Carver M1.5t Flashing Yellow Lights

jjmartec · 6th July 2005, 06:29 AM

I have had this amp since the 80s new , Fuse blow replaced fuse now i get a clicking sound over my speakers and yellow lights flashing. If anyone has seen this problem plez help out THX.

anatech · 6th July 2005, 11:47 PM

Hi jjmartec,
Your amplifier is in protect mode. There is either a fault in one channel or there is a power supply fault. The dual supply caps can go bad.

-Chris

jjmartec · 7th July 2005, 06:45 AM

Thx for quick reply , did the caps first had some at my job will keep on checking...

djk · 7th July 2005, 12:17 PM

The early M1.5T had 3A rectifiers on the ±40 and ±80 rails that would fail. Later versions went to 6A devices.

Check all the outputs and drivers for shorts too.

anatech · 7th July 2005, 11:27 PM

The easiest way to find out what's wrong is to unplug the unit and short the triac with a test clip. Plug the Carver into a variac, 2A model is fine. Bring the AC up to say 20V while watching the current meter on your variac (add one if there isn't one). At this level, you can check for high ripple on the supplies or rail voltage on the outputs. If you draw current, bring the voltage up a bit until you have 1/2 ~ 1 A of current. Measure across the emitter resistors to find the offending channel. Current draw right away normally means shorted rectifier(s) or capacitor.
Never attempt to bring the unit up past about 60% voltage this way. The current draw will be heavy and if you continue, you may overvoltage most of the circuits. You will overvoltage everything if you manage to get the AC up to normal levels. Make absolutely sure you remove the short across the triac whenever you leave the unit (so you don't forget).

-Chris

Eva · 8th July 2005, 12:36 AM

Does anybody have schematics for some model of that family of Carver's amplifiers?

I want to analyze their exotic switching mechanism.

anatech · 8th July 2005, 02:17 AM

Hi Eva,
PM is in order.

If you get a chance to bench one, the operation is interesting. Dual trace 'scope and you can watch the supplies against the output signal. The power supply is a standard triac regulated circuit using a mag coil. Effective, but doesn't like generators or high impedance AC lines.

-Chris

jjmartec · 12th July 2005, 07:15 AM

THX for the advice will try..JUst came back form short trip>>

6th July 2005, 06:29 AM	#1
jjmartec diyAudio Member Join Date: Jul 2005 Location: long island	Carver M1.5t Flashing Yellow Lights I have had this amp since the 80s new , Fuse blow replaced fuse now i get a clicking sound over my speakers and yellow lights flashing. If anyone has seen this problem plez help out THX.

7th July 2005, 06:45 AM	#3
jjmartec diyAudio Member Join Date: Jul 2005 Location: long island	Tried Caps Thx for quick reply , did the caps first had some at my job will keep on checking...

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6th July 2005, 11:47 PM	#2
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi jjmartec, Your amplifier is in protect mode. There is either a fault in one channel or there is a power supply fault. The dual supply caps can go bad. -Chris

7th July 2005, 12:17 PM	#4
djk diyAudio Member Join Date: Feb 2001 Location: USA	The early M1.5T had 3A rectifiers on the ±40 and ±80 rails that would fail. Later versions went to 6A devices. Check all the outputs and drivers for shorts too.

7th July 2005, 11:27 PM	#5
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	The easiest way to find out what's wrong is to unplug the unit and short the triac with a test clip. Plug the Carver into a variac, 2A model is fine. Bring the AC up to say 20V while watching the current meter on your variac (add one if there isn't one). At this level, you can check for high ripple on the supplies or rail voltage on the outputs. If you draw current, bring the voltage up a bit until you have 1/2 ~ 1 A of current. Measure across the emitter resistors to find the offending channel. Current draw right away normally means shorted rectifier(s) or capacitor. Never attempt to bring the unit up past about 60% voltage this way. The current draw will be heavy and if you continue, you may overvoltage most of the circuits. You will overvoltage everything if you manage to get the AC up to normal levels. Make absolutely sure you remove the short across the triac whenever you leave the unit (so you don't forget). -Chris

8th July 2005, 12:36 AM	#6
Eva diyAudio Member Join Date: Oct 2003 Location: Near the sea	Does anybody have schematics for some model of that family of Carver's amplifiers? I want to analyze their exotic switching mechanism.

8th July 2005, 02:17 AM	#7
anatech diyAudio Moderator Join Date: Jun 2004 Location: Georgetown, On	Hi Eva, PM is in order. If you get a chance to bench one, the operation is interesting. Dual trace 'scope and you can watch the supplies against the output signal. The power supply is a standard triac regulated circuit using a mag coil. Effective, but doesn't like generators or high impedance AC lines. -Chris

12th July 2005, 07:15 AM	#8
jjmartec diyAudio Member Join Date: Jul 2005 Location: long island	THX for the advice will try..JUst came back form short trip>>

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