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Eico HF-22's total reassembly.

marloubow

marloubow

Best Day Ever
Hi all,
I recently traded a Garrard RC-60 TT for two Eico HF-22’s. I was aware of their condition and was fully prepared to do a complete restore/reassembly. With the amps, came the original assembly instructions, parts list and the Sams schematic which covers the HF-22 & HF-35. Most of the important stuff is here. Tubes test good, but not sure how matched as I just have an emissions tester.

Before I get too far into the restore, I need some opinions on what to do about the chassis. The first chassis, I was able to remove nearly all the black spray paint and keep 98% lettering intact and about 90% of the original paint. The second chassis has proved to be much more of a challenge. The black spray paint is really gripping, so much so that I’m losing some of the lettering and more of the paint.
Also the second chassis looks to have been dropped as there is a broken weld and a raised “dent” on the top.
The end of the chassis with the “Eico” logo was thankfully not painted.
.

I would really like to keep it original, but that’s looking less likely every day.
Just need a little input from those who have been here before.

I’ll have a lot of questions along the way.

Before I order components, I’d like to get some ideas on which ones should be upgraded.

I’ll add a CL-90 inrush limiter to be sure.

I’ve uploaded the assembly instructions and Sams to the AKdatabase for reference.

Thanks

Martin

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I can't offer any technical help, but I think you got a heck of a deal and it looks like you're in for a really fun project. Hope you can save the original lettering, but even if you can't and have to repaint the entire chassis, you're saving these units from the scrap yard. If you do have to repaint, perhaps you can include some kind of information whether on the outside or inside of the chassis about what they are for future generations/owners. One of the things I like to do is fasten a copy of the schematic to the inside of the bottom cover just in case I or a future owner needs it. After all, we don't actually "own" anything, we're just the temporary caretakers until it gets passed on to the next person.:)
 
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Well I haven't been there before, but looking at the chassis, I believe they're too far gone to be able to retain original paint and lettering. Were it me I'd strip them down, do the metal repair, and give them a brand new attractive paint job.

I will say I find your project very appealing. Lots of folks do recaps, etc. But basically a strip down and start from scratch? Now you're talking! Rebuild with all new components (well except for the vintage iron of course) and you'd have essentially new amps!

I'm keeping an eye on this thread for updates !
 
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babblefish,
I like the deal I got also...it was a good trade for both parties. The other party has already restored the TT and sent me the youtube link. He did an excellent job on it...http://youtu.be/AuhOHUGUtYE
I agree with you about keeping some kind of documentation with a unit.
I have a Setchell Carlson farm radio, circa 1939, that still had a service tag from when it was converted to 115V. I've found a couple of older gentlemen here in town who knew the tech and was able to gather some history about him. Cool stuff.

Ohighway,
Outside of finding some empty HF-22 chassis', I think your observations are correct. Strip and repaint.
I don't suppose I should be too critical of the person who repainted them.
They must have been in pretty bad shape. I think guy struggled with the whole idea of repainting, because, he at least cared that "information" panels were left intact and unpainted. :thmbsp:

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Kyle @ the akdatabase has the sams doc. up.

Anyone have knowledge about which components should be upgraded?

Mouser has nearly all the stock stuff I'll need.

Thanks all

martin
 
I just had an idea. Before you strip the chassis, bring them to a print shop that does silk screening and maybe they can photograph the text, clean them up on the computer then re-silkscreen them onto the chassis after they've been repainted. Might cost you a bit of money, but at least you'll have an intact time capsule.
 
Or, you could at least take some hi-res photos of the chassis as they are and keep them with your record of restoration. That way a future owner would know exactly what to aim at.

I also think you got an amazing deal. I like the grip of this Mullard 5-20 design, though my pair are self-built to the original circuit, including choke. I'll also be following your rebuild.

Nice that the other party in the trade has also done a great job with the TT.
 
Another thought with a chassis repaint -- although I'm hardly pushing this as the way to go -- is that since the original identity will likely be lost, it wouldn't be much of a stretch then to convert the units to HF-35s. Other than drilling for new power transformers, the rest would be quite easy. Just a point to consider in your rebuild effort, with nothing wrong at all simply rebuilding them to their original specification.

Either way, a very neat project. Good luck with it!

Dave
 
Only problem with converting them to HF-35 is that you'd have to get different power transformers. And there are folks who say that even with less power, the HF-22 amps sound nicer than the HF-35.
 
Gentlemen,
I've got a project list started at Mouser with about 95% of the parts I'll need. Sometimes the mmf, mfd, pf and uf confuse me a bit even with a conversion chart. So do you guys mind checking a couple of values and tolerances for me?

_____old_ /_ new__

C1 .05mfd / .047uf
C2 47mmf/ 47pf
C9 850mmf/ 820pf
C13 .03mfd/ .33uf
R6 1.138ohm/ 1.13Kohm
Multisection cans 2x20mfd (old)/ 2x22uf (new). I may try a restuff or just fit them below. Either way I'll have plenty of room.

I'm thinking a lighted toggle for a on/off switch seeing how a previous owner already drilled holes for them.

I need a couple of tube shields for the V1's (23.41mm dia. x 53mm+-).

A pair of RCA inputs.

A pair of power cords...grounded or not?

A pair of fuseholders.

These are my first mono blocks and thinking about them as two separate units takes a little more concentration.

I am ignorant about the "preamp power" sockets. I read over that section, but came away unclear. Reread.

Any suggestions and input are welcome.

Thanks
Martin

P.s. In case you haven't guessed...I'm a real noob at this stuff...a hobbyist at best.
Your patience is really appreciated.
 
