ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
This is the second Archived Forum which was active between 1st March 2012 and 23rd February 2022
Bonjour (from France),
I've fixed some problems on my BM 1900-2 (hum/C66, bulbs, ...)But a small problem persists.When I switch it on, choosing a source from standby, I hear "pop" in the speakers.The muting circuit seems to be OK. When I increase the value of the C98, the sound rises gradually after the "pop" noise. I changed the electrolytics near the TR207/307 with no results.
The muting is OK when switching fron one source to another.
Any suggestion would be welcome.
Thanks for reading
Philippe
Mmm... The usual suspects here are input capacitors. No such pops on my 1900-2 though. That said a thump at startup is quite normal with many amps that do not have a delay relay.
Do you get the pop at tape-out? Is it very loud?
Jacques
same problem without any input (P2 disconnected from preamp board 4).
I don't have an osciloscope but my multimeter shows a temporary offset of 0.3/0.5V. It decreases immediately to 30/40mV.
The 31V and other voltages in amp section seem all OK.
The pop is not very loud but unusual.
I didn't test tapeout...
Thanks
I did the test with tape output. It is perfectly silent when switching on.
The problem is clearly a poor stabilization on the zero Volt output (speakers) when 31V is comming on). I didn't find the culprits...