Topic: Denon POA1500 Gets hot

[damiel]

Hi masters, need your help, my denon poa 1500 get's hot only on the right side. but sometimes, it doesn't. I don't know what it's history, got in the US.

Thanks! 

[qguy]

Better bring it to a qualified technician.  Download mo na rin Service manual as the electronic shop may not have the service manual. The service manual would have the proper setting for the voltages

[juanbote]

get a hold of the service manual and check for ideal bias settings of the idle current for both channels. bring it to a qualified technician and have the idle current adjusted with no load and input signal.

If service manual will not be available, ask your technician to use an ammeter in the milliampere setting to be connected in series with either the positive or negative supply rail. take note of the readings for both channels and make the adjustment corresponding to the idle current trimpot for each channel.

[damiel]

okay, one problem, there is no qualified technician here in our town. they only fix electric fans and such.

i got the service manual, how do i adjust the idle current?

[qguy]

The service manual would have the instructions on where the trimmers are located inside the amp.

Check youtube.com for videos on how to adjust the bias of solid state amps, this would give you an idea of what your about to do.

Note : I have taken apart my Pioneer SX1050 and replaced 100+ plus capacitors, removed the power transistors and applied new thermal conductive paste between the heat sink and power transistors, but adjusting the bias is not something I would do myself.. takot ako hehehe  if you make a mistake goodbye power amp section

[damiel]

aray, hindi ko na rin isususgal. Dadalahin ko na lang sa manila. Where could I have this serviced or repaired?

[markcrenz]

try cleaning the insides first with a soft bristle paint brush. take out as much dust as you can. dust build up can elevate temperatures in all electronics stuff and even mess up the performance of an otherwise good gear.

but adjusting the bias is not something I would do myself.. takot ako hehehe  if you make a mistake goodbye power amp section

Actually masarap paglaruan yang bias current IF YOU KNOW THE ACTUAL SPECS. Doon ka sa higher limit to set bias closer to class A if you want a cleaner sound, or lower (closer to class B) if you always play loud. CAUTION: NOT FOR THE FAINT OF HEART!

[qguy]

Call Rene Rivo AKA Hypertriode at Wiredstate.com.  i know may facebook account siya Hypertriode showroom
Sansuidan ..search mo dito sa pdvd.. he has his own thread.

Since medjo malayo ka pa schedule ka para pwede mong intayin.

aray, hindi ko na rin isususgal. Dadalahin ko na lang sa manila. Where could I have this serviced or repaired?

[damiel]

try cleaning the insides first with a soft bristle paint brush. take out as much dust as you can. dust build up can elevate temperatures in all electronics stuff and even mess up the performance of an otherwise good gear.
Actually masarap paglaruan yang bias current IF YOU KNOW THE ACTUAL SPECS. Doon ka sa higher limit to set bias closer to class A if you want a cleaner sound, or lower (closer to class B) if you always play loud. CAUTION: NOT FOR THE FAINT OF HEART!

tried cleaning already sir, but still the problem exists.

Hindi kaya dahil mataas boltahe sa amin? 240 volts ung line namin just using normal stepdown transformer

[mbtorn]

Found this, see post #12:

http://audiokarma.org/forums/showthread.php?t=426821

Hope this helps.

[damiel]

Found this, see post #12:

http://audiokarma.org/forums/showthread.php?t=426821

Hope this helps.

Thanks sir!

read that already sir, but in my case, the transistors itself heats up. the heat sink is so hot that you wouldn't even want to touch it.

[qguy]

IMHO ...we dont really know without proper testing if the right channel is defective, We dont even know the exact temperature of the right channel, baka naman talagang dapat ganoon ka init hehehe and the Left channel ang defective.

A hot heat sink, means that the heat sink is doing its job properly taking away heat from the transistors

Thanks sir!

read that already sir, but in my case, the transistors itself heats up. the heat sink is so hot that you wouldn't even want to touch it.

[damiel]

IMHO ...we dont really know without proper testing if the right channel is defective, We dont even know the exact temperature of the right channel, baka naman talagang dapat ganoon ka init hehehe and the Left channel ang defective.

A hot heat sink, means that the heat sink is doing its job properly taking away heat from the transistors

I know the right channel is defective because the thermal protect turns itself on after playing 2-3 songs. the left heat sink is hot, but not as hot as the right.

[qguy]

I would stop using the amp until its fixed, baka madisgrasya yung power transistors. Hirap pa naman bumili ng mga original power transistors dito sa pinas.

I know the right channel is defective because the thermal protect turns itself on after playing 2-3 songs. the left heat sink is hot, but not as hot as the right.

[damiel]

I would stop using the amp until its fixed, baka madisgrasya yung power transistors. Hirap pa naman bumili ng mga original power transistors dito sa pinas.

nacontact ko na po si sir rene rivo. I'll try to bring him or kay sansuidan the ampli na lang next week. better to be safe than sorry.

Thanks for the help masters!

[markcrenz]

have you checked the speakers and wirings na pala? baka may nagso-short.

[beatnik]

Have it checked by Dan Medina (sansui Dan), he specializes in vintage ss gear.

[AppleMan]

^_Malamang yung voltage nyan di na sentro yung negative at positive kung split type yung supply nyan...maaring merong nag-change value na resistor, leaky capacitor or yung trimmer nagbago ng adjustment...di ba umuugong yung speaker na nakakabit?

[synchro_01]

I would stop using the amp until its fixed, baka madisgrasya yung power transistors. Hirap pa naman bumili ng mga original power transistors dito sa pinas.

Agree to this. Years ago I had an amp that heats up considerably after 15 minutes of playing time even in low volume. I though that it was normal until one day when I turned it on a loud oscillating noise came out of my speakers. Too late to turn it off. end result: Dead on the spot yung tweeters

[damiel]

have you checked the speakers and wirings na pala? baka may nagso-short.

checked it already sir, used 3 pairs of speakers, same result.

Have it checked by Dan Medina (sansui Dan), he specializes in vintage ss gear.

Nag send na po ako ng email sir

^_Malamang yung voltage nyan di na sentro yung negative at positive kung split type yung supply nyan...maaring merong nag-change value na resistor, leaky capacitor or yung trimmer nagbago ng adjustment...di ba umuugong yung speaker na nakakabit?

Siguro nga sir, hindi ko na kasi alam ang history nito. hindi naman umuugong yung mga speakers sir.

Agree to this. Years ago I had an amp that heats up considerably after 15 minutes of playing time even in low volume. I though that it was normal until one day when I turned it on a loud oscillating noise came out of my speakers. Too late to turn it off. end result: Dead on the spot yung tweeters

Itinabi ko na muna yung amp sir, baka mapaglaruan pa ng mga kapatid ko. Ouch, nasira ung tweets. Sayang sir.

[tigar]

Itinabi ko na muna yung amp sir,

ganyan din ginawa ko, hafler se240 power amp gets hot even without load, pinatugtog ko overnight in not so loud volume di naman bumigay.
I've read on case like this and they say there is a transistor (not power tran) that is failing and is oscillating and driving the power section, even without load. hindi mabuhat ang amp dahil sa init. kaya tinabi ko muna.