SUN MGA 1200 EXHAUST GAS ANALYSER NEWBIE DUMPSTER CHALLENGE - Page 1
Forum section: electronics / repair

author: obd.tech
author_rank: Regular Contributor
timestamp: November 01, 2014, 07:36:00 pm
content: Hi FolksIn the true spirit of the great Dave's Dumpster Youtube videos, which brought me to this great forumI found a great bit of old 1991 pro kit (regarded by some as probably the best 4 gas analyser made) that was in a skip for the great crusherand i had to save it.Being a gentleman, I gave the owner a beer token and now it's my challenge to get it working again.He told me 'it booted up last week to try, but when i turned it on yesterday....it went "woof".After a 'lets look in side'and blow the dust out session.....nothing nasty visible.....i plugged her in....BANG! FLASH!!5amp plug fuse blown....and my reactions testedIt has a toroidal transformer with a power supply pc board, containing 5 reasonable size electrolytic caps....and this was where the flash came from. As a relative newbie (but keen to learn!) i'd like some advice on whats the best way to test/repair and wake up these Caps(and the ones on the infrared gas bench), that probably have been unused for about 10 to 15 years?Caps image attached(how do i insert it here, or is it best to attach?)will post more pics when i get the pcb out and my phone charged.I have a china ESR meter, solder station etc. i did read that its possible/best to apply the rated cap voltage to old caps via a resistor to wake them from there dormant state, do you do this first before testing them? I dont have a 35v dc source but could link some 12v car batteries if this would work?Any help/advice welcome

author: German_EE
author_rank: Super Contributor
timestamp: November 01, 2014, 07:42:15 pm
content: I know nothing about this unit but if something is flashing over and going bang then you should be seeing physical damage, where is this damage located? Normally when electrolytic capacitors go bad the cases bulge on the top and/or the bottom and it's easy to spot but from your picture they look OK.Just take care around the high voltages please.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 01, 2014, 07:54:06 pm
content: Yes i was expecting visible damage too, maybe 1 cap looks at a raised angle from the others?I'll wear my wellie bootsMaybe the 5amp fuse saved some damage?, not sure what the mains plug rating should be, info for this gas analyser was pre internet days and hard to find, tho i did speak with a guy today that was taught at college in Kings Lynn. U.K. by the guy that was the chief engineer on this Tool (sadly, he too is suffering old age)I look forward to more replies

author: obd.tech
author_rank: Regular Contributor
timestamp: November 01, 2014, 08:09:32 pm
content: Picture of the Gas analyser for people to see attached, and also the other Caps, visible on the side of the heated NDIR gas bench that detects the gas makeup

author: poot36
author_rank: Frequent Contributor
timestamp: November 02, 2014, 07:07:38 am
content: I would start by replacing the fuse and connecting the unit to a dim bulb tester (a light bulb in series with the plug lead) using a 40W bulb as a start. If there is a major short in the primary section of the transformer the bulb will glow brightly but the fuse will not blow. If the unit draws more then 80 or so watts use a light bulb that is roughly half of the units wattage for the test. If the bulb glows medium or dim then the primary side of the transformer is most likely fine. Use a multimeter on volts to see if there is any voltage on the various capacitors in the power supply when it is unpluged and if there is not set the meter to ohms mode and check the capacitors for shorts. If there is voltage across the capacitors then there is probably no short but they could have become leaky at higher voltages (hard to test unless you have a high voltage capable capacitor tester). I do not think that you will have to worry about refreshing the capacitors due to the unit been from 1991 or so. I have used a dim bulb tester to power up tube radios from the 40s that the capacitors still worked fine (no reforming necessary)!

author: SeanB
author_rank: Super Contributor
timestamp: November 02, 2014, 07:37:50 am
content: I would probably look for the shorted bridge rectifiers that are now there, if one diode went short or leaky over time it now well have a big hole blown in it.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 02, 2014, 09:58:26 am
content: Thanks for the replies guy's.....please remember i'm a newbie at this electronics stuff.....my knowledge and learning time has been spent on all things automotive......i believe that most things can be fixed if you have 4 ingredients. Knowledge, tools, interest and time......thats why i'm hereto borrow some of that from you guys.......and return some if you have auto questions.SeanB..I've heard of of bridge rectifier....whats it do/look like?......what happens when it goes wrong?poot36....not sure what you meant about powering it up? what parts connected? it's got a separate toroidal transformer with wires going out to different boards.....and to the cap pcb one attached.Any tips on what/how to test the components on this board? i know to discharge the caps first. i have a china esr meter and also the $20 transistor gadget that is followed on this great forumWhat are the 4 gizmos on the heatsink? has a +~- on them. and the 3 legged transistor things on the back of the pcb which are insulated from the case ground (heatsink)with the film and compound.No visible damage??Do i test the caps in circuit or off? I also rescued a later version tester which has a similar pcb with the 5 caps on to compare readings/rob parts from?All help welcome

