Very Low PMT intensity

Hi Harpreet,

i assume that your HCL is new, you have left it 15min to warm up and its current is at the suggested value. I normally check if the beam is reaching the window by placing a white piece of paper on the detector window. If the beam is far from the window and auto adjustment does bring it closer, i adjust it manually. The procedure is written in the manual. Turning D2 lamp off , helps a lot. 

The PMT is on the preamplifier PCB and sits on a socket. Wide range PMT is optional but i do not know if Thermo puts it inside the instrument or sends it separately in its own box.

Good luck

Hi DIM,

Thanks for prompt response. AutoAlignment was bringing HCL beam to edge of sample compartment exit window. With manual adjustment, beam was brought to center of window.  Hence in principle full beam should be falling on PMT. 

I am curious about the 'PMT without connector' which is mounted in slot outside/beside the main optics compartment.  If it is the actual PMT, then it seems that the round 11-pin Connector with cable is missing! Also I suppose a small Pre-amp PCB should also be seen somewhere?  

You have mentioned that PMT is on PreAmp PCB.  Can you inform where this PreAmp PCB should be located? 

Just to check if there is a second PMT somewhere else, I opened the main Optics compartment but could not find any PMT inside. Upon tracing, observed that the beam after travelling horizontally then goes vertically downwards into the another compartment which I could not open since it requires lot of critical dismantling and hence was risky to open.

So I am still confused that the observed 'PMT without connector' is actual detection PMT or whether there is another PMT inside the 'unaccessible' compartment.  If you can throw some light on the PMT connector cable and PreAmp PCB (info or photo or diagram), it would be quite helpful. 

Thanks.

Harpreet 

Hi Harpreet,

i have tried to upload in image from the manual but i could not. The PMT has indeed 11 pins and it is mounted on the pre-amp board. The cable is not needed, as it sits on the board.

D

Hi Dim,

Thanks for the info. Please send photo on my email id cheema_suravi@yahoo.in .

It seems that that the Pre-Amp PCB is missing since only PMT pins are jutting out from the PMT enclosure.

Actually this Unit was shipped from one city to another and maybe somehow this PCB went missing!

Also observed that there is one ribbon cable which is connected one side on the main PCB (7x2=14pin) and other end is lying loose. I guess that the loose end connector could be connected to the connector on Pre-Amp PCB.

If above surmise is correct, then I have to arrange the Pre-Amp PCB. I wonder if Thermo will be able to provide since the S Series is an old model.

The PMT is Hamamatsu model R508 and Thermo part No. 9423 390 08341.

Can you provide some input as to from where to source this PCB? Can you send photo of Pre-Amp PCB to confirm if it has this 14-pin (7x2) Connector?

Thanks.

Hi Dim,

I think the ribbon cable connector is 8-pin (4x2) and not 14 pin as mentioned in my previous post.

Harpreet

Hi Harpreet,

i think the cable from the pre amp pcb goes to control pcb and it is a 14 pin flat (ribbon) cable. On the pcb the connector is PL1. If you look on the control pcb board and the loose cable is hooked on PL1 then you have the solution to your problem. Regarding the pcb and if it is missing your local Thermo distributor will help you find it.

Hope it helps

Kind regards,

Dim

1. Hi Dim,
2. Thanks for the Pre-amp PCB diagram. I will check out on the PL1 connector on control board tomorrow. 

I also feel now that problem is diagonized to missing Pre-amp PCB.

Will contact Thermo if they can help and supply the same. 

Appreciate your prompt responses and help in sorting out the issue.

Thanks

Harpreet