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Vintage Tape (Audio), Cassette, Wire and Magnetic Disc Recorders and Players Open-reel tape recorders, cassette recorders, 8-track players etc. |
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15th Sep 2020, 4:41 pm | #21 | ||
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Ferrograph Series 5 Triggering RCD
Quote:
Its stays high on the resistance scale but briefly decreases and goes back up again. This was tested out of circuit. But I dont think C3 is the cause of the problem (although I still think it needs replacing). C4 seems to be the one which is a completely dead short. |
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15th Sep 2020, 4:52 pm | #22 | |
Dekatron
Join Date: Apr 2019
Location: Worthing, West Sussex, UK.
Posts: 6,603
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Re: Ferrograph Series 5 Triggering RCD
Quote:
David |
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15th Sep 2020, 4:56 pm | #23 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Ferrograph Series 5 Triggering RCD
The capacitors voltage rating won't affect things.
Lawrence. |
15th Sep 2020, 5:37 pm | #24 | |||
Octode
Join Date: Dec 2017
Location: Morden, Surrey, UK.
Posts: 1,559
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Re: Ferrograph Series 5 Triggering RCD
Quote:
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15th Sep 2020, 5:54 pm | #25 | ||
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Ferrograph Series 5 Triggering RCD
Quote:
Been looking around for replacement capacitors. Would these be a suitable replacement? https://www.ebay.co.uk/itm/CBB61-mot...wAAOSwYTpdPbVI Just a bit thrown off because of the different shape. |
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15th Sep 2020, 5:56 pm | #26 | |||
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Ferrograph Series 5 Triggering RCD
Quote:
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15th Sep 2020, 6:16 pm | #27 |
Octode
Join Date: Dec 2017
Location: Morden, Surrey, UK.
Posts: 1,559
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Re: Ferrograph Series 5 Triggering RCD
There you go then.
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17th Sep 2020, 12:29 pm | #28 | |
Tetrode
Join Date: Aug 2005
Location: Leicester, Leicestershire, UK.
Posts: 68
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Re: Ferrograph Series 5 Triggering RCD
Quote:
PS if the stator does have a short, I have a spare i can send you for the postage cost.
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Andrew B. Last edited by flywheel; 17th Sep 2020 at 12:42 pm. Reason: Additions and clarifications. |
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18th Sep 2020, 12:45 am | #29 |
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Ferrograph Series 5 Triggering RCD
Thanks. I'll keep that in mind. I'll get around to removing it soon. Here's hoping it's just the capacitor though
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18th Sep 2020, 1:41 am | #30 |
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Ferrograph Series 5 Triggering RCD
Okay, just tested the motor run cap out of circuit and it seems to be fine. Or at least not shorted. Hmm..
The motors seem to still have resistance too. Might have to go over the schematics again and see what I can spot. What points on the motor do I need to test between? |
18th Sep 2020, 9:58 pm | #31 |
Tetrode
Join Date: Aug 2005
Location: Leicester, Leicestershire, UK.
Posts: 68
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Re: Ferrograph Series 5 Triggering RCD
I'd suggest testing for leakage between the motor connections and the motor frame.
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Andrew B. |
18th Sep 2020, 10:24 pm | #32 |
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Ferrograph Series 5 Triggering RCD
Cheers i'll give that a try. If it's not a complete short is there any amount of resistance which should be considered normal?
Sorry for the basic questions, i've not really dealt with motors before. |
19th Sep 2020, 1:37 pm | #33 |
Tetrode
Join Date: Aug 2005
Location: Leicester, Leicestershire, UK.
Posts: 68
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Re: Ferrograph Series 5 Triggering RCD
Hi, no problem - there should be full insulation between the motor frame and any of the connector plug/solder tag points.
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Andrew B. |
20th Sep 2020, 3:06 pm | #34 |
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Ferrograph Series 5 Triggering RCD
Okay,
So I tried measuring between one of the points which was connected to the motor run capacitor and the motor frame. The meter didnt read infinity but it was not at zero. I then tested the machine again and the fault is still there. After that I measured the same two points again and the meter almost read infinity (needle moves just barely a fraction). I tried rotating the motor by hand to see if the position of the motor had any bearing on it and it didnt. Then just for good measure, I tried it again after doing the second test after the meter read almost infinity (just to see if it had magically fixed itself) and yep, no luck still. Getting a bit stuck for ideas ... Pictures attached are from the first test. On the second test the needle was almost, but not entirely on infinity. I should point out that I powered on the machine with the motor disconnected from the capacitor and it still tripped. |
20th Sep 2020, 3:44 pm | #35 |
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Ferrograph Series 5 Triggering RCD
** Update **
Tested it again and there is definitly some leakage between the motor run wires and the motor frame / ground. I think my meter must have been playing up. I done the exact same test again and this time it shows an almost dead short. For a sanity check I also tried my newer digital meter. Pictures below. I'm guessing that because of this a short still exists between two other points as it should have powered up fine without these wires connected. |
20th Sep 2020, 4:23 pm | #36 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,213
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Re: Ferrograph Series 5 Triggering RCD
If you have 1.3kOhms resistance between the motor windings and the chassis (at the voltage used by a normal digital multimeter, a few volts at most) then you have a fault. Even if that leak doesn't get any worse as the voltage increases and stays at 1.3k, it's going to pass a couple of hundred mA at mains voltage. That will trip an RCD (and with good reason, it's far too high a leakage current to be safe).
I am not sure what the legal requirements are, but I would want a resistance of several megohms at a test voltage of 500V (twice mains). A proper insulation tester is a somewhat specialised instument but actually you have one. The Mohm position of that BT tester (knob fully clockwise) does a test between the ''B' socket (or the 'A' socket if you press the button) and the ground socket at about 110V. That's not really enough, but better than the 2V of a digital multimeter. I think you need to disconnect things and test some more. For example, disconnect all wires from that motor (note where they go!) and do an test between the motor connections and the motor frame. Any significant leakage (<10Mohms say) means you need a rewind. |
20th Sep 2020, 4:54 pm | #37 |
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Ferrograph Series 5 Triggering RCD
Thanks for the help. I'll try and test the motor out of circuit (its a bit of a big job to remove all of those connections.
I am also a little suspicious of the motor run switch since it seems to me like it could be short. Though it's not leaking to ground so that would cause the break. Likely would just cause the motors to run all the time if anything. (I knew that old multimeter would come in handy some day ) |
20th Sep 2020, 7:32 pm | #38 |
Tetrode
Join Date: Aug 2005
Location: Leicester, Leicestershire, UK.
Posts: 68
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Re: Ferrograph Series 5 Triggering RCD
Looks like you've done the hard part by unsoldering the capacitor leads. The other two connections are by a plug, which is most easily got at after you undo the four motor-frame retaining screws (keep hold of the motor while you take the last two out), and then gently drop the motor by about half an inch. The plug is then easy to get at, but have a small screwdriver handy to lever it off the connector in case it's hard to unplug by hand.
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Andrew B. |
20th Sep 2020, 7:51 pm | #39 |
Pentode
Join Date: Oct 2014
Location: Selsey, West Sussex, UK.
Posts: 204
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Re: Ferrograph Series 5 Triggering RCD
Oh okay. I didnt realise it was connected via a plug. That makes life easier.
I'll test it any keep the thread updated. |