HP 5315A wont count

[Daxxin]

Power on test looks fine exit with all 3 zeros but from that status wont give any sign of life
even apply input channel signal.



following the signal 10Mhz from sine generator looks like comparator chip is faulty if someone can confirm



chip 1826-0426  AM68TADL (cannot find any datasheet ...equivalent?)

[Dr. Frank]

What about the trigger level on pin 8?

Is it possible to change this?

Maybe the voltage on this pin is way off, due to another defect, i.e. constantly @ +5V or -5.2V.

Are the supply pins 6, 11 correctly fed?
Are all supply voltages present? I see some tantalum caps, which also could have failed.

What about channel B, is it functional, instead?

Frank

[Daxxin]

What about the trigger level on pin 8?

Is it possible to change this?

Maybe the voltage on this pin is way off, due to another defect, i.e. constantly @ +5V or -5.2V.

Are the supply pins 6, 11 correctly fed?
Are all supply voltages present? I see some tantalum caps, which also could have failed.

What about channel B, is it functional, instead?

Frank

feeds is correct , common button trigger/sensivity , in trigger mode turning the knob i get from -2.54v to +2.54v
in sensivity mode from -0.041v to +0.066v

expecting square waveform on comparator output ..im right?

[Dr. Frank]

Yes, I'd expect complementary square waves on both outputs (180°).
Anyhow, if you apply the signal to channel B, you should see either this correct output (square wave), or also noise, like on channel A.

This would indicate, if the whole IC is dead, or the upper OpAmp only.

As a replacement, you'll need a double fast comparator.
This one might be an ECL line driver, which might not be available anymore, as of today.

Frank

[Daxxin]

Yes, I'd expect complementary square waves on both outputs (180°).
Anyhow, if you apply the signal to channel B, you should see either this correct output (square wave), or also noise, like on channel A.

This would indicate, if the whole IC is dead, or the upper OpAmp only.

As a replacement, you'll need a double fast comparator.
This one might be an ECL line driver, which might not be available anymore, as of today.

Frank

OK thanks for helping Dr.Frank both sides dead i m checking  MAX912 datasheet as replacement it looks very fine

[Dr. Frank]

This MAX912 has a TTL output, which will probably not work.

My guess was correct, see page 8-9, or 83/106 in the manual- the comparators have ECL outputs, which usually means negative output signals.

PS: maxim still offers ECL comparators, like the max9693.
I checked pinning, this type is more suitable, and it's also fast enough for > 100MHz.

Frank

[lowimpedance]

chip 1826-0426  AM68TADL (cannot find any datasheet ...equivalent?)

The part number is AM687ADL   no T
datasheet here
http://www.datasheets360.com/part/detail/am687adl/961240802637534603/?alternatePartManufacturerId=0

And the MAX9693  that Dr. Frank found looks like an excellent replacement.

[andymok]

Hello From Hong Kong.

I have a HP 5315A and I’m experiencing exactly the same thing as you described.  How was your unit?  Did you find the fix?

Much appreciated!