Step1:

would he not measure 81R Hemenex?

Where should he measure 81R? From TR27C to GND? Sorry I don't get it....

According to my schematics both caps are from +15V Stby to GND without any R inbetween... What did I miss?

  Gunther

C71 out and OK, C47a was not there, but looked like from factory "not there"

hemenex:

Step1:

would he not measure 81R Hemenex?

Where should he measure 81R? From TR27C to GND? Sorry I don't get it....

According to my schematics both caps are from +15V Stby to GND without any R inbetween... What did I miss?

  Gunther

My schems too, and the PCB too

Soren,

just to be sure - are we talking BM2400 or BM2400-2? There are (minor) differences and just to confuse everyone both have Type 2901

My 2400-2 schematcs doesn't show C47a either.

And to narrow down the short circuit: TR31 C to GND no short? (will be low ohms as there are the bulbs connected but should have at least more than approx. 30R

TR31 C to GRD 15.4R

BM 2400 T 2902

Sorry Soren - had to find a working example of BM1900 / 2400. As it's one of my favourite receivers (noone younger one believes that it's a 1970 something device) I have several unchecked ones from fleabay...

The first was obviously slaughtered by the previous owner - cutted wires et.

The second was just relay-clicking on power on.

The third had all red lights on but that's it

Ok, so I took my working example and dismantled the bottom cover. That one had good lubrication / grease. It is sticky to the bone. So I had a good some minutes on cleaning hands

The good news: TR31 C to GND is 15R so this part of yours is ok (and it looks like your bulbs are ok, too ).

Now it would be time for me to desolder some of the wire bridges to narrow down the location of the +15V-shortcut. Have to evaluate some good starting point.

Obviously you are sort of on-line actually 

  Gunther

Online and ready

Checked cables to 3 lamp ass. black 0.0 R, red 15.4 R

OK, let's start a Monday thread

Here are 2 wire bridges with the +15V signal. Open them (one side of each bridge is enough) and measure on which side of the traces you have the short circuit. We'll discuss your results

(This is actually a BM1900 (no -2) but IRRC the only difference to the BM2400 is the missing ultrasonic receiver components. Layout should be same.

Søren Mexico:

Checked cables to 3 lamp ass. black 0.0 R, red 15.4 R

Absolutely fine as the red wire is the same signal as TR31 C

And @step1: don't feel like being chased away, I am just puzzled about your response; Your input is surely welcomed

 Gunther

Here

Have to go working will be back tonight, please keep on helping, I'm very greatfull of your help

So we narrowed it to the immediate surroundings of TR27

Next 2 steps:

- check if collector of TR27 touches the chassis (right circle)

- There's only one more wire that distributes +15VStby from here now (left circle). Of course it's right under a plastic bar of the housing.

It leads to board#3. Maybe it's easier to de-solder the light orange wire there:

((EDIT: Seem to have received those BM's from some tinkerer: finally sorted it out: all "non -2" and "-2" versions mixed up (housing differ from content...)

This is -2: (3 IC's) ))

Just found out there seems to be another version of board #3

Here's version 2 (this is from the above mentioned slaughtered BM I am using to get deep into the mechanics of that machine - it's "officially" declared as spareparts anyway from now on...):

(And just ignore that typically damaged red reason for recapping)

((EDIT: this is the non -2 version: 1 IC only))

Again the same question: : where's the short circuit now?

And I'm glad yout posting problems seem to have disappeared

I already have closing time here (7:30 PM); at least officially: if you're self-employed there is no such thing as closing-time

See you tomorrow (speaking in my time...)

  Gunther

Another idea:

What about the insulation of TR27: Collector is also the "tab" with the screw:

Soren suggests he had a short from TR27C to ground, now looking at my CCT diagram there is a resistor between the 15v stndby line (the bit that Soren has measured) and the capacitors you mentioned, just to the right upper part of the touch detectors diagram 1. This then feeds remote reciever / selector circuits with the capacitors you mention. Now, it seemed obvious that if either these capacitors were s/c then we would measure the series resistance. Maybe I have missed something?

I think this has to be an insulator or other weird short as you mention in your later posts, as I cannot see any other single component that could have failed with these results!

hemenex:

Step1:

would he not measure 81R Hemenex?

Where should he measure 81R? From TR27C to GND? Sorry I don't get it....

According to my schematics both caps are from +15V Stby to GND without any R inbetween... What did I miss?

  Gunther

Actually Soren you can  prove this by measuring the resistance between the positive of one of those capacitors and the collector or the transistor!

Step1:

there is a resistor between the 15v stndby line (the bit that Soren has measured) and the capacitors you mentioned, just to the right upper part of the touch detectors diagram 1

Olly,

There must be even more different circuit diagrams around than I have.

Just a moment, I have 3 of those diagrams - didn't see the 3rd one.

There's a version 1/77 that definitely has the resistor R66a / 82R you refer to. Of course this was the diagram I left in the envelope

I looked at version 12/77 A that definitely doesn't have R66a.

And the modification notice 3538401 (danish/english, no datecode found) doesn't have this either.

So all of us were correct. Now we'll only have to find Soren's short circuit Let's wait for his return....

Sometimes it's good to keep "double" diagrams - they might be a slightly different version

And the fourth one I have is the -2 modification...

Ah should have guessed! You shouldn't admit to having nice clean copies of the diagrams you might get mugged lol!

I'm sure Lee already has them so no need for mugging

  Gunther

hemenex:

What about the insulation of TR27: Collector is also the "tab" with the screw:

back after a long day, deep into a frigging varnishing m/c, had varnish all over me, I hate that, when I retire I will do no bigger than the BM/BL 5000.

Yes, the new TR27 I put in, had a smaller hole for the screw, so when I tightened the screw, I just mashed the insulating ring and the screw got contact to chassis, hole difference is 0.3 Mm. the new 3.7 Mm. old 4.0 Mm, screw is 3.5, I found some heat shrink tube, put it on the threads, and with the mashed ring clean there is now no short, will return all desoldered tomorrow if the work allows it.

Step1:

Actually Soren you can  prove this by measuring the resistance between the positive of one of those capacitors and the collector or the transistor!

TR27 C to pos. on both caps 0.0 R and tracking the PCB tracks, there is nothing in between them, exept for a wire bridge TR27C to C47a

Question: Do I add the missing C47a, or just leave it like it was

Søren Mexico:

Question: Do I add the missing C47a, or just leave it like it was

In the newest doc I have - the modification sheet - C47a is gone so shouldn't be neccessary. But I don't think it will hurt if you add it.

As all my opened BM's are 1900's (even the one in the BM2400-housing) I can't have a look at C47a now.

Check your TR27 before switching the BM on - it might not have liked to have been short-cutted

My BM 2400 is now working, on the test bench, nothing connected, FM 1 volume down, addjustment 15 V and no signal current, it has been on for about 1 hour and no channal jumps, will leave it for 1 more and then connect speakers.

The TR27 was shorted to chassis, and may have been half bad before that.

Thank you Gunther, Olly, Jacques, Martin and everybody else who helped, if we ever meet you are in for FREE BEER

Tested the remote I got from Leslie, funny the left side buttons all work, the right side not, will open and investigate, surely some oxidation.