HFT-90 anyone rebuild one before? - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 8th July 2003, 11:20 PM   #1
diyAudio Member
 
Join Date: Dec 2001
Default HFT-90 anyone rebuild one before?

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.

ah
  Reply With Quote
Old 8th July 2003, 11:48 PM   #2
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Hi,

As long as the tuner is working I wouldn't touch it...

This is pretty complex circuitry I wouldn't want to work on blind unless you put a gun to my head...

If the amp is a Eico as well, would you happen to have a model number for it?

Cheers,
__________________
Frank
  Reply With Quote
Old 9th July 2003, 12:06 AM   #3
diyAudio Member
 
Join Date: Dec 2001
Default 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.....

ah
  Reply With Quote
Old 9th July 2003, 12:27 AM   #4
diyAudio Senior Member
 
fdegrove's Avatar
 
Join Date: Aug 2002
Location: Belgium
Hi,

Yes, and that's the tuner.
I can read, thank you.

And from reading you, you won't need any of our mere mortals advise after all.

Cheers,
__________________
Frank
  Reply With Quote
Old 9th July 2003, 12:33 AM   #5
diyAudio Member
 
Join Date: Dec 2001
lol, didnt mean to **** in your wheaties. have a good one dude.
  Reply With Quote
Old 9th July 2003, 10:02 AM   #6
SHiFTY is offline SHiFTY  New Zealand
diyAudio Member
 
SHiFTY's Avatar
 
Join Date: Jul 2002
Location: New Zealand
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.
  Reply With Quote
Old 9th July 2003, 01:13 PM   #7
EC8010 is offline EC8010  United Kingdom
diyAudio Moderator Emeritus
 
EC8010's Avatar
 
Join Date: Jan 2003
Location: Near London. UK
Default 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.
__________________
The loudspeaker: The only commercial Hi-Fi item where a disproportionate part of the budget isn't spent on the box. And the one where it would make a difference...
  Reply With Quote
Old 9th July 2003, 09:45 PM   #8
diyAudio Member
 
Join Date: Dec 2001
Default 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...

ah
  Reply With Quote
Old 11th July 2003, 12:02 AM   #9
diyAudio Member
 
Tom Bavis's Avatar
 
Join Date: Jun 2002
Location: Macedon NY
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.
  Reply With Quote
Old 12th July 2003, 02:04 AM   #10
diyAudio Member
 
Tom Bavis's Avatar
 
Join Date: Jun 2002
Location: Macedon NY
Tried to reply to your email but it bounced.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
KEF - rebuild into OB ? poynton Multi-Way 1 16th August 2007 08:09 AM
Rebuild BMB cs-350 enclosure triast Multi-Way 1 10th July 2007 09:00 AM
RE XXX...Rebuild? DKAudio Subwoofers 0 16th January 2006 03:01 PM
Help with amp rebuild zeke Tubes / Valves 15 4th October 2004 01:39 AM
rebuild offroadbum Multi-Way 2 25th February 2004 04:11 AM


New To Site? Need Help?

All times are GMT. The time now is 02:19 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2