JoulesperCoulomb

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@SyldabiaHacks 2 ай бұрын

To TR4 you can connect a resistor and capacitor to emisor to remove emisor from GND directly. That limit current and can safe the transistor in case of short circuit.

@andresbreteldelpozo 2 ай бұрын

Hi, I have the same unit and the problem I have with it is that the standby button and the source direct buttons have lost either their rubber or springs and don’t push the internal switch (which works perfectly). Could you send me a picture of how those plastic buttons work? I don’t know if they need to have a spring or rubber tube to have proper action. Thanks a lot!

@claudiurus7307 2 ай бұрын

Great video!!! Why they added resistors in series on the data buss between the z80 and the ULC? Is this because they want to limit the ammount of current the ULC draw from Z80?

@gasparinizuzzurro6306 2 ай бұрын

When two devices take over the bus they can set each line to different logic values. For example, assuming Z80 D0 is low and the other device try to drive the same line to high, you have a bus conflict, In terms of electricity you connected two points, one at 5V to another to 0V. This is a short circuit, drawing a lot of current and feeding a lot of current on the 0V side, which can damage both devices. this condition make the logical level not defined and it is unable to identify which logic value is on this line. To solve this, in a more canonical (and better) way, an high impedance state is used, so the conflicting device is electrically disconnected from the bus (as an example z80 can disconnect itself when a bus request is issued), but in order to save money they decoupled both sides using resistors. In this way each side of the resistor can drive and see the logical level he want to assert

@claudiurus7307 2 ай бұрын

@@gasparinizuzzurro6306 thank you for the detailed explanation.

@Nangre8x 3 ай бұрын

Xin chào ban, mình ở Việt nam hiện mình có 1 cái HA- 4800 còn hoạt động nghe nhạc bình thường hệ thống đèn yếu

@wettuga2762 3 ай бұрын

Beautiful detailed explanation about the Spectrum's video signal! I'll definitely make use of your knowledge to improve my picture quality, ghosting is definitely an annoying "feature" of lower quality signals.

@Dandema 4 ай бұрын

Thanks ❤

@buddhistsympathizer1136 5 ай бұрын

10 years now since you made this video, but I must say I LOVE your style. Clear, concise and beautifully presented.Well done!

@campbellmorrison8540 5 ай бұрын

This is the most thorough work through of an oscilloscope I've ever seen, absolutely brilliant thank you.

@mariusdoeland4208 6 ай бұрын

zeer goede cope ,`werkt na al die jaren nog steeds zeer goed .Juni 2024.

@marisakirisame867 8 ай бұрын

I have 1 ZX 128k that seems useless for computing but cool for doing some real hardware music demo

@chris-ip4pk 8 ай бұрын

Do you fix these for people.i got a poorly issue 1

@JoulesperCoulomb 8 ай бұрын

Sometimes. Contact me via the form at zx.zigg.net and I will probably be able to help.

@Mr_ToR 9 ай бұрын

Could you please share the schematic you've used here. I can not find it anywhere. There is a service manual but it's split in 2 pages and the schematic inside is not as good as the one you have here. Please share. Thanks.

@JoulesperCoulomb 8 ай бұрын

I'm not sure now where I downloaded the diagrams from. However, you might find the links on the following page useful: www.retroisle.com/sinclair/zxspectrum/technical.php

@Mr_ToR 9 ай бұрын

I'm so glad I found this series of videos. Your videos are not only great for Spectrum repairs, but also perfect for learning about general electronics repair. Very nicely done sir. Thanks a lot.

@peddersoldchap 9 ай бұрын

Since you seem not to be selling the RAM modules anymore, is there any chance of making them open source? Also, thank you for your videos.

@damianbutterworth2434 Жыл бұрын

I did the R6 mod and got 13.2 volt on the 12 volt rail. I think I used a too lower wattage resistor. I used a 1/4 watt. Should they be 1/5 watts?

@damianbutterworth2434 Жыл бұрын

I was looking at mine and C46 seems to be in the wrong way round. Yours is the same so I`ll put it back as it came out. It`s got a + on the wrong side on the board. OK I got to the end of the video lol. Thanks for clearing that up.

@AK-vx4dy Жыл бұрын

I expected better picture without rf modulator, clearly video signal band is to low but i don't know the reason.

@alanr9496 Жыл бұрын

Just love these videos. Very sorry they have stopped. Hope all is well, Joules.

@RixtronixLAB Жыл бұрын

Nice video shot, keep it up, thanks for sharing it with us :)

@spudhead169 Жыл бұрын

Capacitors that have leakage current often measure significantly higher capacitance than their marked value. This is because capacitance testers often use the time it takes for the cap to charge to a particular voltage to determine the capacitance. When the cap is leaking current, it takes longer to charge because some of the current is being lost, thus the meter erroneously reports a higher capacitance.

@hemiolabooks450 Жыл бұрын

Thankyou, managed to fix my pm 3216 with your video. Had the same trigger fault, same channel.

