Problem with 48k not loading

[hanger312]

New question.

Have 48k Spectrum. Sound clicks from keyboard. Saves program
to device and audio is clear as a bell.

But unable to load programs in. No audible sound coming through
the speaker. Used cassette player, dictation device (which recorded my little program) and also played via pc. But nothing.
Checked board and all seems well. No signs of damage to the
contacts or traces. Images of the board attached.

Any ideas?

[cj7hawk]

There's not much between the ULA and the EAR socket - Just a capacitor and a 680ohm resistor. I assume you are pushing sound into the EAR socket, and not the MIC, because the MIC has a 10K resistor on it, so will be a lot quieter.

Have a look at a schematic - eg https://z00m.speccy.cz/images/ZXS48k-Issue3-sch.gif

The speaker is connected via TR7 through an emitter follows base amplifier - Pretty basic. Check the transistor is OK and not shorted, as is also the diode. If they are good, then use an oscilloscope on Pin28 of the ULA while you run your tape. If the signal is there, and it looks OK then your ULA is most likely broken.

Regards
David

[spider]

I'd concur with above although I would say maybe try ( ! ) to load via the MIC socket, nothing to lose.

It could be something as simple as a bad contact inside the EAR socket...

[goodboy]

standart stereo jack can connect your signal to the ground

[hanger312]

Thanks for the replies. Will try stereo jack and/or mic input to see if that works. Can do continuity tests with test meter but the oscilliscope is over my head. I'll keep you posted shortly.

[cj7hawk]

The note about leads is worth remembering - Are you using the standard audio leads to a mono cassette player? If not, you may have to mess around with Stereo to dual-mono leads and try both leads to see which head the sound is coming from.

[hanger312]

Thanks, will try.

[hanger312]

No further forward unfortunately. Will probably change the jack from a donor board next.

[hanger312]

*** KIND OF RESOLVED ***

Bought a new bush tape recorder from Argos. Works fine loading original games from tape.

Can save programs and can hear the prog on the tape. But it won't reload them using the same volume setting as original games load.

the tape recorder has a usb stick player. The speccy won't load an mp3 downloaded from the net. Can hear the sound coming in the speccy but no sign of loading lines! Bit frustrating.

I really want to just program more than gaming. Can you save programs on an SD card with
the divMMC device?

[Hedge1970]

Welcome to the world of 40yr old computers. It’s a well trodden path you’re walking. Ask yourself what you want then head off in that direction. For old school there are tape players on eBay that will work, they are original 1990 recorders and work just as they did back then, a little temperamental but mostly ok. Then there are Microdrives, you need a IF1 but they mostly work okay. A good replacement is the excellent vDriveZX which is a Microdrive that uses an SD Card. Then of course there is the divmmc devices check the different types and yes one of them will load and save work. However now we enter the world of “conversion” and so while your work can be saved and read no problem you will find some TAP and TZX files won’t load, this is common across all conversions. Now of course the divMMC has no relation to the past - works great but not that old school feel. So there is also the programmable ROMS from fruitcake, these offer load save capability to your PC via a special cable and a PC serial port you get to load and save to your hard drive, but again it’s a converter to TAP and TZX so again same issues as divMMC. The nice thing about Paul’s stuff is it’s all pretty old school, ROM carts in Sinclair Interface 2 or RAM turbo and connecting the serial cable into the IF1, all looks and feels very 80s. I am sure there are a few other options but the main thing to think about is what do you want to get out of this? Of course all this stuff can be done in emulators so no need for a real Spectrum at all. But if you do have the original, do you then want to add more original stuff or go all 2020s. The great thing is you’ve got the choice.

Me I have the old tape deck, original Microdrive, vDriveZX, Paul Fruitcake programmable ROMS and supporting software all through a number of 48ks. My favourite is the vDriveZX but I think the most robust solution is Paul Fruitcakes stuff as it’s saves direct to my HDD on my PC. The DivMMC has such good reviews I can’t believe it would be anything but excellent just do your research to make sure you get the right one.

[flatduckrecords]

Glad to hear you've made some progress!

Bought a new bush tape recorder from Argos. Works fine loading original games from tape.

Can save programs and can hear the prog on the tape. But it won't reload them using the same volume setting as original games load.

Yeah I had a similar experience with that same recorder, I ended up returning it in fact. As @Hedge1970 suggests I got one from eBay instead. WH Smith 8300, Sony TCM-818 and the Boots CR375 are good options with new spare belts available. In any case try and get a mono one if you can.

I agree with Hedge's other comments too. To expand on the DivMMC though, yes you can save and load back from it no problem. You can work with TAP files or save code directly to the SD card. Or just take .SNA snapshots whenever you want to save your progress. Handy for moving back and forth from an emulator. DivMMC Future (£69.99) is a good choice but others are available.

