7bits

Seems like an appropriate thread to continue. Is it normal for the CPU to get so hot to the touch, it feels like it will burn you? I would think not, but what temperature do people think is normal?

Yes, I got some spare supposedly working sideboard/data seperator boards but then I think I fried something trying to narrow it down LOL. It booted once, than that was it... Unless the head burned out. So last place I was at, was I was able to boot off the 810 once, then went to test the data separator board, I think it worked. I swapped the smaller ICs at Z101 and Z104 from my bad side board into the good one. Then it didn't work so was ah ha!, so swapped it back, then didn't work. Thats what I get for trying to narrow down the chips So at this point I can boot off a 1050, and initiate a format on the 810, it does the chunk chunk chunk, gets to the last track on in inner hub and sits there till it times out, this is doing a single density format on the 810. The disk I try to format is a single density disk that is already formatted with DOS 2.5. Still works after the ghost format. Other drives I can test the coils for the erase and read heads if I know the pinouts. Any advice on that? I guess thinking now I can check the service manual.

Narrowed it down to the side board. Data separator board is good.

I also looked up the stepper motor, its a Minebea Co Stepper Motor 17PS-C006-01. Since it was five wires, I did the ohms test to find the + wire between each one, taking the lowest ohm reading. In this case I started with the black wire and each wire paired to that had equal ohms, so that means the black wire is the positive wire. Then ran 12 volts to the black wire on the stepper motor from my bench PSU and was able to cycle each of the 4 stepper wires and move the drive head from back to front and then cycle it backwards to track zero. This convinces me the stepper motor is not shorted/works OK and not feeding anything back to the side board. So back to the side board and waiting on SRAM. Other than the cracked joints on the power regulators, all connections look good. May crack out the oscilloscope next. I love a puzzle If the SRAM doesn't fix it I will be looking closer for some bad transistors. I suspect still that the stepper motor transistors may be bad, the ones that sit between the RIOT and some diodes/stepper motor.

Yep. But I figure at this point, 3 bad ones(1 Original and 2x NOS ones) ? Maybe not. Or the NOS ones I got were bad ones stored back in a package. Pretty sure they were new as they both had Pin Spread so to speak. I just threw it in the Music cart, did EXACTLY the same thing as when I put the 810 ROM in the Basic socket in the 800 XL!

Ok, I picked up a bunch of cheap carts that just arrived today, for a few dollars from an estate sale, don't know what they all are, just a bunch of games and music/writer cart. Will delve into them later/test etc. This lot was cheaper than buying the basic cart alone! My basic cart looks like it is lost in the mail. Anyways will any one of these that are socketed work for dumping the 810 ROM? Anyone better than the other? Just asking before I crack them all open

I have to find the source but I read about someone doing an experiment to erase eproms without an eraser using sunlight, and some other man made sources. I think the one left by the window even after a month was still intact. Now that being said you can still get the space rays to randomly hit it and cause corruption I still cover mine as right conditions and 1 bit flip can ruin your day. And depending on your quality of sunlight it will be faster/slower to cause corruption. Inside I would not worry as much. Edit: This stack exchange author says 1-2 weeks of direct sun for full erasure, 20 min for UV which I agree using my eraser, and much longer with other house hold light sources https://electronics.stackexchange.com/questions/34607/erasing-eproms-with-sunlight

So getting closer. You know its always the last thing you check... I got 2 NOS ROM chips, was x fingers there were C rev ROMs. Only paid $15 shipped. Drum roll..... Popped the package, rev C. Plugged it in and no difference. Granted both of these could be bad too. I think these came out of an old repair shop as it had the nice basement smell Waiting on the SRAM ones next.

That the riot chip, from what I have seen lots of them. They are used in the 2600 too. Used for sure you can find them.

I did notice, while futzing around, it reported bad blocks of memory, I don't remember how far in, maybe the 5th and 6th block? Either way I did notice that when I put it all back together I ran a memory test to double check it was not wonkiness

I tried placing the 810 ROM in the 800XL, all it would do is boot straight to the Memory Diagnostics and start the test. Would not even try to boot the 1050 drive. I let the ROM socket empty and it would then just go to the self test menu. Not sure if this says anything about that ROM from the 810. Ordering a basic cart off ebay.

