Hot Amp....too hot. Ideas??

Amherst
Amherst Posts: 695
edited November 2012 in Electronics
Have aquired a Parasound HCA-3500 dual mono amp. This amplifier is built with two completely separate monaural amps housed in a single case.
One set of heat sinks gets substantially hotter than the set on the opposite side. When I say hotter the heat sinks are so hot they will just about cause a burn on your hand while the other side I would describe as very warm. Also the volume level at the speakers does not sound exactly balanced as my prior amp did. The side with the hot heat sinks sounds more forward meaning louder.

Ideas from the experts here are welcomed :cool:
Parasound C1, T3, HCA-3500, HCA-2205A, P/DD1550, Pioneer DV-79avi, Oppo BDP-83, WD Media Server W/HDD,
Dynaudio Contour 3.3, Dynaudio Contour T2.1, Polk OWM3, Polk DSW micropro 1000 (x2),
Pioneer Kuro 50" Plasma, Phillips Pronto Control w/Niles HT-MSU.
Post edited by Amherst on
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  • pitdogg2
    pitdogg2 Posts: 25,451
    edited October 2012
    needs biased check you tube. I had seen a guy show how to do it or check it yourself.
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  • Amherst
    Amherst Posts: 695
    edited October 2012
    Bias current??

    Thanks pitdogg!
    Parasound C1, T3, HCA-3500, HCA-2205A, P/DD1550, Pioneer DV-79avi, Oppo BDP-83, WD Media Server W/HDD,
    Dynaudio Contour 3.3, Dynaudio Contour T2.1, Polk OWM3, Polk DSW micropro 1000 (x2),
    Pioneer Kuro 50" Plasma, Phillips Pronto Control w/Niles HT-MSU.
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  • zingo
    zingo Posts: 11,258
    edited October 2012
    Yup. Bias is not balanced, and can usually be adjusted with a pot or two per side with recommendation from the company. Contact Parasound and they should be able to help you out.
    Jake
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  • FTGV
    FTGV Posts: 3,649
    edited October 2012
    Amherst wrote: »
    when I say hotter the heat sinks are so hot they will just about cause a burn on your hand ...
    That being the case I would expect thermal protection to kick in.As mentioned that channels bias is likely running too high and I would not recommend using it until that has been corrected.Otherwise there is a potential of nuking the power transistors in the output section.
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  • steveinaz
    steveinaz Posts: 19,538
    edited October 2012
    Give that Parasound plenty of clearance as well, 8" minimum from the top, and an open rack is best. They run pure Class A for the first 15watts.
    Source: Bluesound Node 2i - Preamp/DAC: Benchmark DAC2 DX - Amp: Parasound Halo A21 - Speakers: MartinLogan Motion 60XTi - Shop Rig: Yamaha A-S501 Integrated - Shop Spkrs: Elac Debut 2.0 B5.2
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  • Amherst
    Amherst Posts: 695
    edited October 2012
    Chance of nuking the outputs??? ****..... Protection not kicking in. But not pushing overly hard either. Thing is a beast with power.

    She has clearance Steve. Good point there!

    Thanks for the advise fellows. Thinking a call to Parasound is in order.
    Parasound C1, T3, HCA-3500, HCA-2205A, P/DD1550, Pioneer DV-79avi, Oppo BDP-83, WD Media Server W/HDD,
    Dynaudio Contour 3.3, Dynaudio Contour T2.1, Polk OWM3, Polk DSW micropro 1000 (x2),
    Pioneer Kuro 50" Plasma, Phillips Pronto Control w/Niles HT-MSU.
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  • gdb
    gdb Posts: 6,012
    edited October 2012
    Check the speaker cables for shorting.
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  • unc2701
    unc2701 Posts: 3,587
    edited October 2012
    gdb wrote: »
    Check the speaker cables for shorting.

    This, then the bias. Especially if you're using bare wire. A stray thread can give you those symptoms without shutting down the whole system. Good luck!
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  • Amherst
    Amherst Posts: 695
    edited October 2012
    Have not checked for a stray strand but nothing had changed in the system wiring wise and using bananas.
    Will throw a meter on it and check them anyhow.

    The bias adjustment looks like a simple matter to do. Watched the utube on it. Need the spec for this particular unit and I'll give it a shot. Have an HCA-2205A and should probably check that at the same time.

