The Workbench

Re: Setup of Beolab Penta Amps

nobby — Thu, 18 Mar 2010 13:20:06 GMT

The "official" ones from B and O are about £25 a piece ... ahem ... we wont be using those!!!

I have found another "source" which come in about a quarter of the price, I will let you know how I get on.

The second amp (which had a different fault) is now up and running nicely ... I am very pleased :)

Thanks for your help guys.

Neil

Re: Setup of Beolab Penta Amps

solderon29 — Tue, 16 Mar 2010 18:20:23 GMT

Cripes,thats the only cap I've never replaced in these amps!!

You can get a suitable replacement from Farnell,No 471471,not sure about the dimensions,there is very little room for fitting as you know.Best to replace them both I guess.Not cheap !

Regards,

Nick

Re: Setup of Beolab Penta Amps

nobby — Sun, 14 Mar 2010 18:53:52 GMT

Nick + others,

Seems that the main supply caps are at the end of their life ... one is a direct short ... not good!

Do you have a reliable source or choice for these?

Neil

Re: Setup of Beolab Penta Amps

nobby — Sun, 14 Mar 2010 13:17:29 GMT

Thanks guys ... but i have just found that before i can get to that, I have to get the orange light off ;)

Re: Setup of Beolab Penta Amps

solderon29 — Sun, 14 Mar 2010 12:22:37 GMT

30mV across both resistors,15mv across each.Clip your meter leads on to avoid shorts,and set the current with no speaker connected.Don't forget to set 'tother pot for zero dc across the output.

If the thing won't set up,you may have ripple in the stand'by supply,best to replace ALL the caps!!

Regards,

Nick

Re: Setup of Beolab Penta Amps

Die_Bogener — Sun, 14 Mar 2010 06:05:40 GMT

Across both resistors and 15mV in total. Usually there are testpoints printed on the board.

Setup of Beolab Penta Amps

nobby — Sun, 14 Mar 2010 04:27:07 GMT

The service manual is rather unhelpful in its description ... it says connect voltmeter to 1R103/1R104 ... does this mean across the two resistors ... ie looking for 15mV on each? or 30mV across each resistor?

Neil