@nine I don't think it's for the repair necessarily. I think they knew the chips they had on hand were so bad, that the odds of just soldering one in and have it work would be a little low, so they had to try a few to begin with. Thus the sockets.
Factory sockets for chips that you don't see normally in sockets could be a result of the chip supply issue you mentioned. The factory needs to keep production flow steady with no line stoppages, so to work around parts shortages they just complete the soldering of boards with sockets in place of missing chips, and put the almost complete boards to the side. When the chips eventually show up, they can be installed in the sockets just by hand by pretty much any assembler to complete the boards, without needing to be soldered by someone who's skilled enough to do rework.
That's a really interesting theory and really makes sense. I wonder how many vehicles, PLC's and all sorts of other devices over the last 12-24 months may have socketed IC's. A silver lining for the recent chip shortage cloud.
Not gonna lie, I love seeing my name roll with the credits. Thanks for putting these out early for us, Adrian! Well done, as always. It is pretty amazing the level of production quality you produce these videos with in such a short period of time.
My first C64 (Spring '84) had all the problems you speak of. I was a kid at the time, but I remember for sure the SID being replaced at the repair shop, and I believe the other time it was the PLA. Ended up getting a C64C in '88, but can't remember the problem then.
Brilliant explanations! Love the way you explained the PLA failure modes and how you determined that the PLA was fine. I am happy that I recently got a scope, too. I habe a 1541 to repair and it seems one of the logic chips is broken (ROM and CPU I already replaced with working ones)
Some advice: Remove the chip first before you clean off the thermal compound. If you smear it while it's in the machine the IPA can cause it to flow around and crust onto other parts, making it harder to clean. Especially if it gets into a socket.
On the topic of thermal compounds, while they are not suppose to be electrically conductive, I personally would not leave it going across the legs like that. I'm sure the VIC from the first machine in this video is bad (your testing is very thorough!! Always enjoy it :)) .. is there the possibility that maby it could be contributing to the output we say with it in the "ZIF C64"?
@@DigitalCoffee-OG I would think there is some electrically conductive components in thermal paste, at least some of the higher quality ones...not enough to cause a direct short, but perhaps a resistive shunt. I could be off-base here, though.
you know what, now you've got me wanting to dance with you on the 8 bit dance party, caught myself doing it while you were too, i dont think ill ever get sick of you fixing up old commodore 64's thanks again adrian for you great content please keep the videos rolling in
interesting video has always, but maybe is a stupid question you said that two multiplexor are bad! it can't be possible that only one of the two was broken you had test all two chips off camera ? looking forward for the next video :) greetings from italy
I would bet they installed the sockets because they were out of these ICs at the time the board was soldered, and just later stuck in chips once they had any. That way they can keep the assembly and wave soldering line running even with supply problems.
It would be interesting if you had a small spreadsheet of the contents of your dead parts bin with different C64 chips and revisions and date codes. To see what the most failure prone of the parts were.
Awesome that they're back up, other than the missing SID and VIC in the first one. I WISH I got MOS Logic chips in sockets like that more often than I do, which is hardly ever. I just replace those with new TI parts whenever I see them, as I resell them and I can't trust the MOS chips if working today will work tomorrow.
Commodore was notorious under Jack Tramiel for cutting corners. No surprise seeing their chips failing years later and few socketed chips on the boards. Every pinched penny added up! Conversely, I rarely have heard of Atari chips failing. They even used POKEY sound chips even in their coin op arcade games! 😉 The 2600 chips would fail but that thing got heavy use.
Not really, MOS PLAs from 1985 onwards are reliable, and don't get as hot as the early ones. There are quite a bit of machines with those. You just don't see those machines appear in videos because they don't break as often.
@@danielmantione Ahh you mean the newer ones in the C64C wedge model? Yeah those were solid. Maybe there was a breadbin 85 model with solid ones I guess Ive never seen/experienced an 85 bread bin c64. All mine are 84 and prior.
@@joshhiner729 The C64Cs are tanks; near indestructible, but they were only introduced in 1986. I was talking about breadbins that are reliable from 1985 onwards. Lots of breadbins were produced in 85 and 86 and even after the C64C was introduced the breadbin was still being made in smaller quantities. If you do an image search for "assy 250466" on Google you will find photo's of some later breadbins and you can look at the datecodes of their PLAs.