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 02, 2014, 10:19:17 am
content: Quote from: obd.tech on November 02, 2014, 09:58:26 amYou found themThere is BR2, BR4 written on the pcb, that is a giveaway. If you disconnected the transformer use an ohm meter between the 4 pins and see if there is a dead short between any of the 4 pins for each BR, if so you found the problem.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 02, 2014, 10:34:37 am
content: BR of coursewhat an idiot! thanks for thatno shorts between the 4 pins on all of them, but 2 have readings from one half to the other of say 150kohm and 300kohm depending on which pins you check....but the other 2 'BR's (i'm learninghave nothing on them.....is that because they are in circuit and affected by it and the caps etc?

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 02, 2014, 10:40:17 am
content: Quote from: obd.tech on November 02, 2014, 10:34:37 amYes, and it also depends on what meter you use. They contain diodes which will start conducting at 0.6Volts.If the primary fuse blows, is there maybe an AC filter between the power entry and the transformer? Either a boxed one or one built with descrete caps and coils?The caps in these filters tend to die and can give you the fireworks...

author: Rerouter
author_rank: Super Contributor
timestamp: November 02, 2014, 11:38:42 am
content: From what i can see in this circuit, check the diodes, and those 3 transistors on the back of the board, the transistors on the back check with an ohm meter across all 3 pins, if none are shorted, use the diode check, and from the base you should measure ~0.7V to the other 2 pins (this should only be valid in one polarity, e.g. only 2 pins should conduct like this to any other 2 pins),Next up for the diodes, use the continuity check across them (In both directions, leaky zeners are best found this way), then a diode check across them, only 1 direction should conduct, just be aware if there is anything else in parrellel to them in circuit you may need to lift 1 leg of the diode to properly measure it,

author: obd.tech
author_rank: Regular Contributor
timestamp: November 02, 2014, 11:46:20 am
content: Yes PAOPBZm8 there is one of the ali boxed ones, i nearly took a pic of it...because it has a sort of 'bulge' in the top of it. I did read the printed symbols on the box and saw it had some uF cap rating on it, it got me wondering? It also houses a built in fuse, but the mains plug fuse blew.Does this mains filter box need a load/ how do i test it please? Can i bypass it?I don't know, but i'm guessing the less amount of current surges/test runs i give this & the electronics in the analyser the better?Right i checked the caps on the psu pcb and the readings are herecap- rating - volts - ESR2501A - reading (mastech meter)C1 10K 25 0.08ohm 8.1mF (this is 8.1k?? )C5 10K 25 0.08ohm 8.2mFC11 10K 25 0.06ohm 8.5mFC13 3.3K 35 0.13ohm 2.5mFC17 3.3K 35 0.10ohm 2.9mFplease excuse the cheap test gear.....i spent thousands on auto toolsThanks Guy's

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 02, 2014, 11:48:31 am
content: Yes, just bypass the box and see what happens. Could be an easy repair after allThe caps readings look ok.

author: Rerouter
author_rank: Super Contributor
timestamp: November 02, 2014, 11:52:28 am
content: The readings are likely lower as your tester would not be testing at the frequency the rating is for, even still that small of a drop should not cause explosive bangs,Also i seriously recommend to you a $20 transistor tester off of ebay, (the one that does diodes caps etc), it has helped me out on so many unique failure modes it isnt funny, and for $20 posted plus a 9V battery it will be as handy as a multimeter (It can measure 0.01 of an ohm if you do the 3 lead calibration (connect all three leads together and press test)

author: obd.tech
author_rank: Regular Contributor
timestamp: November 02, 2014, 12:10:37 pm
content: Yes Rerouter,i have one of the $20 transistor testers (posh one in the plastic box, darn the expense) i just don't know how to use it....yeti'm trying to understand your description on the testing transistors.....base is common with the middle leg. what do i test from there?gas analyser is at the auto workshop, but i hope to try later without the filter box connected?can it do any harm.....how can i test the filter box?Cheers guys

author: obd.tech
author_rank: Regular Contributor
timestamp: November 02, 2014, 12:22:14 pm
content: Rerouter, i dug out the $20 'super gadget' ...that i had to buy (big boy's toys, you'll understand)see picture attached.....am i doing right? if so i'll check them all.There are 5 transistors i guess to work with the caps.....what do they do?If you could please simply explain what it's telling 'newbie idiot' meThanks Guys

