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Analog Line Level Preamplifiers , Passive Pre-amps, Crossovers, etc.

Preamp Control - Volume, input, mute, remote
Preamp Control - Volume, input, mute, remote
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Old 9th October 2021, 02:47 PM   #331
rpafenberg is offline rpafenberg  United States
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Join Date: Feb 2004
Location: Washington DC
Preamp Control - Volume, input, mute, remote
John,

Sent you PM.

Roy
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Old 10th October 2021, 02:52 AM   #332
johnhenryharris is offline johnhenryharris  United States
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Join Date: Nov 2012
Location: San Diego, CA
Hi Roy,
Saw your message and sent one back. I have received your boards and will start de-populating them tonight.
Thanks,
John
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Old 10th October 2021, 09:31 AM   #333
rpafenberg is offline rpafenberg  United States
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Join Date: Feb 2004
Location: Washington DC
Preamp Control - Volume, input, mute, remote
thanks!
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Old 11th October 2021, 12:49 AM   #334
johnhenryharris is offline johnhenryharris  United States
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Join Date: Nov 2012
Location: San Diego, CA
Last night I removed 83 relays in about 30 minutes and 12 LED displays in another 30 minutes. 1 minute to remove the 3 decoder chips and another 30 minutes to remove excess solder from the legs and then straighten them all. I was going to ship the parts and boards back tomorrow but before I do is there anything else you need removed?
As they say, good tools are niiiice.
Thanks,
John
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Old 11th October 2021, 01:38 AM   #335
rpafenberg is offline rpafenberg  United States
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Join Date: Feb 2004
Location: Washington DC
Preamp Control - Volume, input, mute, remote
John,

I'm fine with what you have removed. Let me know what shipping and the three programed roms will cost. It's amazing that you were able to remove them so quickly and without damage. How much did it that tool set you back? Can you buy it used?

Regards,

Roy
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Old 11th October 2021, 02:42 AM   #336
johnhenryharris is offline johnhenryharris  United States
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Join Date: Nov 2012
Location: San Diego, CA
The Metcal soldering station with basics retails for around $1K, more with the tips and extras but I got mine from a company going out of business in the Silicon Valley for $0.10 on the dollar. Mine is a P2SE-01, it is older, you can get them used for around $100 on eBay but that is just the Power Supply, then you need the iron and the tips. They use RF down the cable to the tip and keep the heat spot on and heat almost instantly. Probably the best soldering station I have used. The EEPROM are $7 each and I will let you know about the shipping when I come back from the Post Office tomorrow in a PM.
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Old 25th October 2021, 04:18 PM   #337
rpafenberg is offline rpafenberg  United States
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Join Date: Feb 2004
Location: Washington DC
Preamp Control - Volume, input, mute, remote
John,

Finally got the new boards and the parts you were kind enough to remove from my main boards for me. Over the last few days I was able to put together three sets of boards and the cables for the initial digital board to display board test.

Unfortunately I am not getting success with any combination of boards. Powering it on results in a random number display on the volume LEDs (DS2-4) and no display on DS1.
Turning the rotary encoder does not result in any changes and pushing buttons has no results.

I am fairly sure on the cabling, although to get the "red wire" on the dot requires turning one of the connectors over before installing. If you try having the connectors on the same side of the wire, you can't get the red wires to align with the dots.

As I am reusing the LED displays, it appears that DS1 on all three display boards didn't survive the transfer as I would expect them to light even if with garbage.

I can't see any oblivious installation issues and I would expect the display board would start up at 0 even if it wasn't connected to the digital board. Is it possible that the eproms (U12) were not programed before you sent them out?

Regards,

Roy
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Old 25th October 2021, 10:34 PM   #338
johnhenryharris is offline johnhenryharris  United States
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Join Date: Nov 2012
Location: San Diego, CA
DS1 should light up so long as the Display board has power even without the ribbon cable connected. I can't imagine all three LEDs having a problem.

First check voltage and polarity is correct at the PS and each board.

The EEPROMs were programmed, if they were not it would light all the LED segments on all the digits.

First thing to check it that the two timer chips are running. U3 should be around 9 hz and U8 a couple hundred hertz. Then see that the output from the U8 timer to the flip-flop U11 output is toggling then the LED selects from U10 are changing, sequencing the LEDs.

Walk through the mute circuit so you can watch the LED toggle, the button should work.

Worst case, send me at least one set of boards and cables and I can troubleshoot. I have mine working in my preamp to compare with.
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Old Yesterday, 06:49 PM   #339
rpafenberg is offline rpafenberg  United States
diyAudio Member
 
Join Date: Feb 2004
Location: Washington DC
Preamp Control - Volume, input, mute, remote
John,

Good first advice. I built all boards at the same time from the same part order. It seems logical that if I made a mistake, that I made it to all three. Since all boards are acting the same, that would be my first assumption.

Voltage and polarity correctness was checked prior to connecting the boards and always rechecked before power was enabled. I am assuming that a problem exists, at least on the display board since I do not start up with "0" on the volume, but a random sequence.

While the input display LED does not light, what number should it show as a default? Also, think you were saying that the mute logic is contained on the display board, at least as far as the LED is concerned, so it should toggle on and off with the mute button? On my three boards the red mute light will come on for a while for varying lengths of time but doesn't stay on. I suspect that is because pin 15 of J2 is not connected to the digital board.

Before I refresh my Boolean logic knowledge I am going to double check my components one more time in great detail.

Regards,

Roy
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Old Yesterday, 07:00 PM   #340
johnhenryharris is offline johnhenryharris  United States
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Join Date: Nov 2012
Location: San Diego, CA
The input select should start at 0 but without the reset from the digital board it could show anything from 0-6. The analog board can be left off and only the display and digital boards with PS need be connected for troubleshooting.

My version 3 boards came right up the first time.
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