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Old 3rd December 2012, 10:21 AM   #1
Tel is offline Tel  New Zealand
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Default Playmaster Series 200 Circuit

Hiya folks,
I've just picked up an old Playmaster 200 I'd like to refurbish. One channel works fine, the other sounds dead - but there was some warmup "rustle" on the other when turning the bass control, so I think both output channels are good. I haven't started troubleshooting yet, I had hoped it was the balance pot but that checks out OK, although a bit odd - it seems to be 2 linear 10k pots where the range works zeroR to centre then rising to 10k for last 1/2 turn - mirror image each side - presumably to keep crosstalk down. Don't fancy finding a replacement for that, will probably go with Left and Right volumes if it's an issue. BUT! Does anyone have a copy of the circuit diagram, or even the construction articles? I though it must be on the net somewhere, but a couple nights on google haven't found anything... cheers,
Terry
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Old 3rd December 2012, 10:58 AM   #2
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hehe, Mines dead on one channel on the preamp as well. I have a bypass of the preamp and I'm running it off the HTPC direct. I thought that if I didn't fix the preamp that it would give me motivation to work on my new one. Unfortunately not

I have the schematic somewhere, but I have moved house recently so finding it might be an issue.

I've actually modified mine. I bypassed the tone and balance controls completely, and also made some modifications to the last opamp stage (I think after the volume control) based on the revision to the design of the Playmaster 60/60. This improved stability as the preamp section was prone to oscillation.

I like the amp. Definitely worth fixing I'd say. Even if you just bypass the preamp and use it as a power amp

here is a thumbnail (the gallery is dead at the moment) of mine the first time one channel died. My 2yo poked a chopstick in through one of the holes where balance or tone pots used to be and broke a component leg off
Click the image to open in full size.

Tony.
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Old 4th December 2012, 05:26 AM   #3
Tel is offline Tel  New Zealand
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Hmmm - thanks for the suggestion - that's not a bad idea at all. I think I'll pop in a set of pre-out/in sockets, that way I can feed it straight from the PC in my study while I think of my next move. I was hoping to move it to the workshop next door and run some big old Sansui's off it, but that can wait - I have a Sansui AU-D9 that has a dead output side that I'd like to fix for the study, then I can either sort the preamp in the Playmaster or just run it off the tape outputs of the Sansui... hmmm, way too many broken toys, way too little time
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Old 4th December 2012, 11:44 AM   #4
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Just one thing to be wary of. The output of the preamp section has quite a dc offset on it. If you switch from direct to internal preamp you may get thumps. Best to switch the speakers off with the speaker switch before changing between direct input and preamp input.

Tony.
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Old 15th July 2015, 06:51 AM   #5
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Default Playmaster 200

I also have a 200 Playmaster Amp, still goes but need a circuit
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Old 15th July 2015, 09:16 AM   #6
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I posted the schematic for the power amp here --> suggestions for improvement about 12 years ago...

edit: I've also completed the B1 based preamp since the above post

Tony.
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Last edited by wintermute; 15th July 2015 at 09:18 AM. Reason: add comment about preamp.
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Old 23rd September 2016, 04:47 AM   #7
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Hello folks, new starter here.
I have a Playmaster Series 200 which I built in 1985 from a Jaycar kit. It worked straight away, but has had a few problems.
The first is that the Dubbing 1-2 light always comes on. It goes off when pressed and doesn't cause any other problems, so didn't bother to fix it, as it is probably related to a faulty IC on the sub-board, which would have to be unsoldered.
The major problem has been failure (twice) with extreme prejudice (BANG!!) of the mains power switch. Not hard to replace, but the trouble is that both times it took out Q20 (a BC327) involved in speaker switching relay activation - hence Local/Remote/Both/Off switch out of action. Replaced the puny switch on the second failure with a much meatier toggle switch, and routed the mains cables to the switch as far away as possible from circuitry, between the internal fins of the heat sink. No such failure since.
Another major problem has been failure of Aux left channel. This occurred after a loud blat!! on this channel, cause still unknown. Went around this area of the board re-soldering suspect dry joints, but no luck. Am now going to replace IC10 switching IC as the most likely candidate.
When re-soldering dry joints did notice an obvious dry joint at the central earthing point pin. Probably loose because the pin is vulnerable to tugging by the wire when disassembling the amp. This re-soldering fixed a faint background noise audible on occasions.
Also much trouble with the sub-board locating screw posts coming adrift from the bottom panel. Soldered these to the bottom, but not a good fix as they sometimes come loose.
This amp is now over 30 years old so I am wondering about replacing electro caps. Has anyone found a need to do this? It sounds just as good as it ever did, and there are no suspicious bulges or leaks, so I am reluctant to fix what ain't broke.
My overall impression of the amp is that it is great, and as good as I'll ever need for stereo work, but a remote volume control at least would be good.
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Old 23rd September 2016, 11:01 AM   #8
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The CMOS switching IC's are very sensitive to static, so could go if some static discharged on the input I guess (edit I know I have had to replace a few over the years). Not sure it would go with a blat though...