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 02, 2014, 12:30:13 pm
content: Quote from: obd.tech on November 02, 2014, 12:10:37 pmJust take the filter box out, if it then works it's clear that the box has died.The base of a transistor is not always the middle leg, and you probably can't test the transistors without taking them out.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 02, 2014, 12:34:29 pm
content: There's no quick test i can do on the box first? its a bit of a fiddle to get the pcb back in and be nice to see evidence/test failed....rather than 'parts darts' that most garages use as a form of 'diagnostics'

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 02, 2014, 12:39:37 pm
content: Well, you could just connect the box to the mains and leave the output disconnected. Fireworks -> bad box

author: obd.tech
author_rank: Regular Contributor
timestamp: November 02, 2014, 12:48:08 pm
content: Good planThats my logic too.Looking at the pic again......the 'Box' is above the pcb .......maybe the flash did come from there?I'm gonna have to drive 30k now 'to have a play'p.s. is there any real test that can be done on these filter boxes?

author: obd.tech
author_rank: Regular Contributor
timestamp: November 02, 2014, 01:15:24 pm
content: Just tested the other transistor 3 legged things.first 2 the same, then different readings, then faulty one? then ok one?please enlighten me oh knowledgable ones .......i have no idea......yetOff to the workshop now to ........in Dave's youtube words....... "blow some Shit up!!!"

author: obd.tech
author_rank: Regular Contributor
timestamp: November 02, 2014, 03:13:09 pm
content: mmm........test time....removed all the wiring from the filter box, new 5A fuse in mains plug --> OnNothingtested voltage at the filter outputs P-N =230V N-earth =0v P-earth =230vtook box out and small burn hole lower side inline with P terminal in photo attached.Now the question is??......what caused this?Do i chance by passing the filter box? or is there a fault elsewhere.Could the suspect transistor be a result/problem or cause?Ideas please. Cheers guys

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 02, 2014, 04:06:29 pm
content: https://www.eevblog.com/forum/repair/hp3458a-schaffner-mains-line-filter-failure/https://www.eevblog.com/forum/testgear/just-got-3457a-and-then-boom/And lots of other examples, so I'm quite sure it's gone. Test the analyser without the filter.About the transistors: as I said you can't really test them in-circuit.

author: SeanB
author_rank: Super Contributor
timestamp: November 02, 2014, 06:42:05 pm
content: Well, the filter had a fault and blew it open. The thing is those are not transistors on the board, but voltage regulators. Note the Ux designation, which says integrated circuit. You cannot really test them with the simple tester, but must note what device it is ( there will be 1 of 4 types in each position) and look up the device to test the input and output with a multimeter with the power applied but with no output connected to the board. You likely have a 5V regulator, a 12V regulator and a +15V and -15V regulator at a minimum there on the board. You will have to undo the screws and carefully look to see what each one is, and write it down so you can see what each one does, then look up the datasheet and then get the info and then use a voltmeter to check it is working correctly.

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 02, 2014, 07:24:00 pm
content: Quote from: SeanB on November 02, 2014, 06:42:05 pmAh, I missed that!But there is a good chance that the only fault is the filter, I'd certainly try that before going any further.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 02, 2014, 11:10:27 pm
content: Great stuff guysthats a great help!.....i will have more of a 'play' tomorrow after work.That schaffner swiss filter has 91 06 on it....i'm guessing the date of manufacture 1991?Is it recommended to have one (i may have a donor from the other analyser bench) or best to have a straight input socket/fused switch type?Will let you know my findings.Thanks again guyskeep up the good workthat makes this forum

author: poot36
author_rank: Frequent Contributor
timestamp: November 03, 2014, 06:33:04 am
content: The filter block helps prevent the electrical noise that the unit produces from going back into the power grid. It may also correct the power factor (PF) of the device. If you have ever ran a electric motor well watching analog tv or radio you know what the effect of the electrical noise can be. It won't harm the device to run it with out it though.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 03, 2014, 06:42:26 pm
content: Post mortem on the blown schaffner 'Swiss Cheese'picture attached. The dreaded black goo that PAOPBZ posted the forum links about, covers the suspected blown bad capacitor.I found a replacement in the other gas bench i also saved from the skip/crusher (my planned 'spares' department, newer model SUN DGA1800, but calibration locked out).This one is made in Thailand, and to my eyes looks externally better made?Is this one with the possible date stamp of 00 45 (week 45 YR 2000?) likely to have 'short' life caps inside at that age? I will try it as that machine was running ok a week ago.Any reports of the thai versions going bang? or is it just the 'Swiss Cheese' to avoid? (prefer a nice cheddar anyday)More playing continues........

