Thurlby Thandar sm620 scopemaster help - Page 1
Forum section: electronics / repair

author: Priestblood
author_rank: Contributor
timestamp: May 19, 2016, 08:18:57 pm
content: hi Alli bought a Thurlby Thandar sm620 scopemaster of eBay but its not working i have looked for hours to find the service manualany help would be great this it a good looking multi-meter/scope,i really want to fix it.There are some components missingbut i cant find schematics anywherecheers

author: Fraser
author_rank: Super Contributor
timestamp: May 19, 2016, 08:26:11 pm
content: I own a couple of these and may have the service manual. The service manual is £25 from TTi. I think it is paper copy only.The small battery on one PCB ends to leak and cause damage to components around it.Fraser

author: Priestblood
author_rank: Contributor
timestamp: May 22, 2016, 12:11:29 pm
content: Quote from: Fraser on May 19, 2016, 08:26:11 pmMany thanksIf you could send me a copy of the manual schematics pleaseMrturner67@hotmail.com

author: JoeD
author_rank: Contributor
timestamp: May 22, 2016, 03:18:47 pm
content: I also have one of these units needing some tlc so would appreciate a copy of the circuits if you can scan them.ThanksJoeD

author: Fraser
author_rank: Super Contributor
timestamp: May 22, 2016, 07:07:01 pm
content: Sorry guys, my SM620/630 service manual is buried in a storage box that I will not have access to for a while. I can't face moving all the boxes that are in front of it at the moment. If you need it quickly, contact TTi for a copy.Fraser

author: Priestblood
author_rank: Contributor
timestamp: May 23, 2016, 06:54:06 am
content: Quote from: Fraser on May 22, 2016, 07:07:01 pmi can wait for you to sort out,money is tight at min.av waited 6mth so far so i dont mind waitingmany thanks for help i was on the fence if i was going to strip it for bitsso much appreciated

author: Hydrawerk
author_rank: Super Contributor
timestamp: May 23, 2016, 06:41:52 pm
content: It looks like a rare instrument.

author: Fraser
author_rank: Super Contributor
timestamp: May 23, 2016, 07:08:36 pm
content: Yes they are rare. I own the SM620 and SM630.The SM630 includes a backlight and also an RS232 protocol reader that takes its input from the scope probe. Very usefulBoth are a combined DSO and multimeter.Fraser

author: csmithdoteu
author_rank: Contributor
timestamp: May 24, 2016, 06:41:45 am
content: They will sometimes email you service manuals if you ask nicely and explain that you're a hobbyist rather than a professional and promise not to distribute them.

author: Priestblood
author_rank: Contributor
timestamp: May 26, 2016, 10:32:27 am
content: I can't find it on there website any links please

author: Fraser
author_rank: Super Contributor
timestamp: May 26, 2016, 11:16:56 am
content: TTi only have hard copies of the service manual for the SM620/630 units. They make duplicates as and when requested. They claim the £25 is a "no profit" cost to make up the manual, and I believe them. A very helpful company to deal with in my experience.I shall be in the lab today and if I can get to my service manuals storage box I will see if I can extract the SM620/630 manual. No promises though as I have other work to complete first.Fraser

author: Fraser
author_rank: Super Contributor
timestamp: May 27, 2016, 04:48:10 pm
content: SM620 Service manual schematics. I had to crop one to fit the forum limitation on file size but it is all there. 2 posts will be needed though.They are virtually the same for the SM630 as well.Hope they helpFraser

author: Fraser
author_rank: Super Contributor
timestamp: May 27, 2016, 04:52:13 pm
content: 2nd pair of scans.Board layouts to follow

author: Fraser
author_rank: Super Contributor
timestamp: May 27, 2016, 04:57:47 pm
content: Board layouts

author: Priestblood
author_rank: Contributor
timestamp: May 28, 2016, 09:34:57 am
content: Quote from: Fraser on May 27, 2016, 04:48:10 pmMany thanks this is great

