philips: BX495U (BX 495 U);
I am restoring a Philips BX495u that is in very poor condition. One of the parts that seems to be beyond repair is the output transformer. It is contained in a cube box filled with some very hard black resin. It code is A3 168 71.4 (see image, with the cover -and some resin- removed).
I could not in a schematic for this model but I am using those of BX485u/BX491u (no magic eye) and BX505u that are very similar. The equivalent part in these model is coded A3 168 71.0 (485u and 505u) and A3 151 48.0 (491u). Howver the 1949 revison of BX485u uses the same code as my model.
The unit contains a number of connection in the secondary. Apart from forming the speaker's transformer, they give feedback tension for the volume control. These are labelled S45-46-47-48-49-50-55 in the schematics of all models.
The tester indicates that the primary is cut (burned?) but due to the presence of the back resin, it seems impossible to have access and try to repair.
Can anybody help finding a replacement part or suggest an alterantive solution.
Many thanks in advance
Please pictures only <560Pixels !!!
I edit it to the right size. Regards Wolfgang Bauer
Try putting the transformer in boiling water for a few hours. If you have good luck, the resin may soften enough to permit removal of the transformer from the box.
In fact I have been informed that the product is coal tar. I have already been able to remove some by just heating with hair drier but to really remove the transformer clean I need something else. I was going to try with a solvent like xylene but I will try your suggestion first; seems easier.
I will let you know the result.
Well, it took some time and patience but he transformer is now out of the box. After trying other methods, I used a xylene based solvent (International® GTA 822; a solvent used to clean marine paint spraying equipment). By filling the enclosure several times with the solvent, letting it act on the tar and helping to remove the sticky product with a cutter, the transformer finally came out. Very messy job!
I will see now if it can be repaired.
(thanks to Wolfgang Bauer for editing my previous submission)