    Thanks!
    Parasound C1, T3, HCA-3500, HCA-2205A, P/DD1550, Pioneer DV-79avi, Oppo BDP-83, WD Media Server W/HDD,
    Dynaudio Contour 3.3, Dynaudio Contour T2.1, Polk OWM3, Polk DSW micropro 1000 (x2),
    Pioneer Kuro 50" Plasma, Phillips Pronto Control w/Niles HT-MSU.
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  • SugarmillMan
    SugarmillMan Posts: 175
    edited October 2012
    Parasound amps could benefit from some external cooling. I use a small USB powered fan from the coolerguys.com.
    Fronts:B&W 804 Diamonds, Center: B&W HTM2 Diamond, Surrounds: PolkAudio LSi F/X (4)
    Subwoofer: HSU VTK3-MK3
    Electronics: Onkyo TX-NR 3010 receiver, Parasound Halo A31 amp, NAD T975 amp
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  • SugarmillMan
    SugarmillMan Posts: 175
    edited October 2012
    Also, some folks use a fan unit intended to cool off laptops. There are many brands. You can place the fan on the top side to blow the hot air away.
    Fronts:B&W 804 Diamonds, Center: B&W HTM2 Diamond, Surrounds: PolkAudio LSi F/X (4)
    Subwoofer: HSU VTK3-MK3
    Electronics: Onkyo TX-NR 3010 receiver, Parasound Halo A31 amp, NAD T975 amp
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  • steveinaz
    steveinaz Posts: 19,538
    edited October 2012
    Amherst--call parasound, they will give you the specs.
    Source: Bluesound Node 2i - Preamp/DAC: Benchmark DAC2 DX - Amp: Parasound Halo A21 - Speakers: MartinLogan Motion 60XTi - Shop Rig: Yamaha A-S501 Integrated - Shop Spkrs: Elac Debut 2.0 B5.2
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  • FTGV
    FTGV Posts: 3,649
    edited October 2012
    Amherst wrote: »
    The bias adjustment looks like a simple matter to do...
    Well it may be just a simple matter of readjusting or the bias may have drifted upward due to a component failure in the bias circuit etc.To verify the problem is actually with in the amp and not a short or oscillation upstream etc.you can disconnect the speakers and preamp.Let it idle for awhile and see if the channel in question still gets excessively hot in comparison to the other.
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  • drumminman
    drumminman Posts: 3,396
    edited October 2012
    My new amp (Odyssey Dual Mono) runs warm to hot bilaterally when I crank it up. I bought two speed adjustable computer fans, one for each side. I place them on the amp shelf at the back facing forward, turn them on so they're barely moving air which makes them impossible to hear even during quiet passages. Amp runs cool to the touch and I don't worry any more.

    They have sealed ball bearings with a rated life of 67,000 hours, and cost $23 each: http://www.acinfinity.com/speed-control-fans/120-mm-kits/ac-infinity-speed-control-fan-kit-120mm/

    Cheap piece of mind.

    However, I agree with the above posts, I would first get the amp checked, and then get the fans.
    "Science is suppose to explain observations not dismiss them as impossible" - Norm on AA; 2.3TL's w/sonicaps/mills/jantzen inductors, Gimpod's boards, Lg Solen SDA inductors, RD-0198's, MW's dynamatted, Armaflex speaker gaskets, H-nuts, brass spikes, Cardas CCGR BP's, upgraded IC Cable, Black Hole Damping Sheet strips, interior of cabinets sealed with Loctite Power Grab, AI-1 interface with 1000VA A-L transformer
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  • Amherst
    Amherst Posts: 695
    edited October 2012
    Going to implement all the advice above. Thanks everyone and especially FGTV for the insight.The unit is in a cabinet that has fans installed. The cabinet is headed for the trash heap once the new one is complete that is planned. Plenty of air movement already.

    Took some measurements this morning and the heat sink right side is running at about 120*F with a medium volume level set for a half hour run (pic below). The heat sink left side is running 15*F cooler at 105*F. Going to cool down and set at idle with no connections and re-measure the temps.

    Hope to open today and take a good look inside and check bias settings. Waiting on Parasound tech support.
    Emailed Parasound yesterday for specs and no response yet. Will call them later on if nothing shows up to the in-bin.
    All else fails it will have to hit the repair facility.

    P1010358.jpg
    Parasound C1, T3, HCA-3500, HCA-2205A, P/DD1550, Pioneer DV-79avi, Oppo BDP-83, WD Media Server W/HDD,
    Dynaudio Contour 3.3, Dynaudio Contour T2.1, Polk OWM3, Polk DSW micropro 1000 (x2),
    Pioneer Kuro 50" Plasma, Phillips Pronto Control w/Niles HT-MSU.
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  • Amherst
    Amherst Posts: 695
    edited October 2012
    The amp stabilized at 89.1*F left side and 92.2*F right side with no connections and idling for an hour.
    Parasound C1, T3, HCA-3500, HCA-2205A, P/DD1550, Pioneer DV-79avi, Oppo BDP-83, WD Media Server W/HDD,
    Dynaudio Contour 3.3, Dynaudio Contour T2.1, Polk OWM3, Polk DSW micropro 1000 (x2),
    Pioneer Kuro 50" Plasma, Phillips Pronto Control w/Niles HT-MSU.
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  • Amherst
    Amherst Posts: 695
    edited October 2012
    drumminman wrote: »
    My new amp (Odyssey Dual Mono) runs warm to hot bilaterally when I crank it up. I bought two speed adjustable computer fans, one for each side. I place them on the amp shelf at the back facing forward, turn them on so they're barely moving air which makes them impossible to hear even during quiet passages. Amp runs cool to the touch and I don't worry any more.

