Picked up a ShibaSoku AM70A 2CH Audio Analyzer for a good price (I thought). It powers on and the oscillator works (verified signal on scope) but when I route it's output to it's input (either channel) it doesn't read anything. There is also no signal from the monitor output.
Tried searching for service manual and operator's manual but haven't turned up anything yet.
Unit seems like a nice piece of equipment if I can get it back to working condition.
Opened it up and took out all the boards and did a visual inspection. Nothing obvious found. Probed around on power supply voltages that I could see/reach and nothing seems out of the ordinary.
Anyone have any ideas where to start?
Tried searching for service manual and operator's manual but haven't turned up anything yet.
Unit seems like a nice piece of equipment if I can get it back to working condition.
Opened it up and took out all the boards and did a visual inspection. Nothing obvious found. Probed around on power supply voltages that I could see/reach and nothing seems out of the ordinary.
Anyone have any ideas where to start?
After a full day of poking around and checking things I managed to get the unit back up and operational (flying blind with no service manual or schematics). I noticed that the +5VDC rail for the digital logic was reading 0.86VDC on the A1 and A2 input cards. Tracing it back to the power supply it appeared that the LT regulator was faulty (though I had a hard time believing it as they are really rugged - especially this large package one at 5A capability). I started disassembling the unit to get access to the power supply (since the LT +5VDC reg was located on the bottom of the power supply heat sink and was inaccessible - always happens right?).
Problem ended up being a pushed pin on one of the power connectors on the power supply (was a 2 pin one). Noticed that the plastic housing was discolored as if it was subjected to excessive heat but there was no heat source close enough to it. As I usually do I gently tugged on the wires in the connector and one of them pulled out with little to no force. There was the source of the heat - hjgh resistance connection. This wire was the AC supply from the main transformer to one of the bridge rectifiers that supplied the +5VDC. Bent the pins on the connector so that it would engage the housing and reseated the wire. Fired the unit up and everything appears to be working correctly!
Still would like to locate the service manual and operator's manual for the unit. I would like to perform the verification procedure to ensure there are no other problems with the unit.
Problem ended up being a pushed pin on one of the power connectors on the power supply (was a 2 pin one). Noticed that the plastic housing was discolored as if it was subjected to excessive heat but there was no heat source close enough to it. As I usually do I gently tugged on the wires in the connector and one of them pulled out with little to no force. There was the source of the heat - hjgh resistance connection. This wire was the AC supply from the main transformer to one of the bridge rectifiers that supplied the +5VDC. Bent the pins on the connector so that it would engage the housing and reseated the wire. Fired the unit up and everything appears to be working correctly!
Still would like to locate the service manual and operator's manual for the unit. I would like to perform the verification procedure to ensure there are no other problems with the unit.
Contacted who is now supporting the AM70A and they replied with the following:
Thank you for your contact via website.
We are ASACA CORPORATION.
We have taking over the ShibaSoku measurement products business.
We have not prepared service manual for customers.
AM70A has already ended customer support.
The only support we can do about AM70A is the provision of the instruction manual.
Please find the attached AM70A instruction manual.
*For your information, we have a successor products AM50C.
Please find the attached AM50C catalog.
Our dealer in US is Leader Instruments Corporation.
Please refer to the following,
-----------------------------------------------------
Leader Instruments Corporation.
2125 Center Avenue, Suite 407, Fort Lee, NJ 07024 USA
PHONE:1-201-355-4850
URL Leader Electronics Corporation
-----------------------------------------------------
If you have any questions please free contact to us.
That is disheartening. Well at least they provided the operator's manual.
Thank you for your contact via website.
We are ASACA CORPORATION.
We have taking over the ShibaSoku measurement products business.
We have not prepared service manual for customers.
AM70A has already ended customer support.
The only support we can do about AM70A is the provision of the instruction manual.
Please find the attached AM70A instruction manual.
*For your information, we have a successor products AM50C.
Please find the attached AM50C catalog.
Our dealer in US is Leader Instruments Corporation.
Please refer to the following,
-----------------------------------------------------
Leader Instruments Corporation.
