Pioneer SX 1250/5590... Yes, HOT... But how much?

[UrbaXter]

Hi guys, I have read here many posts about these "little beasts" running hot at the right side, just over the stabilizer board.

I just changed some of very well known noise signal transistors in my beloved SX 5590, regulated the stabilizer voltages, checked the DC offset, and set the bias at 65mv, everything is working really good, but I decided to measure the temp at the stabilizer board, and these are the results.

With the thermal sensor of my Fluke DMM touching, yes I mean touching, the regulator transistor I could read 73C/163F, and again, touching, the big resistors, that ones with a kind of fabric around, I read 103C/217F.

Well, to me this seems too much hot... So, as the voltages and bias are adjusted and stable, what could be the cause of this extreme heat??

 

[dmar]

I had the 1250, & now the 1280. Both units never got to those temps.. Somethings wrong.

 

[nj pheonix]

Did you test the voltages there? That would be telling. I agree though. That's too hot and will cause problems sooner than later . I'm surprised it hasn't already.

 

[dmar]

I would have it serviced.

 

[rcs16]

Guess what, power transistors and resistors are supposed to run hot in doing there job.
It is a well known fact that the awr-106 runs the transistors hot. They do eventually fail, measured in years. Every 10c rise in temp, results in halving the life. The solution is to cool the devices by means of adding or improved heat sinking

 

[UrbaXter]

I had the 1250, & now the 1280. Both units never got to those temps.. Somethings wrong.

Have you read the temperatures like me, I mean exactly over the semi and resistors? Because I suppose that over the case it will be 20-30% less.

 

[UrbaXter]

Did you test the voltages there? That would be telling. I agree though. That's too hot and will cause problems sooner than later . I'm surprised it hasn't already.

The voltages at the stabilizer are +65v and -65v perfect, no DC Offset and bias at 65mv and stable...

 

[UrbaXter]

Guess what, power transistors and resistors are supposed to run hot in doing there job.
It is a well known fact that the awr-106 runs the transistors hot. They do eventually fail, measured in years. Every 10c rise in temp, results in halving the life. The solution is to cool the devices by means of adding or improved heat sinking

I know and agree, but the question and what I would like to know is, what´s the temp limit to decide if I should improve the heatsink or better search the cause of the overheat!?

 

[dmar]

Have you read the temperatures like me, I mean exactly over the semi and resistors? Because I suppose that over the case it will be 20-30% less.

I could be pushing my 1280 & it never get hot enough, not to touch!

 

[rcs16]

It comes down to how many years you want it to last? That is what the designer and the beans counter decide as part of there business. If the decision is to last 40 years, if it lasts that long, job done.