Finally, an Eico HF-81
- Thread starter specialidiot
- Start date
specialidiot
Break Glass, Smoke Lucky
question for you resto-freaks.... what's the best way to clean up the plates (if that is the right term) of the transformers? The bells clean up nice, but NEVR DULL doesn't clean up that surface rust.
jaymanaa
RIP 1961-2018
I use a small wire brush, or even sandpaper if they are terrible. Some folks will say that method compromises the lam insulation on the edges, but if you have rust, it's already been compromised on the edges. Any eddy currents caused by this insulation being gone would not affect an audio signal anyhow.
specialidiot
Break Glass, Smoke Lucky
gotcha.... then some kind of rattle can paint to cover it up, correct?
jaymanaa
RIP 1961-2018
Yep, a good paint if you don't already have some, is Rust-oleum BBQ black. It will take the heat and then some, plus it's not overly shiny. Also stops rust and doesn't need any primer.
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Saint Johnny
Bon Ton Roule
+1
I can highly recommend BBQ Black, as well. I've used it on Harley engines and misc. car parts for years, it lasts forever.
HF-81 cosmetics
Congrats on the new hardware.
The wood on the front of your HF-81 looks pretty good. Didn't get a good idea of the condition of the brass front panel, but it's pretty easy to clean up if it's not looking good. I hit mine with coarse steel wool until the brass was cleaned of oxidation and crud. Then I painted the engraved lettering black and when dry, hit the front with emery cloth to get the excess paint off and to leave a horizontal "texture". (You could also polish it with steel wool if that's the look you prefer.) Clean and degrease the brass (dentatured alcohol or your favorite solvent) and spray with Krylon Clear or a similar clear poly. It's not "original", but I'm guessing you don't care, and it stayed bright for many years.
As for the chassis and cover, I found some matte paint at the hardware store that was fairly similar to the original Eico color. It looked pretty good when I was done.
Jim W.
Congrats on the new hardware.
The wood on the front of your HF-81 looks pretty good. Didn't get a good idea of the condition of the brass front panel, but it's pretty easy to clean up if it's not looking good. I hit mine with coarse steel wool until the brass was cleaned of oxidation and crud. Then I painted the engraved lettering black and when dry, hit the front with emery cloth to get the excess paint off and to leave a horizontal "texture". (You could also polish it with steel wool if that's the look you prefer.) Clean and degrease the brass (dentatured alcohol or your favorite solvent) and spray with Krylon Clear or a similar clear poly. It's not "original", but I'm guessing you don't care, and it stayed bright for many years.
As for the chassis and cover, I found some matte paint at the hardware store that was fairly similar to the original Eico color. It looked pretty good when I was done.
Jim W.
specialidiot
Break Glass, Smoke Lucky
Thanks for the info gentlemen.
Jim W. I was actually asking on the Eico list if anyone had a drawing or a source that could fab a new panel. The only answer so far was that the block of wood that's on there could serve well if dressed up.
I could actually veneer it and the edges in my famous rosewood veneer, or maybe something less grained like a mahogany. Then paint the chassis and cover as you suggested.
The brass faceplate does need work. Someone suggested dipping it in boiling water with 1 tablespoonof baking soda per quart of water to remove the laquer, then clean it up with 1600 grit wet sand or 0000 steel wool. It seems the boiling water trick doesn't remove the black paint in the engraving, but even if it did, I could still paint it.
Good stuff, I have hope!
Jim W. I was actually asking on the Eico list if anyone had a drawing or a source that could fab a new panel. The only answer so far was that the block of wood that's on there could serve well if dressed up.
I could actually veneer it and the edges in my famous rosewood veneer, or maybe something less grained like a mahogany. Then paint the chassis and cover as you suggested.
The brass faceplate does need work. Someone suggested dipping it in boiling water with 1 tablespoonof baking soda per quart of water to remove the laquer, then clean it up with 1600 grit wet sand or 0000 steel wool. It seems the boiling water trick doesn't remove the black paint in the engraving, but even if it did, I could still paint it.
Good stuff, I have hope!
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shacky
Addicted Member
That's going to be so sweet when you are done with it.
I just got mine back from Narodow. He put the tone controls and focus back in for me. I'm in tube heaven again. Hope you pots are in better shape than mine. But even with less than optimum pots this baby sounds soooo sweet
Using it with my newer to me Klipsch Forte's. An excellent match.
Nice that you have original Mullards. That will top it off :yes:
I just got mine back from Narodow. He put the tone controls and focus back in for me. I'm in tube heaven again. Hope you pots are in better shape than mine. But even with less than optimum pots this baby sounds soooo sweet
Using it with my newer to me Klipsch Forte's. An excellent match.
