Search found 108 matches

by dizzy33
Mon Apr 20, 2020 10:37 am
Forum: Hardware
Topic: ZX Spectrums problems : diagnostic software ?
Replies: 123
Views: 62610

Re: ZX Spectrums problems : diagnostic software ?

Test 1 PIN 4 OF 4116 https://zupimages.net/up/20/17/224i.jpg Test 2 PIN 15 OF 4116 https://zupimages.net/up/20/17/u4jf.jpg Test 3 PIN 2 OF 4116 (similar on every RAM chips) https://zupimages.net/up/20/17/ghg6.jpg Test 4 PIN 14 OF 4116 (similar on every RAM chips) https://zupimages.net/up/20/17/ljwd....
by dizzy33
Sun Apr 19, 2020 4:45 pm
Forum: Hardware
Topic: ZX Spectrums problems : diagnostic software ?
Replies: 123
Views: 62610

Re: ZX Spectrums problems : diagnostic software ?

I replaced one more time IC12. It seems now the RAM does not get hot anymore. But I still have my original problem : whatever the RAM chip I replace, the diagnostic cartridge still shows some other lower RAM chips as defective (no problem with the higher ones). So there is still a culprit on the mot...
by dizzy33
Sun Apr 19, 2020 4:05 pm
Forum: Hardware
Topic: ZX Spectrums problems : diagnostic software ?
Replies: 123
Views: 62610

Re: ZX Spectrums problems : diagnostic software ?

I tested the voltages of all RAMs, all good. BUT, there is a major issue I think : I got burned just by touching IC12 ! IC13 is also quite hot, and the other RAMs are less hot, but still too much, compared to my working Spectrum. So I think to solve my RAM problem, we just need to guess which compon...
by dizzy33
Sun Apr 19, 2020 3:21 pm
Forum: Hardware
Topic: ZX Spectrum+ video signal problem
Replies: 10
Views: 9587

Re: ZX Spectrum+ video signal problem

Mark, please remember that I am a noob ... On my oscilloscope (FNIRSI 5012h, the one you recommanded from Amazon), there is only one main probe (so only one channel I guess ?). To do my measurements, I put the main probe on the component pin, and a small secondary probe (connected to the main probe)...
by dizzy33
Sun Apr 19, 2020 1:51 pm
Forum: Hardware
Topic: ZX Spectrums problems : diagnostic software ?
Replies: 123
Views: 62610

Re: ZX Spectrums problems : diagnostic software ?

I have 0v on the positive lead of C44 ... C44 has been replaced a few month ago, as part of a full recap operation. EDIT : I tested C44 on another Spectrum, and I have the same result : 0v. So I guess there is a problem in the way I am measuring it : I put the black probe of my multimeter on the RF ...
by dizzy33
Sun Apr 19, 2020 12:57 pm
Forum: FAQs
Topic: Forum : how to receive notifications ?
Replies: 1
Views: 19674

Re: Forum : how to receive notifications ?

Strange ! For a now a few minutes I now receive my email notifications ... So all is OK now.
by dizzy33
Sun Apr 19, 2020 12:55 pm
Forum: Hardware
Topic: ZX Spectrums problems : diagnostic software ?
Replies: 123
Views: 62610

Re: ZX Spectrums problems : diagnostic software ?

Mark, yes, you are right, my diagnostic cartridge says IC12 is defective, but if I replace it, then it will say another one is. That's my problem since the beginning of my investigations. Something is wrong on my motherboard which let the RAM goes bad. Now I don't have no 12v anymore on PIN 8 of my ...
by dizzy33
Sun Apr 19, 2020 12:42 pm
Forum: Hardware
Topic: ZX Spectrums problems : diagnostic software ?
Replies: 123
Views: 62610

Re: ZX Spectrums problems : diagnostic software ?

Thanks a lot Mark. But I think I have found a RAM problem. I don't understand as at the beginning of my investigations, I already have tested the RAM voltages, and as far as I remember they were OK. Now, here is the result I have for IC6 and IC13 (didn't test all the RAM but I guess it's the same is...
by dizzy33
Sun Apr 19, 2020 11:57 am
Forum: FAQs
Topic: Forum : how to receive notifications ?
Replies: 1
Views: 19674

Forum : how to receive notifications ?

Hello, in my profile, user control panel -> board preferences -> Edit notifications options , I activated all the email notifications. in my profile, user control panel -> board preferences -> Edit posting default, I activated "notify me upon replies" However, I do not receive any notifications when...
by dizzy33
Sun Apr 19, 2020 11:46 am
Forum: Hardware
Topic: ZX Spectrums problems : diagnostic software ?
Replies: 123
Views: 62610

Re: ZX Spectrums problems : diagnostic software ?

I tested the ULA voltages. Here is my (bad) results : on pin 13, I should have 5v. I only have 3.5v -> BAD on pin 14, I should have 5v. I have 5v -> OK What could be responsible of this low voltage for pin 13 of my ULA ? (as a reminder my motherboard is an issue 2). EDIT : finally this 3.5v may be n...