Finally.....Pics of my Eico....and some questions!!!!!!

Discussion in 'Tube Audio' started by 910ken, Mar 11, 2018.

  1. 910ken

    910ken AK Subscriber Subscriber

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    I got a chance to get back at this. I kept it in the general tube forum for all to see. This is a very complete/original ST-40. I believe every tube to be, and all of the iron. Enjoy the pics.

    Now some questions for those who know more than I........

    Are the knobs available as a set or does anyone know where I can get used ones?

    The chassis has corrosion, tarnish and minor rust. Anyone have luck cleaning something like this? It might be one that I just keep the screen on, but I would like to show off those bottles. Face plate also?

    It seams many resisters are newer. Is it possible they are from the orig build?

    The selector switch was very hard to get working right. Does anyone else run into this with these switches? I have a Harmen Kardon that took just as long. The Eico really sounded decent but needs caps. Major hum going on. ###20180218_115729.jpg ###20180218_120107.jpg ###20180218_120150.jpg ###20180218_120158.jpg ###20180218_120309.jpg ###20180218_120433.jpg ###20180218_120702.jpg ###20180218_120855.jpg ###20180218_120933.jpg ###20180218_115818.jpg
     
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  2. 910ken

    910ken AK Subscriber Subscriber

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    Some more pics. 20180218_115848.jpg ###20180218_120855.jpg 20180218_115959.jpg 20180218_120559.jpg 20180218_120618.jpg 20180218_120400.jpg 20180218_120810.jpg 20180218_120828.jpg
     
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  3. s-petersen

    s-petersen Scott Subscriber

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    Most of the worst corrosion are the screws themselves, you could try the magic eraser in a hidden area to see if that would work, the faceplate looks good to me.
     
  4. Retrovert

    Retrovert AK Subscriber Subscriber

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    You might want to check out the EICO Forum: http://audiokarma.org/forums/index.php?forums/eico-place.208/

    Best place for all things EICO.

    I have an ST-40 which was given to me by the original builder who assembled it in the early 1960s. Very nice iron.

    The chassis can be cleaned using Fantastik. I suggest you avoid any cleaner which has glycol ethers.

    Magic Eraser is melamine, a plastic which is abrasive. It can wear off plating and lettering. I do not suggest it.

    I instead suggest using a conventional metal polish Noxon, Brasso, Simichrome, Mother's, or Blue Magic are all very good for this purpose. I find that the first two give a soft finish while the latter three give a mirror-bright finish.

    I suggest you strip the chassis, polish it, and then rebuild using all new tube sockets, new metal film resistors (original carbon composites have drifted and were never good when new, being noisy, hygroscopic, and having Vcr), new film capacitors (original ceramics are hygroscopic microphonic, have a DC bias issue, etc.), new tube sockets, and new wiring. It will perform better than new. All of the PECs need to be replaced as well.
     
  5. Dandy

    Dandy Super Member

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    The knobs do come up on that auction site. I also found a guy selling replacement brights for the centres, but that was about 8 years ago. It's good that you've got the dual concentric tone control knobs.

    My chassis was/is the same as yours and I didn't do a complete stripdown. I did need to replace some tube sockets and all the usual caps to get it going again. Cleaning all the pots and switches is essential.

    Retrovert's thorough rebuild route will get the best out of the iron. Check out what others have done here to help you decide how far you want to go. If you decide to rebuild, downoload the original kit assembly manual.
     
  6. Tim D

    Tim D AK Subscriber Subscriber

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    I have a Fisher amp that was rustier than this EICO. I found a product at Wally World called Krud Kutter that I applied with cotton swabs. It takes the corrosion off, but it may take multiple applications and it was very time consuming to apply and wipe off.

    Note that the plating is etched on your IECO and the plating might be cadmium so beware of the possible toxic metals as you clean it. You won't be able to just clean it to get it back to original. I took the path that mine was a survivor and did the best I could. I'm covering my chassis with a case, so no one can see the final result anyway.
     

     

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  7. GordonW

    GordonW Speakerfixer Subscriber

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    Those resistors look consistent with the time it would have been built (mid-1960s). Carbon film resistors were available then, and were starting to be used readily, especially in higher-power resistors (like 1w and 2w applications), since they saved space and were more reliable than composition resistors of the same power rating.

    Regards,
    Gordon.
     
  8. RWood

    RWood Brakes just like a little girl. Subscriber

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    Agree with Dandy about the knobs. Eico made three or four varieties for both the ST40 and ST70 (and others), though, so look closely. Yours are the brown-paper-insert-in-white. So the selector and level just need the paper inserts. Maybe you can take a good one to the paint store and get a match. What I would do to get the Balance knob is post a WTB ad in Barter Town Parts. Show a picture of what you do have. Members here like to help each other. I have both received and sent out Eico parts to guys here.

    The spun aluminum brights look good but I believe they only work on the molded plastic insert knobs. I could be wrong.
     
  9. primosounds

    primosounds SE KT120 w/ 6J5G drivers. LCLC ps + 2 x 5ar4 Subscriber

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    Rust on the chassis is a universal problem with these units. Lots of suggestions on how to deal with it but one of the least disruptive is to use rust conversion solution and paint over the result. I did this and the chassis rust is arrusted, pun intended. I used hammertone silver with a brush but if you use a spray the result is much better. And as others mentioned when you put on the cover it doesn't matter.
    The bright brass knob inserts only fit the knobs that were originally equipped with them. The knobs with the paper insert are slightly smaller so not an exact fit. The guy that used to sell them on the bay may have reproduced the other one so worth a check.
    About your rebuild, one area that can be a problem is that of the grounds. EICO used the nested grounds technique. That is they had areas where many grounds were attached which was also attached by a wire to another ground nest and that nest was attached to the main ground point. This is ok but frequently you will have a cold solder joint as the original builder did not fully heat up the entire joint to allow solder to flow into the whole connection and bond to the lug. I usually but in a ground bus with 2 or 3 legs but that is a lot of work since you need to resolder all the grounds.
     
