ARCHIVED FORUM -- March 2012 to February 2022READ ONLY FORUM
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Hi, I have two pairs of BL4000 MK1. The well known issues of disintegrating foam has affected me, but it is unclear if it affects the PCB as stated in some cases. I cleaned it all with methylated spirits.
The standby circuit is down and hence the power stays red. The standby transformer has a bad decay history and they seem to fail after some years and especially when unpowered for a longer time.
I am trying to find out the spec of this standby transformer as surely it should be available at Mouser, Digikey, RS Components, etc. Sourcing the TR5 fuses is easy, but I cannot find out the exact spec of the transformer.
Does anyone have that info? What spec or P/N will work?
many thanks.
Do you have AC on the transformer secondary?
Martin
I have not checked for that yet, but I suspect not as the symptoms are all like a burned out stdy trafo.
Where do you think the red standby light gets its power from?...
My guess is that the sticky black foam ate away at components and copper traces on the main board.That's what is has done in most others, so why not in yours. I've repaired countless.Diagnose.Don't guess.Look at the relay circuit and the inputs it gets from other circuits. That's typically where most problems are found.
OK will check and get back, I hope you are right.
pilza:The standby circuit is down and hence the power stays red. The standby transformer has a bad decay history and they seem to fail after some years and especially when unpowered for a longer time.
As Martin says, check the AC out of the "Main" transformer assuming you can hear the relay click closed. The relay (RL1) supplies the AC power to the main transformer. However, my guess is that the relay has not been triggered and DC fail signal is triggered.
If the red light is on then there is nothing wrong with the "Standby" transformer.
Given you stated you have had the foam issue, then a component on the main PCB is the most likely cause. In particular I would closely exam the components around the close area to P6 as below.
Regards Keith....
What Keith said.And the components in that area may sit slightly different in your speaker, - but it's that circuit and also a bit of circuitry at the oppositesite of the connector bay - and all interconnecting (long) copper tracks.