author: SeanB
author_rank: Super Contributor
timestamp: November 03, 2014, 06:59:37 pm
content: Non Swiss ones are fine.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 03, 2014, 07:40:29 pm
content: Looked at the transistor/voltage regs? component markings........if you guys can give me some guidance here as i have no idea what this all means (yet.....i'd like to learn)first 2 are the same L78S05CV ST99045 look @ 821jpgnext 1 is(double sqwiggle) ~/9018 LM317T P+ look @ 822jpgsuspect?? 1 is L7912CV ST99052 look @ 823jpglast 1 is L7812ACV ST99050 look @ 824jpgI'll try and see if i can find some info.......but i 'have much to learn'but its all good for experience!Do i take any suspect ones out of the pcb to test againAll help/info welcomed

author: SeanB
author_rank: Super Contributor
timestamp: November 03, 2014, 08:07:17 pm
content: First 2 are 5V 2A regulators, look for a 7805. Next is a LM317, look for that. Third is a -12V regulator 7912. Last is a 12V regulator, 7812.7805 and 7812 have the same pinout, while the LM317 is a adjustable regulator, and the negative regulator is a different pinout.

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 03, 2014, 08:12:37 pm
content: Hmm.... Before you start the fight with the regulators, are you sure there is still something broken?I would just put it back together and see if it powers up, you obviously found the source of the lightning.If it does not work start checking the output of the regulators.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 03, 2014, 08:30:43 pm
content: Thanks....Will have a look?Any of the readings in the photo's ok or do i need to take out the pcb and put in the $20 'super gadget'?Not sure about powering it up in the analyser to test the regs voltage on the legs....as don't they need the case for a heatsink?......and i don't want to damage anything else if i can help it guys.PAOPBZ....thanks......i just wanted to try and learn while it was apart.....and that 7912 in the tester saying faulty...got me worried, i don't want to break the analyser, if it's avoidable, just by being lazy(see that on many cars.....'preventative maintenance is key'...and easier!!.Remember i have no 'experience' in this, to guide me......give me a car and we are talking different.......thats why i'm here, for help from other people with a passion/interest and enthusiasm/experience in this stuff........and i'm really enjoying it so farI'm tempted to go with the 'put back together' option? Let me know.Cheers guys

author: Macbeth
author_rank: Super Contributor
timestamp: November 03, 2014, 08:44:49 pm
content: Is that exhaust analyzer up to current MOT standards? I would love something like that but it does need gas calibration too. I remember the old DIY gas testers you could get fairly cheap in the carburettor and mechanical distributor days, but the <0.3% CO and <1200ppm HC stuff needs pretty specialist and expensive equipment.Mind you, most of my MOT gas analysis certs had SUN as the device, so I guess it's a goodun!

author: PA0PBZ
author_rank: Super Contributor
timestamp: November 03, 2014, 08:48:06 pm
content: You simply can't test the regulators with that device, you have to feed them the proper voltage and see what the output is. The easy way to do that is to put the stuff back together and if it doesn't work... -> measure.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 03, 2014, 09:00:36 pm
content: Yes Macbeth, this is a Pukka bit of kit, this was from the start of the MOT emissions test days, before it had the computer control 'junk' that now times out and requires calibration @£200?? every 6 months.This is just as accurate when calibrated as it has the same gas bench as the later version DGA1800 that i also rescued for spares. Tried searching the web.....and world wide government and research departments all seemed to use the MGA1200 for testing. It's really nicely 'industrial quality' kit inside and made in the U.K. (USA parts inside....SUN was part of Snap on company)She's going back together......How much heat sink compound on the back of the regs each side of the insulating film? minimal or lots?

author: obd.tech
author_rank: Regular Contributor
timestamp: November 03, 2014, 10:36:58 pm
content: I messed up on one of the delicate reg insulator films...man they are delicate...it splitSwitch on timei got a little nervousYIPPEE!!! It LIVESYea....well chuffed!!!!!!!!!Cheers Guys for all your HelpI've probably been a bit of a div here.......sorry....a learning curve for me!First Major hurdle over.......now i can see/find out what works and calibration etcThanks again for all your help and inputp.s. any Auto questions you have....fire them my way (g they are packed with electronics these days)

