maplin 225w 2n3055 mj2955 bipolar x2
i have 2 from a disco project long ago , i recall one or both may need attention after a spearker blow and took out one side of amp, they have been in a box in case ever needed since about 1995 nice tone and plenty volume untill one side blew i have lost the build notes and schematic but think it might have been maplin code lw32k or something if my memory is correct i came across this thread while looking for schematic open to offers or i may auction them dave
i have 2 from a disco project long ago , i recall one or both may need attention after a spearker blow and took out one side of amp, they have been in a box in case ever needed since about 1995 nice tone and plenty volume untill one side blew i have lost the build notes and schematic but think it might have been maplin code lw32k or something if my memory is correct i came across this thread while looking for schematic open to offers or i may auction them dave
Attachments
I bid up to £75 on this item but it went for more.
I will just have to wait for another one to come up.
I will just have to wait for another one to come up.
I'm open to offers for these. 😱
As you can the see the Out puts were upgraded to high power 250W chaps. But I must've robbed a set to repair an amp at some time.
They are however available here.
1pcs 2SA1117 + 1pcs 2SC2608 Complementary Transistor TO-3 (100% NEW) | eBay.
So yes these were both working before I removed the Transistors.
As you can the see the Out puts were upgraded to high power 250W chaps. But I must've robbed a set to repair an amp at some time.
They are however available here.
1pcs 2SA1117 + 1pcs 2SC2608 Complementary Transistor TO-3 (100% NEW) | eBay.
So yes these were both working before I removed the Transistors.
Attachments
Maplin LW32K Schematics
Just posted this for the search engines as there are no schematics on the net .
But here you go folks.
Maplin LW32K schematics, parts list for 150W / 225W power amplifier circuit diagram.
Just posted this for the search engines as there are no schematics on the net .
But here you go folks.
Maplin LW32K schematics, parts list for 150W / 225W power amplifier circuit diagram.
I wanted one for my collection.
Instead I redesigned the Maplin amp with CCS and CCM and newer transistors.
I just put up the original cct diagram lol
I have added a LTP with CCM and CCS.
Replaced old transistor with new ones.
Altered the feedback arrangement slightly.
I have just bought a couple of these modules off ebay for £15.
There are some components missing off both so should be fun getting them working.
There are some components missing off both so should be fun getting them working.
An externally hosted image should be here but it was not working when we last tested it.
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I finished wiring up the amp tonight and mounted output transistors on the heatsinks.
I powered it up and nothing unless I really wound up the volume and then it was heavily distorted.
The DC conditions were find giving zero volts out with no input signal.
I had a look around the circuit but it all seemed OK.
I noticed if I disconnected the speaker the output would look fine.
I buzzed out the driver transistors against the heatsink and my meter said it was OK.
However the plastic bush on the BD711 looked very flattened so I changed it anyway.
Powered up again and the amp burst into life and sounds great.
I don't quite understand why the bushes buzzed out ok but when power was applied it stopped working. I can only guess the 45 volt rail was arcing across the flattened bush.
Really weird fault that I have never seen before.
I powered it up and nothing unless I really wound up the volume and then it was heavily distorted.
The DC conditions were find giving zero volts out with no input signal.
I had a look around the circuit but it all seemed OK.
I noticed if I disconnected the speaker the output would look fine.
I buzzed out the driver transistors against the heatsink and my meter said it was OK.
However the plastic bush on the BD711 looked very flattened so I changed it anyway.
Powered up again and the amp burst into life and sounds great.
I don't quite understand why the bushes buzzed out ok but when power was applied it stopped working. I can only guess the 45 volt rail was arcing across the flattened bush.
Really weird fault that I have never seen before.
An externally hosted image should be here but it was not working when we last tested it.
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