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Old 24th August 2012, 12:15 PM   #191
Reality first!
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Quote:
Originally Posted by romvise View Post
Channel "1" has some problem, when I try to measure the DC offset I found 60mV and sometime the relay cut the circuit, in this situation the DC offset become 5V!
On C101/C102 I've +/-32.7V.
Hi Roberto,

please measure C102/C202:

Click the image to open in full size.

IMHO the LM318 has to be replaced...
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Old 24th August 2012, 12:34 PM   #192
billo44 is offline billo44  United Kingdom
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Quote:
Originally Posted by AndrewT View Post
A 30C (54F) rise for Tc is good. Not excellent.
But, is that actually Tc or is that the surface of the plastic packaging on the chip which could be at a very different temperature from the chipamp?
I would like to add an extra caution to Andrews caution above;-
I am not an expert, but measuring temperatures does fall under the category 'work' for me.
So-called 'laser' thermometers are quite inaccurate especially if measuring a small shiny surface.

The laser dot is not the same size as the field of view of the IR sensor which is actually reading the temperature. (especially up close since the laser and the IR sensor are some distance apart)
For a relatively accurate reading the target should be twice the size of the field of view of the IR sensor, and have an IR emmisivity of 0.95 for most hand held 'reasonably priced' thermometers.

Accuracy is sacrificed for convenience.

I'm Paused in my build, waiting for a couple of susumus which were missing from my Mouser order...

I think I bored myself with my post... must be time for bed...!

Bill

Last edited by billo44; 24th August 2012 at 12:38 PM.
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Old 24th August 2012, 12:46 PM   #193
romvise is offline romvise  Italy
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Quote:
Originally Posted by ClaveFremen View Post
Hi Roberto,

please measure C102/C202:

IMHO the LM318 has to be replaced...
I've +14.55 on C102 and -14.22V on C202.
I've a pair of 5W 8.2Ohm resistor, can I use they as load?
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Old 24th August 2012, 12:55 PM   #194
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Quote:
Originally Posted by romvise View Post
I've +14.55 on C102 and -14.22V on C202.
Fine, so your power supply is working as expected.

Most of the times the broken part is the LM318, I would swap it.
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Old 24th August 2012, 12:56 PM   #195
romvise is offline romvise  Italy
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...but I've only 16V on C14!

edit: correct cap name

Last edited by romvise; 24th August 2012 at 01:05 PM.
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Old 24th August 2012, 01:09 PM   #196
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Roberto, this evening I'll take some measures on mine to give you a comparison.
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Old 24th August 2012, 01:36 PM   #197
romvise is offline romvise  Italy
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Thanks a lot, Dario.
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Old 24th August 2012, 01:54 PM   #198
bcmbob is offline bcmbob  United States
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Hi Bill, You are correct. Andrew did a quite thorough explanation of the pitfalls of the laser temp tools that you confirm on another thread. Mine being a particular cheap model, I keep those limitations in mind. The only hedge against those problems I use is multiple shots at the same spot and an attempt to hold my hand at a uniform distance and position. I try to focus on the variation from a room temperature standard more than the value itself.

So far there have been few temperature related problems with the FE. Hopefully that will continue and there will not be a need for a more sophisticated temp monitoring device.
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Old 24th August 2012, 08:16 PM   #199
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Quote:
Originally Posted by ClaveFremen View Post
Roberto, this evening I'll take some measures on mine to give you a comparison.
Click the image to open in full size.

If voltages are correct I see two possibilities:
  • C32 has been overheated during soldering (try to measure it)
  • LM318 is gone
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Old 25th August 2012, 04:12 PM   #200
romvise is offline romvise  Italy
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Quote:
Originally Posted by ClaveFremen View Post
If voltages are correct I see two possibilities:
  • C32 has been overheated during soldering (try to measure it)
  • LM318 is gone
Thanks Dario, when led is on, the values are:
  • C101: 32.5V
  • C201: -32.5V
  • C102: -14.2V
  • C202: 14.6V
  • C14: 16.5V
  • D4: 16.5V
When the relay switch off D4 is 0V and C14 32.3V
so I think they are correct for my 22v toroid

About the solution, I can't measure capacitance of C32 ;(
For LM318 there are some test to do?
Someone know where I can get a single LM318?
Dario, can I get a new Ero C32 from you?

The other channel is now connect to the speaker and sound!

This is a picture of the "unlucky" channel with connection and case:
Click the image to open in full size.
I've build a direct signal cable from board to preamp without rca plug in the middle

Roberto
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