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Old 2nd May 2021, 2:49 pm   #1
Electricawe
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Default BT Response 20 Answering Machine - How to diagnose?

Hi,

I have an old BT Response 20 that was given to me, but when I plug it in, the tape spins a bit, the heads move a bit, but not down so they are contacting with the tape, and it beeps 4 times, and this happens a few times over. After this has happened, the power and messages lights flash alternately.

Does anyone know of any common faults with these, what this might be or how to fix it please?

Thank you.
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Old 2nd May 2021, 5:05 pm   #2
HamishBoxer
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Default Re: BT Response 20 Answering Machine - How to diagnose?

If this is anything like the BT Robin, then dry joints were an issue. Of course that I do not know, just a guess.
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Old 2nd May 2021, 6:09 pm   #3
Electricawe
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Default Re: BT Response 20 Answering Machine - How to diagnose?

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Originally Posted by HamishBoxer View Post
If this is anything like the BT Robin, then dry joints were an issue. Of course that I do not know, just a guess.
Thank you for your reply. That would make sense, after all of these years in storage. How would I go about checking this? Did the BT Robin do the same thing once the joints got dry?
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Old 2nd May 2021, 6:53 pm   #4
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Default Re: BT Response 20 Answering Machine - How to diagnose?

Hi, it may be worth checking for a stretched drive belt before looking for anything more sinister.

Regards

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Old 2nd May 2021, 7:11 pm   #5
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Default Re: BT Response 20 Answering Machine - How to diagnose?

I check for drys with a head magnifier and I forgot about the sensible suggestion of the drive belt.
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Old 2nd May 2021, 7:12 pm   #6
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Default Re: BT Response 20 Answering Machine - How to diagnose?

Yes, new belt may well fix it.
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Old 2nd May 2021, 11:33 pm   #7
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Default Re: BT Response 20 Answering Machine - How to diagnose?

Second-generation single-tape answering machines have a sensor on one of the cassette spindles producing pulses as it turns, which is fed into the microcontroller as a sort of machine-readable tape counter. A stretched or snapped drive belt might well result in no tape motion pulses, resulting in the machine retrying a few times (in case it has just been brought in from the cold or something; if it is just a bit stiff, the fault may clear itself) before deciding it is fatal and going into a shutdown state.
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Old 3rd May 2021, 11:38 am   #8
Electricawe
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Default Re: BT Response 20 Answering Machine - How to diagnose?

Thank you all for your input. I was thinking that the belt could be a problem too, but wasn't sure. I have opened it, and unplugged some of the connectors, is it easy to check the belts without further disassembly, as I am worried about breaking something?

Thank you.
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Old 3rd May 2021, 5:40 pm   #9
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Default Re: BT Response 20 Answering Machine - How to diagnose?

I decided to bite the bullet and disassemble, found the belt, moved it with my screwdriver and it was floppy, so I removed it. Upon removal, it broke in two, obviously brittle, but I changed it for an elastic band, and it is working again now! Thank you all!

There is something strange though, the audio sounds a bit weird. I take it it is probably from age, I tried cleaning the heads with alcohol, but no difference. It doesn't matter though, just glad that it works!

Also, has anyone got a PDF copy of the manual for this please? I can't find any online?

Thank you.
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Old 3rd May 2021, 10:18 pm   #10
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Default Re: BT Response 20 Answering Machine - How to diagnose?

"Sounds a bit weird" could mean anything. Can you make a recording (with the original if possible as well as the playback, and good enough not to bury the fault .....) and upload it somewhere? The head certainly could be worn; but it's as likely to be the tape that is worn out, so try a different cassette.

An ordinary elastic band will not last long under dynamic loading, so think about replacing it with something more permanent sooner rather than later. You can get packs of assorted belts ("one of them's bound to fit") from eBay.
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Old 3rd May 2021, 10:30 pm   #11
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Default Re: BT Response 20 Answering Machine - How to diagnose?

Perhaps it was wow & flutter (flutter especially).
The improvised belt would not of helped this one bit, but even when working correctly these machines are far from hi-fi.
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Old 4th May 2021, 9:30 am   #12
Electricawe
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Default Re: BT Response 20 Answering Machine - How to diagnose?

That makes sense, I can imagine the tape is worn slightly, I might buy one on eBay at some stage, but at least it is working. And I am only planning for the elastic band to be a temporary fix until I get a belt that fits this machine. I know that 90s tech wasn't best known for sound quality...

It does sound like wow and flutter to me, as it does vary. I will change the belt when I get one.

Thank you.
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Old 4th May 2021, 10:46 am   #13
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Default Re: BT Response 20 Answering Machine - How to diagnose?

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I know that 90s tech wasn't best known for sound quality...
True, but these sounded far better than the early digital machines which replaced them about 2000.
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Old 4th May 2021, 7:49 pm   #14
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Default Re: BT Response 20 Answering Machine - How to diagnose?

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.... has anyone got a PDF copy of the manual for this......
Manuals for this sort of equipment are the stuff that dreams are made of, they were never intended to be repaired, just replaced.

Andrew
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