[hanger312]

Thanks for the comprehensive reply. Others too will benefit from your knowledge. I am looking at the divMMC. I only want to get back to programing for myself so don't need to change the file types beyond save/load options. There is suprisingly little in the way of youtube videos showing
the save program function but I did see only one yesterday.

The divMMC are a little hard to come by. At the moment they are on ebay from Germany. Found a website that's doing them for £69.99 + extra for pre-gamed SD card. I presume this is the going rate? If anyone can let me know any other alternative devices to save programs then much appreciated. I need something that is proven as stable. Don't want the device to pack up after a short while.

Happy Christmas and New Year (2023). Graeme, aged 13, was 53 !

[PeterJ]

@hanger312,

The divMMC that @flatduckrecords mentioned is very popular, and probably one of the cheapest options for divMMC. I did have one, but found it a very tight fit on a +3 though so returned it.

If you have a suitable SD Card you don't need to pay for their one. We can help you get the card ready.

There is also this one from ByteDelight (based in Germany). It's not cased though and sometimes delivery can take a while.

https://www.bytedelight.com/?product=br ... -mini-lite

This guide would apply to all divMMC devices, and includes saving and loading:

https://www.thefuturewas8bit.com/divmmc-future-guide

You could also keep an eye on this website which is like an eBay for retro computing. A user called Zaxon often has devices available:

https://www.sellmyretro.com/

The cheapest divMMC is probably the DivTIESUS from ZX Projects, its made in small batches though so you would need to add your name to the waiting list. It does have wonderful things like WiFi which enable you to code on your PC and send the code wirelessly to your Spectrum:

https://www.antoniovillena.es/store/product/divtiesus/

Like @Hedge1970 I like the alternative devices from Fruitcake, but divMMC is by far the most popular device which means it will be far easier to get support.

Also consider the Retroleum SMART card. It's not a divMMC device and saving and loading isn't as flexible, but it's very reasonably priced and has lots of nice features:

http://blog.retroleum.co.uk/smart-card-for-zx-spectrum/

Finally, if you have an Interface 1, look at the various Microdrive clones (also as mentioned by others)

[hanger312]

Thanks again for the comprehensive reply. I will look at those websites. I regularly scan ebay and auction sites to see if the divMMC is lurking in a box from the pictures. The 48k I am messing with now came from a local auction house which was bundled with a load of other stuff costing £25. Made a profit reselling the other gear so it owes me nothing.

I can't believe all the stuff I sold over the years before the speccy became cool again. How many years has this outlived tv's, washing machines, cookers, microwaves etc?

If you are reading this them Happy Christmas 2022

[Chris23235]

There is also the Dandanator project. This expansion was originally delveloped as a 512KB cartridge for the Spectrum, but later received an update called Multiply which lets you load TAP files from SD card and create snapshots for saving purposes. Not as flexible as a DivMMC as it only can read TAP/SNA/Z80 but it comes at a fraction of the cost. There are several people on ebay selling the device as it is open source.

http://www.dandare.es/Proyectos_Dandare ... ni_EN.html

[hanger312]

Ordered divMMC Future today with UK supplier/maker. Sounds good.

[1024MAK]

On the subject of loading from tape, or indeed any audio source, keep in mind that Sinclair computers are relatively DEAF. They need a nice LOUD volume level.

Only mono 3.5mm plug are compatible. Stereo plug have the contacts in a different physical position. Feel free to compare them against one another

So if you have a device with a stereo socket, you must use a stereo plug. The ZX Spectrum (or ZX80, or ZX81) must be used with a mono plug.

Hence you may need to build a custom cable, or use a mix of cables and adapters.

Mark

[JollyRoger]

There is also this one from ByteDelight (based in Germany). It's not cased though and sometimes delivery can take a while.

https://www.bytedelight.com/?product=br ... -mini-lite

ByteDelight are based in the Netherlands.

I've used their Enjoy! Pro One for quite a while now and its been worth every penny.

https://www.bytedelight.com/?product=di ... oy_pro_one

Prior to raiding the piggy bank for that, I used PlayZX on an Android phone with a stereo to mono cable and it worked well enough but I could never return to that after being spoiled by the benefits of the divMMC world.

[PeterJ]

Thanks for the correction @JollyRoger. I knew he was in the Netherlands. I was obviously having a bad day!

[KWF]

If your ULA is deaf there is a way around the issue. You can add the audio input using one transistor and a 3-state buffer connected directly to CPU data bus. If you go one step further you can also add Bluetooth audio module and it work like a charm, loading software directly from a mobile.