I purchased a 1701A from an estate sale a friend attended that was out of state. A pig in a poke situation, but the price seemed reasonable enough at 125.00 for a clean looking unit. From looking at a picture that was sent to me, the back serial number plate has options 03,04 and 05 installed into the box. I have no idea if the unit works or not. So first off, I am looking for the user/service manual for this unit. Any information in this matter would be greatly appreciated.
I believe the 1701A does have a self test setup and since I don't have the user manual as of yet, what is the procedure to get this self test started? Any other real problem areas with these units, such as bad optocouplers that usually go South in these units? Hopefully this unit is working, but as the old saying goes, prepare for the worst and hope for the best. Any help in this area is greatly appreciated.
I believe the 1701A does have a self test setup and since I don't have the user manual as of yet, what is the procedure to get this self test started? Any other real problem areas with these units, such as bad optocouplers that usually go South in these units? Hopefully this unit is working, but as the old saying goes, prepare for the worst and hope for the best. Any help in this area is greatly appreciated.
Your lucky Houstonvett manuals are expensive but I found a website with colored photos AND circuit diagrams --hope this helps ?
Sound Technology 1710a Distortion Analyzer
Even luckier I found the manual-
https://steampoweredradio.com/pdf/sound technology/sound technology model 1710a manual.pdf
Not bad unit if you got it for $125 (USA) predecessor to the one used by D.Self now .
Somewhat like the the HP 8903B I have although I built a JLH design that goes down to -100db or more.
Sound Technology 1710a Distortion Analyzer
Even luckier I found the manual-
https://steampoweredradio.com/pdf/sound technology/sound technology model 1710a manual.pdf
Not bad unit if you got it for $125 (USA) predecessor to the one used by D.Self now .
Somewhat like the the HP 8903B I have although I built a JLH design that goes down to -100db or more.
Your right blame it on old age I will try to make amends with a "real " 1701 manual.
I downloaded the manual anyway I like studying test equipment.
As its quite similar here is the 1700-
Model 1700B Distortion Measurement System - Sound Technology 1979 1700AB.pdf
I downloaded the manual anyway I like studying test equipment.
As its quite similar here is the 1700-
Model 1700B Distortion Measurement System - Sound Technology 1979 1700AB.pdf
Last edited:
I have had both and understand the confusion. Here is a link for detailed info: http://www.stancurtis.com/Soundtech/1701A Service Info ver1.pdf And more here: Stan Curtis, Engineer, Sound Technology instruments, download service manuals I think the big difference may be making some options standard. The 1700 had IM ALC etc as options and possibly the 1701 made them standard. I do really know what the differences are and lit is pretty rare. The circuits seem to be the same. They use TO99 opamps which are a pain but you can get adapter PCB's amd make adapters to use modern opamps.
Thanks Duncan2 and 1audio for your great replies and information links. Good stuff indeed.
That lad from across the Pond, Stan Curtis, was on the cutting edge back in the day to be sure. IIRC, the Leak TL-50 guru in the early 70s and probably still is.
1audio, your idea of using a separate PCB and newer Opamps, as a work around, if replacing some LDRs. The OEM LDR parts are getting mighty hard to find. Still not too bad considering the 1701A is 40 plus years old and it still can be repaired. I am sure the piece will need some TLC to get it back ship shape. I will be posting what works on the piece here in the very near future and sure do appreciate the help in getting this piece back up and running.
That lad from across the Pond, Stan Curtis, was on the cutting edge back in the day to be sure. IIRC, the Leak TL-50 guru in the early 70s and probably still is.
1audio, your idea of using a separate PCB and newer Opamps, as a work around, if replacing some LDRs. The OEM LDR parts are getting mighty hard to find. Still not too bad considering the 1701A is 40 plus years old and it still can be repaired. I am sure the piece will need some TLC to get it back ship shape. I will be posting what works on the piece here in the very near future and sure do appreciate the help in getting this piece back up and running.
I picked up the 1701A over the weekend and it is a clean looking unit. I am waiting for the manual to arrive, so I can read it, no matter how painful that endeavor might be. 
Never have used a distortion analyzer before, so any help from the group here is greatly appreciated.