author: Fraser
author_rank: Super Contributor
timestamp: May 28, 2016, 10:20:24 am
content: You are welcome.If there are any specific areas of the schematic that you need the technical explanation for, let me know and I will scan the technical description. I also have the parts list for any parts you cannot identify from the schematics.Fraser

author: Priestblood
author_rank: Contributor
timestamp: May 28, 2016, 10:55:20 am
content: Quote from: Fraser on May 28, 2016, 10:20:24 amDo you have calibration pagers pleaseMany thanks for your help

author: Fraser
author_rank: Super Contributor
timestamp: May 28, 2016, 11:01:46 am
content: Yes, I will scan them later today.Fraser

author: Priestblood
author_rank: Contributor
timestamp: May 28, 2016, 04:06:33 pm
content: Quote from: Fraser on May 28, 2016, 11:01:46 amHi Fraser many many thanks I have looked for a long time to find this ,If possibly could you scan whole manual and then compress or if easier photo copy and post to me at my full expenseI really appreciate your help and kindnessFor ever in your depthWayne

author: Fraser
author_rank: Super Contributor
timestamp: May 28, 2016, 04:45:00 pm
content: Hi,It's quite a large manual for me to copy and I lost my photocopying access when I retired. Life is a bit busy with my major test equipment clear out at the moment so spare time really is in short supply.For the moment it will have to be just the bits you actually need for the repair.Fraser

author: Priestblood
author_rank: Contributor
timestamp: May 28, 2016, 05:21:20 pm
content: Quote from: Fraser on May 28, 2016, 04:45:00 pmThanks FraserI totally understand if you could scan anything that you think I could use ,voltage lines oscilloscope reading .calibration notesKind RegardsWayne

author: PureZX
author_rank: Newbie
timestamp: July 21, 2016, 08:24:33 pm
content: Hello everyone. I thought I'd register on this forum to thank the uploader of the schematics for the SM620, so thanks.I brought 3 SM620s and an SM630 from an eBay based surplus/clearance seller last week so I went looking for some schematics before they arrived as I suspected they would be faulty, which they were. I didn't really need the schematics in the end as all 3 SM620s had the same fault, they were dead and drawing about 20mA from the DC supply. To cut a short story even shorter, there are 6 x 470u 10V caps, 3 100u 10V caps and a 220u 25V in the multi rail supply circuit and all were leaking, not from the top as is normally the case, but from the bottom of the caps around the rubber bung. All caps were good quality Elna long life parts. The transformer is driven by an LM3578 which was also found to be faulty as a result. All three units are working fine now.The SM630 had an intermittent channel 1 BNC input which turned out to just be a broken wire.It also had worn lugs on two of the PLASTIC (??) BNC sockets so I changed all 3 for metal ones. I also replaced all the caps in the power supply although none were leaking but...The backlight on the SM630 is not that bright, not sure if this is a fault or if that is just the way they are, perhaps someone who's got an SM630 can let me know.

author: JFJ
author_rank: Regular Contributor
timestamp: July 22, 2016, 09:21:43 am
content: Quote from: PureZX on July 21, 2016, 08:24:33 pmThe outer shell of the BNC connectors are plastic because the instrument can be run from a battery pack (hence, it may not be grounded). Also, the channel 1 BNC connector is used as the multimeter input on all voltage ranges. Substituting metal BNC connectors could, therefore, expose the user to a lethal shock hazard.Insulated BNC connectors are readily available, e.g:http://uk.rs-online.com/web/p/bnc-connectors/2255331/

author: PureZX
author_rank: Newbie
timestamp: July 22, 2016, 08:07:47 pm
content: I see, that didn't occur to me since I certainly wouldn't use one of these to measure anything other than low voltages. Obviously any BNC plugs used would have to be shrouded. There are many scopes on the market that can run from batteries and that have metal BNC sockets, pretty much any that come from China for a start.