  10. Dandy

    Dandy Super Member

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    Thinking of the rust, I saw in a rerun of American Restoration that Rick Dale says that cider vinegar is good for removing rust. I tried it on some areas of my ST40 and it does cause a reaction, but I think to do the job properly you'd have to strip the chassis completely and immerse it in the acidic liquid. Apparently tea and lemon juice also work the same way.

    I read somewhere that it works like this:
    Vinegar contains acetic acid CH3COOH which reacts with rust FeOOH: 3CH3COOH + FeOOH --> Fe(CH3COO)3 + 2H2O and iron (III) acetate Fe(CH3COO)3 is water soluble. YMMV. :)
     
  11. Retrovert

    Retrovert AK Subscriber Subscriber

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    Hot citric acid will remove rust far better than vinegar. Citric acid has a pH of roughly 2, acetic acid pH is roughly 5. Because pH is a log10 scale, each step is ten times the strength. So citric acid is about 1,000 times stronger acid, give or take. BTW: the same kind of relationship exists for borax to bleach to lye.

    Citric acid is available in bulk from Amazon or eBay. I regularly run it through my dishwasher to remove calcium deposits. Whenever I'm doing that I load up the dishwasher with silverware to be cleaned. Removes any deposits. Nothing like hot acid. I just used it to clean out my steam humidifiers which build up calcium and rust on the electrodes. Squeaky clean when finished.

    I built an electrochemical rust remover using a tub, rebar as the sacrificial electrode and anchor point (via chain) to whatever is being de-rusted, a battery charger, and a box of washing soda. The rust just flies off. The interwebs will give you plans. This was the best rust remover I ever made. I used it on all sorts of tools and cast iron objects which were encrusted in rust.

    The rust passivator is generally phosphoric acid, which forms iron phosphide which is black.
     
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  12. 910ken

    910ken AK Subscriber Subscriber

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    Thanks to everyone for your replies. A lot of good stuff there to try. It might take me a week to get back at it. I don't expect too great results but i would like to have it presentable.

    I will start with the electrolytics first though I still am not sold on which way to go. Probably the Hayseed route. Where is a good place to get the Nichicon caps if I want to mount underneath. I have used Sprauge before bit they have gotten pricey!!!!!

    I also will work on getting those pecs out of their. Are they the same ones as the ST-70?

    I know for what I paid the tubes are worth it. One 7591 takes a minute before it heats up. Longer than the other 3 but then it seams to be fine.

    Thanks so much again. Ken
     
  13. Retrovert

    Retrovert AK Subscriber Subscriber

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    Sam Cogley was selling PEC boards in BT. I bought a pair for my ST-40. He might still have some available. I can't find the thread in BT.

    No connection other than as a satisfied customer.
     
  14. primosounds

    primosounds SE KT120 w/ 6J5G drivers. LCLC ps + 2 x 5ar4 Subscriber

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    I dunno how much you want to get into your rebuild or how much experience you have doing something like that. But, the state of the chassis of this amp is not really too bad nor will it impact the sound. Any real effective way to make the rust go away leaving an aesthetically pleasing chassis will require complete disassembly and rebuilding. If you are a novice to this it may be too much work putting it all together again. But, if you are an experienced builder then it is not so daunting.
    If you are somewhat new to tube amps try to get the amp performing properly as the sound quality is of primary importance. cheers, primo
     
  15. 910ken

    910ken AK Subscriber Subscriber

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    Thank again. I wouldn't go as far as stripping it or even rewiring . I do want to try cleaning the areas I can get to. I will try the Braso, a other cleaners . Wipe off the Trans and things like that.

    I can recap and do some things. Most of my experience is with old Fender amps. There is so oooo much more going on with HiFi. For sure. I have learned a ton going through this site. A lot of good folks here.
     
  16. 910ken

    910ken AK Subscriber Subscriber

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    Retro, thanks for all your input as well.
     

     

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  17. primosounds

    primosounds SE KT120 w/ 6J5G drivers. LCLC ps + 2 x 5ar4 Subscriber

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    Brasso is not good for painted parts as it will leave a visible residue especially in cracks. On the faceplate it works nice on the unpainted sections but will remove the letters and numbers as the ST40 faceplate has painted on lettering.
     
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  18. Retrovert

    Retrovert AK Subscriber Subscriber

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    Oh, most definitely not the front faceplate. No no no. Yes, excellent point. I meant the internal chassis portion where the tubes and transformers are mounted.

    The newer paste formulation of Brasso, like Noxon, is far less abrasive than the older liquid one. I've used both without removing silkscreened lettering, but by all means, definitely do a test spot. Never used that on the front for the reasons Primo points out.

    I use Simichrome for many things, as this is a finer abrasive and delivers a mirror-bright finish. But it's expensive and not on the local shelf, and people tend to not want to spend the extra cash for it.
     
  19. 910ken

    910ken AK Subscriber Subscriber

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    I definitely was not going to Brass o the faceplate , although I guess some might try that. Mostly tidying up the inside. Actually the 6 knobs are in really good shape . A guy on the bay sells repro center inserts. $5 a piece though . I actually might get the glue off and paint them with some model paint . I will put an add in BT for the one knob. Maybe someone has a parts unit sitting around .
     
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  20. Retrovert

    Retrovert AK Subscriber Subscriber

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