C1 .05mfd / .047uf Okay
C2 47mmf/ 47pf Okay
C9 850mmf/ 820pf Okay

Multisection cans 2x20mfd (old)/ 2x22uf (new). I may try a restuff or just fit them below. Either way I'll have plenty of room.
Okay, but try to get multisection cans; smaller caps can be less satisfactory or safe, even if of same or higher voltage. Others may chime in.

C13 .03mfd/ .33uf
No, you need a 0.033uf cap. Make sure you get cap voltage right; e.g. this one is a 600V or higher.

R6 1.138ohm/ 1.13Kohm
I think this is right. (The original Mullard circuit has 2k2.) But this is a strange value and the schematic does not say Kohms here, but elsewhere it does, e.g. R11, R12. I hope a true guru like Dave Gillespie can confirm for you.
 
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Martin & Dandy -- The value specified for the EF86 cathode resistor for the HF-22 is in fact 1,138 ohm ohms, or 1.138K. The value for this position is hardly as critical as Eico would have you believe by the use of such an exacting value. Very much more than likely, they needed a resistor of that value for a device of more exacting needs -- say in a multimeter or similar application -- but to get quantities up to get the best price, they used that component in other applications as well (like the HF-22) where it would work appropriately enough.

The value is somewhat important, in that it will help (in part) determine the plate voltage of the EF86 stage -- and -- since that stage is direct coupled to the following 6SN7 phase inverter stage, it also then helps to set the operating point of that stage as well. In reality however, any value between 1.1K and 1.5K should work just fine. If you can get a 1.13K resistor, that will work perfect.

Dave
 
Dave,
Thanks for the insight.
A 1.13K is on my order list as well.

Dandy
Here is the mouser pt.# for the 22uf.
Mouser Part #: 647-TVX2W220MCD
I did use some new multi section cans on my fisher 800c restore that I purchased from hayseed hamfest. Same footprint, nice looking can.
The gentleman that I received the Eico's from gave me a heads up on a couple of others can cap builders...one of them @ 15.00 ea. About half the price I paid at hayseed. But as with anything, price is not the only consideration.
But it does change my bottom line a bit. :thumbsdn:
martin
 
Martin, I hear you on the cost of cans. I've just done a temporary fix this weekend replacing a 50uf+50uf with a couple like you refer to.

But, look at these for example: http://www.amplifiedparts.com/products/amp_parts/C-EC20-20-450 I'd suggest that the quality of the amps you've got there deservese nice caps like these. I've gone both ways, but I think you'd do better with good caps in your power supply.

I've also been severely warned by more experienced restorers of vintage gear against using tubular caps in place of cans for reservoir/smoothing duties in the power supply. Here is a story from one of them:

"Cans or tubular? When I was about 16 or so, one of our engineers came into the workshop one day with a look like thunder and an elderly radio in his arms. He plonked the latter down on the bench in front of my mate Ray and really tore him off a strip.

"He'd just returned the set to an elderly customer, connected it up and switched on. Then, as beautiful music start to issue forth, he carefully placed the budgie's cage back on top of the radio, where it lived.

"A few seconds later there was a loud Bang! and there were budgie feathers everywhere, plus a large amount of silver foil and insulation distributed liberally around inside the set ...!

"Ray had repaired the bad smoothing problem using an 8μF tubular capacitor in place of the faulty cap. Although the replacement was rated at 450V and the HT only around 250V, that didn't help. For his efforts he now got a strongly worded lecture on the ripple current rating[1] of electrolytic capacitors, ending with the stern admonition: NEVER - EVER - FIT - A - TUBULAR - ELECTROLYTIC - FOR - MAIN - SMOOTHING - EVER - AGAIN!"
 
guys,
This thread may slow down for awhile as I vacillating over the chassis'. I'm tempted to leave them as they are and call it "the camo look".
Dandy's advice about the multi section caps has given me some pause as well. $20.00 for 8 lytics or $120.00 for 4 cans. :scratch2:
I can't justify the parts lying around...that would just be wrong...or they may spur me to action.
Tomorrow I'll take the chassis with the broken weld in to see if it can be spot welded. At least it'll be a step in the right direction.

martin
 
Ohighway,

I looked into those when I restored my Fisher 800c. I opted for a pair of cans instead. The Fisher was in primo condition, so putting something nice on it was an easy call...still they ran me about $65.00 for the pair, but worth it.
The 800c is a thing of beauty...naked or clothed....maybe the Eico's can be the nasty step-twins, or "beauty and the beasties"! :D

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Fin_Studio12rs.jpg


Fin_Studio63rs.jpg


I see you have a pair of Fishers. I'd like to see them. And I'm guessing that you're using the Yamaha C-45 as the preamp?
I have a C-70 which I plan to use with these Eico's. I have the C-70 paired up with Adcom GFA/1 at the moment. :thmbsp:
It doesn't get much use since putting the Fisher into service though.


martin

P.s. The 800c sounds pretty "OK" too. :D
 
Martin, I think you could press on with your restoration using tubular caps, but aim for caps that look more like those on the Dynaco power boards which are substantial and go for above 450V if possible. I posted the story about the budgie just to share a good story from an experienced repairman.

Nice multisection cans are fit and forget, I paid a premium for the one on my Dynaco, but I must admit that my 10W EL84 monoblocs are running at the moment with tubular caps in place of aged cans...

Great job on that Fisher 800C!
 
That is a beautiful 800C. Can you imagine that at one time Fisher offered that as a kit for someone to assemble at home? I would give-up a kidney to have one of those kits now.:)
 
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