Nice that you have original Mullards. That will top it off :yes:
specialidiot
Break Glass, Smoke Lucky
well I'm almost done with the recap. The builder of this kit was lucky it worked at all. I have to correct almost every solder connection as he seemed to just hit it with a blob and moved on. I reflowed a ground on the back panel and a pea-sized piece dropped right off.
I've also broken a couple of socket pins but have been able to force unused pins out of the socket to use as replacement.
Here's a shot of V10 (one of the outputs) and a representative view of the "quality" soldering job I'm finding.
Just four more caps to replace and the fuse holder, then it's time to bribe my favorite cabinet builder...
I've also broken a couple of socket pins but have been able to force unused pins out of the socket to use as replacement.
Here's a shot of V10 (one of the outputs) and a representative view of the "quality" soldering job I'm finding.
Just four more caps to replace and the fuse holder, then it's time to bribe my favorite cabinet builder...
clydeselsor
Lunatic Member
Well I think the wood front is kinda cool. I have been wanting one of those for a long time! Fellow AKer Ekmanning5 has one of those in his living room hooked up to some beautiful Klipsch Cornwalls that sounds really sweet!!!
Congratulations!
Congratulations!
thefragger
Certified Crazy.
specialidiot
Break Glass, Smoke Lucky
some before and after pics:
I replaced a lot of caps and 4 power supply resistors:
So tonight I brought it up on the variac...
How's it work you might ask?
I'm almost there....
No smoke, even the pilot lamp worked.
Very nice sound out of the left channel, but weak output and some hum out of the right channel. I only had time to troubleshoot for a bit and swapped the output tubes. Then I got some staticy/dusty sound out of the right channel until I tapped the rear tube a bunch of times.
I ran out of time but I should be able to track this down. I'll swap the other tubes around, clean sockets, and maybe trace my work to see what is different between left and right....
I replaced a lot of caps and 4 power supply resistors:
So tonight I brought it up on the variac...
How's it work you might ask?
I'm almost there....
No smoke, even the pilot lamp worked.
Very nice sound out of the left channel, but weak output and some hum out of the right channel. I only had time to troubleshoot for a bit and swapped the output tubes. Then I got some staticy/dusty sound out of the right channel until I tapped the rear tube a bunch of times.
I ran out of time but I should be able to track this down. I'll swap the other tubes around, clean sockets, and maybe trace my work to see what is different between left and right....
gogofast
Addicted Member
wow, great work!
i thought mine was in bad shape, but after looking at yours "before" pictures, i feel quite lucky.
seems like you've replaced pretty much all critical caps, so the problem must be easy to track down - like you said. one thing i noticed from mine was that those tube sockets were very dusty and bits and pieces of dust, cleaning paste, and etc got into the holes. i had to eventually replace a few to get rid of statics and crappy noise. your problem might be from the pots, too.
anyways, i think highly of your great work! :thmbsp:
i thought mine was in bad shape, but after looking at yours "before" pictures, i feel quite lucky.
seems like you've replaced pretty much all critical caps, so the problem must be easy to track down - like you said. one thing i noticed from mine was that those tube sockets were very dusty and bits and pieces of dust, cleaning paste, and etc got into the holes. i had to eventually replace a few to get rid of statics and crappy noise. your problem might be from the pots, too.
anyways, i think highly of your great work! :thmbsp:
specialidiot
Break Glass, Smoke Lucky
Well it's going to be good, I can tell. I'll need to spend some time with the right side and I just pulled a gig that is going to consume my weekend... might even miss the Super Bowl. Oh well.... more jing for my obsessions.....
wa2ise
Super Member
As a troubleshooting method, you can compare voltage readings of the bad channel to the same points in the good channel. And if you are careful enough, try crossconnecting from the good channel to the bad channel to see if you can, say drive the output stage of the bad channel with the corresponding signal from the same point of the good channel. Just be sure you don't misconnect say a plate to a grid, or such. Use a capacitor in the crossconnection, so if you do manage to mismatch DC levels you don't fry something. Be sure to exercise safety rules (one hand in pocket, etc.) so you don't put 400VDC across your heart.
specialidiot
Break Glass, Smoke Lucky
uh, thanks for your insight Jack!
ah, the voice of reason... I hope to be able to spend some time with it tomorrow. First I'll try Jack's method and when that fails I'll clean pins and sockets. Then start checking voltages. I have the chart from the SM too.
Glassweights
Compulsive about tubes
Seriously
They really had ceramic caps in places important enough you put Paper in Oil caps in their place?
That is just mind boggling how much of an upgrade that is going to be. or are my eyes fooling me?
Dan
Nice work!
They really had ceramic caps in places important enough you put Paper in Oil caps in their place?
That is just mind boggling how much of an upgrade that is going to be. or are my eyes fooling me?
Dan
Nice work!