Advantest R8340A Picoammeter, High resistance meter review

[PartialDischarge]

In my units the fan blows outwards

[leighcorrigall]

Eventually, I am going to have to recoat the board with some protective layer. As I have never seen coatings like this on circuit boards before, I would also appreciate it if someone with experience could provide a recommendation on a product that they have used.

I purchased a clear insulating varnish called "EL 600" manufactured by Sprayon https://www.sprayon.com/product/el600-clear-insulating-varnish/. According to McMaster-Carr https://www.mcmaster.com/7437K21/ and the information printed on the can, the coating has a dielectric strength of up to 2300 volts per mil and an operating temperature of 150 °C (I will assume that maximum temperature comes from the ASTM D115 specification). To apply the coating, I will have to remove the board again and take it outside. I will share my results with anyone that is interested. 

[Kleinstein]

This spray varnish likely contains quite some solvents. So one should be careful with some film capacitors: they may get damaged from solvent. Especiall PS type caps are quite sensitive to solvents and could be damaged.

[BD1QMP]

found another instruction manual of R8340
https://manualmachine.com/advantestcorporation/r8340a/4666782-instruction-manual/

[serg-el]

https://cloud.mail.ru/public/JMtw/YPi1wbxUM

Manuals, foto and firmware

[Kosmic]

I disassembled my R8340 for clean-up and did not notice where the white cable from the transformer was going exactly. Now i'm reassembling and i'm not sure where it should be fixed.

Is it the guard and should be screwed with the shield standoff ? anybody know ?

[Kosmic]

I found my answer looking at some pictures from serg-el.

[BD1QMP]

Today, My 8340A was broken  . the reason is when I output 1000V, it is short with ground. the main fuse was broken, when I replace the fuse, it give out Err HV kV.   it can output 1~100V.   cannot output >100V.

No I have to repaire it
     

[BD1QMP]

1 days later, I turn on it for a while, 0-100V is fine.
but when I setup the source output to 101V, the V source output voltage is 1050V. there should be some mosfet/transistor broken.
when I remove the cover, I found Q55(C3150. NPN, 800V) and Q56(K786 N-Mos,900V) are very hot.
 

Today, My 8340A was broken  . the reason is when I output 1000V, it is short with ground. the main fuse was broken, when I replace the fuse, it give out Err HV kV.   it can output 1~100V.   cannot output >100V.

No I have to repaire it
   

[BD1QMP]

I found Q60 （Mosfet K786）is broken, after replace it with a used K786 (bought from Taobao, 0.8RMB/unit), the HV output can reach 400V, but beyond 400V setup is output 400V. 

[PartialDischarge]

Check the resistors that are varnish coated, they may be bad/burnt