@@joshhiner729 If it is just about the breadbin case, look for an Aldi C64 or C64G (those were the final breadbins). They have the short boards though. Regular breadbins with long boards from after the C64C introduction are rare, but do exist. Some early C64Cs also have the assy 250466 long board inside.
Interesting as always. I now have to wonder about the breadbox C64 I once had... it was from the same era as machines 3 and 4, paper shield and all. It was a Christmas gift in 1984. But by the time I sold it in the early 90s, it had a full set of new RAM (thanks to the factory power brick bricking my 64) and a new VIC-II (thanks to my kid sister pulling a game cartridge out with the power on... only one bit in one register was bad, but it made many games unplayable until I bought a new VIC-II chip in the late 1980s).
Another idea for a diagnostic tool would be a small device that would blink if more than one chip select like was active. Or some kind of high impedance light that uses the CS as a ground to light up. Then you could watch chip select in real time.
I'm thinking that the uncommonly socketed-from-the-factory chips are from when a board failed it's first run through the production line and it was reworked at the factory until it was functional, then it was finally sold. Whatever the case, convenient fix!
Yeah, he's used his minipro to test LS chips in previous videos.. I think in the case of this specific one, there wasn't really a point. He had spare versions of those specific chips. I'm not sure both of those were bad and maybe it would have been good to run it through the tester just for completeness, but he probably didn't want to use those MOS chips even if one of them was still good since it's a matter of time.
Watching this repair-a-thon makes me only hope it is just the PLA bad on my Rev A C64. On the other hand a repaired C64 requires an 8 bit dance party every time.
Don't socket the SID. They're really sensitive. At least wait until it's dead. My first SID removal was done by my ham-fisted younger self with a crappy soldering gun and the SID was almost dead (some waveforms on some voices still worked). The second time I tried removing a SID I was being careful and using a solder sucker. The SID worked, but the filters were bad. Sucks on the more awesome tunes. The third time, I was extra careful and even took time after each pin to allow the chip to cool down. Still blew the filters.
Congrats dude! Hopefully the SID stays working, both of mine had the same filter die after a couple days of use. Ended up just getting some FPGASIDs And before anyone asks, PSU has been rebuilt and SID chips were well heatsunk with big chipset heatsinks
If you are not afraid to use your zif64 VIC2 chip in an unknown machine you could take another socket and stack it so it's higher and the heat sink doesn't bump into that metal cage or whatever that's around the VIC2.
Did you ever took a closer look at the date code of the chips in your dead chip bin to see if there is a correlation between production date and chip type? especially with the c64 chips like PLA, SID - some production badge more prone to fail than others?
Seeing this a couple of years later.. I do agree that the VIC is still an issue as Kawari isn't that available and still expensive so mostly for uber nerds building new systems. But the SID while sure it would be nicer to have the original there's always the goto ARMSID which even back when this video was made is decent and fair priced and it supports mouse and paddles unlike lower priced alternatives. Now there's even a few more replacements including FPGA and open source intivaties which although lacks ready made PCBs for the masses to become real alternatives.
Looks to me like a factory repair or qc failure they did get some of the line that needed for some reason components replacing and they used anything that worked they had
You should always measure the volts. The voltage regulators may be defective and are emitting too much voltage. It seems that Commodore bought the RAM cheaply and threw what they had lying around on the board.
Edit 20:09 fixed. The white heat sink compound on the VIC chip R8, it spreads onto the pins. Could it be shorting out the pins/ or altering incoming signals due to some conductivity? Or the opposite, could it cause the pins not to make a good connection to the test socket?
Not uncommon for Commodore to mix and match IC manufacturers; probably to save costs! My store-bought C16 had an assortment of MOS, TI, Fairchild, and Signetics 74xx series logic chips -- (they're all TI now).
I’ve got a candidate machine for pt 5 if you like! I have an Aldi machine with crappy video quality. I think it’s for Europe looking at the psu plug but is here in the UK. I’ve no idea what to do. I can pay the shipping both ways...
