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Old 2nd July 2003, 06:02 PM   #21
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Quote:
Originally posted by tiroth
Is the tab voltage 0.3V for both units when disconnected?

You should list the separate disconnected voltages as well as the common connected voltage.

yes, this is the reading from both chips, when they are disconnected. i will see what the voltage it when they are connected.
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Old 2nd July 2003, 07:37 PM   #22
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Quote:
Originally posted by Matttcattt
yes, this is the reading from both chips, when they are disconnected. i will see what the voltage it when they are connected.
Hi,

tab (heatsink) voltage on plastic package must be -Ve, metal TO3 is isolated; N.C. What voltage is between two noelectrically connected heatsinks?

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Old 2nd July 2003, 08:14 PM   #23
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Quote:
Originally posted by moamps


Hi,

tab (heatsink) voltage on plastic package must be -Ve, metal TO3 is isolated; N.C. What voltage is between two noelectrically connected heatsinks?

Regards

both tabs (heatsink) (plastic package) are at 0.3v with the common lead of my multimeter connected to star ground. i do not understand your question. they are both at approx. 0.3v so, no more than 0.1v difference between the heatsinks. have i understood your question correctly?
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Old 2nd July 2003, 08:41 PM   #24
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Quote:
Originally posted by Matttcattt
both tabs (heatsink) (plastic package) are at 0.3v with the common lead of my multimeter connected to star ground



What voltage is between pins 3,4 and tab?
What voltage is between 3,4 and stargnd?
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Old 2nd July 2003, 08:43 PM   #25
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Quote:
Originally posted by moamps





What voltage is between pins 3,4 and tab?
What voltage is between 3,4 and stargnd?

i cant measure at the moment, but i guess:

A) -14.7v
B) -15v
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Old 2nd July 2003, 08:59 PM   #26
moamps is offline moamps  Croatia
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Quote:
Originally posted by Matttcattt

i cant measure at the moment, but i guess:
A) -14.7v
B) -15v
Strange, according to apps note (A) voltage must be zero....

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Old 2nd July 2003, 09:40 PM   #27
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it should be -15v accrording to the datasheet. the amplifier uses dual power supplies. +/-15v.
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Old 2nd July 2003, 10:28 PM   #28
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Quote:
Originally posted by moamps


Strange, according to apps note (A) voltage must be zero....


that is because both are at -Vdc?
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Old 3rd July 2003, 10:33 AM   #29
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Quote:
Originally posted by millwood
that is because both are at -Vdc?
Yes,
good readings between some points for PS+/-15V are:

"3,4" - gnd ......-15V
"10,11" - gnd ......+15V
"3,4" - tab ......0V
tab - gnd ......-15V
"10,11" - "3,4" ..... 30V

If IC is directly mounted to the heatsink, then the heatsink must be electrically isolated from all parts inside the chassis and from the chassis itself (if the chassis is metal).

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Old 3rd July 2003, 12:39 PM   #30
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Quote:
Originally posted by moamps


Yes,
good readings between some points for PS+/-15V are:

"3,4" - gnd ......-15V
"10,11" - gnd ......+15V
"3,4" - tab ......0V
tab - gnd ......-15V
"10,11" - "3,4" ..... 30V

If IC is directly mounted to the heatsink, then the heatsink must be electrically isolated from all parts inside the chassis and from the chassis itself (if the chassis is metal).

Regards

i know this should be true, but both chips tabs are at 0.3v from ground. also, i know that the chips and heatsink should be insulated, and it will be, but i wish to know why the tabs are at 0.3v, and why the two chips will not work when the tabs are electronoically connected.
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