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Rebuilding Michaelson&Austin M100 -schematic needed

Hi, I'm a new member here and have been surching for help with my Papworth Burgundy TVA-8 stereo amp, one of my output trannies has gone low resistance, I need a new one and need to try to match it with the other, I have emailed Eddie but suspect it's an old email on the Papworth site, any help or assistance would fantastic, ideally a schematic and need to know if there are any new old stock or where the original transistors were sourced, many thanks Tony
 
Hi Anthony and welcome.
I've not worked with Eddy for many years and TVA-8 came after my time, but I just tried to call him, as we've kept intermittent contact. Unfortunately his number came up 'Not recognised'.
I will try a few other possibilities and get back to you.
 
Hi Anthony and welcome.
I've not worked with Eddy for many years and TVA-8 came after my time, but I just tried to call him, as we've kept intermittent contact. Unfortunately his number came up 'Not recognised'.
I will try a few other possibilities and get back to you.

Thank you, really appreciate your time, if all else fails and I have to buy an off the shelf el34 25w transistor, I assume I'll need two, also would I need to change any components?
 
Erm I think you mean "transformer"! If like any of the other TdP designed Papworth amps the OPT (output transformer) is anything but standard and you will not be able to obtain any suitable replacements.

What makes you sure that the OPT is faulty?
 
Eddy Fincham designed the TVA-8 as a single ended pure class A amp. As such it differs from other (Tim DcPVC designed) Papworth products which are all push pull as far as I know. All of the Papworth production of original M&A TDePVC models has improved build quality.
 
Eddy Fincham designed the TVA-8 as a single ended pure class A amp. As such it differs from other (Tim DcPVC designed) Papworth products which are all push pull as far as I know. All of the Papworth production of original M&A TDePVC models has improved build quality.

As it happens I just looked this up about 20 mins ago Mull! 15WPC single ended yep... It says Walrus Systems were the UK distributors so maybe they have some spares... or maybe long defunct...
 
Sadly it looks like Walrus have gone. I visited a couple of times. Nice shop. Les Wong IIRC.
Yes sorry transformer, it’s a stereo amp, with I believe push pull type transformers, 6 wires 3 for 0 4 and 8ohms and 3 wires centre taped for the plates, the left channel was thin tested against the right one of the centre to valve is 20ohms almost half the other and across both valve taps measures 41ohms compared to the rights 73ohms, can I replace both with a 20w pp one
 
I have managed to contact Eddy, but not had a conversation yet. Anthony, you have a PM.

For the benefit of all, I should state that my electronics knowledge is minimal. My association with Papworth was more sales/distribution based. So, whilst familiar with the history and product range, I am next to useless on the technical front.
 
P.S. I should think that if you can't get a transformer from 'stock', you could get it re-wound, especially if you can find out who made it. Have no idea what that might cost though.
 
Hi

Today I bought one Michaelson&Austin M100 amp. It is in terrible condition. Hope to get it working. Finding a second amp will probably be nearly impossible, so maybe it will be possible to build a clone if the transformers are available somewhere.
I am very happy to find the schematic on this page. That will help a lot, since it seems parts are missing or modified and the power cord has simply been cut out.
One thing I noticed is that my amp doesn't have a seperate recitfier board in it, so that could be a problem.
Anyway this will be a challenge for sure. I will try to post a picture later.

Rob.
 
Here is the picture, hope this works. If not, I also included a link.

BXQh8EW


http://imgur.com/gallery/BXQh8EW

Rob.
 


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