JCM900 SL-X Questions/Problems

[Spanngitter]

The original BR3 was rated at 1A RMS. The replacement is rated at 1.5A RMS. The heater draw is around 900mA. A very safe margin, I would say.

Nope. If somebody would have read the datasheet correctly they would have seen that it states "For capacitive load, derate current by 20%." which makes max current less then the minimum required 900mA...

But, if you have written proof from Marshall Amplification, of your assumptions, I and most other people, would be grateful if you shared it.

Again RTFM, it's all in there, even that it requires to be mounted 9.5mm away from PCB and capacitive load is 500-5000uF




BTW: this above is the Datasheet of the original part vendor (FAGOR).
Modern W005 Rectifier, e.g. from Vishay, do not have the capacitive limitation in Spec but still the requirement to mount them off board and the 20% reduction in current.

 

[jagrenet]

When I get items like this for rework, (they are usuall a lot worse than yours) and the track has been damaged by heat and/or removal of components, I use my fibreglass pencil and rub it on the remaining track.
The fibreglass pen removes the varnish and leaves the copper track intact.
I then form a length of 25gauge solid tinned copper wire, to make a loop for the new component head and run along the freshly cleaned track for at least 3/8". That makes a good mechanical and electrical joint.

Glass fibre pencil - 4mm | RS

uk.rs-online.com

Probably cheaper on fleabay but if you own one of these, it makes repairing what was a complete mess, a doddle.
When you have completed the electrical repair don't forget to revarnish the cleaned off track and copper wires.

RS PRO Clear Acrylic PCB Coating for Electrical Circuit Protection | RS

uk.rs-online.com

Shown inside a Messa with component damaged PCB eyes. Prepared for wire treatment.

Don't forget, if a job is worth doing, it is worth doing right.

Thank you for the input Jon ..... and the links to the proper tools. Much appreciated !!!