Eico Hf 81 Noisy After Short Sleep

tube-a-lou

Addicted Member
Hi all,
Have not been around these parts in awhile, and wow what a change the site looks
great. So I've been playing my Fisher X202C for awhile and decided to change it to my
Eico Hf 81, everything sounded good but after a few minutes of play it started to get a
static sound in the right speaker I did change some tubes around but tonight when I played
it, it did it for a few minutes and then it stopped. I guess I have to go into this week and
check it out, Resistor, tube socket or other??

Thanks
Tube
 
If it's been sitting for a while, I'd try cleaning and "exercising" all the controls by running them to both stops slowly several times. Also not a bad idea to re-tension and clean the sockets. I do know the treble/power control tends to go south on these - there's exact new production replacements available if that seems wonky.

Also worth checking - I had some intermittent noise that could be traced to a loose tube shield ... make sure those are locked down tight.

Killer sounding amps when they're working right. Luck wit it, eh.
 
Thanks, I did replace the treble control awhile back, took the switch out and rebuilt it. I did replace a few tube sockets which
might be the problem or some of the older resistors. Where do you get the replacement controls from?
 
If it was a kit, check for cold solder joints. I use a wood chopstick to lightly tap on components to reveal bad connections

but I second sKiZo's recommendation about general "wake-up" maintainence as I have experienced this myself

great amp the HF-81

Mark will build new precision controls or restore old ones
http://www.oldradioparts.net/
 
  1. Carbon Comp resisters in the plate circuit are known to get noisy, usually 100K, replace with carbon film or metal film. Fender guitar amps have the same problem....
 
Okay so tonight I went in and replaced the two 1.8K resistors in each channel and resoldered
all the pins in the socket that gave me noise when I put it back on so far no noise, the two 1.8K
resistors looked pretty old with there cardboard covering and all.
 
If it was a kit, check for cold solder joints. I use a wood chopstick to lightly tap on components to reveal bad connections

but I second sKiZo's recommendation about general "wake-up" maintainence as I have experienced this myself

great amp the HF-81

Mark will build new precision controls or restore old ones
http://www.oldradioparts.net/
Plus one should you need a volume pot rebuild, Just a shout out! Not that it's the source of your problem, Mark did one for my HF-85, just be careful reinstalling because the backs of the new pot has a thin film covering and is easily damaged.(I know because I damaged mine)..
 
Thanks for that, I put in a new Alps blue pot. It's not original looking but it's that taper that's
so smooth!
 
On mine, the treble switch was broken on day one: adding a slide-switch behind in the AC receptacle cured the problem. I didn't thought about Mr Oppat however ( he rebuilt my Fisher X-100-2 volume pot a few years ago ).​

I had noise-static problems too but it was the 12AU7's.

It is presently in duty for our TV set, some kind of two-channels home cinema with two big Electrovoice speakers...:music:
 
I'm using it with a pair of old GNP speakers, I purchased them off ebay for $35.00 and with their
French drivers in them it was the best $35.00 I ever spent.
 
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