"you know it's an NTSC unit because it has a FCC sticker on it" With that comment, I can only think of my GameCube Game Boy Player. Add-on for which the one I bought is orange, which I'm almost positive was a Japanese-exclusive color yet has an FCC sticker on it which would not apply to that market. :D
I think its about time to fit an esd mat to your work desk, these old chips don't like static at all. As chips get harder to obtain the more you need to protect the environment they are moved about in. Just my $0.02 worth as it makes my inner engineer shout no! As you pull them out. Still like to see computers younger than my PET 4016 being fixed. As I jumped from the pet to pc's due to working on custom embedded systems.
The reason they shields were there is because they provided a crude way to block RF interference in order to meet FCC regulations. These days, RF interference from our retro machines is basically a non-issue, and all the cardboard does is trap heat, which will cause an early death to our precious vintage microchips. Unless you really really want your C64 to be 100% original... #DitchTheCardboard
Another question to the Basement Community , if I may ? On the same C64 Rev. B I found Q1 Transistor D880 . It is just below the cassette port . The first time , I oscilloscoped no signal on the Collector , just a flat voltage . The same on the Base , which is what I expected of the Base . While I found signal on the Emitter . So I thought , the transistor must be faulty . Then tonight , I looked at it again , and I found the Collector had oscillation 50 Hz , the Base had oscillation 50 Hz and the Emitter had the same oscillation with extra roughness . My question is ; is this due to more breakage ? or is this transistor using AC power ? Thanks for reading .
What about a FPGA replacement for the VIC2 chip or go for broke and replace all custom chips with FPGA replacements for the broken chips. What about using 74AC*** chips for all 74LS*** chips.
I am kind of confused over why some of the machines came with a bunch of sockets from the factory and why some did not. Wasnt there any consistency or quality control?
First step of troubleshooting: Make sure your diagnostic test equipment is functioning properly.
It was nice of Commodore to leave you a clue about what was wrong with #4. :D
@nine I don't think it's for the repair necessarily. I think they knew the chips they had on hand were so bad, that the odds of just soldering one in and have it work would be a little low, so they had to try a few to begin with. Thus the sockets.
"Hey! Look at that! It's garbage" good sound bite.
7:16 the SID chip is sending Morse code 😁
Factory sockets for chips that you don't see normally in sockets could be a result of the chip supply issue you mentioned.
The factory needs to keep production flow steady with no line stoppages, so to work around parts shortages they just complete the soldering of boards with sockets in place of missing chips, and put the almost complete boards to the side.
When the chips eventually show up, they can be installed in the sockets just by hand by pretty much any assembler to complete the boards, without needing to be soldered by someone who's skilled enough to do rework.
The soldered chips seem to be from late 1983 while the socketed ones are all from early 1984. This would support your theory.
That's a really interesting theory and really makes sense. I wonder how many vehicles, PLC's and all sorts of other devices over the last 12-24 months may have socketed IC's. A silver lining for the recent chip shortage cloud.
You know you love 8-bit Commodore stuff when you feel happy about that working SID just blaring out :o)
Not gonna lie, I love seeing my name roll with the credits. Thanks for putting these out early for us, Adrian! Well done, as always. It is pretty amazing the level of production quality you produce these videos with in such a short period of time.
I agree completely. How he puts out so many quality videos is beyond my comprehension.
It's todays version of owning a private number plate on a vehicle ain't it :D
My first C64 (Spring '84) had all the problems you speak of. I was a kid at the time, but I remember for sure the SID being replaced at the repair shop, and I believe the other time it was the PLA. Ended up getting a C64C in '88, but can't remember the problem then.
Any video with an 8-Bit Dance Party is a good one in my book!
"Would you look at that!" would be perfect for ADB merch!
Your hand gesticulating is always on point!
the 8 bit dance party wouldn't be the same without Adrian's 'hand dancing'
I love your surprise reaction to a fix "Ohhh Would you look at that bad multiplexers!" It's epic, keep up the awesome awesome work Adrian.
My memory is from 1979 too, I think I have a few stuck bits occasionally though ;-)
Mine is older than that. The bits all still work, but the access time isn't what it used to be and the whole service has degraded :)
@@greendryerlint yep, 1979 would be a year after I graduated from high school.