Putting the juice to the box, it passed the smoke test and all lights seem to be working. The analyzer is seeing the oscillator, which is a very good thing. When switching the oscillator down to low distortion, a pretty loud click can be heard coming from inside the box. Happens every 4 seconds or so, but I am thinking that isn't normal. If it is a problem shouldn't be to hard to track down the noise and it will be a good starting point to get the box back up and running 100% again.
This box is way overkill for my needs, working on tube FM tuners and various other old HV tube sets. Looks well made and I sure don't need to learn where are all of the different functions sub menus are located on today's GIF test pieces. TIA
Never have used a distortion analyzer before, so any help from the group here is greatly appreciated. Putting the juice to the box, it passed the smoke test and all lights seem to be working. The analyzer is seeing the oscillator, which is a very good thing. When switching the oscillator down to low distortion, a pretty loud click can be heard coming from inside the box. Happens every 4 seconds or so, but I am thinking that isn't normal. If it is a problem shouldn't be to hard to track down the noise and it will be a good starting point to get the box back up and running 100% again.
This box is way overkill for my needs, working on tube FM tuners and various other old HV tube sets. Looks well made and I sure don't need to learn where are all of the different functions sub menus are located on today's GIF test pieces. TIA
The clicking is common is the ST analyzers. The oscillator has a relay that switches from fast settling to low distortion after a short period. I have not looked at that circuit in "forever". The relay is circled in red in the attached schematic. Once the oscillator has stabilized it switches. There is an adjustment but I hope there are instructions in the manual for adjusting it. Its possible the photocell has deteriorated and needs replacement. The silonex optocoupler would be the prefered option.
You can upgrade the opamps and get the distortion floor lower. You will need to make adapters to fit the TO99 to a dip footprint.
Enjoy.
You can upgrade the opamps and get the distortion floor lower. You will need to make adapters to fit the TO99 to a dip footprint.
Enjoy.
Attachments
Thanks for the schematic Demian, greatly appreciated. Still waiting on the manual and will then see if there is an adjustment for the oscillator when shifting over to low distortion mode. Probably the op amp is kaput and I will poke around in there tomorrow and see what I find. A simple LED check on the light side and I am thinking the resistance on the other side should be under 50 Ohms. (?)
You can upgrade the opamps and get the distortion floor lower. You will need to make adapters to fit the TO99 to a dip footprint.
Sounds like a great idea Demian, while in there refreshing the unit to begin with. IIRC, the U7 LDR is very ripe for failure in the oscillator circuit. When checking Mouser there are options for thru hole TO99 op amps, are these the units you are mentioning Demian? I am thinking they are as you can solder these right to the adapter PCB board and then have the male dip footprint adapters mounted to the other side of the board from the new TO99. Is there a PCB diagram available? TIA
You can upgrade the opamps and get the distortion floor lower. You will need to make adapters to fit the TO99 to a dip footprint.
Sounds like a great idea Demian, while in there refreshing the unit to begin with. IIRC, the U7 LDR is very ripe for failure in the oscillator circuit. When checking Mouser there are options for thru hole TO99 op amps, are these the units you are mentioning Demian? I am thinking they are as you can solder these right to the adapter PCB board and then have the male dip footprint adapters mounted to the other side of the board from the new TO99. Is there a PCB diagram available? TIA
You have it reversed. The PCB's are layed out for TO99 packages (this is vintage) but the best current opamps are available only in SOIC actually. You need an adapter with pins in the circular side to fit the sockets (fortunately it is socketed) and then mount the opamps on the dip side. Also I would suggest an LME49710 but all you can get now are fakes. So next adapter for soic to dip and get OPA 1611 or similar. John Curl had success with AD797 in his 1701 (shares a lot of circuitry).
If there is output from the oscillator then the OPAMP is ok. finding the appropriate Silonex LDR would be the next step and change all of them. I think there is some discussion on DIYaudio of which ones are the best match. That could take some searching. Here is something: Sound Technology 1700/1701 | Audiokarma Home Audio Stereo Discussion Forums
If there is output from the oscillator then the OPAMP is ok. finding the appropriate Silonex LDR would be the next step and change all of them. I think there is some discussion on DIYaudio of which ones are the best match. That could take some searching. Here is something: Sound Technology 1700/1701 | Audiokarma Home Audio Stereo Discussion Forums
Also I would suggest an LME49710 but all you can get now are fakes.
