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Old 26th March 2011, 07:48 AM   #1
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Default EA Playmaster 136 Amp.

Hello all? I have a bit of a problem and need some advice.
I resently was given an Amplifier that my late brother in law built. It is an EA Playmaster 136, can anyone tell me how to find a circuit diagram for it.
I can be contacted by email if that helps: auzzie2307@live.com.au
I am an electrician also so I know my way around a circuit and electronics also.
Thanks in anticipation.
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Old 26th March 2011, 09:23 AM   #2
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What is wrong with it ?.

Eric.
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Old 26th March 2011, 09:48 AM   #3
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There's nothing like a schematic for the unknown that is unknown, if you know what I mean.
Likely, the 136, designed perhaps as an early effort by the current Silicon Chip Editor, is well known to him and there's a schematic and construction article available there. It goes back to the early 1970's so you have a few pleasant hours ahead swapping out caps before sending the semis also to oblivion.

As I recall, It was Electronics Australia's first and very popular budget kit amplifier design marketed in one box. Sound wise? Well, I did say early seventies and silicon there somewhere.
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Old 26th March 2011, 12:20 PM   #4
teemuk is offline teemuk  Finland
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I recall "Playmaster" was a brand for kit amps sold by some Australian electronics magazine. I remember seeing some schematics online but can't remember where. There is a site named something like ozvalveamps.com, which is about vintage australian guitar amps. (I don't know if the site exists anymore, though). Quite contrary to the name it also included some stuff about SS guitar amps, so might be worth checking that out. It could be where I a saw those Playmaster schematics.
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Old 26th March 2011, 01:46 PM   #5
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Thanks Teemuk, you're right. The site was operated by Roly Roper for some years but closed and now is back at this new domain: Classic ANZ Valve Guitar Amplifiers As the name says, it is 99% Australian and particularly DIY guitar amp designs by the EA magazine referred to earlier. There are references, (incorrect) to numbers 134 and 136 as possible solid state guitar amplifiers but these are just that, no detail.
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Old 26th April 2012, 06:56 AM   #6
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Default Looking for an AY9171......Old thread, but...

All,
I have a Playmaster 136 with a broken AY 9171 transistor (the PNP part of the complementary output pair). I have a sentimental (ha) attachment to this old amp I built in 1973 and use in the shack but I can't get a replacement transistor. The only site listing it available (Nucleus) unfortunately tells me it is an error on their site. Can anyone help with one or a suggested supply? Happy to buy and cover postage. There is no apparent equivalent in a TO66 case, closely matched as it is to its NPN mate, the AY 8171 which perversely is still available.
cheers
AntonOfOz

BTW fault finding in this direct coupled amp was a b$%^&. The AY9171 has a shorted b-e junction.
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Old 26th April 2012, 07:19 AM   #7
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Not sure where in Aust' you live but the big metropolitan libraries and the older Uni libraries will have old "Electronics Australia" in their shelves. May have to speak to a librarian but a place like RMIT in Melbourne is pretty accessible. I am in Qld now but I found Monash(Hargrave Engineering Lib)/RMIT/and Melb State Lib very helpful. You don't have to be a student and for the cost of a photocopying card you can get a lot of info'
But it will help if you know the year the 136 was published!
From Anton's comment sounds like it was pre-1973.
You might try "bumping" this thread this evening and see if people can be more specific.
Good luck, Jonathan
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Last edited by Jonathan Bright; 26th April 2012 at 07:22 AM.
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Old 26th April 2012, 07:28 AM   #8
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There is a thread here in diyaudio that might be worth following up it is called "PLAYMASTER 40/40 schematic needed" and the second post (#2) look promising because although it is the later 40/40 refered to this guy looks like he has all of the EA's

The thread is dated 31st August 2007. that might help.

For what its worth I just Googled Playmaster 136 and got some interesting sites.
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Last edited by Jonathan Bright; 26th April 2012 at 07:31 AM.
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Old 26th April 2012, 07:38 AM   #9
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Thanks Jonathan,
I have all the info I need about the amp but just need the AY9171 transistor
cheers
Anton
(Sorry if this reply duplicates earlier one - not used to this forum yet)
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Old 26th April 2012, 09:30 AM   #10
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Hi Anton
Here is an older thread that answers your questions but doesn't give you the antiques.
http://www.diyaudio.com/forums/solid...ind-print.html
So you aren't the first to come up against TO66 power transistor problems. You'll see that no data sheets are availaabke for them but if you really want to know, perhaps Leo Simpson at Silicon Chip will assist, After all, it was his baby, AFAIK;

The TOP-66 plastic power types were developed to replace them wayback-even then. These will fit into the same holes if you trim off the collector lead and attach with the appropriate mounting bolt. I assume you can identify the connections of both original and replacement types. Don't forget to insulate with a new mica and grease, perhaps the old bush is OK.
What you need is a complementary pair (don't iust swap the bad one) that meets the AY9171/8171 pair spec. 35W output is max. rating. I believe the 136 was rated at 13W into 8R so it should be possible to find suitable TOP66 (TO220) types.

I can't find suitable local types retail, though I'd be tempted to try TIP41/42B or C, if all else and common sense failed. Perhaps someone else would know a common TO220 pair that will run up to 25V rails and deliver 20W/4R?



I
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Last edited by Ian Finch; 26th April 2012 at 09:56 AM.
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