Advice on modded Eico HF20 monoblocks with issues

Wes_in_VA

Super Member
I'm looking for some input from my tube lovin' brethren on what to do here:

My BIL gave me these Eico HF20s a while back and I fell in love with them. I used them as monoblocks for a while by pulling the V2 tube and that worked great. In my quest for sonic bliss I wanted more, so I sent them off to Stu at Eico Builders and asked him to convert them to true monoblocks and remove all the un-needed stuff. Also, upgrade the speaker connections to 5 way posts and install better RCA jacks.

I put some cash into that, about $400 IIRC so not tons, but a nice chunk. Got them back and they were really superb, but that only lasted for about a month. At that time one of the power transformers died. Back they went. Stu fixed them up and took care of me. I was happy with how we handled it.
Now, though, one of them has developed a pretty severe 60hZ hum. I can't remember at the moment whether it's the same one that had the transformer issue but I think it is.

My question is this: Do I try to get these fixed, and if so, will a knowledgeable tube tech be able to work on them without a schematic of the changes that Stu made? It's all point to point wiring, so I'd think so,l but I know nothing about working on tube amps. I had a local guy look at these when I had the first issue since I really didn't want to lose them for a month while they got fixed. He gave them back to me because they had been modded.
If I decide to divest myself of them, are people going to be interested in modded units with no schematic? I am NOT asking for advice on value and don't want to discuss that at all. I can figure that out myself if I know how much difficulty there will be with the mods for someone who buys them.

I'd appreciate anything you guys have to offer.
 
There's plenty of folks here who can help talk you through pin-pointing where the problem is -- but that is only good if you in fact want to work on them yourself. Still, plenty of folks have been in your shoes, and gained the satisfaction of fixing their unit themselves with the help of the folks here.

On the other hand, the circuit of the HF-20 is a classic that any good tech will either already be familiar with, or with just a few minutes study under the hood will be able to figure it out -- and what was done to mod it. To simply remove the phono preamp and tone control circuits, and then add an input into the power amplifier section is not that difficult a task for an experienced tech. Therefore, if you send them out, talk to the tech first -- you'll be able to know pretty quickly if they are up to this work or not.

I hope this helps!

Dave
 
I will be looking at this thread, My first project, HF20 for a mono system. Needs a complete rebuild.
 
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