Beomaster 901 - Heatsink (too) Hot/Warm

3 replies
S(
Offline
staffanrosvall (archived2)
Bronze
Posted August 26, 2018 at 15:09 GMT
#2264367

Dear Forum,

I have recently bought a Beomaster 901. It works fine playing music from both my record player and aux-connection.

However - the heatsink on the back of the amplifier gets very (worringly) warm. According to a forum thread somewhere I read it is due to too much idle current being drawn. It is the right hand side of the heat sink when viewed from the front/top gets the warmest.

STATS @ ZERO VOLUME:
After Running 5 min - 0,19 AMP @ 235 V [Voltage selector set to 220 V]
After Running 10 min - 0,21 AMP @ 235 V [Voltage selector set to 220 V]

After Running 5 min - 0,19 AMP @ 235 V [Voltage selector set to 240 V]
After Running 10 min - 0,17 AMP @ 235 V [Voltage selector set to 240 V]

Anybody got any suggestions on how to solve this? I am not confident enough in electronics to fix the circuit board myself, but would like to know what the issue is. (I live in Copenhagen, so I believe there are qualified Bang & Olufsen-repair-people around).

/Staffan

S(
Offline
SteveAndBell (archived2)
Bronze
Posted January 19, 2019 at 10:38 GMT
#2264368

Hi Staffan.

I just picked up a 901 with this exact same issue.  I'm tempted to just replace all the output transistors just for the heck of it... but did you eventually find a solution?

M(
Offline
mcolliva (archived2)
Bronze
Posted January 22, 2019 at 09:16 GMT
#2264369

Hello Staffan

on mine 901 recently restored I changed both trimmer 1K and fixing on 10-11 mV across 0.39 ohm resistor without warming on heatsink.

Same changes shoulf be done on 500 ohm trimmer to set right 32 V on supply voltage.

Have a nice Tuesday

MArco

or
BeoWorld Gold Membership card
Join BeoWorld

Register to access the forums, reference material, and exclusive member benefits — including our monthly prize draw.

Become a Member

December 2026 Prize Draw

Gold Members Only

As a Gold member you're automatically entered into our exclusive prize draw — your chance to win iconic Bang & Olufsen products. A unique benefit of BeoWorld Gold membership, every draw brings a new opportunity to win something special.

View Prize Go For Gold