A Grand Day Out

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Tomswork
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Re: A Grand Day Out

Post by Tomswork »

More family members nice addition

Tom
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rubber_jonnie
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Re: A Grand Day Out

Post by rubber_jonnie »

Tomswork wrote: Mon Feb 05, 2024 4:30 pm More family members nice addition

Tom
I'm definitely happy with the additions :)

The Sharp needs some work on the cassette side, it isn't loading anything, either using the internal or an external deck, so going through the service manual ATM.

Given basic needs to be loaded from cassette, it's a pretty important thing to get working.

It suggests the amp is a problem, but I'm struggling to find it and wondering if it's on the PCB for the internal cassette deck. More digging required.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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stephen_usher
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Re: A Grand Day Out

Post by stephen_usher »

Check your -5V line. That's usually the problem on the BBC Micro if there are loading problems as the amp uses it.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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alexh
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Re: A Grand Day Out

Post by alexh »

Nice cheese Gromit
Principal ASIC Engineer - SystemVerilog, VHDL
Thalion Webshrine - http://thalion.atari.org
STf,STfm,STe,MegaST,MegaSTe,Falcon060
A500+,A600,A4000/060,CD32,CDTV
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rubber_jonnie
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Re: A Grand Day Out

Post by rubber_jonnie »

stephen_usher wrote: Mon Feb 05, 2024 9:13 pm Check your -5V line. That's usually the problem on the BBC Micro if there are loading problems as the amp uses it.
I'm trying to figure out if the amp is on the mainboard, or on the PCB inside the cassette deck.

The cassette deck does play OK, so it's clearly getting +5v there, but the mainboard seems to be just a sea of 74LS chips with nothing that looks like an amp. Need to read the service manual some more.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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rubber_jonnie
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Re: A Grand Day Out

Post by rubber_jonnie »

alexh wrote: Mon Feb 05, 2024 9:23 pm Nice cheese Gromit
😁
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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rubber_jonnie
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Re: A Grand Day Out

Post by rubber_jonnie »

And yes, finally found the op amp :)

And yes, it was in the cassette player module:

Screenshot 2024-02-05 at 23.31.35.png
Screenshot 2024-02-05 at 23.31.35.png (1.42 MiB) Viewed 261 times

There is a uPC358C, and then the motor controller is an LA5522. I don't think there is an issue with the motor controller at the moment, so I'll focus on the tape input first.

There are also two transistors, Q3003 & Q3004 which seem to be the input/output stages either side of the uPC358C, and I have all the waveforms and test points along the signals journey, so I can get to testing.

I've ordered replacement op amps just in case.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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stephen_usher
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Re: A Grand Day Out

Post by stephen_usher »

Yeah, Q3003 does pre-amplification and Q3004 squares the waveform and makes it TTL level.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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rubber_jonnie
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Re: A Grand Day Out

Post by rubber_jonnie »

So it seems Sharp were like their name in that the construction of the MZ-700 and built it very sharply, with a minimal number of plastic screws and the majority going into brass inserts.

They were also good enough to mark up their PCBs with component locations:

PXL_20240206_085056584.jpg
PXL_20240206_085056584.jpg (373.13 KiB) Viewed 237 times

Which means finding the test points and checking agains the waveforms in the excellent service manual should be easy :)

The PSU is a dinky little fella with no RIFAs thank god and was actually very clean inside:

PXL_20240206_085633768.jpg
PXL_20240206_085633768.jpg (254.1 KiB) Viewed 237 times

So should be back together and fingers crossed with a working tape deck soon. What's interesting is that it seems like the external cassette connections appear to rely on the internal cassette deck for the amp circuit, which surprised me a bit.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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stephen_usher
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Joined: Mon Nov 13, 2017 7:19 pm
Location: Oxford, UK.
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Re: A Grand Day Out

Post by stephen_usher »

rubber_jonnie wrote: Tue Feb 06, 2024 10:30 am So should be back together and fingers crossed with a working tape deck soon. What's interesting is that it seems like the external cassette connections appear to rely on the internal cassette deck for the amp circuit, which surprised me a bit.
Why duplicate the circuitry? Sounds like a smart thing to do as then the computer only needs a single input and doesn't need extra circuitry itself.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.
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