Slauri wrote: ↑Fri Feb 14, 2020 6:15 pm
Hi everyone, i got 2,98 volts on the pin 1 of the lower ram. The other voltages were good.
The -5V supply (pin 1 on the lower RAM sockets) should be between -4.45V and -5.1V.
Can you please post up the actual voltages you get on the +5V, +9V and +12V rails please.
Do you still have a heatsink on your 7805 voltage regulator? If yes, the machine screw holding it in place nice and tight? Or have you fitted a more modern DC/DC converter switching type?
Mark
Standby alert
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Slauri wrote: ↑Mon Feb 10, 2020 12:10 pm
On the ULA pin 13 there is only 3.17 volts. On the pin 14 there is almost perfect 5 volts. Is this normal?
On pin 13 of the ULA in an issue 1 board, I get 2.9V soon after power up, with the voltage rising slowly a little bit.
Mark
Standby alert
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Standby alert
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Slauri wrote: ↑Fri Feb 14, 2020 6:15 pm
Hi everyone, i got 2,98 volts on the pin 1 of the lower ram. The other voltages were good.
Yestreday i measured the -5v rail the voltage was much lower.
Strange
Standby alert
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
@Slauri
Can you please post a photo of your Spectrum board as it is now.
Mark
Standby alert
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
Can you please take a close up photo, under good light, of the underside area of the board where the 4116 DRAM chips are.
Mark
Standby alert
“There are four lights!”
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb
Looking forward to summer later in the year.
I've cleaned the board multiple times with alcohol. Those bridges weren't there before. Maybe they have come from my workdesk? I have not cleaned it for a while. Some of those may look like bridges but they are just reflections of the soldering mask that has melted away due to my bad soldering skills.