Congratulations on reaching 100,000 subscribers!
Brilliant explanations! Love the way you explained the PLA failure modes and how you determined that the PLA was fine. I am happy that I recently got a scope, too. I habe a 1541 to repair and it seems one of the logic chips is broken (ROM and CPU I already replaced with working ones)
👍 Another cool and interesting one, thank you! Every Wednesday and Saturday it’s great to get your new videos! Tony from Italy
Loving the repair videos . Great mini series for lovers and learners
Cardboard RF Shields - “IN THE BIN!”
Oh man, I feel so spoiled on Patreon. 8 days early! So much Digital Basement content.
I could watch you doing this for days
We got a twofer, and a dance party. This was a most positive episode from the reparathon...
Wooooo!! 100K subscribers!! Great achievement Adrian!! Cheers from Italy!!
It's been a wonderful treat watching Adrian repair Commodores the past few weeks: Jordan went back to basketball. Great content as always!
I like how Adrian was like “I’ve got job stuff that might slow things down, so expect less vids”, then bang! repair-a-thon series!!!
100k subs. Yey. Well done. I don't think anyone would unsub your channel so it will only grow!
When #4 booted up after you swapped the multiplexers I burst out laughing. It doesn't get any easier than that, already socketed and everything.
Some advice: Remove the chip first before you clean off the thermal compound. If you smear it while it's in the machine the IPA can cause it to flow around and crust onto other parts, making it harder to clean. Especially if it gets into a socket.
On the topic of thermal compounds, while they are not suppose to be electrically conductive, I personally would not leave it going across the legs like that. I'm sure the VIC from the first machine in this video is bad (your testing is very thorough!! Always enjoy it :)) .. is there the possibility that maby it could be contributing to the output we say with it in the "ZIF C64"?
@@DigitalCoffee-OG I would think there is some electrically conductive components in thermal paste, at least some of the higher quality ones...not enough to cause a direct short, but perhaps a resistive shunt. I could be off-base here, though.
you know what, now you've got me wanting to dance with you on the 8 bit dance party, caught myself doing it while you were too, i dont think ill ever get sick of you fixing up old commodore 64's thanks again adrian for you great content please keep the videos rolling in
I'm loving these C64 repair videos and your excitement when things work! 😁
interesting video has always, but maybe is a stupid question you said that two multiplexor are bad! it can't be possible that only one of the two was broken you had test all two chips off camera ? looking forward for the next video :) greetings from italy
To the tune from Donkey Kong Arcade... "Would you look at that!?! Adrian's TWERKING!" ;-) Another great, enthusiastic, entertaining video.
Thanks again Adrian. I just repaired one C64 today :) I can't get enough C64's
Awesome as always! Love to learn from you Adrian, and this is the best way. One day I will have a basement myself to repair all electronics!
I would bet they installed the sockets because they were out of these ICs at the time the board was soldered, and just later stuck in chips once they had any.
That way they can keep the assembly and wave soldering line running even with supply problems.
Half way through the video, i just noticed you hit 100k. Congrats!
Nice work . I love repairathons. Especially when one that I'm working on irritates me. Lol. Keeps me going to fix it. Thanks
Great episode and an 8 bit dance party is always the highlight!!!
It would be interesting if you had a small spreadsheet of the contents of your dead parts bin with different C64 chips and revisions and date codes. To see what the most failure prone of the parts were.
Awesome that they're back up, other than the missing SID and VIC in the first one. I WISH I got MOS Logic chips in sockets like that more often than I do, which is hardly ever. I just replace those with new TI parts whenever I see them, as I resell them and I can't trust the MOS chips if working today will work tomorrow.
Great job as always Adrian...! I love watching your C-64 Videos! :)
I would think some of these old C64 had cap problems...but I guess not 🤷♂️ ....but maybe these machines should be recapped? 😇
Commodore was notorious under Jack Tramiel for cutting corners. No surprise seeing their chips failing years later and few socketed chips on the boards. Every pinched penny added up!
