ZX Spectrum 128K Toastrack - Composite Mod and some Service Mods
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- Опубліковано 7 лют 2023
- Another Toastrack dropped through the letterbox! (Not literally)
An interesting composite video mod and some service mods.
The RGB blanking mod was not performed as it wasn't required for the intended use.
Joulespercoulomb on the shadow mod - • ZX Spectrum +2 Repair....
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Lovely tidy work old boy! This keyboard mod would've made many a teenaged geek positively explode in the 80's!
FYI - Back in my day, we would put (or more commonly screen-printed printed) solder paste onto the board, carefully place all the surface mount components and then briefly bake the board at a temperature high enough to melt the paste - although I daresay you're already aware of this method...
Yes if the kit came with a mask that could be a good path to go down! I've never played with solder paste before
Lovely video! Definitely bookmarking this one for future toast rack adventures. 😁
Thank you my friend, very kind
thanks for useful tips 👍
Very nice.
I'm surprised you didn't swap the linear voltage regulator for a switch mode one.
Various pros and cons to both! It tends to come down to the owner's preference
@@HappyLittleDiodes no 'need' to , maybe just change to a 2 amp 78S05 if a 1a/1.5a 7805 is fitted ..
👍🏼👍🏼
Nice will have to see how my 128k is after the re capping.👍
probably ok as is. is it working now? far too much 'blanket' recapping
@@andygozzo72 Should be Was last time I used it. I want to to the sound chip mod.
@@ClassicRetroByte what mod? equalise the sound between AY and beeper?
@@andygozzo72 ABC stereo
@@ClassicRetroByte aha 😊
toast rack continues to be on my shopping list .. should the composite have a 15ohm resistor on to reduce the voltage down to 1.0 volt
Not that I'm aware of. The signal we hijacked is an oven ready composite signal unless I'm mistaken
@@HappyLittleDiodes yep no need to add anything if tapping off directly at the din socket pin ,
Good job, but how about the unrainer mod? Also why would anyone wanna use a Toastrack with composite video?
Interesting I've not come across this mod. I explain about the composite mod earlier in the video, he's using a peripheral that blocks the RGB port
Some people think that RGB looks too perfect and emulator-like. Composite video adds analogue "warmth" which can be part of nostalgia. Also, most games and demos were created to look good on CRT TVs, assuming certain amount of blur and colour shift. I prefer to have that option even though it's not my default display method.
@@baze3SC I certainly prefer RGB over Composite. RGB output of the Toastrack is not that pixel perfect. Even with an LCD monitor, it is never like a PC emulator or like the VGA or HDMI add-ons. With a CRT, it is nostalgic enough less the eye strain 😁.
@@borayurt66 Yeah of course, it's a personal preference. Btw if I were to use the composite output with our beloved toastrack I'd just use the signal that's available at the RGB connector, no need to touch the modulator at all - however that was not the option for the owner of the machine shown in this video.
@@baze3SC why wasnt it not an option.? if 'cause a din plug wouldnt fit with the opus, you can get right angled ones that likely would do, and make up a din to rca adaptor lead
I got mine down from the loft a couple of weeks ago. It's not working, of course. Black bars top to bottom on start up and the reset does nothing. Seems to be giving all the right voltages etc so I plan to re-cap it. Is that the right thing to do? I'm new to this and am using this as a learning exercise. So far I have learned that I don't have a clue what I'm doing ... 😁
I don't think I've ever had a failure that a recap fixed, so I would recommend doing some diagnostics first, are the bars vertical or horiztonal? It sounds indicative of a CPU failure
@@HappyLittleDiodes Vertical, solid black and white bars with the occasional coloured byte in random places.
See, I told you I didn't know what I was doing! 🤪
My spidey senses say Z80 but needs investigation!
@@HappyLittleDiodes It will get it, soon. BTW is there anything I shouldn't do that's likely to kill stuff?
Make sure your voltages are ok and don't run it for any amount of time without the heatsink attached. Use a current limiting power supply if possible. Is the Z80 socketed? If not then I wouldn't recommend it being your first chip removal, you can easily damage traces. The best thing would be to get a diagnostic ROM running to rule out anything else before such a job
So the composite mod is identical to the one that it done on the 48K boards, right?
Not quite!!
@@HappyLittleDiodes Why's that?
If you simply connect the modulator input to the socket it's not going to work, you have to route it from elsewhere on the board
no need to composite mod a toastrack as you said it already has it on the monitor din socket, so why? make up a din to rca adaptor...
As mentioned in the video the owner wanted to use a peripheral that is so large is blocks that socket
@@HappyLittleDiodes a right angle din plug may fit? if its that opus , i have one but not as yet tried it on a toastrack to see how things fit
I think the owner's preference was to have the machine appear unmodified and to have composite video available at the modulator output, he didn't send the Opus otherwise I may have experimented
@@HappyLittleDiodes the opus has a composite output but it takes it off the edge connector, which isnt present on the 128 models , its supposedly possible to have simultaneous rf and composite out of the modulator rca connector, you leave the modulator connected as factory, except lead a wire out of the can connected to phono centre, you then rig up a simple emitter follower buffer fed from modulator video in pin to base of a pnp transistor, collector to ground, emitter to +5v via a 220 ohm resistor(may need value tweaking), emitter also to rca centre via a 100uf minimum cap ...