Repair of  Mackie SRM 450 MK1 Powered speaker


Fault - Dead   

The Mackie SRM450 MK1 Powered speaker is the 1st generation version of the SRM450, it differs from the MK2 in the fact that it has a conventional transformer type power supply instead of  switched mode unit.

The Customer dropped off the unit

On first inspection the main 3.5 amp fuse had gone nothing else seemed to be blown, a quick check of the various transistors mosfets power diodes etc all tested out fine, the problem was that the transformer primary winding had gone short circuit, removed the transformer for a closer inspection, see below the transformer removed. 

No external damage to the transformer was evident, this was obviously due to a manufacturing defect/poor construction materials.

We contacted the official UK Mackie spares supplier and they informed us the transformer was no longer available, this presented us with a problem - well actually not just us but anybody who has the misfortune to blow an SRM 450 transformer.

Time for a radical solution - it occurred to us that we could probably get hold of a used transformer, however it is quite likely that this might not be such a good idea - I will explain, the original transformer was made by Eaglerise Electric & Electronic, the date of manufacture was 2007 so it has not even managed 7 years of service, a good transformer could last 50 years or more - just think how many vintage VOX, Marshall, Fender etc amplifiers from the 1960s are still going strong on the original transformers, so this particular unit has not done very well, as you may have guessed the transformer is Chinese, we have encountered problems with numerous Chinese made transformers, basically they are cheaply  made with sub standard materials in particular the enamel on the windings breaks down causing short circuits, so fitting another of these would be asking for trouble, its a wonder that Mackie haven't worked out why they get these transformers made for such a low price ! 


Our brilliant solution was to get some completely new transformers specifically wound for the SRM450, identical in every detail except these transformers are reliable and made with top quality materials, see below.



Brand new manufacture upgraded replacement transformer made in England (built to last)

See new transformer fitted to the chassis




Chassis being fitted into cabinet and speaker on test 



We tested the speaker for several hours before the customer picked it up all ok. 


We have a new batch of these transformers available for sale in our online store @ 95.00 each, these are the cheapest and best quality transformers available for the SRM 450 MK 1 for more information, contact us

We hope the above information has been of assistance to those attempting a repair, we add more examples all the time, a lot of work goes into this section of our site from the doing the repairs, photos and answering technical support emails, to keep this a free service we rely on the goodwill of people who benefit and learn from the information supplied.

Please show your appreciation, feel free to make a  donation no matter how small to keep this service going.



TELEPHONE (UK) 01803- 324589 

TELEPHONE (INT) +44 1803- 324589

Head Office



2015 A&J AUDIO. All Rights Reserved.