WTB: Keithley TR-299B transformer for model 2000 multimeter - Page 1
Forum section: electronics / general

author: atsthng
author_rank: Contributor
timestamp: June 26, 2014, 04:11:41 pm
content: As per the subject: I'm looking for a replacement transformer (TR299B) for a Keithley model 2000 multimeter. Used is fine as long as it it works. Please let me know what the revision number is if you have one to offer.Thanks.

author: KJDS
author_rank: Super Contributor
timestamp: June 26, 2014, 04:39:40 pm
content: Is it also used in the 2015THD? if so then I should have one.A picture of it will help me check.

author: jpb
author_rank: Super Contributor
timestamp: June 26, 2014, 06:20:37 pm
content: Quote from: KJDS on June 26, 2014, 04:39:40 pmThe two transformers that I (temporarily) have taken out of my 2015THD are labelled TR328 and TR332, they are also labelled K1-442 and K1-446 but I would guess that one of them is the same as a 2000 but looking at the K2000 repair manual it is shown as a TR299B as per the original post.

author: atsthng
author_rank: Contributor
timestamp: June 27, 2014, 03:13:01 pm
content: Thanks for the responses.I don't know whether the transformer in a 2015THD is compatible; I suspect not, given that both the OEM and Keithley part numbers are different. Attached is a photo of the transformer. The photo does not show the primary leads at the bottom.The Singapore Keithley agent has flat out refused to sell me the part (I have to send the unit in for repair). The US service centre does have the part, but I'm not sure whether they'll sell it to me given that my billing address is outside the US. In any case, it's expensive and would be my last resort.So the other options are buying a replacement transformer, buying a parts multimeter for the transformer, or DIY rewinding the transformer. (I suspect a primary short - there is minimal inductance when the primary is measured with an impedance meter, mostly pure resistance, and it keeps blowing the AC input fuse. I have verified that the main board and display work.)

author: KJDS
author_rank: Super Contributor
timestamp: June 27, 2014, 03:56:28 pm
content: That looks just a little too different from the 2015THD

author: jpb
author_rank: Super Contributor
timestamp: June 27, 2014, 09:17:47 pm
content: I think that the TR332 may be possible as a replacement.I attach three photos I took whilst tearing down my K2015 to recap it. Note the TR332 supplies power to the main board which is shared with the K2000 I think (they are both marked on it).Also note the colours of the wires - brown/brown/yellow/yellow and grey-red/orange/orange/green/green which I think match the photo of the TR299.EDIT : I just realise from looking at the photo and post on the TR229 that it has other mains leads going into it which the TR332 doesn't have. I attach another photo showing that the mains connection goes to the bottom board and is then fed to the other transformer so the two seem to be used in combination in some way.

author: atsthng
author_rank: Contributor
timestamp: June 28, 2014, 03:36:55 pm
content: TR332 might work, yes.The secondary side connections match those of the TR299; the primary side connections (white, blue, brown, grey, red) match except for the end connector. Those of the TR332 connect to the bottom board; those of the TR299 connect to the IEC socket / switch assembly - but they should be the same taps for the 100, 120, 220 and 240Vac power plus return.I've attached two photos of the TR299B coil with the transformer core removed, and top insulation layer removed.The other uncertainty would be the transformer power rating. But if I don't plan to install a scanner card, it should be OK.I've a model 2000 parts unit on the way, but if salvaging a transformer off that or rewiring the original transformer don't work out, sheer curiosity might get me to try the TR332.

author: atsthng
author_rank: Contributor
timestamp: July 09, 2014, 04:26:03 pm
content: Update: Received the parts unit, removed the transformer, checked out the transformer impedances - no shorts, swapped the transformer in - and it works.Parts unit appears to be an early version- there is an Altera in place of the asic on the main board, and the board layout is slightly different. The transformer vendor name is different - it's Multicomp.

author: jpb
author_rank: Super Contributor
timestamp: July 09, 2014, 05:34:57 pm
content: Quote from: atsthng on July 09, 2014, 04:26:03 pmI'm glad that you got that sorted.Getting spares seems a slightly hit or miss affair. The display on my K2015 is rather dim, I tried to get a replacement display board and this wasn't possible but Keithley were happy to sell me the display itself as a spare part. It arrived this morning but it is going to be quite tricky to desolder the old display and put in the new one.