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Old 15th Nov 2021, 6:38 pm   #1
darkwingmanor1
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Default Caroling Christmas Bells- Play Too Slow-Help, Please?

Hello,
Thank you for adding me to the list. I found you all through Google, troubleshooting my Caroling Christmas Bells. I found the previous posts on these, but I don't understand any of the technical discussion. I have a set from the1980s with the green power unit that is about the size of a TV remote. The tunes all play but they are at about half the speed they should be. It's painful to listen too. My inquiry is this, please... What is wrong with the thing and how can it be fixed? Thank you so much for your time. Tina R.
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Old 16th Nov 2021, 10:23 am   #2
Brigham
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Default Re: Caroling Christmas Bells- Play Too Slow-Help, Please?

Are you sure there is a fault?
These are painful to listen to anyway, in my view.
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Old 16th Nov 2021, 12:06 pm   #3
PaulR
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Default Re: Caroling Christmas Bells- Play Too Slow-Help, Please?

Hello Tina and welcome to the forum. Actually I think they sound like a nice idea and quite "high tech" for the time they were made.

If there is anything wrong with them I don't think that it would be an easy diy fix. There is another discussion about them here

https://antiqueradios.com/forums/vie...p?f=2&t=182070

If anything the discussion is more technical than the previous one on here was, though.
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Old 16th Nov 2021, 1:26 pm   #4
SiriusHardware
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Default Re: Caroling Christmas Bells- Play Too Slow-Help, Please?

Reading through other posts on the internet it seems these may use a simple pulse generating circuit to produce a series of pulses to 'step' through the play sequence, rather like an electronic version of a Metronome.

If so, it may be possible to adjust the 'play speed' by looking inside the control unit to see if there is an adjuster. I find it a little bit surprising that there is not some kind of speed adjustment accessible on the outside of the unit, are we sure there is not?

A lot depends on how confident dwm1 feels about opening up the unit and looking inside. If we could see some good sharp pictures of the inside of the control unit we would be in a better position to advise.

Last edited by SiriusHardware; 16th Nov 2021 at 1:50 pm.
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Old 16th Nov 2021, 1:50 pm   #5
SiriusHardware
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Default Re: Caroling Christmas Bells- Play Too Slow-Help, Please?

Further, there are a few Youtube videos featuring this type of unit, most typically those made by 'Capricorn' - most just show the bells playing but this one

https://www.youtube.com/watch?v=NW5ECcRoueI

...shows the internal PCB - essentially a 555 timer chip acting as the overall clock / metronome generator, driving some counters which in turn step through a ROM which is acting like an electronic equivalent of a piano-roll.

To change the overall playing speed it would only be necessary to alter the running speed of the 555 - either by adjusting a speed setting control if there is one, or by making one of the fixed components variable. Unfortunately the video linked to above is shot in rather poor quality so I can't see if there is an adjustment control on the PCB.

It would be useful if dwm1 could give us more info, like the make and model on the control unit, and some good photos of the control board inside if possible.
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Old 17th Nov 2021, 10:44 pm   #6
robin0577
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Default Re: Caroling Christmas Bells- Play Too Slow-Help, Please?

If it's a 555 based circuit and it's running too slow, wouldn't that suggest the timing cap has gone leaky and is taking too long to charge?
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Old 17th Nov 2021, 10:59 pm   #7
SiriusHardware
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Default Re: Caroling Christmas Bells- Play Too Slow-Help, Please?

We're a little bit short of information regarding the actual unit in question. They are typically as described earlier but Tina's might not be. We really need a good view of her unit, outside and inside.

The other thing we don't know is whether these have ever worked the way Tina thinks they should in her ownership - did they once play at the right speed and now don't, or were they already playing too slowly the first time she tried them (did she pick them up second hand?)

Tina has made clear that she didn't really understand previous discussions about these at the technical level, so we can only really assist if we can get a good look at the PCB from both sides and maybe work out which components are responsible for determining the running speed. At that point we might be able to say 'change part x or have it changed by a friend who can do it'.

Last edited by SiriusHardware; 17th Nov 2021 at 11:16 pm.
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