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Vintage Test Gear and Workshop Equipment For discussions about vintage test gear and workshop equipment such as coil winders. |
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8th Jun 2018, 3:50 pm | #1 |
Dekatron
Join Date: Jun 2015
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AIM/Racal LCR Databridges
This follows on from a thread in the 'stuff wanted' section, concerning making an adapter for the Racal Databridge.
Some years ago I was given one of these instruments, non-working and with no accessories. Mine is badged 'AIM Databridge' and doesn't have the IEEE488 interface (it's described as an option in the manual) but is clearly much the same instrument. The real reason it didn't work was poor conenctions at the EPROM sockets inside (the unit is controlled by a Z80 microprocessor) which were easily cured by replacing the sockets with turned-pin types. Alas The Phantom / M0RON had got there first and replaced 74C906 and 74C907 ICs (logic level shifters) with 74C90 counters (!). Getting replacements for those was interesting (and annoying as I'll wager the originals were not defective, they just didn't test as 74C90 counters!), I think I had to make a bodge up for one of them. It now works fine apart from one missing display segment (I forget if it's the display or the driver IC that's failed, but the instrument is useable without it). One thing I did get with mine was the circuit diagram. This does not seem to be available on-line anywhere (I am sure it is not 'up top', so I don't think I am breaking any rules by saying this). It's a fairly poor copy, but a lot better than nothing. If anyone wants it I will be happy to get it to them. I'd be interested in hearing how others get on with making up the adapters, as I might have a go myself... The user manual I have does mention using a scrap of double-sided copper-clad board in the right-hand component connector to connect to an external PSU to apply a bias voltage (up to 50V) to a capacitor under test. |
8th Jun 2018, 6:56 pm | #2 |
Heptode
Join Date: Jun 2009
Location: St Helens, Lancashire, UK.
Posts: 641
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Re: AIM/Racal LCR Databridges
Tony
I have two Racal Databridges, one with a full set of accessories if you need any pictures or other information. I also have a full service manual for the Racal 9341, which the schematics are from AIM, but no designation as to which AIM model. I have the user manual for the 9343M If any of these are of use to you let me know and I will scan them for you.
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8th Jun 2018, 7:06 pm | #3 |
Dekatron
Join Date: Jun 2015
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Re: AIM/Racal LCR Databridges
I am pretty sure the AIM and Racal units are much the same internally, I think they carried other manufacturer's names too. I am not sure what the different models are, though.
I found the Racal 9343 user manual on-line, but not the service manual. Does the latter contain any useful information other than the schematics (which I have)? I have some basic troubleshooting information in the AIM user manual, but it's really just checking power supplies and clocks, and a few analogue signals. |
8th Jun 2018, 7:18 pm | #4 |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
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Re: AIM/Racal LCR Databridges
Can you test power transformers and chokes with these bridges? I have a Marconi TF2700 but without the power tfmr test jig, so testing these is pretty much impossible. They look like good bridges.
Andy.
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8th Jun 2018, 7:31 pm | #5 |
Dekatron
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Re: AIM/Racal LCR Databridges
Strictly it's not a bridge, at least not electrically. It measures the in-phase and quadrature components of the connected impedance (at either 100Hz or 1kHz) and calculates the resistance and capacitance/inductance from that. But it does the same job as a traditional AC bridge, so I guess the name stuck.
It'll measure inductance up to some quite high value. But it will not measure mutual inductance (maybe needed for some transformer tests) and it will not measure inductance (AFAIK) with some DC current flowing to check the core material performance. What does the power transformer testing jig do for your Marconi instrument? |
9th Jun 2018, 9:36 am | #6 |
Heptode
Join Date: Apr 2003
Location: Ayr, Ayrshire, UK.
Posts: 630
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Re: AIM/Racal LCR Databridges
I have one of these - it's an AIM LCR Databridge 401 and I would be very interested to get a copy of any user manuals/circuit diagrams.
Andy |
9th Jun 2018, 11:14 am | #7 |
Moderator
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Re: AIM/Racal LCR Databridges
Thanks for the diagram, Tony. There really doesn't seem to be one anywhere else.
David
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9th Jun 2018, 12:31 pm | #8 | |
Heptode
Join Date: Jun 2009
Location: St Helens, Lancashire, UK.
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Re: AIM/Racal LCR Databridges
Quote:
Circuit descriptions, calibrations, fault-finding tree, parts list, schematics. Same as any other Racal maintenance manual. What schematic drawing numbers do you have? I do not have any schematics for the 9343 in my collection. Just for information, I collect Racal manuals, then scan and upload to KO4BB I keep a list of Racal manuals I own on the Racal_Dana user group on Yahoo and on my website http://www.g0rsq.co.uk/manuals.htm (along with many other manuals) if anyone is looking for something particular that is not already on KO4BB.
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9th Jun 2018, 1:24 pm | #9 |
Heptode
Join Date: Apr 2003
Location: Ayr, Ayrshire, UK.
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Re: AIM/Racal LCR Databridges
Thanks for that information - I managed to download the service manual from KO4BB for the Racal-Dana 9341 which, from the information in it, looks to be the same as the Aim 401 I've got.
Andy |
9th Jun 2018, 1:42 pm | #10 |
Dekatron
Join Date: Jun 2015
Location: Biggin Hill, London, UK.
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Re: AIM/Racal LCR Databridges
Thanks, I've downloaded the service manual too. It's almost identical to the manual that came with my AIM databridge.
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10th Jun 2018, 1:15 pm | #11 | |
Dekatron
Join Date: Jul 2009
Location: Sleaford, Lincs. UK.
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Re: AIM/Racal LCR Databridges
Quote:
Andy.
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