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Eico HF-81: dead switch...

Patrice B

Patrice B

Super Member
Hi,

I just bought the Eico today for a low price...

Ran the thing to test if it worked and (don't do it) put probably too much cleaner somewhere (maybe alcohol when cleaning the inside of the amp, or Deoxit in the pot!) and the power/treble switch is now obviously dead.

I jumpered the wires temporarily but is there a way to dismantle and repair the switch part (with pliers maybe...)?

I know I could rewire the switch on the obsolete tape speed slide switch instead but I wanna know if there's a fix before doing it.

Don't worry, I ordered the necessary caps for the rebuild...

Amazingly, no hum and clean sound even if some caps appeared to had bad time before.

BTW, it was full of Amperex Bugle Boy 12AX7's. However, all shields are missing and someone managed to drill holes in the cover to install two 1/4 inches jack for speaker outs (it was used by one of the precedent owner as a guitar amp... waste of hifi!!!)

**Treble is working in case you ask...

Thanks.

Patrice
 
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Wasn't on the Auction famous site but on local classifieds.

The jacks are on the side on mine (I'll maybe use one of them to install an headphone out...).

Anyway, nobody's got something about fixing these pots/switches?

Thanks.

Patrice
 
I just repaired a HF-81 treble control and switch that had a bad switch and a broken front bushing. I salvaged the switch from an old NOS mono volume control that I had that used the same switch. The control in my Eico was made by Centralab, as was the donor control. It just involved carefully prying open the various tabs holding the control together and then re-bending them when assembling.
 
Yeah, pliers or a thin bladed screwdriver. You can't make it worse but don't bend the tabs too far, just enough to get it apart. Study it before putting tools to it.
 
Bob91343 said:
Yeah, pliers or a thin bladed screwdriver. You can't make it worse but don't bend the tabs too far, just enough to get it apart. Study it before putting tools to it.
Click to expand...

Thanks...

I will temporarily wire it to the tape switch during the recap process and investigate further for the pot after.

Patrice
 
bkmcallister said:
I just repaired a HF-81 treble control and switch that had a bad switch and a broken front bushing. I salvaged the switch from an old NOS mono volume control that I had that used the same switch. The control in my Eico was made by Centralab, as was the donor control. It just involved carefully prying open the various tabs holding the control together and then re-bending them when assembling.
Click to expand...

I'll try to carefully open the housing and look if it could be repaired.

In the case it's a no-go, do you think I could fit another switch mechanism, like one from another switched-pot, not necessarily from the same brand?

Thanks.

Patrice
 
drknstrmyknight said:
or bypass it and replace one of conveinience outlets with a sturdy switch.
Click to expand...

Outlet is gone... so I could put a power switch here.

In fact, this Eico was modified:

- two 1/4 inch jacks coming from common and 8 ohms taps;
- a grounded power cord attached directly to chassis (death cap is gone!!!).

Strangely, two 0.025uf caps and two 0.033uf (all ceramics) as coupling caps...

The four .1 caps in the line section appears to had a bad time (full bubbles on them, kind of overheating signs).

There's also a "thump" from the power tranny when starting the amp. No buzz or rattling however once started. I plan to add thermistors on the AC line to correct it (after filter caps replacement).
 
The thump is a common thing, not a problem unless your power line isn't solid. And that's maybe what did in the power switch.

There are times when you can get insanely lucky and can find the exact switch to go on the pot. But those times are rare. I recall when you just ordered it out of any distributor catalog, but them days is long gone. <shudder> Yeah, I'm old.
 
Bob91343 said:
The thump is a common thing, not a problem unless your power line isn't solid. And that's maybe what did in the power switch.

There are times when you can get insanely lucky and can find the exact switch to go on the pot. But those times are rare. I recall when you just ordered it out of any distributor catalog, but them days is long gone. <shudder> Yeah, I'm old.
Click to expand...

Well, at least the treble pot is functionning so even if I loose the original switch, I'm not at lost...
 
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