Power Resistor Smoking on HF-81

HolyGhostFire20 · 11th August 2005, 10:29 PM

I just changed all the caps and out of tolerance resistors and now my Eico HF-81 amp starts smoking from the 10w resistor and one of the rectifier tubes sparks. I took out the transformers to repaint them. If someone could help me that would be great.

EC8010 · 11th August 2005, 11:07 PM

Is a power supply electrolytic connected the wrong way round?

HolyGhostFire20 · 11th August 2005, 11:19 PM

They are connected in the right way. It only started doing this after I resoldered the transformers wires back into place. I don't know whats going on. Thanks for your help.

EC8010 · 11th August 2005, 11:28 PM

Damaged insulation on a transformer?

karma · 11th August 2005, 11:30 PM

i have had the same problem in the past removing old iron.
best thing to do is to tape it off and paint it. looks as good as removing it. and its faster

Butterylicious · 11th August 2005, 11:31 PM

What kind of paint? Are the coils exposed? Are you 100% certain it was reconnected correctly?

HolyGhostFire20 · 12th August 2005, 12:16 AM

Okay I inspected the amp really well with a flashlight and poked around a bit for loose connections. I found two which I would have not of found without a flashlight. I tried plugging the amp in again, but I am too scared to wait for something to smoke. I noticed that I didn't hear a sparkle from the rectifier tube which is good news. The power resistor gets very hott to the touch after 10 seconds or so. Should I try a higher watt resistor? Thanks again for your time.

HolyGhostFire20 · 12th August 2005, 12:33 AM

I painted the transformers with Rustoloem Black Satin Spray Paint. The insulation looks alright to me. No more sparks from the tubes, but the power resistor still smokes alittle bit. Is it just because the resistor has gone bad? I also can't find the resistor's value which is 350 ohm should I go lower and get the 330 ohm or the the 390 ohm? Thanks for your time in this matter, Kevin.

karma · 12th August 2005, 02:11 AM

what was loose? if you got a variac use it. bring it up slowly or u may risk loosing more parts.

if you can get a Schematic for is amp and double chech everything

does this resistor smoke right away?

Butterylicious · 12th August 2005, 02:15 AM

A 10 watt resistor is going to get hot, but it shouldn't smoke unless you painted it too. Grab a voltage measurement across the resistor and figure your current followed by power.

I couldn't function at my bench w/o my lighted magnifying glass.

11th August 2005, 10:29 PM	#1
HolyGhostFire20 Account Disabled Join Date: Jun 2004 Location: Indiana	Power Resistor Smoking on HF-81 I just changed all the caps and out of tolerance resistors and now my Eico HF-81 amp starts smoking from the 10w resistor and one of the rectifier tubes sparks. I took out the transformers to repaint them. If someone could help me that would be great.

11th August 2005, 11:07 PM	#2
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	Is a power supply electrolytic connected the wrong way round? __________________ 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...

11th August 2005, 11:28 PM	#4
EC8010 diyAudio Moderator Join Date: Jan 2003 Location: Near London. UK	Damaged insulation on a transformer? __________________ 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...

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Turning a power resistor into a power amp (sorta)	N-Brock	Chip Amps	25	7th October 2009 05:10 AM
Smoking Resistor?	65blkbkgt	Car Audio	14	3rd January 2009 03:55 AM
Power Amp P.S. Bleeder Resistor Reg?	fastcat95	Solid State	2	28th April 2008 05:10 AM
Resistor power rating for XO?	JC Fardo	Parts	4	16th December 2004 07:52 PM

11th August 2005, 11:19 PM	#3
HolyGhostFire20 Account Disabled Join Date: Jun 2004 Location: Indiana	They are connected in the right way. It only started doing this after I resoldered the transformers wires back into place. I don't know whats going on. Thanks for your help.

11th August 2005, 11:31 PM	#6
Butterylicious diyAudio Member Join Date: Aug 2005	What kind of paint? Are the coils exposed? Are you 100% certain it was reconnected correctly?

12th August 2005, 12:16 AM	#7
HolyGhostFire20 Account Disabled Join Date: Jun 2004 Location: Indiana	Okay I inspected the amp really well with a flashlight and poked around a bit for loose connections. I found two which I would have not of found without a flashlight. I tried plugging the amp in again, but I am too scared to wait for something to smoke. I noticed that I didn't hear a sparkle from the rectifier tube which is good news. The power resistor gets very hott to the touch after 10 seconds or so. Should I try a higher watt resistor? Thanks again for your time.

12th August 2005, 12:33 AM	#8
HolyGhostFire20 Account Disabled Join Date: Jun 2004 Location: Indiana	I painted the transformers with Rustoloem Black Satin Spray Paint. The insulation looks alright to me. No more sparks from the tubes, but the power resistor still smokes alittle bit. Is it just because the resistor has gone bad? I also can't find the resistor's value which is 350 ohm should I go lower and get the 330 ohm or the the 390 ohm? Thanks for your time in this matter, Kevin.

12th August 2005, 02:11 AM	#9
karma diyAudio Member Join Date: Feb 2003 Location: hamilton,ontario	what was loose? if you got a variac use it. bring it up slowly or u may risk loosing more parts. if you can get a Schematic for is amp and double chech everything does this resistor smoke right away?

12th August 2005, 02:15 AM	#10
Butterylicious diyAudio Member Join Date: Aug 2005	A 10 watt resistor is going to get hot, but it shouldn't smoke unless you painted it too. Grab a voltage measurement across the resistor and figure your current followed by power. I couldn't function at my bench w/o my lighted magnifying glass.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read