At 30+ years old I would not be surprised if some caps have failed, I re-capped mine at somewhere around the 16 year mark I think (except the main supply caps, which I purchased some time ago but have not yet replaced.

Mine was a Dick Smith kit. Not sure whether the Circuit board quality is better in the jaycar, but one thing to be very careful of if doing a re-cap is not lifting tracks on the board! I did mine with Panasonic FC's at the time for the electros, and I think I used evox pps for the greencap bypass caps, and replaced all of the ceramics with NPO types.

If you are happy with it and there are no obvious problems then it's probably safest just to leave it as is. There are a LOT of electro's on the board, and pulling the amp apart to get good access is not fun, you need to set aside some serious time if you are going to tackle it

Tony.
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Last edited by wintermute; 23rd September 2016 at 11:02 AM. Reason: add comment about replacing cmos switch IC's
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Old 23rd September 2016, 01:10 PM   #9
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Thanks for the tips and thoughts wintermute. Have ordered the IC to fix the aux left problem and will check all the voltages around the board (written on the board when first assembled) and if any have changed will consider looking at the electros. The amp had constant use for the first 5 years or so of its life and intermittent thereafter - so hopefully hasn't seen too much heat stress.
Re the blat!! The RCA connectors have always been rather tight, and I assumed at the time that the connections to the board had been strained to failure. If the earth was open circuit there might be loud buzz. Re-soldering all these joints (which looked OK) didn't fix the left channel - but might have caused the original failure if the IC proves to be u/s.
The Jaycar kit has a fibreglass board and I haven't encountered any track lift problems.
Disassembly to the point required for easy access means removing both top and bottom, back and front and unsoldering the main DC leads - not fun as you infer. Won't do this unless I have to that's for sure. If care is not taken reassembling, strain on the input and output panel soldered joints and volume, balance and tone control soldered joints can cause them to fail. For some reason the volume control was worse in this respect, so in the end I made the connections for it flexible.
The Dick Smith kit came out later than the Jaycar and had better presentation as I remember. The Jaycar kit has sockets for all of the ICs on the main board, but not for he sub board.
Other problem I had was failure of the volume control - noisy, not fixed by cleaning and lubrication. Couldn't get the multi detent original, had to make do with 10 detent, quarter of the original 40. Bass control also became noisy but cleaning and lubrication was a fix.
Also fitted a relay to prevent plops in the headphones.
Just been listening to Dire Straits, Money for nothing - still does the percussion soon after the start of this track beautifully through a pair of Richter predator Sabres. Has to be loud!!
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Old 23rd September 2016, 01:51 PM   #10
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Yes volume pots were my biggest problem. I bypassed the tone controls and balance pot years ago when pots started getting dodgy. I also changed the preamp section to add the components that were in the playmaster 60/60 which had a slightly revised version of the series 200 pre (without all the cmos switches) which improved stability.

My preamp is completely bypassed now (I never went back to find the fault on one channel) and a DC-B1 with my active crossover now feeds 270Hz and down to the series 200. an LM3886 handles the frequencies above 270Hz.

I prefer the sound of the mosfet amp to the LM3886 running full range, but this makes the most sense for a biamped setup.

I built mine in 1987, and it has been in pretty much constant service (except for about 1 year when I was using the LM3886 because there was something wrong with the preamp (again) and I didn't have time to fix it. It copped a lot of abuse at UNI parties and never missed a beat! I don't think you have to worry too much about heat stress!

It's funny you say the Dick Smith kit had better presentation, I wanted a jaycar one, but the DS one was on runout special and I got it for $399 (which was already a stretch for a uni student supporting himself), I think the ones at Jaycar were still selling for the original price which from memory was $599.

Tony.
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Last edited by wintermute; 23rd September 2016 at 01:52 PM. Reason: minor fixes
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