Todd wrote:

Hey Evan,

"In any case would you mind doing a photo showing exactly what Chartz is suggesting?...especially the pre-amp section ot the 47k trimmers?

*Oh and thanks for answering my previous questions on the Caps & why the use of the bubble plastic*

Circled in red is the main 5000uF reservoir capacitor. Jacques recommends I change this because of potential failure. The failure of these three main capacitors give a distinct symptom to the sound output of the amplifier, a low 60Hz buzz (AC current).

Circled in green are the trimmers on the main amp board. These are used to fine tune the amplifier and over time corrode, losing sound quality. There is also one in the upper right of the photograph, circled in yellow, on a different board that will be replaced.

Finally here is the preamplifier board, with no less than 6 trimmers. These will be replaced also and for the same reasons.

Hey, Thanks for circuling out the trimmers and showing the preamp board! Yes, few more things I know and can follow now😁

Evan wrote:

Finally here is the preamplifier board, with no less than 6 trimmers. These will be replaced also and for the same reasons.

Hi Evan, I would like to change all the trimmers in my BM 4000, but as I only have a digital and an analog multimeter I dont know how to adjust them, or do I check the setting on the old ones, once out, and then set the new ones to the same value ???

Søren Mexico wrote:

Evan wrote:

Finally here is the preamplifier board, with no less than 6 trimmers. These will be replaced also and for the same reasons.

Hi Evan, I would like to change all the trimmers in my BM 4000, but as I only have a digital and an analog multimeter I dont know how to adjust them, or do I check the setting on the old ones, once out, and then set the new ones to the same value ???

Indeed my friend, indeed!

Thank you Jacques, will do.

Hey Søren, sorry I could not reply in time, I have been busy. Good thing we have Jacques around, otherwise these projects would never get finished! 😂

😳

Well I'm no Martin or Peter but ta!

Hi everybody, just thought I would post my current status. There it is - in a pile! Sitting down to sort out my cap shortage now and order a few things.

Does anyone know exactly what the value of the trimmers are on the pre-amplifier board? The service manual says 50k ohm. Should I trust that figure? And also, are they all the same? There is only one trimmer listed in the parts list. I don't know how to shop for these - any size measurements? Help!

Thx, E

In my 4000 there are also 6 pcs. but they are all 100K R so 50 K for yours could be right.

Alright. Many sources are saying 50k Ohm. Do you know how to size these things? Do I shop by lead spacing or what?