I am not sure what to do yet? I will not mess with the face that's for sure, I feel as some that to mess with it would take away from the originality of the piece. On the other hand it needs to be looked over and worked on as one CH has Hum. So what do we do? I am in no hurry so I guess for now it will sit on the shelf and look cool.
WO
WO
I would just clean it up and replace the electrolitics which might sort the hum issue. I would also be tempted to change the power supply such that it uses a solid state rectifier and regulated supply (as the output voltage from the stock transfomer would be too high) however this would need more work.
This isn't something to use; anything you build from scratch will be better in every way. This is a historical artifact that shows how things were done and with what parts in a certain time period. It may be one of only a couple examples still in existence- you'd have to research that. I'd certainly want to know before touching it.
Not much of a new project just to change a few caps and resistors.
Conrad - did he find this in Pompeii?
I would find out how much it's worth, if it goes for silly money I would sell it and buy a better amp. Unless I were a collector which I'm not. Certainly, the cool eyes is not reason strong enough to keep it; although some people have done crazy things for a couple of heavy-lidded green eyes - like getting married.
Why would anyone recommend that a newb start their learning curve with activities like changing power supply from valve to SS, or changing topology, or pulling everything out and starting afresh? Keep It Super Simple is to me the only path he really should be taking as a first step - and that would start with safety and then move to basic 'old component' management - quite enough to keep him scratching his head and asking questions for many weeks. (Sorry WO for making you the 'thrid party').
Ciao, Tim
Ciao, Tim
The first step would be to use a damp brush with a bit of Dawn detergent to clean off all the dirt. Be sure to dry it well.
The hum is probably a bad electrolytic capacitor. If you have one around with at least the same voltage ratings as the old units you can try just connecting it across the old ones, one at a time. Be sure it is fully discharged before moving it. Around 10uf or whatever is marked on the cans should be enough too big could bad. The bad news is sometimes as the old capacitors fail they show resistance across their terminals so just bridging it doesn't work completely.
To keep the look of the old unit you can actually carefully pry open the bottom of the can of a bad capacitor and put new ones inside! They are so much smaller for the same ratings it is not very hard. You can then bend over the bottom rim again and it will not look quite the same but will work and not change the top side view.
You will be shocked at how much money some people will pay for a clean working and not butchered unit!
If any tube glows blue that is an indicator that the input coupling capacitor is bad. You can check the values of the old resistors in circuit with an ohmeter. (Power off for a day first!) Any that are within 20% are fine. Any that are higher than that should be replaced with a similar resistor. Any that are lower disconnect one lead and check again. If still off replace it.
That is 90% of what needs to be done and since this is a working unit should be everything you need.
Good Luck, Have Fun. If you do it right you can buy all the gear your heart desires and if you screw it up, you ain't out much and can eBay what is left!
The hum is probably a bad electrolytic capacitor. If you have one around with at least the same voltage ratings as the old units you can try just connecting it across the old ones, one at a time. Be sure it is fully discharged before moving it. Around 10uf or whatever is marked on the cans should be enough too big could bad. The bad news is sometimes as the old capacitors fail they show resistance across their terminals so just bridging it doesn't work completely.
To keep the look of the old unit you can actually carefully pry open the bottom of the can of a bad capacitor and put new ones inside! They are so much smaller for the same ratings it is not very hard. You can then bend over the bottom rim again and it will not look quite the same but will work and not change the top side view.
You will be shocked at how much money some people will pay for a clean working and not butchered unit!
If any tube glows blue that is an indicator that the input coupling capacitor is bad. You can check the values of the old resistors in circuit with an ohmeter. (Power off for a day first!) Any that are within 20% are fine. Any that are higher than that should be replaced with a similar resistor. Any that are lower disconnect one lead and check again. If still off replace it.
That is 90% of what needs to be done and since this is a working unit should be everything you need.
Good Luck, Have Fun. If you do it right you can buy all the gear your heart desires and if you screw it up, you ain't out much and can eBay what is left!
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I'd change the power cord, all caps and resistors, and even the pots if the original knobs will fit the shaft type of the new pots, otherwise use a good contact cleaner spray that's designed for pots. If you change the front panel significantly, you lose most of it's value. You could probably get some good bucks selling it on ebay to someone who can restore it if you decide you don't want to bother with it. It is pretty cool looking, and would probably sound pretty good restored.
In eleaboration is too big is bad if the capacitors used for smoothing the DC power supply are too large they will overload the rectifier causing it to arc over on turn on, best idea would be to use the original value (at any higher or equal voltage rating to the originals).
Fist off I would like to say this is just one of many!
I started collecting tube amps about 6 weeks ago, But I have 15 now,
danco
heath
HK
Eico
Bogen
So as I said I do not need to do anything hasty, I will wait and see what should be done and I really have no idea of value of it??
I have bought also in the last 6 weeks new scope new 179 a Eico 667 and a host of other goodies.
I will learn as I go, I am reading and reading and reading a little more!
(Tired of reading)
I bought a Heathkit learning coarse new un-built for me to play with also. I do not have any spare parts and would love to start getting the little things needed on a everyday bases but not sure what they are yet.
Would love to have a mentor who lived close by!
WO
I started collecting tube amps about 6 weeks ago, But I have 15 now,
danco
heath
HK
Eico
Bogen
So as I said I do not need to do anything hasty, I will wait and see what should be done and I really have no idea of value of it??
I have bought also in the last 6 weeks new scope new 179 a Eico 667 and a host of other goodies.
I will learn as I go, I am reading and reading and reading a little more!
(Tired of reading)
I bought a Heathkit learning coarse new un-built for me to play with also. I do not have any spare parts and would love to start getting the little things needed on a everyday bases but not sure what they are yet.
Would love to have a mentor who lived close by!
WO
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