2125 Center Avenue, Suite 407, Fort Lee, NJ 07024 USA
PHONE:1-201-355-4850
URL Leader Electronics Corporation
-----------------------------------------------------
If you have any questions please free contact to us.
That is disheartening. Well at least they provided the operator's manual.
Congratulations, you got further that I ever did on getting info from them.
I think the AM70 shares a lot in design and implementation with the 725D. PM me your e-mail and I'll send you all the accumulated data on that beast which could be useful.
I would also be interested in getting an AM70 but I'm really cheap.I'm waiting for one to float by for $300 or so. It will be a long wait.
It seems the replacement product dropped the IM distortion measurement.
I think the AM70 shares a lot in design and implementation with the 725D. PM me your e-mail and I'll send you all the accumulated data on that beast which could be useful.
I would also be interested in getting an AM70 but I'm really cheap.I'm waiting for one to float by for $300 or so. It will be a long wait.
It seems the replacement product dropped the IM distortion measurement.
TheDarkWraith,
Can you post pictures of it, boards etc?
This might be and interesting find.
I've got the ShibaSoku 725D
and missed getting a 725C.
Demian,
Didn't you snag one of those All in one ShibaSoku's as well?
You know, of you don't buy anything for a few months you can
add those months together and get something more, example follows:
Assume $300 monthly limit
add months 1+2+3 = $300 +$300 +$300 = $900.
Assume $300 annual limit
year 1 + year 2 = $300 + $300 = $600.
The Financial Hack (youtube):
Use credit card, gift card etc.
Source the change jar, from buying
grocery, gas, liquor store, pan handling,
must use cash all the time.
Collect the change and store in an unobvious
jar/vase etc.
Create false bottom so you can water the plant
but the money won't get wet.
Lift plant and false bottom out together and
collect change.
Combine change from your sources hidding in
Books, tools, plugins, software boxes, shipping
containers, frozen food boxes, unscrew pencil holder's,
lift the toilets water tank lid, et.al.
Pour change into one of those
machines at grocery store to receive erout and
Buy the meter, gauge, analyzer, scope, electronic device,
etc and make sure you are home for delivery or have it
delivered to another residence and pick it up when the
dragon isn't home.
Then place the new device backwards and intermingle it
with all the collection pieces that you have so it won't be
noticed.
Cheers,
Post Scrip - I disavow any knowledge of the above.
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Here is an update- My AM70A is all working and seems to meet specs etc. Some numbers-
Loopback distortion at 2V 1KHz (best result) .00037 or -108.5 dB w/ 30 KHz filter engaged. The distortion product is 2nd harmonic with almost no trace of higher harmonics.
20 KHz loopback 80 KHz band .004% and no filter .010%
I think all of these and the analysis measurements are noise limited.
IM floor seems to be n.002% which seems odd. Should be much better i think)
Oscillator flatness at 1V is better than .03 dB from 10Hz to 100KHz
Analyzer flat to 100 KHz but seems to roll off.3 dB at 10 Hz.
Noise floor- Ch a 1.8 uV ch b 3.5 uV The 30 KHz filter (whioch doesn't seem to affect ch B)
Here is a comparison between the AM70A and the AD725C:
AM70A
pro-
oscillator contained in it. Oscillator measures down to -115 dB THD+N on the 725!!
digital readouts for all measurements
includes IM distortion
many built in filter options (more that I can see having utility)
Con
no reconstruction of the distortion components (this is where DiAna becomes important)
Noise floor seems significantly higher than the 725C that has been modified.
Oscillator is open loop and tuning/level steps are coarser than I would like.
I have not found a way to shut off the oscillator output.
I have not found a way to do SNR measurement.
AD725D
Older design fewer filter options
No oscillator
A little clunkier in operation
Pro
distortion waveform reconstruction
My next steps are some maintenance (it seems to have warm up issues and some intermittent noise issues) and to explore some key component upgrades as Davida's work on the AD725D show will benefit. This is a newer design and should incorporate any of the "fixes" patched into the older instruments.
I already designed and sent for fab a PCB to fit the optional filter slot to provide outputs on the back for both the monitor and to have a reference of the input since that is also routed through the filter slot. More when the boards arrive (2 weeks).
