Meridian 103 overheating

Impman71 · 22nd September 2010, 09:32 PM

Hi,

Does anyone have any idea why my Meridian 103 amp is overheating?
I changed 2 820ohm 2 watt resistors as you could see they had got hot from the discoloration on the board & this seems to have stopped it distorting through my ls3/5a's, but even when it is just on & not playing anything it gets really hot & when you play anything it trips out within a few minutes! I also re-capped it when I was in there.
I'm a newbie to electronics, so please be gentle with me

Thanks for any suggestions,

Colin

nigelwright7557 · 23rd September 2010, 12:02 AM

Could be a high bias problem.

Is there a fan ? is this working ok ?

Impman71 · 23rd September 2010, 12:15 AM

There isn't a fan, how do I check the bias (in laymans terms please).

Thanks,
Colin

sippy · 29th September 2010, 01:07 AM

I had a pair of 105's that started to run hot, a freind had been badgering me for a while about swapping for his quad 2's which is what i did.
A few whiles later they self distructed and killed his bose 901's (i think).
my utterly humble oppinion is get shot of it and buy something else if u can, i just bought a mint in boxes cyrus2 + psx for £200...... for my bedroom system.

Doow · 27th February 2012, 04:39 PM

Hello,
i buyed a broken Meridian 101 - 103 Kombination several Month ago. At this time i start to repair the 101 and it wors fine now.
The 103 was totaly damaged, some Transistors, Diodes and Resistors was dissoldered and lost.
But i was able to complete the lost Parts and changed the broken one.
Now it works fine but.... where are the messurepoints for the BIAS-Adjust ?
The Schematics shows "Iq approx 30mA"
The messurement accross the both R22 (Emitter - Collector Resistors of the Powertransistors)
results aprox 0 to 2.7mA ?
So i speculate that´s are the wrong Pionts ?
Any Ideas ?

sgrossklass · 27th February 2012, 06:24 PM

You're measuring at the right points, but the wrong thing - Ohm's law is your friend. You should be getting about 6.6 mV across one 0R22 or 13.2 mV across both.

If you can't get to these values, something is still amiss and you'd have to check the adjustment range of the Vbe multiplier, and verify that the current limiting transistors and their diodes are OK.

Doow · 9th March 2012, 09:15 AM

thanks,
with this information i´ll measure once again.
hopes for me no other surprises will wait.

Doow · 10th April 2012, 10:15 AM

It work´s great
THX

22nd September 2010, 09:32 PM	#1
Impman71 diyAudio Member Join Date: Apr 2010	Meridian 103 overheating Hi, Does anyone have any idea why my Meridian 103 amp is overheating? I changed 2 820ohm 2 watt resistors as you could see they had got hot from the discoloration on the board & this seems to have stopped it distorting through my ls3/5a's, but even when it is just on & not playing anything it gets really hot & when you play anything it trips out within a few minutes! I also re-capped it when I was in there. I'm a newbie to electronics, so please be gentle with me Thanks for any suggestions, Colin

23rd September 2010, 12:02 AM	#2
nigelwright7557 diyAudio Member Join Date: Apr 2008 Location: Carlisle, England	Could be a high bias problem. Is there a fan ? is this working ok ? __________________ http://www.murtonpikesystems.co.uk PCBCAD40 pcb design software.

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23rd September 2010, 12:15 AM	#3
Impman71 diyAudio Member Join Date: Apr 2010	There isn't a fan, how do I check the bias (in laymans terms please). Thanks, Colin

29th September 2010, 01:07 AM	#4
sippy diyAudio Member Join Date: Jun 2008	I had a pair of 105's that started to run hot, a freind had been badgering me for a while about swapping for his quad 2's which is what i did. A few whiles later they self distructed and killed his bose 901's (i think). my utterly humble oppinion is get shot of it and buy something else if u can, i just bought a mint in boxes cyrus2 + psx for £200...... for my bedroom system.

27th February 2012, 04:39 PM	#5
Doow diyAudio Member Join Date: Feb 2012	Hello, i buyed a broken Meridian 101 - 103 Kombination several Month ago. At this time i start to repair the 101 and it wors fine now. The 103 was totaly damaged, some Transistors, Diodes and Resistors was dissoldered and lost. But i was able to complete the lost Parts and changed the broken one. Now it works fine but.... where are the messurepoints for the BIAS-Adjust ? The Schematics shows "Iq approx 30mA" The messurement accross the both R22 (Emitter - Collector Resistors of the Powertransistors) results aprox 0 to 2.7mA ? So i speculate that´s are the wrong Pionts ? Any Ideas ?

27th February 2012, 06:24 PM	#6
sgrossklass diyAudio Member Join Date: Nov 2004 Location: Germany	You're measuring at the right points, but the wrong thing - Ohm's law is your friend. You should be getting about 6.6 mV across one 0R22 or 13.2 mV across both. If you can't get to these values, something is still amiss and you'd have to check the adjustment range of the Vbe multiplier, and verify that the current limiting transistors and their diodes are OK.

9th March 2012, 09:15 AM	#7
Doow diyAudio Member Join Date: Feb 2012	thanks, with this information i´ll measure once again. hopes for me no other surprises will wait.

10th April 2012, 10:15 AM	#8
Doow diyAudio Member Join Date: Feb 2012	It work´s great THX

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