Technics SL-P999 remote control problem

[Bagpuss]

I recently acquired a Technics SL-P999, without a remote, which appears to work perfectly.

I was hoping to control it with my Logitech Harmony remote, but after configuring that, the player does not respond to it.

I've also tried a Technics remote (EUR643900) from a more recent player, and tried a vintage One-For-All remote with the various Technics CD player codes but no luck.

So conclusion is that there is a fault with the player. I know next to nothing about electronics, but:

I've tried connecting a multimeter to the player's photodiode, and I can see that when any IR remote is used on it, the voltage output drops from 4.9V to 3.6V which (I think) is expected behaviour, as at that point the voltage will be fluctuating from 4.9V to 0V at high speed and the multimeter is averaging it out.

I've also traced the connection from that output all the way to pin 17 of the IC301 MN6622 chip, and there is no break.

So now I'm at a loss. Is it:

• a fault with the MN6622? (seems unlikely as everything else is working). Or...
• could the photodiode not be outputting 'clean' enough pulses, is it worth trying a replacement? Or...
• is there something unique about the original SL-P999 remote (a EUR64729) which means that is needed? (although that seems unlikely as the presence of the codes on the Logitech Harmony site suggests that it should work). Or...
• Something else?

Thanks for any advice

 

[Bagpuss]

Been looking into this a little more.

I hadn't realised that the remote control receiver on this was a little tin box full of discrete components - a couple of electrolytic capacitors, an IR sensor diode, a tiny IC and other odds and ends.

If I understand correctly, these days that's all combined into a single component, an IR receiver/demodulator?

So (if I'm getting this right) I can remove the tin box, and replace it entirely with single component like a Vishay TSOP32138, and see if that fixes the player?

But I just need to get the carrier frequency correct, to match the Technics standard of that era - does anyone know what that is?

((The original receiver has part number HC-MD10E, but Googling that just brings back Technics service manuals, no actual data on the part itself...))

 

[raffcjab]

Hi Bagpuss,

have you been successful?

I have a SL-P770. The remote is emitting, but the HC-MD10E stays at 5V DC. I guess it is a PLL circuit?

Will it help you, if I record the signal of the remote? Should show the carrier frequency.

 

[Sansuiman]

Frequency should be 38kHz which is industry standard for most IR remote controls. There are a few - B&O specifically that I know of - that don't share this standard, and which make the use of universal remotes impossible.

I think before I'd go replacing the entire IR receiver block, I'd change the caps within it. This generation of Technics CD Players was prone to bad caps on the FG spindle motor control board, and a few others. These are getting pretty long in the tooth now anyway, dating to 1988/89. I have a 770, 777 and couple.of 999 here. Great units, very fully featured and both sound and look great.

 

[Bagpuss]

Thanks for the replies. I'd rather let the problem slide until recently though. The player is now working - but I'm wondering if it always was, and my efforts were pointless!

Quick recap:
SL-P999 would not respond to
(i) Harmony 300 remote programmed with relevant codes from their server
(ii) Technics EUR643900 remote (a few years 'newer' than the player)
(iii) Old One-4-All 5 remote tried with every Technics 'magic number'.

Tried replacing the entire IC602 (HC-MD10E) sensor circuit with a Vishay TSOP32138 - still no luck.

Bought a Technics EUR64767 remote (which is from the same era as the player, although for a cheaper model) - no luck.

Removed the Vishay sensor, replaced the three capacitors in the HC-MD10E (quite a fiddly process, had to cut a hole in the shield for one to poke through!) and reinstalled that.

And it worked, with the EUR64767! So, it was the capacitors then?

Well maybe - except that it still doesn't respond to the Harmony remote. Although if I tell the Harmony to 'learn' a keypress from the EUR64767, it does then work... just not with the 'downloaded' codes.

And the One-4-All 5 also still doesn't operate it, using various Technics 'magic numbers'

Unfortunately I no longer have the EUR643900 remote. If that worked, it would prove it was the caps that were bad - if it didn't, that would show that the P999 was working all along, and all my soldering was pointless, but it's just a player that's very fussy about remotes.

So all a bit bizarre. If anyone has an SL-P999 and a Harmony 300 remote though, out of interest maybe they could see if using the 'downloaded' Harmony codes works for them....

Although that's all academic really, as I am happy that it's working, I don't need it to work with the Harmony, and I'll now be scanning eBay for the matching EUR64729 remote, although they tend to go for fairly high prices so I'll wait for a bargain!

 

[MegaHurts]

I just fixed a non working ir sensor on a Technics SL-P600C multi disc.

Just adding pics of what was discussed above in case it's helpful to the next person.

The one 10uF was bad and corrosion evident.

Would be easier with smaller caps that fit in the box, but I drilled out a hole for it to poke out of and lubricated the edges with my blood to slide easier and then stick in place although not intentionally.

Presto, working remote.

 

[Sansuiman]

@MegaHurts, good call. I have not yet encountered bad caps within an IR receiver block assembly, but it is only a matter of time as these age past 40 years. I will say that I've had remotes that wouldn't transmit properly due to failed caps.