Hi folks!

The strobe on my SP-10 has finally given up working. As the bulbs are just about unobtainium now, I'd like to replace mine with LEDs.

Have found a couple of examples online, but neither list the full circuit values & parts used, and I'm not savvy enough to work them out myself alas. I have contacted each user directly with no luck.

Would anybody here be able to hazard a guess as to the values/parts used?

Many thanks!

John


LED replacement V.1)

mdlover: new strobe lamp

LED replacement V.2)

Restauration Technics SP-10 MKII • LS3/5a le forum

Last edited by johnm; 23rd October 2012 at 10:22 AM.
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Old 23rd October 2012, 05:18 AM   #2
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a simple circuit for reference:
aaa.jpg
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Old 23rd October 2012, 07:40 AM   #3
johnm is offline johnm  United Kingdom
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Quote:
Originally Posted by eaglebear View Post
a simple circuit for reference:
Attachment 307793
Thanks, but that won't work here. The SP-10 uses a strobe arrangement for speed control.

I'm after the circuit values for one of the two links published in my first post only.

Cheers.

John.
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Old 23rd October 2012, 08:24 AM   #4
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Thanks to Google translate (wish I'd known about this many moons ago) I have the following info translated from this link:

Restauration Technics SP-10 MKII • LS3/5a le forum

"J'ai donc installé 3 leds orangées (ref 7821 chez sélectronic) sur une carte prototype avec un 2n2222 (r1=2,11k et r2=27ohms). Pour préserver le côté pro (démontage) une connexion par 3 points pour l'alim +5v, le 0v et pin 1 de ic10 côté cuivre"

"So I installed 3 leds orange on a prototype board with a 2N2222 (r1 = 2.11k and r2 = 27ohms). To preserve the pro side (removing) a connection by 3 points for the power supply +5 v, 0v on pin 1 of IC10 and copper side."

Does 2.11K sound correct for R1? Looks like a different value entirely on the photo of the proto-board pictures there (post#4) - red/brown/brown/red/black/yellow?!

John.

Last edited by johnm; 23rd October 2012 at 08:31 AM.
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Old 23rd October 2012, 08:50 AM   #5
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they are SMD resistors,2.11K marked by “2111”,270ohms by "2700" .The 2.11K is used to limit base current of transistor,270 limit the collector current.You can use other value such as 2.7K and 390ohms.
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Old 23rd October 2012, 10:21 AM   #6
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Quote:
Originally Posted by eaglebear View Post
they are SMD resistors,2.11K marked by “2111”,270ohms by "2700" .The 2.11K is used to limit base current of transistor,270 limit the collector current.You can use other value such as 2.7K and 390ohms.
In the link/translation I posted above your second reply, they're definitely not SMD. I think you're looking at the other version (LED replacement V.1)? My last post was referencing LED replacement V.2 link. And it says in the translation 27R, not 270R or 2K7...

My question is, does 2.11K sound like the correct value, based on the following picture shown in link 2, because it looks like red/brown/brown/red/black/yellow which can't be right:

Click the image to open in full size.

Last edited by johnm; 23rd October 2012 at 10:24 AM.
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Old 24th October 2012, 05:44 PM   #7
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Must be losing my memory! Was looking at some older SP-10 threads, and there was a question from myself, about spare neon lamps suitable for use in the Technics. Somebody mentioned this item:

Buy Neon Indicator Lamps T2, wire end neon lamp, 110/230V, 0.5mA RS MWT0198 online from RS for next day delivery.

As luck would have it, I had a few in the parts box. Tried one out, and it worked fine, albeit a little less brighter than the original larger item. No need to muck about with LEDs and proto board afterall!

I believe I can increase the brightness a little by reducing the value of the voltage limiting resistors which - according to the service manual - are R239 and R240. Both 4K7 1W metal oxide. Might try substituting a pair of 3K3 resistors instead to see if that brings the brightness up just a little.



John.
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File Type: jpg neon_lamp_SP_10.jpg (179.5 KB, 186 views)

Last edited by johnm; 24th October 2012 at 06:04 PM.
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Old 25th October 2012, 02:18 PM   #8
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Could anybody confirm/deny that the above mentioned resistor change from 4K7 to 3K3 would work please?

Could somebody also confirm (it's bugging me!) what value that resistor is in the picture in post 6 please? It's obviously red/brown/brown/red/black/yellow, but this doesn't appear to be a recognised value, and certainly not 2.11K?...

Cheers,

John.

Last edited by johnm; 25th October 2012 at 02:29 PM.
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Old 26th October 2012, 08:09 AM   #9
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Oh well, guess I'll have to try it for myself and keep my fingers crossed!
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Old 9th March 2013, 06:21 PM   #10
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Well the replacement strobe bulb didn't last as long as I'd hoped, so having a look into replacing with LEDs again.

Since last posting I found this layout by doing a Google search (and if you're the originator of this mod and would rather it wasn't shown here PLEASE let me know and I'll take it down straight away).

Looks simple enough, and nice and neat, but I just wanted to ask those in the know if that LED on the end has had its polarity reversed by mistake, or is this deliberate?

Cheers,

- John
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File Type: jpg vueimplantation.jpg (50.1 KB, 109 views)
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