Elderly Thurlby Thandar TG502 Function/Sweep Generator - Page 1
Forum section: electronics / general

author: icon
author_rank: Regular Contributor
timestamp: August 19, 2012, 07:03:52 pm
content: HiNot really a review, since these are as old as dirt, but just sharing for interest.I saw this on Ebay and was faintly interested, but since I'd just bought a very nice Hewlett Packard one I just stuck a £42 'snipe' on it and forgot about it - got it for £41! Damn, what am I going to do with two function generators?Thurlby Thandar still have a price list PDF on their website from 2000 on their website; the TG502 cost £575 back then.It took me a while to work out what all the buttons did, in the absence of a manual, but everything works fine - the vernier is quite accurate. The 'marker' function is quite neat - it puts a variable length step in the frequency sweep, at a variable point in the sweep. This makes sense on an analogue scope, apparently, as it produces a noticeable brightening of the display at a given point. I have no idea why this might be useful, nor do I own an analogue scope, but it still appeals to me. This is the front panel - enough buttons?Round the back there are these three sets of sockets. As far as I can tell, two are inputs that replicate front panel buttons and the third is an output - I've no idea why 'Pen Lift' though.Inside there are two PCBs, back to back. The main board is on top and the sweep generator is on a separate board underneath. I counted 30 trim pots on one PCB and 18 on the other. Every IC is socketed - there are a skip-full of TL071s and LF441s and a smattering of 74LS stuff. This is the sweep generator board:And this is the main board:The only thing that's not quite right is the TTL output is a bit 'ringy'. I wish I had a service manual - maybe there's an adjustment.CheersJohn

author: SeanB
author_rank: Super Contributor
timestamp: August 19, 2012, 07:19:24 pm
content: Pen lift is for use with an external chart recorder, it lifts the pen from the paper during the retrace of the sweep so that you do not get a line drawn there during multiple sweeps across a range. Sweep out is used to drive the one axis of the recorder ( normally X) and the output from the DUT drives the Y input ( after rectification and a little smoothing, or by using an AGC line) so you can get a multitrace frequency response, perhaps changing level between sweeps.

author: Rufus
author_rank: Super Contributor
timestamp: August 19, 2012, 07:50:48 pm
content: Quote from: icon on August 19, 2012, 07:03:52 pmIt is just a marker. If for example you were sweeping through a filter you could position the marker where the amplitude is 3db down (or whatever) and read the corresponding frequency from the dial.

author: icon
author_rank: Regular Contributor
timestamp: August 22, 2012, 08:31:04 pm
content: I phoned Thurlby Thandar here in the UK on the offchance that they had a service manual for this device. Whaddya know, they emailed me a PDF of the TG501 (which is the non-sweep version, so covers the main function gen board) service manual. So, some happy pot-twiddling time ahead.They also said that they had no problem with it being 'public domain' - where would be a good archive to upload it to?CheersJohn

author: mianchen
author_rank: Regular Contributor
timestamp: August 22, 2012, 09:01:53 pm
content: Quote from: icon on August 22, 2012, 08:31:04 pmThis guy atelektrotanya.comseems to have a nice collection of all sorts of service manuals. Website is a bit weird though

author: Fraser
author_rank: Super Contributor
timestamp: August 22, 2012, 10:09:28 pm
content: I attach the brochures for the TG500 series for your interest.RegardsFraser

author: Ronald1962
author_rank: Contributor
timestamp: April 19, 2013, 06:16:44 pm
content: Hi folks,I also bought a TG502 on Ebay.Unfortunately it dos not work at all.So I was looking also for a service manual but could not find one.Does anybody already got one and can give me an advice how to get it?Thank you very much in advance for your replies.RegardsRonald

author: ddavidebor
author_rank: Super Contributor
timestamp: April 19, 2013, 06:32:10 pm
content: great piece of equipment for great price! nice score!

author: ecat
author_rank: Frequent Contributor
timestamp: April 19, 2013, 06:41:11 pm
content: Quote from: icon on August 22, 2012, 08:31:04 pmhttp://www.ko4bb.com/manuals/http://bama.edebris.com/wiki/index.php/News

author: kfitch42
author_rank: Frequent Contributor
timestamp: April 19, 2013, 06:42:58 pm
content: Quote from: icon on August 22, 2012, 08:31:04 pmBama (Boat Anchor Manual Archive) ?http://bama.edebris.com/manuals/

author: icon
author_rank: Regular Contributor
timestamp: April 20, 2013, 03:46:38 pm
content: Quote from: ecat on April 19, 2013, 06:41:11 pmI've submitted the manuals (I have the service manual for the TG501 and a schematic for the TG502) to both websites.John

author: Rascal
author_rank: Contributor
timestamp: April 24, 2013, 11:30:38 am
content: TG502 is a good function generatorI have used one for a few years until it recently gave up the ghost. Opening the bonnet revealed a burnt out resistor and now duff transformer!Unfortunately i havent had much time to sort it out - eventually i will get around to it