anarchist Posted May 8, 2006 Share Posted May 8, 2006 Hi guys, I have an Eico HF-81 which was in very good shape with all new caps. The nightly routine is to turn it on when headed to bed, listen (fall asleep) to CD's through it, and turn it off in the morning. Last night I turned it on and the ONLY tubes which lit up were the rectifier tubes; every other tube is dark. Now I find it hard to believe every single tube burnt out simultaneously (while the amp was off) so this obviously is a more serious issue. Any ideas on what has happened? Transformers go bad (simultaneously?) Power supply caps give up? When I turned it off everything was copacetic. How did it go bad while it was turned off? The only idea I have is it will likely end up being shipped to Craig. Quote Link to comment Share on other sites More sharing options...
fini Posted May 8, 2006 Share Posted May 8, 2006 Maybe your problem is that you turn it off. They're supposed to be powered-up all the time, like that song, where Dr. John sings "Eico, Eico all day..." Quote Link to comment Share on other sites More sharing options...
SilverSport Posted May 8, 2006 Share Posted May 8, 2006 Fini...you're the best!...Fuse perhaps??? Bill Quote Link to comment Share on other sites More sharing options...
anarchist Posted May 8, 2006 Author Share Posted May 8, 2006 Ok. I disconnected the amp and pulled it out. Took off bottom plate and examined the green wires. They come off the transformer and go directly to what I guess is the hum pot. They are solidly connected. From there I see where other wires (brown/yellow) jump off to each of the heaters. Everything looks tight and connected. As further information, maybe it helps, this amp isn't moved around or anything. Turned it off in the morning and it was working fine, turned it on that evening and it suddenly doesn't work. Could the transformer have popped out on only one side? Can I check the transformer by using a multimeter on the green outputs? How to test? Thanks for the response and attempts to help me... Quote Link to comment Share on other sites More sharing options...
3dzapper Posted May 8, 2006 Share Posted May 8, 2006 First measure the AC voltage across the green wires. Then make sure it appears on the other side of that pot. Then trace the wires to each tube heater. If the builder made the heaters run in series or series parrallel one burned out filament can shut all of them off like astring of xmas lights. If there is voltage on one tube in the string and none on the next, the one with voltage is the culprit. Continuity can also be measured with the amp off on the Ohms scale. Attach the clip end to one of the green wires, then check for continuity at each side of the filament. Continuity on one side and not the other indicates the bad tube. Here is a link to the schematic: http://users.rcn.com/fiddler.interport/HF81.HTM Rick Quote Link to comment Share on other sites More sharing options...
anarchist Posted May 8, 2006 Author Share Posted May 8, 2006 Ok. Let me tell you what and how I did and see if I followed along correctly. My meter has 200 to 2000k selections for ohms. I set it to 200. Checked the one leg on the hum pot and it showed .5, checked the other leg and it was .3. Then I plugged in the amp and turned it on. Set voltage to 200. Connected the red lead to one green wire and then connected the black to the other green wire. Zero. Have no clue no I set the voltage to 500 and redid it. Same result. Zero on the meter. This would mean I either don't know what the hell I am doing or something is very bad with the transformer? Quote Link to comment Share on other sites More sharing options...
DRBILL Posted May 8, 2006 Share Posted May 8, 2006 I pulled my file schematic and took a quick look. It is somewhat unusual to have the heater winding open (burned out). The usual thing to go is the secondary (B+) or the primary. Those Eico power transformers really run hot. It is surprising that more of them don't burn up. It really doesn't matter except in a sort of academic way. You will need a new power transformer. Craig does a lot of Eico work and probably has a new or used one on his shelf. Wait a discreet period before contacting him out of respect for his father's death in case you han't heard. DRBILL Quote Link to comment Share on other sites More sharing options...
anarchist Posted May 8, 2006 Author Share Posted May 8, 2006 Hi Mark, it is a digital readout meter. It was set to AC - measured household current while I was at it - which by the way is 121.7 volts. I am not certain about the "pilot" light. There is a on/off light which shows through the face of the amp - it is burnt out but don't know if you mean this one or not. There is no other light I am aware of which is near the transformer... So I assume transformers can go bad on one side (winding) since the rectifier lights still come on? If this is the case, I would assume my best bet is to check this thing into the Craig hotel... or I guess I could solder in a replacement if it were possible to obtain one that was good... Quote Link to comment Share on other sites More sharing options...
SilverSport Posted May 8, 2006 Share Posted May 8, 2006 maybe someone replaced the fuse with one too big??? Quote Link to comment Share on other sites More sharing options...
anarchist Posted May 8, 2006 Author Share Posted May 8, 2006 Ok guys. I was curious after Marks & the following post so I went back in (sounds like an adventure movie.) Checked the fuse and think its probably the original but I don't know; it is a BUSS fuse with 250 volts on it and AGC 3 on the other end. Moved the pot so it was in the center of the two poles rather than directly on one of them. Readings on it suddenly went to 20 - 30 per side rather than the < 1 I was seeing before. Of course, if I rotate the pot back to where it touches the pole, it goes back to < 1. So, with readings of 20-30 per side, I turned on the amp and checked the green wires. Zero. Now if I understand Mark, you are suggesting eliminating the pot from the circuit and checking it. Two ways to do that: desolder the wires connecting to the clips that come out of it or clip the clips off - which would render the pot to the trash bin. Given the new information, do you think it likely the pot is still the problem or is this transformer junk. Quote Link to comment Share on other sites More sharing options...
