Need some help fault finding / repairing my Apple ][ europlus
I stupidly plugged in the Disk ][ Interface Card in while it was still switched on and now it just makes a clicking noise out of the speaker.
Is definitly not the power supply clicking as it stops when I unplug the speaker. I have also tested the power supply and getting the usual +5 and 12 and -5 and 12.
I have also tested the 6502 in another computer.
Hoping someone has made this mistake before me and managed to sucsefully repair.
Thanks
You likely damaged the 8T97 or the 8T28, or if you have a RFI model, 8304. These bus driver chips take a lot of damage from being directly connected to the I/O bus.
Did you try powering up without the disk II controller installed? If the hot plugging resulted in some high current flow you could have damaged the disk II controller so suggest getting that back out and try again.
Thanks robespierre for the reply
So as you suggested I started with the three 8T97s (in my case 74LS367) and ran them through my EPROM programmer. It found pin 5 on H5 was dead. Following from pin 5 on the schematic (which is the RW line) I traced it to all the other ICs and found A2 74LS00 and C14 74LS32 were also damaged.
The 74LS11 on the ROM card and my A2DVI card were also dead.
Luckily I have spares for all damaged ICs and the A2DVI
Thanks for your help.
My 2 cents, the 8T97 and 74LS367 are not exactly equal replacements. If you have a lot of expansion boards connected, you may have problems with their operation.
I would say all three 74LS367 were factory fitted but cant be certain
.
Almost surely not original. Apple would have only used proper 8T9x parts because 74LS367 in my experience will result in extremely flaky operation at best. They will work with no cards installed or maybe with just one, possibly two if they are light loading on the bus. But even with just a Disk ][ card, they usually will cause weird memory errors and corruption.
There is a 74*367 which will work reliably as a replacement but it isn't L or LS. I don't remember if it is 74H or 74F, but one of those worked for me in the past because they were either fast enough or could handle the load better than a 74LS part could. I'm not sure if I ever remember seeing a 74367 so that's probably not an option.
Anyway, the 8T* parts are available if you look. But keep in mind if you buy from a source where counterfeit or remarked chips are common like Aliexpress or sometimes even eBay you may end up getting 74LS367 remarked.
Make sure you test a ][+ or clone with at least 4-5 cards installed before you assume it is working correctly. Ones that hit the bus hard like a lot of Z80 cards, hard drive controllers or modern mass storage cards, etc., are good ones to use for testing.
I completely concur with this. It was my experience exactly back in the day, and others have also reported the same thing. It is pretty common that when people have a ][+ or clone exhibiting weird behavior, especially like after someone installed a new card that is othewise known good that either one of their 8T97 is going bad or a 74LS376 has been substituted.
Dear All,
certainly, i really don't wont to query all your experience, but my experience is a little bit different. My ][+ (Clone) is fully loaded. It has an expansion card in every slot.
#0 : 16K-LC (expanded to 512K, for use as RAM-disk, under UCSD,ProDos,CP/M)
#1 : A2VGA
#2 : SSC
#3 : Videx 80C
#4 : Z80
#5 : Disk ][ (expanded to use with Shugart drives, like an Ehring FDC4 disk controller)
#6 : SD-Disk plus
#7 : Hires ][ (an Hi-Resolution graphics card)
This system is running fine with 74LS367 drivers, so from my point of view, there is no need to worry about the LS367's !
Did you ever think about the PSU when a system is loaded with many additional cards? I believe an original Apple PSU may reach it's limit with many slots loaded. My ][+ is powered by a modified PC-PSU, which can deliver much more power on the +5V rail than an original PSU.
But i have a question:
In an earlier post an A2DVI card was mentioned. Does someone know if this card can really replace a Videx 80C, when plugged in Slot 3 of an Apple ][+ ? There is a seller on Tindie offering this.
https://www.tindie.com/products/a2store/a2dvi-v41-digital-video-card-for-apple-ii/
Regards
Eberhard
Yes, it can.
Interesting comment...While I don't necessarily disagree, my experience has been different. I have several clones based off the Unitron (Rev7 / RFI clone almost one-to-one) motherboard and all of them have 74LS397 in place of th 8T97 chips, all of them ran (and sometimes still do) full card compliments - RAM card. printer, serial, 80 Col, Disk-II and Z80, sometimes a clock or a second Disk-II - and I haven't experienced bus flakiness in any of them.