Conversely, I rarely have heard of Atari chips failing. They even used POKEY sound chips even in their coin op arcade games! 😉
The 2600 chips would fail but that thing got heavy use.
I think you have the last functional MOS PLA. Wow. Those PLA’s (as you know) degrade over time. Amazing its still functional. Great video as usual.
Not really, MOS PLAs from 1985 onwards are reliable, and don't get as hot as the early ones. There are quite a bit of machines with those. You just don't see those machines appear in videos because they don't break as often.
@@danielmantione Ahh you mean the newer ones in the C64C wedge model? Yeah those were solid. Maybe there was a breadbin 85 model with solid ones I guess Ive never seen/experienced an 85 bread bin c64. All mine are 84 and prior.
@@joshhiner729 The C64Cs are tanks; near indestructible, but they were only introduced in 1986. I was talking about breadbins that are reliable from 1985 onwards. Lots of breadbins were produced in 85 and 86 and even after the C64C was introduced the breadbin was still being made in smaller quantities. If you do an image search for "assy 250466" on Google you will find photo's of some later breadbins and you can look at the datecodes of their PLAs.
Wow ok good to know. Did not know they continued the breadbins after the C64C. Ill definitely look into that thanks. Id like a later breadbin.
@@joshhiner729 If it is just about the breadbin case, look for an Aldi C64 or C64G (those were the final breadbins). They have the short boards though. Regular breadbins with long boards from after the C64C introduction are rare, but do exist. Some early C64Cs also have the assy 250466 long board inside.
Thanks for doing another C64 repairathon. Fascinating! Great channel and content
Interesting as always. I now have to wonder about the breadbox C64 I once had... it was from the same era as machines 3 and 4, paper shield and all. It was a Christmas gift in 1984. But by the time I sold it in the early 90s, it had a full set of new RAM (thanks to the factory power brick bricking my 64) and a new VIC-II (thanks to my kid sister pulling a game cartridge out with the power on... only one bit in one register was bad, but it made many games unplayable until I bought a new VIC-II chip in the late 1980s).
30:00 there's something amazing about fixing that C64 with a couple of 42 year old chips...
Awesome! Can't wait for number 5!
Wow, so many repaired C64s! You must have piles of them all over the place! 😁
Another idea for a diagnostic tool would be a small device that would blink if more than one chip select like was active. Or some kind of high impedance light that uses the CS as a ground to light up. Then you could watch chip select in real time.
I'm thinking that the uncommonly socketed-from-the-factory chips are from when a board failed it's first run through the production line and it was reworked at the factory until it was functional, then it was finally sold.
Whatever the case, convenient fix!
Awesome fixes, Adrian!
Now i know, why i love your videos so much :) my year of birth was 1974 :D Keep on doing such cool stuff! Greatings from germany.
We are waving back with our Commodore 64s! 😀👋
Again with your minipro, Adrian you can test LS TTL chips, you might need a software update to do so. But testing LS chips seems incredibly useful.
Very usefull. if i use any i will test them first
Yeah, he's used his minipro to test LS chips in previous videos.. I think in the case of this specific one, there wasn't really a point. He had spare versions of those specific chips. I'm not sure both of those were bad and maybe it would have been good to run it through the tester just for completeness, but he probably didn't want to use those MOS chips even if one of them was still good since it's a matter of time.
I might be late, but congratulations on 100K!
Watching this repair-a-thon makes me only hope it is just the PLA bad on my Rev A C64. On the other hand a repaired C64 requires an 8 bit dance party every time.
If the PLA is from 1983 or 84, there is a good chance it is the PLA. If you have MT4264 on your board, it for sure needs new memory.
Lighter fluid gets thermal compound off easily. Just clean residue with IPA
It warms my heart that each hand has the other to dance with at the party. :)
Don't socket the SID. They're really sensitive. At least wait until it's dead.
My first SID removal was done by my ham-fisted younger self with a crappy soldering gun and the SID was almost dead (some waveforms on some voices still worked).
The second time I tried removing a SID I was being careful and using a solder sucker. The SID worked, but the filters were bad. Sucks on the more awesome tunes.
The third time, I was extra careful and even took time after each pin to allow the chip to cool down. Still blew the filters.
