Keithley 2015 THD ebay bargain

[Signal Simon]

Thanks for the reply Ian,
I left my meter powered up all day. Since I saw yours do the same as mine, I've decided it isn't faulty.
I've removed the front panel and given everything a good clean and polish.
The wires to the 4mm sockets just pull off, but the white wire on the Amps jack doesn't.
You need to remove the fuse and then the spring and contact can be unthreaded through the bottom of the fuseholder moulding.

After it's been in bits, cleaned and made to do some work, it seems to behave a lot better.
The mV offset is showing 0.0015mV at the moment, but it was 0.0089mV just a few minutes ago.
Given the input impedance of the unit, I think there may still be some absorbed moisture that needs to be driven out.

Simon.

[jpb]

I've just rechecked mine and it also cycles to -1.2V on open circuit with default settings.

Shorted out (just two terminals shorted) is around 0.0025mV though it varies up to about 0.0030mV so Signal Simon yours seems fine (or mine is equally broken!)

I took mine apart quite a few times to change capacitors and the screen and most of the screws but I was careful to wear white cotton gloves to avoid
compromising the high impedance.

[bingo600]

I took mine apart quite a few times to change capacitors and the screen and most of the screws but I was careful to wear white cotton gloves to avoid
compromising the high impedance.

@jpc

I have a K2015 , and haven't changed the caps yet.
Do you have a list of what caps i need to get (please) ? .... I'm in a lazy mood right now

/Bingo

[jpb]

I took mine apart quite a few times to change capacitors and the screen and most of the screws but I was careful to wear white cotton gloves to avoid
compromising the high impedance.

@jpc

I have a K2015 , and haven't changed the caps yet.
Do you have a list of what caps i need to get (please) ? .... I'm in a lazy mood right now

/Bingo

I'm sorry I did have a list (or rather the highlighted and annotated print out from the service manual) but now I can't find it.
I basically changed all the electrolytics listed under replaceable parts in section 6 of the service manual (you have to go through the lists for each board):

http://exodus.poly.edu/~kurt/manuals/manuals/Keithley/KEI%202015%20Service.pdf

I made the mistake of ordering the parts before my K2015 arrived and then found some of them were physically the wrong size. Also there was at least one that was on the list and not on the board (or was it the other way around).

So to avoid wasting money as I did, you need to look on the board and get the exact specs from the manual. But be very careful to get both the lead spacing and the physical height correct. I replaced one on the main board with one that was a bit taller and then found it kept scraping on the lid when I tried to close things up again!

Sorry  not to be more helpful, it was a little while ago that I did this and my office/study/lab/library is in a state of chaos at present!