anarchist Posted May 9, 2006 Author Share Posted May 9, 2006 You talked me into it. lol. Might as well use this high-dollar soldering station and de-soldering tool I have. I will desolder them tomorrow and we will have the final answer. If the transformer is bad, then Craig will have two fewer connections to remove when he has to fix this thing or hell, I might get carried away and just desolder the whole thing and see if Craig has a transformer that is good. I replaced every cap so I should be able to monkey around with a transformer. Course someone will have to tell me how to test resistors because I may as well check them out at the same time and replace those that have drifted. Will let you know tomorrow what I find. Quote Link to comment Share on other sites More sharing options...
Clarence Posted May 9, 2006 Share Posted May 9, 2006 hmm 2 months ago you were slinging mud at craig and now you want to send him your amp? hows that opera runnin? Quote Link to comment Share on other sites More sharing options...
anarchist Posted May 9, 2006 Author Share Posted May 9, 2006 The Opera is running perfectly. Perhaps you should know what the hell you are talking about prior to making such comments; I have known and been friends with Craig long before you ever discovered this forum. It would appear others do have the proper opinion of you. Quote Link to comment Share on other sites More sharing options...
anarchist Posted May 9, 2006 Author Share Posted May 9, 2006 Hi Mark, desoldered the green wires coming off the power trans. 6.8 - 6.9 volts. i assume the extract .5 volt is due to my ac service provide over 120 volts (121.9 or whatever I mentioned previously) So what does that tell us; the hum thing is toast and shorting them out? next steps? solder them directly to the leads heading to the heaters - bypassing the pot - and see if it all works? ps. i plugged it a SS receiver (older Pioneer) i had here to substitute for the Eico on the Heresies. Yuck. Two seconds of sound and the fall-off in quality was so blatantly apparent (no bass, no imaging, no air) I felt compelled to not even bother listening to it. That should be enough of a demo to convince anyone they want tubed equipment over SS anyday if they are passionate about their music. Quote Link to comment Share on other sites More sharing options...
anarchist Posted May 9, 2006 Author Share Posted May 9, 2006 Mark, I cheated. Tacked the the leads to the heaters to the green wires. Back in business. All lit up. Here is my dilemna. The green wires and the heater leads all connected to the "terminals" on the hum pot. With no hum pot - the leads are hanging out in air where I just know if they contact something it won't be good, right? Wonder if I can just wrap them with electrical tape until I secure a new hum pot. Quote Link to comment Share on other sites More sharing options...
Daddy Dee Posted May 9, 2006 Share Posted May 9, 2006 Is this forum a great place or what?!!! Quote Link to comment Share on other sites More sharing options...
anarchist Posted May 9, 2006 Author Share Posted May 9, 2006 It is and I thank Mark tremendously. Unfortunately, I think we have found a larger problem. After about 2 hours of being on, the system went dark once again except the rectifier tubes. It has been turned off for about an hour and while the output transformers are very cold, the power transformer is still quite warm. I tried turning it on and no dice. The rest of the system is still dark. I think we are looking at a bad transformer somehow or could something else downstream be the problem... Mark? Quote Link to comment Share on other sites More sharing options...
anarchist Posted May 9, 2006 Author Share Posted May 9, 2006 Wow! Being impatient, I decided to check if the power transformer wires had come loose where I tacked them to the wires leading to the heaters. Was pulling the tape off when my pinkie touched one of the smaller capacitor leads. Jesus. 15 mins is apparently not enough time for the system to fully discharge. Any rules on this because I don't want to repeat the electro-shock therapy again? Oh yeah. The leads were still secure and the transformer still warm. Damn that shock is memorable. Quote Link to comment Share on other sites More sharing options...
Clarence Posted May 9, 2006 Share Posted May 9, 2006 [] karma Quote Link to comment Share on other sites More sharing options...
anarchist Posted May 10, 2006 Author Share Posted May 10, 2006 Hi Mark, Well the cool thing is I know the difference between a shock provided by a electric fence (pulse) and that provided by a capacitor (continuous). New day, new learning experience. Amp still won't turn on - transformer leads back at zero. I have a resistor - just don't know what to do with it so I will skip that. lol. I looked at the power transformer a bit more and I read something about them losing their wax and having issues then. I don't know where the wax is but I can see the winding itself (barely) and it looks pretty bare. At one point, there was quite a bit of wax that had dropped out so I guess this may be the issue. I think it will go to Craig. Besides just fixing whatever the current problem is, I know he has some upgrades and other tricks to improve the sound particularly the phono section so it will be money well spent and I have wanted him to check these resistors and the tape output section for a while now. It occurs to me I need another system (preamp & monoblocks) so I have a spare integrated for the bedroom system. Will have to seriously look now and make a purchase. Let me know if a used BB becomes available you need to unload. Quote Link to comment Share on other sites More sharing options...
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