Hoefer SE640 - Manual (Page 34)

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Upper buffer
chamber leaks Mis-aligned parts Check that the glass plates, spacers, and clamps are aligned
and fit snugly into the upper chamber gasket.
Check that both gaskets are centered and that the position-
ing ridges fit inside the grooves.
Dirty or damaged
components Check that the gasket is not damaged or pinched. Replace
if necessary. Check that the upper buffer chamber is not
warped from prior exposure to excessive heat.
Power supply
detects current
leak Electrical path to
outside ground/earth Add more silicone grease to seal heat exchanger grommets.
Check for leaks or cracks in the heat exchanger. Replace
worn grommets.
Dye front curves
up (smiles) at
edges Uneven heat
distribution Fill the lower buffer chamber to the level appropriate for at
edges the run. (See Fig 7, page 19).
Use magnetic stirrer and stir bar to keep buffer well mixed.
Excessive heat Circulate ext. coolant. Decrease the current or voltage setting.
Prechill the buffer. Run the gel in the cold room.
Protein streaks
vertically Particulates in
sample Centrifuge or filter sample before loading to remove
particulates.
Overloading Load less sample.
Degradation Add protease inhibitor such as PMSF.
Unusually slow
(or fast) run Current leakage
around gel Check for leaks; all plates and spacers must be aligned and
free of grease and cracks.
If used, the buffer dam must be secure.
Sample or reagent
preparation If the required pH of a solution is overshot, do not
back-titrate. Discard and prepare fresh buffer.
Check recipes, gel concentrations, and buffer dilution. (For
instance, do not use Tris-HCl instead of Tris for Laemmli
tank buffer.)
Decrease the salt concentration of samples.
Reagent quality Dispose of older acrylamide solutions and use only stock of
the highest quality. Use only freshly deionized urea.
Voltage or current
settings To increase or decrease the migration rate, adjust the voltage
or current by 25–50%.
problem possible cause remedy