Eico HF-81 Tube Amp to Restore

Your right after a few hours they do get hot. I did get a fan for them one of the
large computer fans that I made a funky cord and switch and it works great cooling
them off.

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Dandy, it really sounds great it just opens up. It totally different sounding than the
Fishers, it must be those EL84's and everything else, the last EL84 tube amps I had
were the Scott's and they didn't sound as good as this.
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The Scott's are much more complicated.....it takes some real know how and experience to get the best out of them. The EICO is dead simple in comparison. The Sounds of most Scott's is much more controlled, tighter and more accurate then the HF81... sometimes with audio you just have to chalk it up to personal preference.
 
Had some work to do on the Eico today, I purchased a quad of
Micamold PIO Caps, They were a good size fit really nice from a
good dealer on ebay. Still I want to remove that top switch from
the amp, Is there a special way of doing that, or just cut the wires
on the switch and add wires to bypass from the grounded wire to
pin 7 on both V-5 to V-6 tube any thing else?


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Here's something new when I play something thru AUX 1 both channels play
but thru AUX 2 only left channel plays??

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Check/clean connections to the Aux 2 RCA sockets, and the rotary selector switch.

BTW, what do you mean by that top switch? Can you post a pic of it?
 
Thanks that what I did tonight and lo and behold the Aux connections were
done wrong, the Left and right Aux 1 were correct but the Aux 2 right had
been put in the wrong place and had to be redone and it works good now.

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Next thing is when I turn the amp on there's a slight buzz from the PT, it goes away
quick and it's silent after that and if I hold my hand on it it does vibrate a little
and it does not affect the sound at all.

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I think I fixed it, I tightened the screws on the side panels and it stopped,
still is there a way to dampen it. Is there any other upgrades that can
be done to the amp.

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fawset bibb washers between trans and chassis and end bells to laminations.
just get ones that fit.
helps damp out buzzes and such.
 
The tube sockets are not good, thanks for that info. I did take a ohm reading of the
OP transformers and I got readings, so I think there good. I'm going to put in a power
switch in the back to not use the front treble switch which it a odd design, I see a lot
of them with switches put in the front drilled in and it doesn't look that good. Dandy
I'm only at this point going to put in new .1 coupling caps and new electrolytics and
test the resistors and change some wiring.

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I broke that f****g switch in the first minutes I owned this amp. I've put a switch in the accessory AC outlet.
 
That worked for me, I would of put it in the front but then you have the
power wires going around the amp which I didn't want.

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Been playing the Eico for awhile, it's been sounding great. there is one question
there's a slight hum in the right channel none in the left is there a problem or not?

Thanks
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Been playing the Eico for awhile, it's been sounding great. there is one question
there's a slight hum in the right channel none in the left is there a problem or not?

Thanks
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Depends whether it's enough to bother you. Try flipping the tubes left to right to see if it's a tube. If not, you should be able to trace it down if you have a scope. Compare the amount of ripple at each stage left to right.

Integrated amps have a lot of components participating in the process - I don't know of an easy way to trace it besides walking through the whole pipeline.
 
No scope But I did a little work on it today, TB19 and TB20 I missed those two areas that are
grounded to the chassis so I cleaned the areas and reattached the screws and tightened them,
and I decided to tighten all the tube socket's as well.

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Last edited:
update!

There was a bit of buzzing from the power transformer of late, so I removed the
bolts and found out the four screws that hold the cover were loose so I tightened
those up, next someone put in the PT pieces of wood the were moving back and
forth so I removed them and added two new pieces and you know when I turned
it on this time it really quiet down.

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I think it goes like this with the restoration of vintage pieces. It takes a while till all the bugs are shaken out.
 
Hi Dandy, Your right It does and when you find little pieces of wood stuck in there
that doesn't do anything, it just amazes me what people do to try to get it to
work right.

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Turn the useless tape switch into a power switch....
Until you might want to play tapes. The hf81 is one of the very few integrated tube amps that has not only a tape head input, but also permits switching eq from hi to lo speed. Tape rules—give it a try. Old tape decks are really cheap and taped not much more than lost on eBay.
 
Until you might want to play tapes. The hf81 is one of the very few integrated tube amps that has not only a tape head input, but also permits switching eq from hi to lo speed. Tape rules—give it a try. Old tape decks are really cheap and taped not much more than lost on eBay.
Of course I mean tapes not much more than lps. Curse you autocorrect.
 
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