Hello Matt,
I might need some chips I will let you know
thanks
I might need some chips I will let you know
thanks
Apogee AD8000 DA converter chip
- Thread starter mata_haze
- Start date
Help Support GroupDIY Audio Forum:
Obsoletemachines
Member
are there variations
AD8000SE is said to be
AK5391 (AKM) for ADC (AK5392 was issued later for general release); and
AD1851 DAC
AD8000SE is said to be
AK5391 (AKM) for ADC (AK5392 was issued later for general release); and
AD1851 DAC
Obsoletemachines
Member
fixed an AD8000 showing clipping, overloaded, LEDS into Ch1 without any signal present.
15+ rail failed on that side of the AK5391 ADC. Opamps were all ok. It turned out five tantalum 10uf/20v had gone short and taken out a trace. Without a schematic and the PCB being black it is difficult to work out what goes to where but i figured it out by removing components and probing and found the broken trace. Replaced all five tantalums because when i re-engaged the 15+ rail (by fixing the aforementioned trace) they began smoking - all five were bad.
Speculate that failure mode began with one of the five tantalums getting damaged, it probably was from a bad batch and this in turn caused the others to fail short and eventually burn out the supply from the 15+ rail for Ch1. Note all other channels were uneffected, there is good redundancy in the circuit design, as you might expect at this level.
Note there is no datasheet for AK5391 but there is one for the AK5392 which was the 'general release'. Suspect AK5391 was made with Apogee for Apogee, so they could take the lead on 24bit/48khz. The AK5392 datasheet shows that the differences in 'pin out' relate to VREF and a select pin for 20/24bit mode.
The front panel was designed by Bob Clearmountain and I expect he had a hand in getting this unit to sound so good.
15+ rail failed on that side of the AK5391 ADC. Opamps were all ok. It turned out five tantalum 10uf/20v had gone short and taken out a trace. Without a schematic and the PCB being black it is difficult to work out what goes to where but i figured it out by removing components and probing and found the broken trace. Replaced all five tantalums because when i re-engaged the 15+ rail (by fixing the aforementioned trace) they began smoking - all five were bad.
Speculate that failure mode began with one of the five tantalums getting damaged, it probably was from a bad batch and this in turn caused the others to fail short and eventually burn out the supply from the 15+ rail for Ch1. Note all other channels were uneffected, there is good redundancy in the circuit design, as you might expect at this level.
Note there is no datasheet for AK5391 but there is one for the AK5392 which was the 'general release'. Suspect AK5391 was made with Apogee for Apogee, so they could take the lead on 24bit/48khz. The AK5392 datasheet shows that the differences in 'pin out' relate to VREF and a select pin for 20/24bit mode.
The front panel was designed by Bob Clearmountain and I expect he had a hand in getting this unit to sound so good.
blue_luke
Well-known member
Tantalum are so much prone to problems! 
Here is my two CDN cents...
Never use a tantalum below 35 volt rating and if possible, due to cost / space constraint, try to use a rating at least 20 volt over the actual voltage being filtered or decoupled...
I earned that trick from an engineer when I was working at a service center for AIWA in Montreal and MOST of the problemes we had on the portable 'walkman' type af recorder and the boom boxws were due to tantalums being to close and quite intolerant of rated and used voltages.
Here is my two CDN cents...
Never use a tantalum below 35 volt rating and if possible, due to cost / space constraint, try to use a rating at least 20 volt over the actual voltage being filtered or decoupled...
I earned that trick from an engineer when I was working at a service center for AIWA in Montreal and MOST of the problemes we had on the portable 'walkman' type af recorder and the boom boxws were due to tantalums being to close and quite intolerant of rated and used voltages.
Obsoletemachines
Member
Tantalum are so much prone to problems!
- myth
Tantalums are still in use today. Low ESR, will last longer than wet-electrolytic as long as they are not exposed to ripple upstream.
The issue with tantalums is that they fail catastrophically.
- myth
Tantalums are still in use today. Low ESR, will last longer than wet-electrolytic as long as they are not exposed to ripple upstream.
The issue with tantalums is that they fail catastrophically.
