• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

Velodyne CHT-10 Subwoofer running HOT

E

electronhick

Active Member
How warm should the regulator transistors get? TIP 29C and TIP30C? Running approx 130F and climbing.
How warm should the Driver and Output transistors get? TIP32C and TIP31C, 2SA1386 and 2SC3519. Running approx 130F.

Sub is about half volume for almost two hours.

The slab heat sink will get over 130F

DC offset is low (10mA) and idle current difficult to measure because goes into protect mode when I measure across the emitter resistors. Emitter resistors are 0.1 Ohm.
 
Last edited:
Register to hide this ad
Thank you for your comments!
When I got it, it would run for about 15 minutes then go into protect mode.
I replaced two zeners in the power supply and the caps. It works well now, but gets hot.
No idea how warm the external heat sink should get.
Does appear that the amp board has gotten warm because it is discolored in the area of the regulator transistors.
 
Board pic.
One side of the amp outputs gets very warm, the other side not as much.
The side with the TIP32C and 2SA1386 outputs gets about 15/20F warmer than the other side at the transistors. The outputs that get warmer are closer to the filter caps(just for reference).

Amp works but gets hot at the external heatsink. Up to 150F after about two hours.

The one side outputs get hotter than the other side: TIP32C and 2SA1386.

I checked the bias transistor mounted on the heat sink: 2SD669 and it tested good out of circuit.

Tested the TIP32C out of circuit - good.
Tested the TIP31C and 2SC3519 in circuit and 2SA1386 in circuit- good.
 

Attachments

  • IMG_3307[1].JPG
    IMG_3307[1].JPG
    234.6 KB · Views: 24
  • CHT 10 Schematic.png
    CHT 10 Schematic.png
    141.7 KB · Views: 20
Last edited:
This uses sil pads between the transistors and heat sink. I put a small amount of compound on the bias control transistor pad.
 
I checked board visually for cracked resistors and broken traces.

When I first got it, it went into protect mode after 10 minutes:
One of the 15V zeners in the power supply was bad, replaced both.
Replaced all of the electrolytics.

After that it worked and stayed out of protect mode, but was overheating.
 
Last edited:
After two hours of how much and what type of output?

"Half volume" isn't a reliable quantitative indicator.
 
Unable to quantify it better than that. I would say two hours of moderate level as if you were watching a movie. The person who owns it told me that's how he uses it.

Looked at a couple of pics online of similar subwoofers (CHT series) and it appears that the heat is a common issue - amp board discoloration.
 
Last edited:
I reflowed all the solder joints in the area of the bias circuit. I may have got erroneous measurements with the IR thermometer at the output transistors due to the heat radiating from the regulator heat sinks. The regulator transistors definitely get hot, approx 130F at the TO-220 heat sinks. The reflow of the solder around the bias circuit seems to help in a 20 minute run of the amp. Will run for couple hours. Will be away from it for a couple days.
 
Last edited:
Ram amp for 2+ hours at half volume. Monitored temps at TIP31 and TIP32 with a thermocouple type temperature meter. No warmer than 95F.
The regulator TIP get over 125F. Going to install larger heat sink on the TO-220 to get the heat away from the board.

I think this is fixed.

TY everyone for your help!
 
The external heatsink gets about 130F after 45 minutes of running. I still don't have a good reference for this. Is this too hot?
Low DC offset voltage, Idle current appears to be in the range of 6mA when cold and 12mA when warm.

I know the transistor can handle a lot of heat, but this heatsink temp seems excessive to me.
 
electronhick said:
The external heatsink gets about 130F after 45 minutes of running. I still don't have a good reference for this. Is this too hot?
Low DC offset voltage, Idle current appears to be in the range of 6mA when cold and 12mA when warm.

I know the transistor can handle a lot of heat, but this heatsink temp seems excessive to me.
Click to expand...

That doesn't sound that bad to me but that's just my feeling and not based on experience with that amp.
I would be more concerned if the amp got hot while simply idling.
 
I reassembled the rear cover so the entire amp plate circuit board area is enclosed by a box.
Have a temp sensor on the inside of the box and one on the external heat sink.

After nearly 45 minutes on with no input signal, the inside temp and heat sink temps were 75F.

Will run the amp tomorrow with an input signal and record the temps over a period of 2-3 hours.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom