As mentioned on my homepage, the Aminco Bowman is my favorite instrument, it is often called just the AB2. It does have flaws and one of them is very serious. However when I refurbish them, I carry out preventative maintenance to avoid these traps and despite their age I feel confident that the end userwill be able to still obtain 5-10 years of useful life out of these spectrofluorometers. I love this instrument, I have virtually everything cross referenced and the only thing I have ever had to buy from Thermo Electron is the software and at the time of writing, I am developing my own software to control this instrument and to remedy this last dependency. This instrument can be dangerous to service with a very high voltage power supply and a powerful UV lamp but with some precautions, it is very enjoyable to work with. While I hope to replace it someday soon, the software offered from Thermo is actually pretty well designed. The executable is small and works with a wide range of Windows versions. The AB2 offers an excellent signal to noise ratio. The top cover is load bearing so other instruments or the computer can be placed on it and it offers a wide wavelength range as standard as the photomultiplier tube is based on the R928(it has a black coating to block out stray light but is otherwise the R928). The beam is also small and horizontal so that the cuvettes do not need to be filled very full in order to take good quality measurements. There are BNC connectors on the right side of the instrument and analog signals from other instruments such as a PH meter, can be brought into the software. The circuit boards slide out of the instrument. Sometimes it requires a bit of gentle force to pull them up and out of their holders but only one cable needs to be disconnected and then they can be pulled up and out and sent for repair. Once here, I can repair virtually anything that goes wrong. However, I have had trouble with a problem that appears to be a design flaw in the CPU board. There appears to be consistent re-work done in one area of the board by the manufacture. I had a very humiliating experience with this circuit issue. I had a bad board here. I repaired it. I tested it more than 40 times and used it in a sale of an AB2 to a university in Michigan. I am no longer able to travel far away as I need to care for loved ones here but at the time, I was hired to travel to this university to provide training to staff. I drove from north of Toronto to Michigan and when it came time for me to train staff with the instrument that I had JUST sold them, it would not power on. I was extremely lucky that the university had another AB2 and I was able to complete the training by borrowing a board and I was able to send a replacement board two days later but it is still painful to think about this day and what might have been. This problem affects the initialization of the excitation monochromator and it is highly unpredictable. Once it has failed, it does not pass again so it is not really an intermittent issue but rather one that can strike after a good deal of testing. I can replace the chip that causes this issue but the chip can fail again and at the time of writing, I am not sure why. I am confident that I will find a solution but at the time of writing I have several of these boards here put aside. I have other boards to sell that do not have this problem. Once I figure this out, I intend to notify customers upfront of the issue that the board previously had and to only sell them to customers relatively nearby in the event they do need to be sent back. Aside from this, there are no other issues I have been unable to repair and I always make sure to have good boards on hand to help customers. I also have three of these hard-to-fix mystery boards and again, I hope to resolve this issue soon. Yet again, I love the Aminco Bowman Series II but there are some other downsides I want to mention. The stirring motors are slow and noisy. I can modify the instrument if needed. There is a shutter that closes to protect the photomultiplier when the lid on the sample compartment lifts off. However, the shutter to the lamp does not activate and if someone was exciting at UV range and had the sample compartment removed, they could potentially look into the UV beam. I have never heard of this happening but I think a warning label is justified. If I forget to add such a label, please make sure you do. I always replace the cooling lines that run to the sample holder but if the lines do break for whatever reason, the water can fill the sample compartment and damage accessories such as the 4 place turret and the clearance under the instrument is not great enough and water can wick back up into the instrument and damage the power supply. Both of these happened to one of my customers. With lessons learned on my part and a few extra precautions during installation, this can be avoided. There are several model numbers that were used with the Aminco Bowman series II line. I do not actually remember them all. Virtually all of the revisions are the same. The very oldest AB2 units did not have fans to cool the photomultiplier and the very latest ones have the lens holders in the sample compartment fixed in place. The lenses in the sample compartment are removable in most units produced. A label to warn people not to remove the lenses is also probably justified as missing lenses have end up being the source of the problem with some people that have called me for help. However, the polarization accessory will not work with the lenses installed. You might want to glue a box or a pouch to the instrument to store them in. It is particularly easy for someone to forget about them years later. How would someone know that the lens holders are in a drawer across the hall etc. Another disadvantage is that the instrument needs a GPIB card. PCI slots are much harder to find now with new computers. I believe that a PCI-E card will also work but I try to buy the GPIB cards used and this option would likely add a few hundred dollars to the price as I would have to buy new or used at a premium price. I can quote a computer when quoting the Aminco Bowman but recently I have been suggesting to people that they might not want one included in the quote. The software can run on many different versions of Windows and most people have some sort of older computer lying around. The hardware specifications are fortunately very modest and pretty much anything you already have will work. This cuts down the cost of the quote, not just for the computer but also for the shipping. I would like to mention that I quote with 2 year warranties but the new lamp has a 90 day limit. They are quite expensive, will not typically last two years with heavy use and can last few little time at all if abused. Please note that there is a lamp enable switch on the left side of the instrument. This is really important. The user must shut off the lamp 20 minutes before powering down the whole instrument. Failing to follow this protocol will cut the life of the lamp in half or worse. Please also read my description of the Perkin Elmer LS-50B. I will contrast it to the AB2 and there will be some more information about the Aminco Bowman Series II.