Just picked up an EICO HFT-90 mono tuner. Its basically my first venture into tube audio. I have built many solidstate amplifiers (thanks much in part to this site) and look forward to extending my knowledge into tubes. I have done a little looking and I plan on upgrading all the capacitors (excluding the tuning cap) in this unit, besides that can anyone make any good reccomendations on the general overhaul of one of these guys. It is completely functional, but doesnt sound GREAT...yet. PS I believe I have the HIFI amp that goes along with it, which works but needs overhauled aswell, its a 6SN7 driver tube with 2 6V6 in a PP arangment if anyone has a schematic for the amp I would appreciate it, I found one for the tuner luckily.
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complex?
well first of all the sound sucks to be completely honest with you I know the unit can produce better. Secondly I appreciate your concern but have been working with electronics since I was about 10 years old, just nothing tube related so I feel more than safe working on this tuner. I am not doing anything blind, I have the schematic for the tuner just not the HIFI amp that used to come along with it. The model # is HFT-90 right there in the title.....
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well first of all the sound sucks to be completely honest with you I know the unit can produce better. Secondly I appreciate your concern but have been working with electronics since I was about 10 years old, just nothing tube related so I feel more than safe working on this tuner. I am not doing anything blind, I have the schematic for the tuner just not the HIFI amp that used to come along with it. The model # is HFT-90 right there in the title.....
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I have recapped a couple of old radios with good results- basically replace all wax paper jobs and leave all the mica ones, they dont seem to go bad... Leave all the tuning section ones alone.
Sometimes the big 60s power supply filter caps will be ok, but if it is leaking goo then replace it. To keep the original look you can leave it in place, just solder caps under the chassis.
If you have the matching amp you should definitely restore it too! PP 6V6 can give 15-20W which is a pretty usable amount, and they are nice rugged tubes. I had a 6V6 stereo amp but it has been "bitzed" for my latest amp... More soon.
And as for mono.... well the jury is still out but get yourself another matching amp and call them monoblocks!
Stereo is the only way, even 5.1 sux0rs in my humble opinion.
Sometimes the big 60s power supply filter caps will be ok, but if it is leaking goo then replace it. To keep the original look you can leave it in place, just solder caps under the chassis.
If you have the matching amp you should definitely restore it too! PP 6V6 can give 15-20W which is a pretty usable amount, and they are nice rugged tubes. I had a 6V6 stereo amp but it has been "bitzed" for my latest amp... More soon.
And as for mono.... well the jury is still out but get yourself another matching amp and call them monoblocks!
Stereo is the only way, even 5.1 sux0rs in my humble opinion.
Run away, run away!
As ShiFtY says, you can replace the power supply capacitors, and paper ones in the audio department, but keep well away from the RF department unless you have a wobbulator (it's a real word, honest) and know how to use it. I know just enough about RF to know how much I don't know...
It should be fairly easy to trace out the circuit of the power amplifier. With only a double triode and a push-pull output stage, there's not a lot of variation possible. It's probably a common cathode input stage with some feedback from the secondary of the output transformer, then a concertina phase splitter feeding the output valves.
As ShiFtY says, you can replace the power supply capacitors, and paper ones in the audio department, but keep well away from the RF department unless you have a wobbulator (it's a real word, honest) and know how to use it. I know just enough about RF to know how much I don't know...
It should be fairly easy to trace out the circuit of the power amplifier. With only a double triode and a push-pull output stage, there's not a lot of variation possible. It's probably a common cathode input stage with some feedback from the secondary of the output transformer, then a concertina phase splitter feeding the output valves.
Retube?
Just curious I am running the tubes that came with the tuner, without having a tube tester, is there any other way I can test my tubes, a retube would only be around $80 but if the tubes that are in there are good I dont want to shell out the money. Thanks for helpin out a tube newb.
P.S.
Why is it that everyone makes you pay for the manuals for these tube amps and radios. I mean this is 2003and on the WWW it doesnt cost anything to send it to someone...just seems like someone would have a little warmth in there hearts...
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Just curious I am running the tubes that came with the tuner, without having a tube tester, is there any other way I can test my tubes, a retube would only be around $80 but if the tubes that are in there are good I dont want to shell out the money. Thanks for helpin out a tube newb.
P.S.
Why is it that everyone makes you pay for the manuals for these tube amps and radios. I mean this is 2003and on the WWW it doesnt cost anything to send it to someone...just seems like someone would have a little warmth in there hearts...
ah
I don't recall ever seeing an Eico amp with 6V6 outputs... you might check the EICO page here: http://users.erols.com/fiddler.interport/EICO.HTM
There are a couple of 6V6 schematics scattered across my web site - http://www.audiophool.cjb.net/ a Stromberg one on "Made in Rochester", another one I haven't built yet on the audio page. Lots more if you follow a few links from the tech page.
If you want a spare set of tubes for the tuner, I'm sure I have all but the eye tube.
There are a couple of 6V6 schematics scattered across my web site - http://www.audiophool.cjb.net/ a Stromberg one on "Made in Rochester", another one I haven't built yet on the audio page. Lots more if you follow a few links from the tech page.
If you want a spare set of tubes for the tuner, I'm sure I have all but the eye tube.
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