author: HighVoltage
author_rank: Super Contributor
timestamp: November 04, 2014, 08:31:18 pm
content: I have the previous model, the SGA9000 USA Version with 4 Gas analysis.When I got it, it was broken and dead.Turned out to be a bad main transformer.After I got it working, I also replaced all hoses with new pure silicon hoses.And I cleaned the optics in the IR detectors.The SUN 4 Gas analyzers have been the best in the industry.Something like this is not being built anymore.Just the Infra Red detectors alone are a work of art.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 04, 2014, 09:11:41 pm
content: Hi HighVoltageGreat to hear that it's not just me that had a liking to this 'Big Boy's Toy'.I couldn't bare to see it go for scrap, engineering like this is worth saving.The pump unit has proper little conrods and pistonsI guess there are older pukka electronics test kit that the guys on here would appreciate to own for the very same reason. 'Quality Remains long after the price is forgot' I understand you guy'sI've seen the 9000 unit...looks very similar....does it have the Andross 257E gas bench?I'd really like to know how to clean the optics if you could share the info and anything else tooMine has HCR (hardware calibration required? on the Co and Hc channels)Finding info is really rare as this is pre internet kit. But i'm hopefulI rescued a couple of spare gas benches tooDo you have the operators manual in english, would love to get the service manual and schematics too....i'm working on that.Great forum to share a bit of engineering interest & passionCheers Guys

author: HighVoltage
author_rank: Super Contributor
timestamp: November 04, 2014, 10:45:27 pm
content: Hello obd.tech,I have the full calibration procedure for the SGA9000. It is probably very similar to yours.It took me "forever" to get this information, but it is only on paper.Without this paper, you don't even know of how to get in to the calibration mode.You need a test gas in a bottle and then you can calibrate CO, CO2 and HC.Butane is good enough for HC calibration.O2 calibration is done with the oxygen from the air.I am not sure, who made the gas bench.But let me take some pictures in the next few days and upload them.It is a real quality lab equipment and was far too good for typical car repair shops.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 06, 2014, 07:06:24 pm
content: Hi HighVoltage,That would be greatI Cleaned out the plumbing & pump chambers, sorted out better routing and blew lightly across the gas bench ports......mmm.....a fair bit of fine dust came outnot surprising because of the age and also there is no filtration when the unit 'purges' the gas bench for zero calibration.....daft? or maybe job creation for the service guys?I did have the CO2 channel reading before, but now they are all HCRlooks like i made it worseGas bench strip & clean required, with the help from you pleaseDecided to 'have a play' on the gas bench that was 'in the skip'.Strip down photo's attached......well nearly stripped. The opto emitter end is easy enough, but i'm stuck on the other end with the motor 'chopper' and receiver sensors?The 2 motor to heatsink screws didn't do much. Those wires look a little delicate!what parts need cleaning (emitter end window film +?) and what did you use?Thanks

author: HighVoltage
author_rank: Super Contributor
timestamp: November 07, 2014, 10:13:30 pm
content: Interesting pictures of your MGA 1200It seems very different from my older unit.I do have an extra gas bench and will take some pictures tomorrow.But essentially you just open the optics and clean it all with some alcohol.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 07, 2014, 11:53:48 pm
content: What type of alcohol?Is it best if i drink some tooI just carefully cleaned the ruby mica window by the optical emitter? with a soft cotton cloth and some 'huff'. That mica is pretty delicate!! what are the other optic lenses like?I look forward to the photo's. Thanks

author: obd.tech
author_rank: Regular Contributor
timestamp: November 08, 2014, 07:19:25 pm
content: I now have the service technical manual, just need to know the access password to have aplay. Seems the uk versions have a different password

author: HighVoltage
author_rank: Super Contributor
timestamp: November 09, 2014, 05:38:49 pm
content: obd.tech,I finally got the time to open up an extra bench that I had laying around.This one came out of a dead SGA-9000 and it looks like it was never opened and cleaned.For cleaning the tubes and the optics, I have used denatured alcohol in the past and it worked really well.As long as the good filtering is used, there should not be any dirt coming in to the bench itself.But over time they do get black.I am surprised how clean this one actually is.These gas analyzers work based on nondispersive infrared technology. The infrared radiation is absorbed by the gas(CO, CO2, HC ect.) and the IR receiver detects more or less of the absorbed transmitted IR energy. The IR transmitterin this emission tester is just a wound up wire (See pictures). The IR energy is then sent and reflected from a parabolicmirror and sent through a rotary shutter through the test tube and then it will reach the IR detector. The test tube isflooded with the test gas and depending on the gas, different wavelength will absorb from the IR spectrum.These gas analyzers have one of these chambers per gas and they are made for the spectrum of just these three gases.That is why they have also different length in the test tubes.I also found an original brochure of this tester, which must be from the early to mid 80th, I would guess.The PCB seems to be the heater control for the IR transmitter. Looks like the resistors have seen better days.

