Sun EPA-75
- Thread starter capriguy7
- Start date
I have the same manual problem is the three way valve does not point out which port goes to what. The low pressure port which port do you use top or bottom
That's why I asked for pics.
Oh, sorry. I don't have one anymore but will look around and see if I can find any. I did take a bunch of pics at one point. Did you search on here? I know there were a couple threads about them.
Yes please take pics of all the vacuum lines top and bottom. The back side between the bowls are still there.
Thanks, I will look
So, here we are. The unit is an EPA-75, manufactured in Kings Lynn/UK facility, back in the 80's or even the late 70's.
I received it some time ago as defect.
It powers up, the IR light source apparently works, the blower operates, the pump might need a kick with the finger but then it runs.
Pushing the calibration button (the one with the circled triangle), the calibration flag will move into the light path, but the gauges will not move the pointer towards the calibration mark.
Most likely the optical unit is too dirty. The mirrors need being wiped with some metal polish and the lenses have to be carefully washed with mild detergent. I would use some dish liquid.
Be careful when doing so.
a) the lenses are made of thin glass but have to be removed from the tubes (and being reinstalled afterwards in same direction)
b) some coating might have been steamed on the lenses. Whatever goes off with water and detergent is dirt. But do not scrubb the lenses.
I took a couple of photos. The hoses are marked with numbers on each end. So you might be required to download and magnify.
I received it some time ago as defect.
It powers up, the IR light source apparently works, the blower operates, the pump might need a kick with the finger but then it runs.
Pushing the calibration button (the one with the circled triangle), the calibration flag will move into the light path, but the gauges will not move the pointer towards the calibration mark.
Most likely the optical unit is too dirty. The mirrors need being wiped with some metal polish and the lenses have to be carefully washed with mild detergent. I would use some dish liquid.
Be careful when doing so.
a) the lenses are made of thin glass but have to be removed from the tubes (and being reinstalled afterwards in same direction)
b) some coating might have been steamed on the lenses. Whatever goes off with water and detergent is dirt. But do not scrubb the lenses.
I took a couple of photos. The hoses are marked with numbers on each end. So you might be required to download and magnify.
Thanks that was the ticket. But now that all is hooked back up, I now have a noisy CO gauge. Can not get it to zero out at all. I guess I have a bad IR chip. Now have to run one or two of those downPlus another five. Upload suffered a hiccup, so I wanted to reduce the number of photos within a single post.
You should be able to put an oscilloscope on the detector signal somewhere on the board. That's how it's done on an Allen machine to determine if it's a detector fault.
If I only had a scope
Looked for a patent number, no luck.
Unless it does not say "patent no#"
There are a few numbers on paper stickers but nothing that looks like a patent number.
Attachments
EPA70, inside the optical unit. But there is a sticker on the outside as well. Stating patent number and a serial number.
Sun aquired the right to manufacture a certain quantity of units, using this patent. Or they were supplied with a certain number of pre-manufactured optical units.
How ever, the serial number reflects the batch it was from.
EPA 75. Here you can see mentioned sticker.
Sun aquired the right to manufacture a certain quantity of units, using this patent. Or they were supplied with a certain number of pre-manufactured optical units.
How ever, the serial number reflects the batch it was from.
EPA 75. Here you can see mentioned sticker.
The frequency function on a multimeter might give some indication. If you get a signal then you know the IR source is working and the detector is at least partially working.
Btw: US3932754A
Ok will try thanks
And this is what? Patent number?
Ok so HC shows no hertz reading at all BUT can adjust it when the zero button is pushed in its rock steady. But when I do the span button nothing will not move.
Now the CO gives a reading of about 34 hertz. BUT can not adjust nothing, zero or span. Ohmn checked the leads and all are good.
Check the function of the switches and check that the IR sources get power.
The switches are known to play up on Sun machines.
Within the optical unit, between the tubes, there is a white phenolic block. On top it shows a screw and a small tube or some round metal thing.
That's the IR-source. It will be heated up to a certain temperature, start glowing in result and therefore emitting IR in a certain frequency.
Have the opened unit powered a short while. Switch it off, unplug the power cable and feel the temperature of the IR-source.
Note: make sure the unit is absolutely withot power when touching some.
Allow the IR-source cooling down a bit before touching.
Otherweise severe injury might occour.
If the IR-source ist hot, it will be powered.
Ok the IR unit is getting power, it is just not warming up. Can that go bad. Seems like it's a solid state piece of equipment. It is getting 120 ac v across it
I don't believe the IR source heats up, the heating up is a different part but I'm not even sure if the EPA-75 would have a heater.
My Allen machines have an IR source per tube and it is on the opposite side of the chopper to the detector.
Its a cartridge heater, it glows red hot, they do burn out with age you can get a replacement from the watlow company The I.R. bench was made by Infrared industries for Sun, Allen, Bear The HC. and CO detectors tend to get noisy...meter needles jumping, with age. I think temp and humidity causes them to degrade. They are a I.R. sensitive photo cell Lead/Selenide chip, with a glass filter over them