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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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Old 17th Feb 2019, 6:23 pm   #1
NorfolkDaveUK
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Default Teac 2340R tripping mains supply.

Ok so here`s another strange one .

Its playing fine , recording "ok", its been re-capped etc .

I`m trying to calibrate it , but , as soon as I plug the Millivoltmeter or scope into the output , it trips the house .

I can plug an amp into the output no problem and it plays out through the amp with no issues , but the scope or milivoltmeter , and boom trips the house . ?

um @
Help ?
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Old 17th Feb 2019, 6:51 pm   #2
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Default Re: Teax 2340R tripping

I presume when you say "trips the house", you mean the RCD (earth leakage trip) is operating as opposed to the 32A MCB (overcurrent trip)?

Check the mains plug wiring. If Earth and Neutral are reversed, this can happen.
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Old 17th Feb 2019, 9:43 pm   #3
NorfolkDaveUK
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Default Re: Teax 2340R tripping

Hi Julie.

I'm using a kettle lead with a moulded plug and the machine has not got an earth.

Thanks for your assistance.

David.
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Old 17th Feb 2019, 9:55 pm   #4
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Default Re: Teax 2340R tripping

Could it happen if live and neutral are reversed ? The socket has been changed out for a kettle lead so its entirely possible that the person that did it got those the wrong way around ?

David
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Old 17th Feb 2019, 10:00 pm   #5
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Default Re: Teax 2340R tripping

The fact you say that "it trips the house" suggests that the protective device operating is an RCD, although you haven't answered Julie's question about this.

Does tripping still occur if the test equipment, which I assume is earthed, is unplugged from the mains supply?
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Old 17th Feb 2019, 10:08 pm   #6
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Default Re: Teax 2340R tripping

THe amps probably are double-insulated and floating. The test equipment will be earthed.

Did you recap the line and neutral to chassis EMC capacitors by any chance?

David
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Old 17th Feb 2019, 10:10 pm   #7
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Default Re: Teax 2340R tripping

Well I did answer the question , but as usual someone here is deleting part of my messages . I dont know why they feel its nescessary to keep doing it , but i wish they would stop it its getting on my nerves . Its tripping the upstairs mcb . I`ll check if it is tripping with the devices unplugged in a second . I just want to look at the schematic and see where the live is supposed to go on this , the fuse is going to the neutral pin at the moment .
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Old 17th Feb 2019, 10:13 pm   #8
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Default Re: Teax 2340R tripping

Nothing has been deleted from your posts.
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Old 17th Feb 2019, 10:14 pm   #9
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Default Re: Teax 2340R tripping

Sounds like you have a leakage between a primary side circuit of the mains transformer and chassis.

Lawrence.
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Old 17th Feb 2019, 10:17 pm   #10
NorfolkDaveUK
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Default Re: Teax 2340R tripping

Quote:
Originally Posted by Station X View Post
Nothing has been deleted from your posts.
Believe me , it happens time and time and time again .

but , nevertheless ,

I`ve just looked at the schematic , and live should be going to the fuse (of course ) and when I switched it around , I now have a live chassis , so there is definitely a short in here somewhere . Dont ask me how I found out the chassis was live , I`m still rubbing the spot . lol

Lawrence you are on the money as usual . I`ve not recapped the power supply yet I`ll do that in a sec .
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Old 17th Feb 2019, 10:31 pm   #11
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Default Re: Teax 2340R tripping

Quote:
Originally Posted by NorfolkDaveUK View Post
Dont ask me how I found out the chassis was live , I`m still rubbing the spot . lol
It takes a lot of current to trip an MCB serving a ring main or radial circuit!
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Old 17th Feb 2019, 10:32 pm   #12
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Default Re: Teax 2340R tripping

Check for an obvious short or trapped wire, there is no connection by whatever means between the mains side circuits (motors etc) and the chassis in the schematic I'm looking at, the switchery is a bit of a nightmare in the schematic but if you need help with that side of things say so.

One of the relays has a set of contacts in a secondary side circuit of the mains transformer with the other sets of contacts on the same relay being in the primary side circuits of the mains transformer.

I would nail the tripping before changing any capacitors.

Lawrence.
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Old 17th Feb 2019, 11:11 pm   #13
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Default Re: Teax 2340R tripping

Thanks Lawrence ,
I found a trapped wire , GRN/WHT/BLK on PC board 6 , but , Its not broken though , and once un-trapped the problem didnt go away . I have a reading of 5.6k between the live pin and the chassis which tells me its not dead short but the belt I got from it says otherwise ..lol

Last edited by AC/HL; 18th Feb 2019 at 12:26 am. Reason: Unnecessary repetition of the previous post deleted
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Old 18th Feb 2019, 12:12 am   #14
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Default Re: Teax 2340R tripping

OK I have made slight progress . Not really too sure how , but hey , I no longer have a live chassis , which , is well , great . I dont think I can take too many more shocks.

Secondly , the machine is now letting me connect the machine to the scope and play a tape , BUT , its now trips when I press STOP where as before it would just trip as soon as I moved the "play mode" lever over to "play" position , or when i powered the machine on with it in the play position with the scope connected to the output. So it is progress , still not ideal though .

Edit : I have noticed that C1 on the rectifier board , is bulging really badly so that definitely needs to be changed . I dont have anything suitable at the moment so I`ll have to order one . 100uf 160v.

Last edited by NorfolkDaveUK; 18th Feb 2019 at 12:19 am.
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Old 18th Feb 2019, 4:07 am   #15
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Default Re: Teax 2340R tripping

Did you find and fix a solid reason why the chassis was live?

I'm always nervous if just disturbing things seems to cure a fault, especially a fault with safety implications.

David
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Old 18th Feb 2019, 10:04 am   #16
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Default Re: Teax 2340R tripping

It may also be why the live and neutral were originally reversed.

If you are carrying out this service for another person, then there a huge safety and potentially legal implications here.
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Old 18th Feb 2019, 10:38 am   #17
NorfolkDaveUK
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Default Re: Teax 2340R tripping

Quote:
Originally Posted by Radio Wrangler View Post
Did you find and fix a solid reason why the chassis was live?

I'm always nervous if just disturbing things seems to cure a fault, especially a fault with safety implications.

David
No I didnt David , and yes it does make me nevrvous , I have looked and looked and looked , but I cant find anything that would have caused it at all .

As for the fault , I still havent figued out whats causing it to trip on stop .

Michael , it my machine
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