Menahem Yachad wrote:

Martin,

What's the BG4000 transformer "problem"?

Menahem

They short on the primary.

Martin

OK, nice to know - I haven't had that problem on any of the ones I've serviced.

Anyway, there is always the option of the workshop in Tel Aviv which rewinds these C-cores with no problem.

Anyone who wants this done, is welcome to contact me - I offer this as a service only, and put you in direct contact with the technician.

Menahem

Hi,

I don't have a BG4000 or 4002 here right now to check. Nothing is in my notes about it, but lately I have decided to write down inductance and resistance on all future transformers I work on, so I will have a reference if I have any troubled ones in the future.

I have not had any BG4000 or 4002 transformers fail, but other B&O transformers have failed, and I have had this workshop do the rewinding. The tech is very familiar with B&O C-core transformers, and his excellent results show.

Now, I will give you some numbers from my memory, but I do not guarantee them. I remember on the BG4002AC that the voltage immediately after the bridge rectifier should be about 41VDC, with the turntable at rest.

The voltage drops as soon as you push any buttons.

That voltage is basically the AC rectified. If you have that, your transformer is fine. If not, you have a problem in the transformer or your control circuit is not OK. You can easily disconnect the control circuit to eliminate that as a possible cause.

Unfortunately, I cannot give you any more information about the voltage in that part of the circuit.

A shipment France / Israel and the price of the repair may cost me dearly, so I would try to be sure Beogram before he did anything else ...
voltage of 4000 I can measure because the transformer is good that this problem is to know the output voltage of the 4002-type 5501 (this is the same as the 6000 Type 5502). what's crazy is that this voltage is indicated on the manuals nowhere and nobody knows ...

Circuits after diode bridges appear on the 4000 are voltage 50v to above, another 15v and the other has nothing indicated.
The diode bridge circuit after the 4002-6000 shows 22.8 v
so it seems to me that the transformer 4000 is more powerful than I would get resistances may be necessary to obtain the voltage ... I'm going crazy with this unit

Question: (maybe stupid) Is it possible to connect a variac AC to the bridge rectifier OD1, then slowly increase the voltage until the 41 V DC after the OD1 is reached.

With the BG in off and the 80 mA fuse out, then check the AC voltage on the variac.

Søren Mexico wrote:

Question: (maybe stupid) Is it possible to connect a variac AC to the bridge rectifier OD1, then slowly increase the voltage until the 41 V DC after the OD1 is reached.

With the BG in off and the 80 mA fuse out, then check the AC voltage on the variac.

Yes, it's possible. But be careful.

Martin

yes I'll see if I can find a variable power supply ..
I'll let you know when I have new

yes I'll see if I can find a variable power supply ..
I'll let you know when I have new

Just been talking to Tim Jarman and he would be very interested in the 4000 power transformer. He would get you a suitable transformer for your 4002 in return. Email me if you are interested.