@RudysRetroIntel Жыл бұрын

Excellent video!! Just got my first Speecy so very helpful. Thanks for sharing

@ВиталийКобец-в6р Жыл бұрын

А...Можно...Так...Сделать...Взять...Микросхему...От...Спектрума...Взять...Наушники...От...Советского...Плеера...И...Через...Микросхему....ЗВУК..ПОЛУЧАЕТСЯ...ПРОСТО...ПОТРЯСАЮЩИЙ...УДАРНИКИ..СУПЕР...И...ДАЖЕ...СОВРЕМЕННЫЕ...НАУШНИКИ...В...ПРОЛЕТЕ...А...Один...Товарищ...В..Нашей..Деревне...Который...Считался...АСОМ...В...IBM...Так...Вот..Он...Мог...Даже...С...Южной..Америки...Файлы...Скачать...И...Он...Долго...Утверждал...Что..К..Спектруму...Нельзя..Микрофон...Обычный...Подключить...А...Я...Скажу...Я...Взял...Микрофон...От...Обычного...Магнитофона...И..Всетаки....После....Недолгих...Манимпуляций...Подключил....Микрофон...К...Компьютеру..А...Я...Скажу...Как...Включил...Вот...И...Все...И...Записал...Одну..Очень...СОВЕРШЕННО...СЕКРЕТНУЮ...ИНФОРМАЦИЮ...

@marcusdowney71 Жыл бұрын

use a pin or piece of paperclip in the jaws of your alligator clips to help ya with them hard to reach places. Great vids.

@repetto74 Жыл бұрын

Wondering where you are as no videos from you since years. Hope you are ok. Your ZX Spectrum repair videos are awesome and learned a lot!

@cv643d Жыл бұрын

Great videos!

@trevorrobinson7614 Жыл бұрын

I've bought a vga interface it costs £50 but it worked fine my 128k spectrum had video problems

@dragan2708 Жыл бұрын

Hello my friend , i have that amplifier and only phono input works do you have schematics to send me

@breezebenitses397 2 жыл бұрын

Hi there joules great video. I picked Hitachi system deck amp cassette and tuner for£15. Absolute bargain. I need to change the belts on D 35s. They'd melted. Any videos or suggestions would be gratefully received. Do you have an email? Regards

@breezebenitses397 2 жыл бұрын

Hi there a bit above my pay grade but I have ha2700 with slight scratch noise when turning the balance. Can I squirt some contact cleaner (Halfords brand) on the pot inside? Got a full system for £15. Cassette needs new belts. Next job if I can find on youtube haha. Thank you. Interesting videos. Thank you

@breezebenitses397 2 жыл бұрын

Hi there I've got a ha2700 it makes static sounds when I turn balance treble and bass. Could I squirt contact cleaner on them from the inside? Thank you

@breezebenitses397 2 жыл бұрын

Impressive videos by the way

@MrLurchsThings 2 жыл бұрын

Sorry, for commenting on such an old video, but quick question: should this circuit also work on a ZX80?

@darrenconway8117 2 жыл бұрын

It is 2022. I have owned the PM3217 50MHz version for 25 years. It developed a fault so I re-capped it. I added a IEC socket to replace the cord. It still works and I still use it. It is still a good scope.

@kaiwenwu1947 2 жыл бұрын

What happened to part 2.

@networldworld4333 2 жыл бұрын

Hell ! can you help ? i own a zx spectrum sinclair 48k that doesn´t load the games. They just get errors when first game screen opens or crash during the doalings and green little squares on some loading drawings. I inserted that to check the upper RAM chips : PRINT PEEK 23732 + 256 * PEEK 23733 the value result was wrong it was 32863 instead of 6553 »»»» I tested all the 8 upper RAM chips group on the board below (right side not the logical ones) using a fully working sinclair 48k and all 8 are good.

@scottd5888 2 жыл бұрын

Thank you for this excellent video it helped me diagnose my faulty TR4. 😊

@kaiwenwu1947 2 жыл бұрын

Hi my AG H350. Teac amp is overheating as fan is not speeding up as temperature goes up. Any ideas would help not opened it yet I am an electronics engineer. Cheers sir

@Chuxonja 2 жыл бұрын

Awesome repair diary. My HA-3700 had identical symptoms and was able to get it running again thanks to your detailed procedure, cheers!

@Tenraiden 2 жыл бұрын

Thanks but the diagrams and text are too tiny!

@tenminutetokyo2643 2 жыл бұрын

Jam in a TSR-1 2450.

@paulklasmann1218 2 жыл бұрын

You're videos are excellent, to the point, informative and without silly background music or advertisements. Thank you!

@fictionhouse 2 жыл бұрын

Good job!

@tenminutetokyo2643 2 жыл бұрын

Can you do one in refurbing a TS 1016.

@Pamberjack_ 2 жыл бұрын

Great video. I’m at a loss as to what you did to get the trace showing on the screen. What did you change to get the power light to come on and the trace to appear? 🤔

@cooldryplaceuk5873 2 жыл бұрын

Loving this video - It reminds me of one of those old science videos from school.

@Kholaslittlespot1 2 жыл бұрын

Thanks, I look forward to going through these tests before powering up. I'm guessing it's normal for the large foil trace around the video output on the rear of the board to be all crinkled? I initially panicked upon seeing this but after watching a few videos I've seen the same thing on every machine.

@TheBezumax 2 жыл бұрын

I have black centre and white border and think problem is on upper RAM how to check it by multimetr? Should I replace all chips with TMS4164-15NL or just wich was broken?

@kikurass322 2 жыл бұрын

Where are you mate, hope you're safe and well. I really love how you work and would LOVE to see more, please upload something.

@gilmarrodrigues6840 2 жыл бұрын

part two?

@ChrisWalshZX 3 жыл бұрын

Great video. Very insightful. Thanks

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