author: HighVoltage
author_rank: Super Contributor
timestamp: November 09, 2014, 05:40:53 pm
content: More pictures

author: HighVoltage
author_rank: Super Contributor
timestamp: November 09, 2014, 05:42:08 pm
content: More pictures

author: HighVoltage
author_rank: Super Contributor
timestamp: November 09, 2014, 05:43:30 pm
content: More PicturesThis is the original brochure of this gas analyzer

author: obd.tech
author_rank: Regular Contributor
timestamp: November 09, 2014, 09:26:18 pm
content: Thanks HighVoltage, interesting photo'sreminds me of an older EGA i looked in some time ago, that had separate channel cells too, i'm pretty sure they looked just like those aluminium ones.24kg of proper engineeringThis MGA1200 only has the one sample chamber(plastic) in the Andros gas bench, the optic that i cleaned appears to be the collector then? (i said it was the emitter) i'm not sure how to dismantle the emitter & rotor end for cleaning to optics yet.what was the password for getting to the service adjusting mode?if i can get that then i think i can adjust the base settings for the analogue bench pcb and i might be operational? This has an analogue to digital converter board and uses a canbus network with the other control boards. Higher tech than i expected.Was yours a sadly thrown away piece of engineering?

author: HighVoltage
author_rank: Super Contributor
timestamp: November 09, 2014, 10:32:10 pm
content: I have one fully functioning 4 gas analyzer SGA-9000, almost in like new condition with very little use.When I got it, it was dead.Then I bought another one and used it as a parts donor.It was the opposite, totally used up and bad and also dead, so I just removed the parts I wanted and the case went in to the dumpster. Out of the two, I do got the first one going and it works like new, including the chemical O2 Sensor.The SGA-9000 only has serial communication, no CAN bus in this old one.If your only has the one chamber, then it is detecting the different absorption rates of the different wavelength in one single chamber. This was probably not possible at the time, they built the older model.Hmmm your picture looks like it is the transmitter, based on the heat sink?I am not sure.The transmitter should be located across from it of the other side of the tube.Usually only the transmitter broke. They have a lifespan like a light bulb and moving the analyzer around, while it was turned on, reduced the life span of the transmitter.I have no idea about the password.The SGA-9000 has 3 potentiometers for each gas to set the zero, the max and the span.A complete calibration process of the SGA-9000 takes about 1 hour with different test gases.I just love the quality of these machined aluminum parts for the bench.No wonder, the price was over $ 10.000 for the base 2 gas unit in those days.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 09, 2014, 10:56:44 pm
content: The MGA1200 also has the 3 potentiometers on the Andros analogue board for setting.Have to agree on the real engineering quality thereThe first GA single Co meter i used was a Sun analogue 'needle'type in 1984/5 and that was about $6000at the time in the U.K. 30 years on......and a far better one is thrown in the skipCriminal throw away tech worldBut Hey, good for us that can appreciate what we have gainedAdvise for the O2 chemical cell......it has a limited life if left in the gas it's detecting, i have read that if it is not used much.....to place it in a small sealed container, better still to vacuum it or fill will OFN, to extend its useful lifespan. Hope this may help you?Cheers

author: Macbeth
author_rank: Super Contributor
timestamp: November 10, 2014, 12:49:39 am
content: I just found a couple of MGA1800 rigs complete with dot matrix printers, terminal, etc. going for £50 or less on ebay UK (Pickup only of course). Bargain, but just too far south for me.I'm amazed to see that some dealers still sell the old Gunson analyser as brand new (old stock maybe?) that are only good enough for ancient carb vehicles with lax emission standards for over £150 too.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 10, 2014, 01:08:34 am
content: The DGA will all be locked out as calibration expired, same gas bench as the MGA1200, quality industrial sturdy stand. I rescued the gas bench draw from one going for scrap, for spares. Not sure what Sun would charge to unlock & calibrate the DGA1800 ? £150/200?Give them a call? Sun Electric (uk) Ltd, Oldmedow Rd, King's Lynn, Norfolk PE30 4JW 0843 259 5464The gunson is just a hot wire toy, useless. The kane may & snapon handy gas are supposed to be rubbish for automotive use too.

author: poot36
author_rank: Frequent Contributor
timestamp: November 10, 2014, 06:56:44 am
content: obd.tech check your pm, I took you up on your automotive knowledge offer.

author: obd.tech
author_rank: Regular Contributor
timestamp: November 10, 2014, 06:13:44 pm
content: stop/tail bulb pwm from opel corsa attached mr poot36. Hope this helps?p.s. thats the sidelight phase, brake light is fully 'On'

author: poot36
author_rank: Frequent Contributor
timestamp: November 11, 2014, 04:29:41 am
content: Thanks for the scope trace but the issue that I am having is BMW specific.

