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Old 7th Jun 2020, 9:57 pm   #1
Zelandeth
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Default Dead Mybelle Spotlight 753

I've had this thing since it was new in the early 90s when it was given to me as a birthday present (I was a slightly odd child), but it has been in storage for quite a while as I had nowhere to put it. Having an actual office space now it would be nice to get it reinstated.

Unfortunately when I went to plug it in last time it was utterly dead.

No audio from the earpiece, no light from the two yellow LEDs behind the keypad, nothing. Ringing in to it also results in absolutely nothing from the ringer or the discharge lamps which usually flicker in time with the ringer.

I've checked that the line from the socket is intact, all the lines in the cord between the handset and the base are fine and that the (always slightly crackly) on hook switch was behaving. I did give that a bit of a clean as it's always been a bit crackly...it now transitions cleanly from on to off hook and back again, but the unit is still dead.

I'm not a telecoms expert so need a bit of assistance to help me know where to look next.

I realise it's not exactly a high quality item, but it's got quite a lot of sentimental value so it would be nice to get it going again.
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Old 8th Jun 2020, 7:31 am   #2
Dave Moll
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Default Re: Dead Mybelle Spotlight 753

I appreciate that, as a birthday present, that particular one has sentimental value, but I notice that there is a like-for-like (including crackly sound!) replacement available on eBay for under 20. I have no connection with the seller.
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Old 8th Jun 2020, 8:43 am   #3
OscarFoxtrot
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Default Re: Dead Mybelle Spotlight 753

Are you using the original line cord between the phone and the socket? BT have the line on pins 2 and 6 (of a 6-position plug), USA on the centre pins 3 and 4.

If you've borrowed a line cord from another phone (or fax machine) you may have a crossover cord when you need a straight, or vice-versa.

I wonder how many here were a "slightly odd child". I know I was
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Old 8th Jun 2020, 9:09 am   #4
Dave Moll
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Default Re: Dead Mybelle Spotlight 753

Quote:
Originally Posted by OscarFoxtrot View Post
BT have the line on pins 2 and 6 (of a 6-position plug), USA on the centre pins 3 and 4.
Do you mean 2 and 6, which is different from the normal 2 and 5?
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Old 8th Jun 2020, 5:52 pm   #5
TonyDuell
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Default Re: Dead Mybelle Spotlight 753

Is the attached circuit of any use?

A few points...

It needs a strong ringing signal (high voltage) to light the neons. It'll ring the bell at a lower voltage, but it doesn't light up.

The UK version needs a straight-wired line cord (6p4c plug at the telephone end, BT Plug 431A at the other end). It needs the ringing capacitor in the master socket. I _think_ other versions had C1 fitted on the 'base' PCB which would act as the ringing capacitor.

The handset cord is cross-wired as they usually are.

If you take the base apart (4 corner screws), the gravity switch actuator comes off with the cover. In this state (gravity switch itself not pressed) it appears to be _on hook_ to the line. You can test ringing like this. The base will ring on its own (and the 2 neons in it light) without the handset connected.
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Old 9th Jun 2020, 9:07 am   #6
OscarFoxtrot
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Default Re: Dead Mybelle Spotlight 753

Quote:
Originally Posted by Dave Moll View Post
Quote:
Originally Posted by OscarFoxtrot View Post
BT have the line on pins 2 and 6 (of a 6-position plug), USA on the centre pins 3 and 4.
Do you mean 2 and 6, which is different from the normal 2 and 5?
No I don't. I should stop posting before first tea of the day.
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Old 10th Jun 2020, 1:31 pm   #7
Zelandeth
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Default Re: Dead Mybelle Spotlight 753

Thanks for the input folks, gives me a couple of things to check. I'm 90% certain the line cord it's being used with is the original, but given we moved house four times in 12 months a few years ago anything is possible!

Actually having the schematic will be helpful if I do end up having to do more component level faultfinding.

Also thank you...my brain was utterly refusing to find the term "gravity switch" when I was writing the original post despite spending a good few minutes trying to bring the correct terminology to mind.
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