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Vintage Audio (record players, hi-fi etc) Amplifiers, speakers, gramophones and other audio equipment. |
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8th Apr 2020, 3:59 pm | #1 |
Diode
Join Date: Jun 2011
Location: Kings Lynn, Norfolk, UK.
Posts: 8
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Marantz PM230 amp
Hi, for some years I have successfully used this amp. Then it started to blow when switched on. I replaced all fuses x 3 times and although it looked likely as soon as volume was increased it blew. I read that it would not be financially viable to have it looked at. So I bought a replacement from Ebay,plugged it in and when volume was over a third it blew. Help please
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8th Apr 2020, 4:05 pm | #2 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,967
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Re: Marantz PM230 amp
This suggests that there is something wrong with your speakers or the associated wiring.
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8th Apr 2020, 4:47 pm | #3 |
Diode
Join Date: Jun 2011
Location: Kings Lynn, Norfolk, UK.
Posts: 8
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Re: Marantz PM230 amp
Hi, thank you. I will check the wiring. I have tried two different pairs of speakers and the amp still blows. Actually the problem started when I changed from original speakers to replacements. I have since put the original Marantz speakers back but blew again. Simple question, should the lined wire from speaker connect to plus on amp
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8th Apr 2020, 4:56 pm | #4 |
Moderator
Join Date: Jun 2003
Location: Oxford, UK
Posts: 27,967
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Re: Marantz PM230 amp
It doesn't matter which way round you connect the speakers so long as both are the same.
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8th Apr 2020, 4:57 pm | #5 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
Posts: 5,215
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Re: Marantz PM230 amp
Normally the marked wire (lined, whatever) is usd for the positive (plus) connection.
But unlike a lot of electrical things where it does matter which way round you connect them, in this case if you wire a speaker up the wrong way round it will not damage the speaker, it will not damage the amplifier. All that will happen is that you won't hear much bass because the sound from the 2 speakers will cancel out |
8th Apr 2020, 4:57 pm | #6 |
Dekatron
Join Date: Nov 2003
Location: Heckmondwike, West Yorkshire, UK.
Posts: 9,642
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Re: Marantz PM230 amp
Were the replacements the same impedance, probably 8 ohms?
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8th Apr 2020, 4:58 pm | #7 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,225
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Re: Marantz PM230 amp
It should but I think there is something more fundamentally wrong.
Check your cables to see that there are no short circuits or strands of wire from one terminal to the other. Check the length of the cable to see if there is any damage. If you have a test meter remove the wires from the amp and test the resistance of both cables buy putting the meter on each pair of wires at a time. The meter shold read approx 6 ohms. If it reads 0 ohms then have have a short circuit. |
8th Apr 2020, 5:14 pm | #8 |
Diode
Join Date: Jun 2011
Location: Kings Lynn, Norfolk, UK.
Posts: 8
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Re: Marantz PM230 amp
Hi. Thank you all. Mr Maurice. I have 6 ohms on one and 0 on other speaker wire. Oh dear. Just checking the wire under the carpet
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8th Apr 2020, 5:32 pm | #9 | |
Heptode
Join Date: Oct 2008
Location: Aalborg, Denmark
Posts: 903
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Re: Marantz PM230 amp
Quote:
What strikes me is that you write the fuses starts to blow when the amp. is switched on. If this is to be taken literally the problem likely should be found elsewhere as the overload caused by defective speakers and/or shorted wiring is only present when the amp outputs a signal. Did you replace the fuses with new ones of the correct rating? The two fuses pos.no.: F801 & F802 are rated at 3,15A of the type Slow-Blow. Another common fuse rating is 315mA which will allow for 10 times less current before blowing and if this type was mistakenly used, I imagine it would be too small to handle the power-on surge current. So, you need the check what was advised above AND the rating on the replacement fuses used. Rgds, /Torben |
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8th Apr 2020, 5:40 pm | #10 |
Moderator
Join Date: Feb 2006
Location: Wembley, Middlesex
Posts: 7,225
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Re: Marantz PM230 amp
The one with 0 ohm is the faulty one it should also measure 6 ohms.
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8th Apr 2020, 7:08 pm | #11 |
Dekatron
Join Date: Nov 2009
Location: Lincolnshire, UK.
Posts: 5,000
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Re: Marantz PM230 amp
I think she said it blew the fuses when the volume was turned up, indicating speakers or their wiring or connections shorting.
I should go without saying that wires should never be put under carpets - they always end up being rubbed through and short out. This particularly applies to any mains cable - a fire may start when you're fast asleep in your bed! |
9th Apr 2020, 7:38 am | #12 |
Diode
Join Date: Jun 2011
Location: Kings Lynn, Norfolk, UK.
Posts: 8
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Re: Marantz PM230 amp
Please don't be impatient. I am at the end of my tether too. I have replaced wires to the speakers, using either pair of speakers or either Marzntz amp ....they still blow
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9th Apr 2020, 11:04 am | #13 |
Moderator
Join Date: Mar 2012
Location: Fife, Scotland, UK.
Posts: 22,901
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Re: Marantz PM230 amp
Understood.
The shorted speaker wires may have done damage to the amplifier, and the amplifier could then blow fuses without any connections being made. I suppose the next thing to do is to measure the resistances at the amplifier ends of the wires once more to check that the short circuit which caused the trouble has been fixed. Otherwise it will sit there waiting for the next amplifier or if this one is fixed. David
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9th Apr 2020, 11:27 am | #14 | |
Nonode
Join Date: May 2004
Location: Halifax, West Yorkshire, UK.
Posts: 2,587
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Re: Marantz PM230 amp
Quote:
Alan |
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10th Apr 2020, 6:08 am | #15 |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
Posts: 7,667
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Re: Marantz PM230 amp
Sounds like you have a short circuit, when the fuses blow, what do they look like? Are they clear or black/silver - ish. Try and make a lamp limiter if you can and use that to power the amp up on next test might save on fuses and will be indicitive. Do you have a meter?
If you get stuck and you have transport your welcome to drop it off here, am about 1 hour from Kings Lynn or a courier would be about £8. Actually, come to think of it I might have a PM230 somewhere, will look. Andy.
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