All Activity

Hmm, I don't have an MPU3 to hand to confirm the input to the chip but I'm wondering if the voltage level is too high? Did you change all the components on the input (R83, 84, 85, C39 and D43)

Hard to see from the pic...but the solder pads look fresh and unsoldered

Cheers I will check but sure it’s ok

The soldering on the ic on the right of ic20 looks like it's been forgotten

Hi and welcome, i have emailed you as well just in case you are still having problems. As the saying goes "been there done that"

Your English is better than my French welcome to the site hope the fix works

I’m probably missing something you would spot right away ! Here is the trace into pin23 it looks odd in the pic but it’s peaks and troughs to the eye, but it differs slightly compared to a working board

Can you look at this thread it might help. If not the answer was to scroll to the bottom of the screen and change your theme. If that doesn't work someone else has suggested sending you a PM so I'll do that as well. Hope it works. Bon chance Bob

I must admit I steer clear of HFC for no other reason than I don't like buying chinese stuff but they should be fine. I must admit I'm stumped so far which is unlike me.

I know Bob it’s driving us both bonkers! the chips are HFC branded? But I did fit a pull first and it passed a vector test on my programmer I bought 10 new ones I will test them also and will take a pic of the waveform going into pin13 thanks Ronnie

Hello everyone, I'm sorry to be stuck in this thread. I recently registered. I can log in. But, I can't read the threads. I get an error message every time. >>> Sorry, there is a problem Something went wrong. Please try again.<<< I sent a message to the webmaster and Pete, but no response. If anyone could help me, that would be great. I'm giving an email, because I don't know if I can read my messages through the website. lamiral29@free.fr Thank you very much @+ Sorry for my poor language.

Of course it is 14 pin, I'm losing my marbles I think. I wouldn't be to concerned about the difference of the continuity and Ohms reading as there's enough voltage/current to operate a junction of a semiconductor on the continuity setting. I think the main enigma is the waveform goes into 13 and doesn't come out on 12??? and there's no short on it (as you had the pin removed anyway). It was a bona fide chip you replaced it with? You can see I'm clutching at straws now!

Hi Bob, sorry ic18 is a 14 dip chip so pins 14 and 7 are vcc and I get a good 5 v pin12 to ground now this is strange! On continuity I get 600 ohms but in ohms check I get 4k ohms? Not sure how that can be? pin12 to pin28 of the 6840 has continuity hope I’m not doing something daft again!

Blimey Ronnie this is turning into a real poser??? Without the chip in (IC18) is the power and ground good to pins 16 and 8 ie don't use any other ground. Next what does the resistance measure from pin 12 to ground? Also check the via isn't broken on pin 12 ie make sure there's connectivity from pin 12 to the 6840 pin 28. I'm sure that will be OK but might as well confirm. Lastly can you post a pic of that area with chip in. There's got to be an obvious answer to this but I'm scratching my head at present.

Can’t find any issues with the socket or the traces from it, even if I leave pin12 out the socket I still don’t see the signal on the pin on this board the trace on pin 13 looked slightly shallower than on the working board but was still near 100hz

Lol yeah that stumped me I was checking vcc arse for tit! But once I realised vcc is fine as is ground And I see what you describe on a working board, so god knows what's happeng here?

Please forgive me for mentioning this but pin 1 is top right hand as you look at the board.

I know it's a bummer! Vcc is fine on the chip too, I must be missing something, going away to compare to a working board

Don't understand that Ronnie? If the 100Hz is going in it should come out as a nice 100Hz square wave about 5v p2p assuming the chip is powered ok. Pin 12 feeds IC2 (6840) and IC3 (6821) but I can't believe they would be causing anything.

Ark Aid Repairs is repairing it.

Thanks appreciated

Got the new chips today so pin12 still the same! Pin13 is like this does that look right? Sometimes it will come up with 50pm loked alarm on the alpha when I’m probing ? thanks Ronnie

Great work again bob and there's no end to the 3d printing capabilities. The mpu3 boards seem somewhat wrong without the cart surround protector so a very worthy project .

Nice to see an admc machine crop up .has to be worth £60 just for the parts

I have a few 80s mpu4 game cards... I'll.check and let u know tomorrow ..