I will also get extender board (details soon) so I can explore the mods/upgrades. And I need to get my Quantech running with chip adapter boards so I can select parts for this. A separate project.
Loopback distortion at 2V 1KHz (best result) .00037 or -108.5 dB w/ 30 KHz filter engaged. The distortion product is 2nd harmonic with almost no trace of higher harmonics.
20 KHz loopback 80 KHz band .004% and no filter .010%
I think all of these and the analysis measurements are noise limited.
IM floor seems to be n.002% which seems odd. Should be much better i think)
Oscillator flatness at 1V is better than .03 dB from 10Hz to 100KHz
Analyzer flat to 100 KHz but seems to roll off.3 dB at 10 Hz.
Noise floor- Ch a 1.8 uV ch b 3.5 uV The 30 KHz filter (whioch doesn't seem to affect ch B)
Here is a comparison between the AM70A and the AD725C:
AM70A
pro-
oscillator contained in it. Oscillator measures down to -115 dB THD+N on the 725!!
digital readouts for all measurements
includes IM distortion
many built in filter options (more that I can see having utility)
Con
no reconstruction of the distortion components (this is where DiAna becomes important)
Noise floor seems significantly higher than the 725C that has been modified.
Oscillator is open loop and tuning/level steps are coarser than I would like.
I have not found a way to shut off the oscillator output.
I have not found a way to do SNR measurement.
AD725D
Older design fewer filter options
No oscillator
A little clunkier in operation
Pro
distortion waveform reconstruction
My next steps are some maintenance (it seems to have warm up issues and some intermittent noise issues) and to explore some key component upgrades as Davida's work on the AD725D show will benefit. This is a newer design and should incorporate any of the "fixes" patched into the older instruments.
I already designed and sent for fab a PCB to fit the optional filter slot to provide outputs on the back for both the monitor and to have a reference of the input since that is also routed through the filter slot. More when the boards arrive (2 weeks).
I will also get extender board (details soon) so I can explore the mods/upgrades. And I need to get my Quantech running with chip adapter boards so I can select parts for this. A separate project.
That is good Demian what maintenance are you thinking about?
Also when on do you have fan noise rubbing?
Does your ch 2/B always seem to be on for some reason?
I was wondering if mine defaulted to that, internally or something.
let me see if I can find the sheet I wrote my measurements down on.
I filed it, then re arranged, so now they are hidden somewhere.
Cheers,
Also when on do you have fan noise rubbing?
Does your ch 2/B always seem to be on for some reason?
I was wondering if mine defaulted to that, internally or something.
let me see if I can find the sheet I wrote my measurements down on.
I filed it, then re arranged, so now they are hidden somewhere.
Cheers,
AM70A next steps:
1) check notch filter alignment
2) Run through the calibration tests and confirm
3) Check the oscillator for frequency and level
4) replace the critical opamps around BEF1 that limit the overall performance
6) rework my GPIB program to run the system through a set of standard tests.
These are waiting for the extender boards and the internal connection boards. I also need to finish the adapters and adjustments for my QuanTech 5173 so i can select opamps for the AM70A.
1) check notch filter alignment
2) Run through the calibration tests and confirm
3) Check the oscillator for frequency and level
4) replace the critical opamps around BEF1 that limit the overall performance
6) rework my GPIB program to run the system through a set of standard tests.
These are waiting for the extender boards and the internal connection boards. I also need to finish the adapters and adjustments for my QuanTech 5173 so i can select opamps for the AM70A.
AM70A:
3.0V RMS out = -118.5db, THD Anaylsis, noise(?) -104db.
1.0 V RMS out = -118.5db, THD Analysis, noise -104db.
.300VRMS out = -116.0db THD Analysis, noise -96.5db.
.100V RMS out = -98.0db THD Analysis, noise, 87.5db.
.030V RMS out = unstable.
Second check, 1.000V RMS = -118db, noise -99.5db
1.0V 1kHz out = -117db, noise 99.5.
Those were from my notes. Now I need to recall
How I configured with the shibasoku 725D,
I'm not sure how to get just a standard noise floor
measurement with it. I don't have an operational
FFT to view the spectrum either.
