Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Sharp HP400H in cup pot bypass/replacement
New Posts  All Forums:Forum Nav:

Sharp HP400H in cup pot bypass/replacement

post #1 of 7
Thread Starter 

I bought a pair of these on ebay for £8 + £5 P&P but when they arrived the volume controls in the cups are damaged - on asking the seller they haven't been used for years but were supposedly working when last tested.


I opened a cup to find more wires than I was expecting (see pic below, I assume the yellow and one of the black wires go to the second driver on the front) but everything makes sense so I shorted blue to brown on the PCB leaving the pot attached, and compared it to the other ear (which is also dodgy but usable) and it sounds much worse - most the shimmer has gone from cymbals.


Can anyone more experienced comment on how I should bypass the pot (or tell me it needs to be there) or whether a dead resistor or cap could be the culprit? 


I guess it could be that the tweeter has died, and the woofer is actually full range but quiet/bad at highs?


I don't want to spend more if the drivers are damaged but don't mind doing so if they're fixable.



Thanks in advance for any help :smile:

post #2 of 7
Thread Starter 
No-one familiar with these, or similar old school designs? triportsad.gif
post #3 of 7

You didn't just return them when the got delivered DOA? 


Draw a schematic of what you have.

Bust out the multimeter and start measuring stuff to see what makes sense and what doesn't. 

Taking VERY highly detailed photos of everything, printing them out (in color) and writing which wires go out of frame to where is also a good step.


These 3 steps are not necessarily in any specific order, and may be done in any order, but it is usually wise to start with good photos with notes of EVERYTHING. 


It is not unreasonable to spend as much time documenting a vintage restoration and figuring out how it ever worked in the first place as it is to spend actually replacing parts.

post #4 of 7

Your account does not have the required permissions to access this page.


My not upload photos. Error.

post #5 of 7

Az enyém már nagyon sok. A hibák közül:
Jack forrasztási és réz vezetékeket lóg összeolvadt.
A shell (csésze) szakadt fekete (föld) drót.

post #6 of 7

Mine is already very much. The errors were:
Jack solder and copper wires hanging merged.
The shell (cups) torn black (ground) wire.

post #7 of 7
Did you ever do this mod? Got a set that were my Dad's - he got them when I was a young boy - I'm 44 now and they look as new.

Only issue is that either the pots are gone or the wiper track is corroded over since they haven't been adjusted from full for years. They work well and sound very nice as they are though.
New Posts  All Forums:Forum Nav:
  Return Home
Head-Fi.org › Forums › Misc.-Category Forums › DIY (Do-It-Yourself) Discussions › Sharp HP400H in cup pot bypass/replacement