I stick to modding others stuff to my liking, its bad enough P*****g about trying to find a case never mind racking the brains to come up with something original
Don't most of us do that ? The few times that I do something completely original, is when I can't readily find something to do what I need, like video distribution switchboxes, etc. Or the promised Silicon Chip Class A preamp that never eventuated ! There's nothing like getting prepunched, and labelled metal work if you are able, even if the guts are different ! Alex
A very quick "how to" refer to the pics in the previous threads..... the "names" of the caps don't matter just the values.
When replacing caps always ensure polarity is correct! The side of the cap with the banding running down it is the NEGATIVE side. With Non Polar caps it doesn't matter what way round you fit them, same goes for film caps.
1: Remove the 1000uF cap (the one laying on it's side) you can fit the new ELNA 1000uF in the same position or you can move it closer to the pins of the opamp (see picture on page one of the MB-45 thread) by soldering the 1000uf direct to the tracks. You can bypass the 1000uF with the 474J if you like..... basically this means soldering one leg of the 474J to one leg of the 1000uF and the other leg of the 474J to the other leg of the 1000uF. Doesn't have to be directly soldered to the leg but as long as it's pretty close by.
2: Remove the 2 x 10uF caps and replace with the capXon 10uF non polars (can be fitted any way round)
3: Remove the 470uF cap and replace with the blue Philips 470uF
4: Remove the two 100uF output caps and replace with the Yellow 1000uF Nitai non polars.
5: Remove the two 1uF caps and replace them with the two red 2.2uF Dubilier caps
6: Remove the diode and replace with the UF4007. You can bypass the diode if you wish with the 100nF red WIMA film cap (make sure you fit the diode the correct way round, grey band on diode lines up with mark on PCB)
7: The Rifa PME271 is optional, you solder it directly across the DC input, ie: solder one leg to the + track and the other leg to the - track, this beauty soaks up a lot of noise.
Afternoon all I have just fallen across one of these - the older metal cased version which I hope to use to drive my 600 ohm DT880S. I need to source a power supply - does it need to be regulated or can I use an old 12v 2.5 amp psu that used to power my Scalextric?
Canjunkie could you please repost your earlier photos of your version before I ask Mike for a kit?
I have also just found this after having found my old one at the weekend and doing a quick Google, a new member of my tribe means I have to go away from speakers for a while and I would really dearly like to get this working again if I could (if I try and spend significant money on any kind of new hi-fi at this point means the hormones will have me killed!)
Anybody know anyone who can do this kind of thing for someone else (south of England would be great?)
Mike kindly modded mine for me (with many thanks to Ian for the useful intervention swap thingy!)
I've been running mine for a little while now and it's really surprisingly good, I have to say it doesn't really suit the Beyer 770's or maybe it's the phones?
My 701's sound pretty good though, in fact although it is a little quieter than I might like (okay, I probably shouldn't have it too loud, I know...) it's really very detailed for something this cheap even with all those good new modifications Mike added.
I think the base is probably still not there yet, I just haven't run it in properly, but considering this was really cheap when it was new and you can get them for free (or near as dammit) now this is bloody good
Just completed my mod......Will be keeping this wee amp! Sounds great. Took me a few hours. Used Elna Silmic II capacitors for output caps and Elna Cerafines for power side....definitely an improvement, though spending just under £40 might seem a bit overkill. Got Elnas from hificollective and others from ebay and Maplins. Have connected it to my pc and am listening to mp3s. Have took some pictures. Will post them as soon as I work out how to. Cheers...a great mod...thanks. jim
I realise this thread is rather old, but thought I'd "revive" it a little!
I've recently picked up one of these little beasts cheaply from eBay. It's VERY noisy, so I reckon it needs some work anyway. As I haven't done any soldering for about 20 years (and I can be hamfisted at best), I wondered if anyone would be interested in modding it for me? I'm in NW England.
Amplifier Found - one of the metal cased versions. Legend says 12-24v dc while I think the plastic cased versions use 12v? So the higher the voltage the better? e.g. an old laptop psu?
I will have to enter my "dusty" amp museum and prod my MB45 (to release the spiders) before even attempting a look under the bonnet. Apparently I need to comply with "health and safety" regulations and become a "center of excellence" before I can even touch the amp but let's see what I can do for you (avoiding the rats and spiders webs) in my spare time
videoguy: Hi Jon: I am in Florida & am in frequent contact w Alex Kethel. Am in need of some single ripple eater boards. Wpuld you mind giving me the address of the pcb manufacturer; as I need ten boards. Thank You in advance. Bill Wilson
Dec 2, 2019 1:54:46 GMT