Heh, well that is what I am doing, circles I tracked down all the hot transistors. This is on the side board, its fed 12+ volts from pin 20 on the side board connector off the power-supply board. This is used to drive the stepper motor on connector J2 on the sideboard. All other J2 connector pins tie back from the stepper motor to the bank of transistors that get super hot to the touch. These in turn all connect to the RIOT chip. Probably a red herring... If I remove the J2 plug to the stepper motor its cool as ice. Same problem of course, ordered some RAM and will try to dump the ROM again soon. Transistors I am talking about 4 above the blue wire bundle:

Looking at the rev2 service manual, it looks like Q100 is a large transistor with a heat sink, not a voltage regulator transistor or my electronic knowledge sucks. I guess where is the -5v regulator supposed to be? Does anyone have a clean copy of the rev2, the ones I have are bad scans and near impossible to read when it comes to the curcuit diagrams.

Thanks Nezgar! Will def delve more into your advice and links. Good thought on the 800XL to dump the rom. Since I am stuck a little and the hot transitors got me thinking a short to ground somewhere, I decided to pull the 810 power board and take a closer look. Do some isolated testing by powering the power board up without the side board. While this drive has been opened before, I only see evidence of someone looking around, not replacement or repair. All the boards look factory soldered, no bodge work. I checked the bottom of the power board and while the joints don't look cold, they are arguably short on solder! So I went ahead and reflowed, inhaled 40 year old flux, and added fresh solder. Before: After: I also went ahead and re-checked the voltages. I see about 13 in 5 out and 26 in and 12 out respectively, like before. Now I realize I am a dummy, and never saw nor checked the 3rd regulator I see it is about -12v in and -1.1v out. Keep in mind this is just the power board only with the pin 1+2 jumpered on the header pins for the side board. I assume this is not normal? Would explain why the LEDs look slight low. Looking at this chart is should be -5v I think. Anyone know what part number I need for this regulator on the negative rail?

Thanks! Once I get the 810 up and running, will clean that up

So I swapped the following in the 1050 I have seemed to work ok i.e. booting DOS 2.5: The 6532 RIOT (810's A104) can be tested in the 1050's U7 socket. The 6507 CPU (810's A101) can be tested in the 1050's U9 socket. I didn't do this, as I had never opened the 1050 since it just worked and I have had it for around 5 years now. Last time I opened a 1050 was in 1985 to install a Happy Upgrade The 6810 SRAM (810's A103) can be tested in the 1050's U8 socket. Reason I did not swap the A103 is because I saw this in my 1050: Don't want to get too far off topic I am guessing I have a us doubler type mod? Never knew I had it. I assume this doubles the SRAM via some weird chip select method and I have a custom ROM thats been flashed... Looks like a poor piggy back mod and I think I may break some solder connections and I don't need a 2nd broken drive right now! Is this likely just a bootleg US Doubler? Anyways back to the 810. I was not able to dump the ROM off the Side Board, I need to find a spare LS logic chip to float some pins low on a bread board to get that chip to read ok on my burner. Believe it or not I have zero 8 bit carts! I don't dare put the good chips in the 810 for fear that the 810 has some other over voltage situation I am missing. So what I have noticed, the 1050 hooked to my 800XL with no disk and powered on I get the following when turning on the 8 bit host: Boot error, repeated, which I think is normal When I hook the 800XL to the 810 powered on with no disk, it just goes straight to the Ready prompt. So I could get an SRAM and Mask ROM chip for giggles, it they are a few bucks to try, but I wonder, should I be looking a the power board again? The diagnostic flow chart says replace 104, 103 and 102 first, so RIOT, SRAM, ROM. The 810 below is what I have for reference. I am putting in a lot of info for the next googler with the endless spinning drive If anyone has the SRAM an ROM chips that are known good for sale, let me know please!

Thanks, I have a usb rom burner, will see if I can read these mask rom chips. If they are the same as the c64 kernel/basic/os ones I think I can dump them. Here is the flow diagram I was following from they guide: to be attached later

I have a similar problem, I have both the power and busy light on, and it just spins, no seeking, track 0 reset or anything else. The field service manual says check chip a104 pin 9 to drop from 5v to 0 after 7 seconds, if it's doesn't replace the chip. This is the riot chip on the side board so I ordered one. However I doubt this is it but the chip is only 5 dollars so ordered to test and replace. Says to then replace certain transistors. I did check the test points on the power board, all good, and the regulators have good voltage. I have the rev c rom, the data seperator board, last psu and the analog board on top of the drive. Only other thing I noticed is some of the transistors get hot on the side board on top, above the psu board connector. I also pulled all the chips and deoxit and tested all the 74ls chips on the data seperator board

Funny, I just had the same problem, grabbed 10 of these mux chips for like 7 bux shipped I think, they worked great. Didn't want to wait for ebay ones from Asia that may more may not be good quality for 1$. CD4051BE Single 8-Channel Analog Multiplexer, PDIP-16 from Harris, chips