Realistic HP-100 Eletrostat

[Big Bill]

Suggestions?

They have been charging days, I try them, they play, but are weak, then they “discharge” (?) within 30 seconds. I’m going to bypass the switch with soldered jumper wires and then try again. Anyone have any other suggestions?

Bill.

 

[Big Bill]

I went ahead and...

I decided to disassemble the switch once I went in. This switch is a joke! I am surprised any of these still work! The copper slide jumpers are so thin, that there was no “crimp” to them left. Please see the attached pictures for an illustration of what I’m referring too.

I decided to remove and solder the leads directly together and use heat shrink insulation. I reassembled and reinstalled the switch for appearances sake and to keep it original for the next guy down the line. I hope to have news to report on the morrow!

Bill.

 

[wualta]

Good detective work there. Yeah, if the switch is flakey, it just ain't no use. I hope that fixes the problem.

 

[Big Bill]

Good detective work there. Yeah, if the switch is flakey, it just ain't no use. I hope that fixes the problem.

Thanks brother! I'll keep my fingers crossed....

 

[Sir.Byrd]

Nice discovery (well not really nice)

Let's see if it works.

 

[waltzingbear]

for those following along at home, they should have also checked the PTC resistors, they can be either removed or replaced with regular resistors (PTC= POSITIVE TEMP COEFFICIENT)
also the bias supply needs checking, its marginal anyway. Depending on what kind of caps they used it may not be working anymore.

 

[timb5881]

I just revived a HP-100 setup and it works great. It took about two days to get them fully up and running plus balanced. Not a bad headphone but not a great one. It does pick up low level details fairly well and the frequency response is good. Not a bass monster but does present bass with good detail. Same with the treble detail is there but it is a bit low in volume. These sold new for $79 in 1974, so If they were new today maybe $400. I got mine off of eBay for $75 with transformer box.

 

[timb5881]

It has been many days of being plugged in for bias the sound is still getting better. The bass has filled out more and details are becoming clearer