    They have sealed ball bearings with a rated life of 67,000 hours, and cost $23 each: http://www.acinfinity.com/speed-control-fans/120-mm-kits/ac-infinity-speed-control-fan-kit-120mm/

    Cheap piece of mind.

    However, I agree with the above posts, I would first get the amp checked, and then get the fans.

    That is a real nice cooling kit and looks like an excellent price. Great heads up...thanks!
    The blower unit looks awesome also....if you can handle more noise.
    Parasound C1, T3, HCA-3500, HCA-2205A, P/DD1550, Pioneer DV-79avi, Oppo BDP-83, WD Media Server W/HDD,
    Dynaudio Contour 3.3, Dynaudio Contour T2.1, Polk OWM3, Polk DSW micropro 1000 (x2),
    Pioneer Kuro 50" Plasma, Phillips Pronto Control w/Niles HT-MSU.
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  • nhhiep
    nhhiep Posts: 877
    edited October 2012
    120 mW DC is way too high. normal amps shouldn't be more than 60.
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  • Amherst
    Amherst Posts: 695
    edited October 2012
    nhhiep wrote: »
    120 mW DC is way too high. normal amps shouldn't be more than 60.

    Not sure what you are referring to here.

    The multi-meter is not measuring any currents or voltages of the amplifier internal circuits.
    These are temperature measurements with a temperature probe in direct contact with the heat sinks.
    Parasound C1, T3, HCA-3500, HCA-2205A, P/DD1550, Pioneer DV-79avi, Oppo BDP-83, WD Media Server W/HDD,
    Dynaudio Contour 3.3, Dynaudio Contour T2.1, Polk OWM3, Polk DSW micropro 1000 (x2),
    Pioneer Kuro 50" Plasma, Phillips Pronto Control w/Niles HT-MSU.
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  • drumminman
    drumminman Posts: 3,396
    edited November 2012
    Amherst wrote: »
    That is a real nice cooling kit and looks like an excellent price. Great heads up...thanks!
    The blower unit looks awesome also....if you can handle more noise.

    Yeah, for me noise was a major consideration. THat and longevity. I usually leave the fans running 24H from Thur-Sun, didn't want something that would burn out right away. Beware of fans with sleeve bearings - they're supposed to be noisier and less durable.
    "Science is suppose to explain observations not dismiss them as impossible" - Norm on AA; 2.3TL's w/sonicaps/mills/jantzen inductors, Gimpod's boards, Lg Solen SDA inductors, RD-0198's, MW's dynamatted, Armaflex speaker gaskets, H-nuts, brass spikes, Cardas CCGR BP's, upgraded IC Cable, Black Hole Damping Sheet strips, interior of cabinets sealed with Loctite Power Grab, AI-1 interface with 1000VA A-L transformer
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  • BlueFox
    BlueFox Posts: 15,251
    edited November 2012
    Amherst wrote: »
    Not sure what you are referring to here.

    The multi-meter is not measuring any currents or voltages of the amplifier internal circuits.
    These are temperature measurements with a temperature probe in direct contact with the heat sinks.

    He is probably looking at the display, which says it is 120 milli volts DC. I wonder why they didn't change the display for temperature.
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  • Amherst
    Amherst Posts: 695
    edited November 2012
    BlueFox wrote: »
    I wonder why they didn't change the display for temperature.