However, I do have some jibberish with the filters
and analysis of the harmonics that couldn't be measured
on the 725D. That is when 2H,3H,4H,5H were engaged,
the meters, needle went to full left. Even with the +10dB
button pressed it couldn't be read.
Do you know if the AM70A has two oscillators?, one for each channel?
I'll go run the numbers in the AM70 in loop back mode and see what
I get on the AM70A.
Some if the filter options had to do with Euro/Asia Broadcast requirements, I think.
I'll have to look. and yes, there was one screwy filter in the group too.
PS - Save a set of each board for me please.
3.0V RMS out = -118.5db, THD Anaylsis, noise(?) -104db.
1.0 V RMS out = -118.5db, THD Analysis, noise -104db.
.300VRMS out = -116.0db THD Analysis, noise -96.5db.
.100V RMS out = -98.0db THD Analysis, noise, 87.5db.
.030V RMS out = unstable.
Second check, 1.000V RMS = -118db, noise -99.5db
1.0V 1kHz out = -117db, noise 99.5.
Those were from my notes. Now I need to recall
How I configured with the shibasoku 725D,
I'm not sure how to get just a standard noise floor
measurement with it. I don't have an operational
FFT to view the spectrum either.
However, I do have some jibberish with the filters
and analysis of the harmonics that couldn't be measured
on the 725D. That is when 2H,3H,4H,5H were engaged,
the meters, needle went to full left. Even with the +10dB
button pressed it couldn't be read.
Do you know if the AM70A has two oscillators?, one for each channel?
I'll go run the numbers in the AM70 in loop back mode and see what
I get on the AM70A.
Some if the filter options had to do with Euro/Asia Broadcast requirements, I think.
I'll have to look. and yes, there was one screwy filter in the group too.
PS - Save a set of each board for me please.
Last edited:
I believe your numbers are consistent with mine.
The AM70A has a single oscillator (except in IM mode) and separate drivers/attenuators for each channel. It also has some odd limitations in ch 2 measurements. The Oscillator is good for -115 dB THD+N on the tweaked 725D.
I'm partway there on my Quantech. Its all functioning but now I need to dive into calibration stuff. I have the quantech noise generator but i need to verify it and it seems I may need to make a special cable so not out of the woods yet. (and bipolar transistors oscillate in my kludged test fixture.)
The AM70A has a single oscillator (except in IM mode) and separate drivers/attenuators for each channel. It also has some odd limitations in ch 2 measurements. The Oscillator is good for -115 dB THD+N on the tweaked 725D.
I'm partway there on my Quantech. Its all functioning but now I need to dive into calibration stuff. I have the quantech noise generator but i need to verify it and it seems I may need to make a special cable so not out of the woods yet. (and bipolar transistors oscillate in my kludged test fixture.)
Hi Damien
I was wondering whether you are designing ( or PCB part ) for this extender? I need an Extender fabricated for Yamaha B1 - having a Cinch socket with 0.156 inch spacing - 28 pin on each side. Is there an easy way to adapt existing one or do a pcb design - for getting it fabricated ?
thanks
kannan
Edge connectors are a PITA but they can be created in the PC layout systems. They seem to be one of the more challenging items however since they are not distinct parts. I started with Kicad but found it too slow and clumsy to add parts so I tried Easyeda. For a simple one off project it worked pretty well and the close integration with a PCB vendor made it all pretty painless. I would not attempt a major multilayer project with either. I would turn to someone who does this stuff for a living but extender boards are pretty trivial.
Somehow i can't find your message. I have not yet received the first pass on the PCB's i ordered. Shipping seems to be around 1 month from JLPCB.
If you can find one on eBay that would work you will be way ahead. There may be some HP extendered that would work. Making extendereds is a pain especially since the edge connectors are roll your own today. The few in the systems are never the right ones and creating them is not easy.
If you can find one on eBay that would work you will be way ahead. There may be some HP extendered that would work. Making extendereds is a pain especially since the edge connectors are roll your own today. The few in the systems are never the right ones and creating them is not easy.
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