These 49710s must have been popular back in the day, as it looks like maybe Rochester is manufacturing the 49710s once again. Minimum order of 286 pieces might be a stumbling block, but will call up Rochester and see if I can buy a handful of pieces from them.
Rochester Electronics (en-US)
: Search for lme49710
Thanks for the link Demian. I will read it without a doubt.
These 49710s must have been popular back in the day, as it looks like maybe Rochester is manufacturing the 49710s once again. Minimum order of 286 pieces might be a stumbling block, but will call up Rochester and see if I can buy a handful of pieces from them.
Rochester Electronics (en-US)
: Search for lme49710
Thanks for the link Demian. I will read it without a doubt.
Again, not so simple. The LME series was created by National specifically for audio. When TI bought National they discontinued a lot of products they saw as redundant. The LME49710 was one of them. I'm not sure what Richardson is selling but the process was very specific and not easily duplicated. I got some China LME4971 parts and they had 20 dB higher noise than authentic parts. The OPA stuff from TI if you get it from an authorized distributor should be genuine. All the opamps in the box are singles and some of the best new opamps are duals.
Rochester helped start the anti counterfeiting effort in electronic parts here in the USA. If Rochester made the 49710s themselves, they should be the real deal. I will call them up Monday and find out. TIA
Rochester Electronics (en-US)
: Anti-Counterfeiting
Rochester Electronics (en-US)
: Anti-Counterfeiting
With all this talk of the LME49710 I thought it rung a bell , on looking at my old self built variable gain buffer I have two of those original chips installed.
I can certainly vouch for the quality of reproduction and they act like a "straight wire with gain " , no noise etc but I used the same earthing techniques and very short distances between components that I use on larger audio projects .
I can certainly vouch for the quality of reproduction and they act like a "straight wire with gain " , no noise etc but I used the same earthing techniques and very short distances between components that I use on larger audio projects .
Calling up Digi-Key, they do sell the Rochester LME49710s in their online marketplace. DK has the 49710s flagged as a new product in their data base. Rochester doesn't answer their phone, so I sent off an email to them, to find out if they actually do manufacturer new 49710s. Sure hate to buy 296 of them at 1 time to rehab the 1701A.
finding the appropriate Silonex LDR would be the next step and change all of them.
After checking thru various threads about the LDRs that are in the 1701A, it looks like substitutes are still available for these failure prone pieces. The Clairex 6000 looks like it is still available from Little Bear electronics. These substitutes work better in the analyzer side of the box. The Perkins and Elmer VTL5Cs supposedly work better on the oscillator side of the unit. Any ideas as to why?
The VTL5Cs are popular with the guitar crowd and they have exhausted the old manufactured NOS supply for the most part. CoolAudio is making the pieces once again, but I know nothing about this manufacturer, or the quality of it's end products. It seems like CoolAudio is filling a niche market of discontinued audio parts and producing them once again. I sure don't mind paying 9.00 for a part, that use to cost less then a dollar back in the day. Especially if it helps the 1701A work correctly here in 2020.
Photocoupler Clairex CLM6000 O.S. - Small Bear Electronics
Coolaudio Semiconductors - COOLAUDIO International Ltd
After checking thru various threads about the LDRs that are in the 1701A, it looks like substitutes are still available for these failure prone pieces. The Clairex 6000 looks like it is still available from Little Bear electronics. These substitutes work better in the analyzer side of the box. The Perkins and Elmer VTL5Cs supposedly work better on the oscillator side of the unit. Any ideas as to why?
The VTL5Cs are popular with the guitar crowd and they have exhausted the old manufactured NOS supply for the most part. CoolAudio is making the pieces once again, but I know nothing about this manufacturer, or the quality of it's end products. It seems like CoolAudio is filling a niche market of discontinued audio parts and producing them once again. I sure don't mind paying 9.00 for a part, that use to cost less then a dollar back in the day. Especially if it helps the 1701A work correctly here in 2020.
Photocoupler Clairex CLM6000 O.S. - Small Bear Electronics
Coolaudio Semiconductors - COOLAUDIO International Ltd
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.