author: waz480
author_rank: Newbie
timestamp: February 06, 2018, 07:03:31 pm
content: Hi all,I used to work for a Jaguar specialist back in the 90's , We had a Sun MGA1200 there and had fond memories of that job and also remembering what a great machine it was , so i was looking on ebay and saw a MGA1200 which i bid on and won for £40 !but a 360 mile round trip to pick it up lol ,I owner said it was working perfectly when he last used it 15 years ago but it was sold as seen so was expecting problems , After i did some Googling i found this forum and discovered lack of technical knowledge,So i plugged it in and it came up with an error and a code number but after about 5 minuets of running there was a huge bang and flash from the back tripping the rcd on the workshop fuse board ,The power switch had blown up so i bypassed it now i had a new code AC bugger ! ,I phoned my Snap on man and he gave me the number for Sun support , I was lucky enough to speak to Paul how used to service and repair them back in the day and first off sent me a pdf of the owners manual , He is so knowledgeable and patient , he did all over the phone and email it was not easy but i have got it working now a part from he is waiting for a new service code but he did all of this for free ! including the service code , he was happy that someone was still interested in this machine ,I would recommend phoning them with any problems , I hope this has helped you guysCheer WazI can not attach the pdf of the owners manual its too big so email me and i will send it on sorry

author: Macbeth
author_rank: Super Contributor
timestamp: February 07, 2018, 01:57:33 am
content: Quote from: waz480 on February 06, 2018, 07:03:31 pmFor large files you can sign up completely anonymousmega.nzaccount(s) for a free 50GB each of encrypted cloud storage. You can use a throwaway email address to signup likeuser121gw@mailinator.comsee themailinator website for thatThen just provide themega.nzlink to the file or folder. I find folder links are easier to share. Don't forget to tick the box for the decryption key to be included in the link

author: ace1903
author_rank: Regular Contributor
timestamp: February 07, 2018, 10:26:58 am
content: I had one MGA1200 but couldn't find service manual and decided to take it apart.If there is service manual available I would like to try to use only CO and HC measurement part.Theory for NDIR measurement of gas concentrations is interesting and if the IR source lamp is not damaged should not be difficult to try to use it.I have all the parts so if one is interested in component values I can take a look at the boards.

author: HighVoltage
author_rank: Super Contributor
timestamp: February 07, 2018, 11:04:30 am
content: Quote from: ace1903 on February 07, 2018, 10:26:58 amEven if they are damaged, you can repair them easily.

author: waz480
author_rank: Newbie
timestamp: February 10, 2018, 07:32:17 pm
content: https://mega.nz/#!99AVAbDA!9BqUYc0voIAcSxU14rtPC8KKV1h0Cd9CGatmfinjEnwMGA1200 PDF

author: davesaab
author_rank: Newbie
timestamp: November 10, 2018, 10:43:21 pm
content: hi there i don't know if anyone can help me ,today i purchased a 4 gas analyser sun mga 1200 and it was not working,i replaced a few pipes stripped the pumps down cleaned and now I'm not getting LOF lack of flow great fixed,the problem i have now its asking for service this is a Mot thing these can be switch off does anyone know how to do this or they have a unlock code cheers DaveModify message

author: HighVoltage
author_rank: Super Contributor
timestamp: November 10, 2018, 11:28:24 pm
content: Is the pump running?Are all check valves clean ?Did you replace bad and plug up hoses ?

author: CJay
author_rank: Super Contributor
timestamp: November 12, 2018, 02:04:05 pm
content: Quote from: obd.tech on November 09, 2014, 10:56:44 pmThere's a test point on the board you can monitor to aid setting those pots (interesting waveform BTW, it makes the operation of the bench really clear) but there are more than three pots, the bench is calibrated for span and zero so with a 'scope attached you set the zero gas levels to be equal, then feed it cal gas (find a friendly SPX/Bear user if they're not extinct and borrow their tank (1 year cal interval and only £150 or free with service contract but my UKAS lab is now in the hands of someone else) or beg some from a cal engineer's UKAS bottle) and adjust the other pots for correct values on the display/computer screen.There's also reference voltage, 'black' level, speed of the 'wheel', servo for the IR source (you can fry the source) and a bunch of other 'stuff'. You can get yourself in a proper mess if you 'twiddle' randomly.I preferred the later Andros 6100 benches as used in the later machines because the early bench electronics didn't have the analogue resolution for accurate work on catalytic converter equipped vehicles, the later Andros 6000 benches with the larger piggyback board were really good.Quote from: obd.tech on November 09, 2014, 10:56:44 pm.Meh to engineering quality, they were built heavy but were shit, unreliable and that six month cal was as much for drift as well as regulatory requirements.O2 sensor, nope, don't seal it in a bag, starving it of oxygen can ruin it as it won't 'restart', they're an electrochemical fuel cell, you're best just to purge the analyser with fresh air through an activated charcol filter.The cells are usually supplied in a packet with an air port (unless someone has repacked it to sell it on form a bulk pack) and should have a life of over 2 years in atmosphere but it's shortened by exposure to hydrocarbons and various organic compounds.City technologies have a bunch of useful information on their site about care and feeding of O2 and NOx cells.There is an unlock on most if not all MOT analysers, but if it's a standard Andros 6x00 bench then there's a lot of software out there that doesn't have a cal interval enforced (obviously it can't be used for certification)*edit* I am reliably informed the calibration bypass is a firmware change on the MGA1200, not an unlock as such, my source is probably correct but YMMV, I've asked how much it costs for the EPROMs.