    Most if not all battery powered temperature probes for multi-meters return a 1 milli-volt signal for each degree of temperature to the meter. The meter is set to read milli-volt DC and read accordingly. I simply did not use that position on this read. There are some meters with an actual temp position built in, this is one of those, and will show the reading as degrees. No difference.
    Thermocouple type probes are not powered and produce a mili-volt signal directly. Generally this type of probe is more accurate but built for a smaller and more specific range of temps. The powered probes are more general purpose.
    Parasound C1, T3, HCA-3500, HCA-2205A, P/DD1550, Pioneer DV-79avi, Oppo BDP-83, WD Media Server W/HDD,
    Dynaudio Contour 3.3, Dynaudio Contour T2.1, Polk OWM3, Polk DSW micropro 1000 (x2),
    Pioneer Kuro 50" Plasma, Phillips Pronto Control w/Niles HT-MSU.
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  • SugarmillMan
    SugarmillMan Posts: 175
    edited November 2012
    So what did you end up doing with the unit?
    Fronts:B&W 804 Diamonds, Center: B&W HTM2 Diamond, Surrounds: PolkAudio LSi F/X (4)
    Subwoofer: HSU VTK3-MK3
    Electronics: Onkyo TX-NR 3010 receiver, Parasound Halo A31 amp, NAD T975 amp
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  • Amherst
    Amherst Posts: 695
    edited November 2012
    The scenario according to Parasound is that to make the actual adjustments to this particular amplifier is difficult and can be costly. Bottom line is it is going to see a pro.
    There are three adjustment pots for each side and they are located on a lower level board which has bad access. I will not risk a mistake. The thing I can do before sending it out is actually check the voltages (a simple matter) and compare the differences. That will be done over the weekend when there is time.
    Parasound C1, T3, HCA-3500, HCA-2205A, P/DD1550, Pioneer DV-79avi, Oppo BDP-83, WD Media Server W/HDD,
    Dynaudio Contour 3.3, Dynaudio Contour T2.1, Polk OWM3, Polk DSW micropro 1000 (x2),
    Pioneer Kuro 50" Plasma, Phillips Pronto Control w/Niles HT-MSU.
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  • SugarmillMan
    SugarmillMan Posts: 175
    edited November 2012
    Amherst wrote: »
    The scenario according to Parasound is that to make the actual adjustments to this particular amplifier is difficult and can be costly. Bottom line is it is going to see a pro.
    There are three adjustment pots for each side and they are located on a lower level board which has bad access. I will not risk a mistake. The thing I can do before sending it out is actually check the voltages (a simple matter) and compare the differences. That will be done over the weekend when there is time.

    Was this a brand new Parasound or an older unit?
    Fronts:B&W 804 Diamonds, Center: B&W HTM2 Diamond, Surrounds: PolkAudio LSi F/X (4)
    Subwoofer: HSU VTK3-MK3
    Electronics: Onkyo TX-NR 3010 receiver, Parasound Halo A31 amp, NAD T975 amp
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  • Amherst
    Amherst Posts: 695
    edited November 2012
    Read up SugarmillMan this is a vintage amp. Considered desirable. The predecessor to the JC1. Getting harder and harder to lay your hands on one. Discontinued for better than ten years. S@!t happens.
    A newer Parasound (or this one) is without question probably as good as any dollar you have spent in audio.

    Enjoy the music!
    Parasound C1, T3, HCA-3500, HCA-2205A, P/DD1550, Pioneer DV-79avi, Oppo BDP-83, WD Media Server W/HDD,
    Dynaudio Contour 3.3, Dynaudio Contour T2.1, Polk OWM3, Polk DSW micropro 1000 (x2),
    Pioneer Kuro 50" Plasma, Phillips Pronto Control w/Niles HT-MSU.
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  • SugarmillMan
    SugarmillMan Posts: 175
    edited November 2012
    Amherst wrote: »
    Discontinued for better than ten years. S@!t happens.
    A newer Parasound (or this one) is without question probably as good as any dollar you have spent in audio.

    Enjoy the music!

    Fuuny thing you should say that. I just hooked up my new NAD t975 amplifier today and posted a picture of it. Love it so far.
    Fronts:B&W 804 Diamonds, Center: B&W HTM2 Diamond, Surrounds: PolkAudio LSi F/X (4)
    Subwoofer: HSU VTK3-MK3
    Electronics: Onkyo TX-NR 3010 receiver, Parasound Halo A31 amp, NAD T975 amp
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  • Amherst
    Amherst Posts: 695
    edited November 2012
    Congrats!
    Nice unit with a pair of balls to boot. Enjoy!
    Parasound C1, T3, HCA-3500, HCA-2205A, P/DD1550, Pioneer DV-79avi, Oppo BDP-83, WD Media Server W/HDD,
    Dynaudio Contour 3.3, Dynaudio Contour T2.1, Polk OWM3, Polk DSW micropro 1000 (x2),
    Pioneer Kuro 50" Plasma, Phillips Pronto Control w/Niles HT-MSU.
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  • SugarmillMan
    SugarmillMan Posts: 175
    edited November 2012
    Thanks.
    Fronts:B&W 804 Diamonds, Center: B&W HTM2 Diamond, Surrounds: PolkAudio LSi F/X (4)
    Subwoofer: HSU VTK3-MK3
    Electronics: Onkyo TX-NR 3010 receiver, Parasound Halo A31 amp, NAD T975 amp
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