AOIP CMU 310 / CMU EX - Page 1
Forum section: electronics / general

author: RikV
author_rank: Regular Contributor
timestamp: September 18, 2025, 12:30:59 pm
content: Just got one of these: not working, no battery.I am unable to find any schematics of this. Can anyone give a hint as to where they are available?Could someone give me some information about the battery? Voltage? capacity? Chemistry?Any kind of information is more than welcome.I found that the original battery probably is a NiCd-7.2V-1.8Ah. Could this be confirmed?

author: 2N3055
author_rank: Super Contributor
timestamp: September 18, 2025, 03:29:22 pm
content: Quote from: RikV on September 18, 2025, 12:30:59 pmIt does say Ni-Cd on a photo... Datasheet for the device also states so clearly.Voltage per cell is 1,2V then which seems right.NiMh are possible replacement.

author: RikV
author_rank: Regular Contributor
timestamp: September 18, 2025, 03:53:21 pm
content: 2N3055, do you have any relevant information in PDF format? Besides what battery it should be, it is also unclear where to connect it: there are no pin headers whatsoever nor any text on the PCB.

author: 2N3055
author_rank: Super Contributor
timestamp: September 18, 2025, 04:47:55 pm
content: I have this..

author: RikV
author_rank: Regular Contributor
timestamp: September 18, 2025, 06:08:28 pm
content: OK. Thanks. AOIP seems not too popular.... This might be a wrong buy.

author: picburner
author_rank: Frequent Contributor
timestamp: September 18, 2025, 06:26:24 pm
content: Quote from: RikV on September 18, 2025, 03:53:21 pmCould you take a picture of the pcb? Besides satisfying my curiosity, maybe someone can see the plugs you can't find.

author: RikV
author_rank: Regular Contributor
timestamp: September 18, 2025, 07:26:50 pm
content: The 3pin header visible on the left side has all of its pins connected to the bottom (shield) layer of the PCB. Note the 3 solder-filled through holes under the 1A fuse. I thought these were the connections to the batt pack. One is connected to the Adapter +, One is the adapter - and the third is only connected to the left side of the fuse.

author: Overspeed
author_rank: Frequent Contributor
timestamp: September 18, 2025, 08:07:10 pm
content: Quote from: RikV on September 18, 2025, 06:08:28 pmHelloAOIP is a quite good brand I have several of them , calibrator , data acquisition systems, standrd resistors , the problem with AOIP is the ....technical support / serviceRegardsOS

author: 2N3055
author_rank: Super Contributor
timestamp: September 18, 2025, 08:15:42 pm
content: Quote from: Overspeed on September 18, 2025, 08:07:10 pmYes,dealing with them was... different...But 2 AOIP devices I have are working fine for me.

author: Overspeed
author_rank: Frequent Contributor
timestamp: September 18, 2025, 08:31:53 pm
content: HelloAll my AOIP works fine , you need to know as during years the first customer of AOPI was .. the french Gov so they are not very easy with private compagnies or individuals .I have just purchased this week some AOIP standard resistors , nice catch , cheap and in very good shape up to NIB .RegardsOS

author: RikV
author_rank: Regular Contributor
timestamp: September 18, 2025, 10:46:08 pm
content: No doubt AOIP is a prime brand. The build quality of the instrument in front of me is outstanding. Whan I say "they are not popular", I mean there is not much information on forra like eevBlog, there is almost no documentation around... I really would like to fix this instrument but given thr information available I'm afraid it will turn out to be a disappointment.

author: picburner
author_rank: Frequent Contributor
timestamp: September 20, 2025, 10:53:19 am
content: Your only help is the datasheets for the components used in the circuit. Using them, you can reconstruct the schematic of the instrument's power supply section and thus find where the battery should be connected.I imagine there are components on the other side of the PCB as well.

author: RikV
author_rank: Regular Contributor
timestamp: September 20, 2025, 04:09:56 pm
content: Well, already a couple of days ago I started collecting these datasheets. Have most of them except for a SOT123 and a SOT323. The bottom side only contains the firmware EPROM. But reverse eng won't be easy as this is a 4-layer board AND the bottom side is one big copper surface. My old X-ray eyes cannot look through.The missing Datasheet is "PH91 52-10A" . OH yes, there is also an unknown SO8: "51A 2CEUA" and a SOT323 marked "E2 / DT".As next step I will make a pic and printout to have a component layout and then start tracing starting at the adapter connector...

author: Overspeed
author_rank: Frequent Contributor
timestamp: September 20, 2025, 06:04:12 pm
content: Quote from: RikV on September 18, 2025, 10:46:08 pmHelloAOPI service manual exists I have some of them , I try to loacte the CMU310 in France if that possibleRegardsOS

author: RikV
author_rank: Regular Contributor
timestamp: September 20, 2025, 06:50:08 pm
content: Please, do!!

author: RikV
author_rank: Regular Contributor
timestamp: October 09, 2025, 06:14:43 pm
content: I found a bunrt spot near the ON/OFF transistor and a missing component, presumably a diode to choose between adapter or battery supply. I am afraid some of the internal tracks are burnt...Could someon who has such a device check for continuity of the "adapter" ground with the "digital ground? It looks like the 5V VCC is produced by an oscillator around ad HEF4011, but no way to get it running...Really need a schematic to exclude all anomalies.

author: Overspeed
author_rank: Frequent Contributor
timestamp: October 11, 2025, 09:29:02 am
content: HelloI will perhaps received a pdf of the manual next week I will put it on this forumRegardsOS

author: RikV
author_rank: Regular Contributor
timestamp: October 11, 2025, 09:34:21 am
content: Many thanks in advance for the effort.