Eico HF-85 preamp help needed

[Newbie22]

I've recently acquired an almost mint Eico HF 85 preamp and hf 86 amp. I need help. I am taking it in to be overhauled. I wondering if any of you could tell me what to look out for when I take it in and receive it from service. Both currently work. The caps have a waxy goo on them which I assume means they are leaking. I expect to replace all of the capacitors. BUT the tubes.. how concerned should I be about them? 5 of them are amperex tubes which seem to be expensive online. Are they original? It has on rca tube mounted at a 45 degree angle in there. (I'm speaking of preamp at this point). When I tested the preamp and amp they had a low frequency hum which seemed to subside after a bit. Of course all of the pots need cleaned. I would like to have them put in an additional line out and maybe move the original preouts to accommodate larger cables. I'm new to this and any help would really be appreciated.

 

[Nyjblbob]

At the very least provide your tech with a couple strong or NOS Spare tubes from Known tube sellers with good feedback that do thorough testing. You don't know the condition of the ones in them.

 

[captouch]

Hopefully you have good reviews on whoever is servicing your gear. If so, they should be able to tell you if adding a line out is an issue or not.

And if they have experience restoring tube gear, they should be able to test your tubes for you. The angled tube is a rectifier, which can also be tested.

I have one that was completely rebuilt from scratch (everything replaced except transformer and chassis), but I wasn’t there during the restore. He left out the loudness circuit, which I believe wasn’t well thought of (but I’d research that) and tape monitor.

It’s a very nice sounding preamp.

 

[s-petersen]

The loudness circuit if left in, should be rewired so that it works in the standard way, there are threads in the Eico section on the changes needed

 

[tubeactive]

Yes, Eico HF-85s are contenders, done right...

Do check the Eico threads here at AK and then google "Eico HF-85" for some interesting stories...

The original Loudness circuit in the HF-85 was an error. If u like low level listening, consider fixing that. However, since the dual volume control is directly after the phono stage, this tap on the vol control is a great place for a phase accurate, hi-cut scratch filter. For my spinning disc record playing needs, this works wonders for all inputs...

Note also, the Tape Output on the HF-85 is also directly after the Phono input, or tape head input, or mic input, after the volume control ! Versatile preamp ! I have converted the Tape (Head) and Mic inputs to extra phono inputs, by adding/changing proper phono EQ networks. So, I have three turntable inputs. My "Tale of Two Eicos" as posted in lencoheaven.net's "Phono Stages and Step Ups" section might be worth reading for the OP, his tech and all interested. If you google: Phono EQ: Design, Retrofit + Disc Playback Charts, that essay should come up quick. Scroll down to the second post for the Eico retrofit. The first post is rather lengthy and technical, but historically relevant to phono playback curves.
Here's the link, hopefully...

https://www.lencoheaven.net/forum/index.php?topic=25066.msg338123#msg338123

Eico HF-85 and HF-81 share the same phono circuitry, very well designed, imho...

Enjoy ur Eico !

 

[tubeactive]

@Newbie22 , The tubes might be gems. If you can test them, before handing it over, you might save some hard-earned money. The original tubes were actually branded Eico, made for Eico by Mullard. Since the pre was introduced in late 1958, some of the first units had long plate, 17mm long plates. Soon, though, the Eico by Mullard short plates, 14-15mm tall, were used. Both types, long or short are great sounding tubes, imho....

 

[Newbie22]

Based on what I've been hearing about my local shop, think I will be recapping the EICOs myself. I have a basic understanding of electronics and a bit of technical know-how. I'm going to give it a shot. I believe these will cost about $800 bucks to restore. What would be the best place to go for poly and paper caps?

 

[Newbie22]

Also I have the manuals with the parts lists.

 

[captouch]

Also I have the manuals with the parts lists.

For the common, non-boutique type caps, I use Mouser or Digikey.

For caps in the signal path that you may want to go with something a little fancier, it’ll depend on what exactly you go for. Parts Express, Amplifier Surgery, eBay - just depends.