Best LDR for Sound Technology ST 17xx gear

jblmar · 05:32 PM

Since there is little mentioned on the 'net re Sound Technology gear, perhaps it would be a good idea for those who have successfully repaired their gear to list the LDRs used along with any mods they have made to the circuit(s). Both in the Oscillator & Analyzer sections.
As a folllow up, they can comment on their findings. In addition, it would be helpful to establish a listing of results using different LDRs in different locations on the analyzer board.
ANALYZER BOARD
U205
U206
U207
U208

U7 (OSCILLATOR board)

The 17xx models share similar LDR circuits.

1audio · 27th June 2010, 11:23 PM

This is copied from another reply by me. I'm adding it here so I can find it myself later:
When it switches from fast to low distortion it engages the LDR. Those are the real weak point in the analyzer (aside from the many switches). ST didn't reveal the actual part number. The original vendor doesn't exist. Vactec does : Welcome | PerkinElmer so if we can figure out which part it was we can cross check- Silonex Inc.: Products: Audiohm Optocouplers . My schematic shows a CL614m note next to the part. That seems to lead to a black hole. I have a very foggy memory of 200 Ohms on resistance. The coupler has a 10K parallel resistance so that may be a real target value. I believe a VTL5C10 will work as a replacement so the Audiohm http://www.silonex.com/datasheets/sp...pdf/103465.pdf NSL-32B-101 might be a good replacement.

jblmar · 1st July 2010, 02:10 PM

The Silonex NSL-32 seems to be a good starting point.

18th June 2010, 05:24 PM	#1
jblmar diyAudio Member Join Date: Dec 2005 Location: Brooklyn, New York	Best LDR for Sound Technology ST 17xx gear Since there is little mentioned on the 'net re Sound Technology gear, perhaps it would be a good idea for those who have successfully repaired their gear to list the LDRs used along with any mods they have made to the circuit(s). Both in the Oscillator & Analyzer sections. As a folllow up, they can comment on their findings. In addition, it would be helpful to establish a listing of results using different LDRs in different locations on the analyzer board. ANALYZER BOARD U205 U206 U207 U208 U7 (OSCILLATOR board) The 17xx models share similar LDR circuits. Last edited by jblmar; 18th June 2010 at 05:32 PM.

27th June 2010, 11:23 PM	#2
1audio diyAudio Member Join Date: Mar 2004 Location: SF Bay Area	LDR sources This is copied from another reply by me. I'm adding it here so I can find it myself later: When it switches from fast to low distortion it engages the LDR. Those are the real weak point in the analyzer (aside from the many switches). ST didn't reveal the actual part number. The original vendor doesn't exist. Vactec does : Welcome \| PerkinElmer so if we can figure out which part it was we can cross check- Silonex Inc.: Products: Audiohm Optocouplers . My schematic shows a CL614m note next to the part. That seems to lead to a black hole. I have a very foggy memory of 200 Ohms on resistance. The coupler has a 10K parallel resistance so that may be a real target value. I believe a VTL5C10 will work as a replacement so the Audiohm http://www.silonex.com/datasheets/sp...pdf/103465.pdf NSL-32B-101 might be a good replacement. __________________ Demian Martin Product Design Services

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1st July 2010, 02:10 PM	#3
jblmar diyAudio Member Join Date: Dec 2005 Location: Brooklyn, New York	The Silonex NSL-32 seems to be a good starting point.

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