author: mahdiks
author_rank: Newbie
timestamp: April 14, 2020, 09:41:21 am
content: Can anyone upload the MGA-1200 manual again?My MGA-1200 is not work, I think some pipes are attached in the wrong position.

author: dirkpassat
author_rank: Newbie
timestamp: April 22, 2021, 06:35:15 am
content: Hallo ich besitze auch ein SGA9000 leider sind alle Schläuche kaputt hat eventuell jemand Bild material?würde mir sehr helfen.wenn jemand ne Anleitung hätte wäre auch tollDanke

author: HighVoltage
author_rank: Super Contributor
timestamp: April 26, 2021, 11:39:28 am
content: HelloI looked but can not find pictures of the SGA9000 with installed hoses.But I found my SGA9000 binder with lots of instructions and schematics. However, nothing in regards to hose placements. But it is very simple, just follow common sense and it will work.

author: PA0PBZ
author_rank: Super Contributor
timestamp: April 26, 2021, 03:31:10 pm
content: Found this:

author: lrx automotive
author_rank: Newbie
timestamp: June 28, 2021, 05:24:36 pm
content: hi everyone,i'm new, i found your forum on googlei got a sun mga1200 that i need to overhaul, i would like to give a second life to this great tool, but it has the pipes completely disintegrated. ..unhappily for me it is impossible to know which pipes go to which place.Does anyone have the manual for repairing or using an MGA1200? or then someone who could open the box and provide me with fairly precise photos of the location of the pipes?Thank younico

author: SteveyG
author_rank: Unknown
timestamp: August 15, 2022, 08:24:05 am
content: Adding another request for the service manual or a few decent photos of the internal pipework. Picked up an MGA 1200 over the weekend, but the pipes are perished with little trace of where they're supposed to go! Strange since the wiring is well labelled, but not the pneumatics.

author: HighVoltage
author_rank: Super Contributor
timestamp: August 15, 2022, 09:55:48 am
content: Quote from: SteveyG on August 15, 2022, 08:24:05 amThis is not complicated. Just follow common sense.It is a series connection of a flow or two independent series connections of two independent flows like in the SGA9000.Make sure to use good quality silicone rubber.When I did such a job, I always used medical grade silicone tuning because they last forever.

author: SteveyG
author_rank: Unknown
timestamp: August 15, 2022, 10:09:11 am
content: I managed to get the service manual - there's no way I would have worked it out. There's several "Y" connectors which were just laying at the bottom of the unit. I would have not figured out the aspirator line either.Hopefully I can get it up and running, though it definitely needs a few new filtersSteve

author: jmsteknik
author_rank: Newbie
timestamp: July 13, 2023, 08:25:25 am
content: I'm helping a friend with his Sun MGA 1200 and I've managed a couple of time to get it up running. But this time I'm stuck. The display says Sr ( service ) after warm up and calibration sequence and I don't even know where to beguin to look. The operators manual only refer to service so I guess I need a Service Manual. Anybody that can share that thing with me or know where I can get hold of it?

author: Aapj3h
author_rank: Newbie
timestamp: September 25, 2023, 09:26:13 pm
content: Quote from: jmsteknik on July 13, 2023, 08:25:25 amI get the Sr (Service Required) notification on my MGA 1200 when the RTC/Dallas clock is removed (and only the ram is installed).The clock in these machines are a DS1216 with a piggy-backed TC5565APL-15 Toshiba that gets converted into a nvram by the Dallas as long as it has power.My understanding is that older rom versions like v3.0~3.2 do not have a lock e.t.c. in the ROM. So i'm hoping that if someone reads this and has a MGA 1200 could dump the two 27C256 eproms.I've got the manuals and my roms dumped and online on my personal blog/website.Sofar i figured out that SUN used a password: "515324" to get into the service menu's. And you can skip the warmup by using the keys "451".Update a few months later:I have the service manual for the MGA-1200 now thanks to SteveyGI also have the service manual for the SGA-9000.And i've got the older rom versions that do not have MOT-lockout stuff build into them.