Congrats dude! Hopefully the SID stays working, both of mine had the same filter die after a couple days of use. Ended up just getting some FPGASIDs
And before anyone asks, PSU has been rebuilt and SID chips were well heatsunk with big chipset heatsinks
Great work. ✔️💯🏆
Thanks so much for sharing. 😉👌🏼
If you are not afraid to use your zif64 VIC2 chip in an unknown machine you could take another socket and stack it so it's higher and the heat sink doesn't bump into that metal cage or whatever that's around the VIC2.
or change the heatsink. to more slim fit to the VIC-II
Commodore only socketed the vic-ii chip, if anything else is socketed it failed at the factory and was replaced or was done after market.
Wohoow, congrats to 100k subscribers!!
Did you ever took a closer look at the date code of the chips in your dead chip bin to see if there is a correlation between production date and chip type? especially with the c64 chips like PLA, SID - some production badge more prone to fail than others?
8 bit dance party! We haven't had one of those in a while. 😄
"so rare to find a working SID"
Sounds about right for a guy named Sid from the 70's 😅
Seeing this a couple of years later.. I do agree that the VIC is still an issue as Kawari isn't that available and still expensive so mostly for uber nerds building new systems. But the SID while sure it would be nicer to have the original there's always the goto ARMSID which even back when this video was made is decent and fair priced and it supports mouse and paddles unlike lower priced alternatives. Now there's even a few more replacements including FPGA and open source intivaties which although lacks ready made PCBs for the masses to become real alternatives.
Looks to me like a factory repair or qc failure they did get some of the line that needed for some reason components replacing and they used anything that worked they had
I wonder if they fitted sockets on the production line when they were short of chips so they could be added later?.....
Hi Adrian! Very nice episode once again! Nice to know that you are also a 1975 child like me! 😉
Stay healthy, greetings Doc64!
Please we need Would you look at that compilation in our lives!
Always love the Repair-a-Thons! :)
You should always measure the volts. The voltage regulators may be defective and are emitting too much voltage.
It seems that Commodore bought the RAM cheaply and threw what they had lying around on the board.
In regards to the thermal compound... Are you sure it isn't conductive? Many types are.
You should clean the compound off the pins...
Edit 20:09 fixed. The white heat sink compound on the VIC chip R8, it spreads onto the pins. Could it be shorting out the pins/ or altering incoming signals due to some conductivity? Or the opposite, could it cause the pins not to make a good connection to the test socket?
We all came here for the classic "Would you look at that! It's working!".
Definitely an idea for merch. 8)
Adrian I'm worried about your lime intake. I believe living so close to the coast has turned you into a pirate.
Hi Adrian... i hope you have material to make it till part #50 at least 😬. I like them a lot.
I love these repairathons!!!
Make a lip around your work space, lay out the dead chips in a pattern and cover with epoxy. New cool work space.
Not uncommon for Commodore to mix and match IC manufacturers; probably to save costs! My store-bought C16 had an assortment of MOS, TI, Fairchild, and Signetics 74xx series logic chips -- (they're all TI now).
Thermal compound is conductive and you had it on the Vic's pins
Adrian, you really have to start thinking about a new dead parts container. No more room there :-)))
You lost me at dance party. ;-) Nice work.
Adrian, love the channel. Where can i get a mini pro tester like yours for testing ICs?
clean the Thermo paste from the conectors of the vic 2, mayby it work
I’ve got a candidate machine for pt 5 if you like! I have an Aldi machine with crappy video quality. I think it’s for Europe looking at the psu plug but is here in the UK. I’ve no idea what to do. I can pay the shipping both ways...
"you know it's an NTSC unit because it has a FCC sticker on it" With that comment, I can only think of my GameCube Game Boy Player. Add-on for which the one I bought is orange, which I'm almost positive was a Japanese-exclusive color yet has an FCC sticker on it which would not apply to that market. :D
15:00 IMHO a dead SID chip requires a proper funeral, not this mass grave :)
actualy she is in good company
I think its about time to fit an esd mat to your work desk, these old chips don't like static at all. As chips get harder to obtain the more you need to protect the environment they are moved about in. Just my $0.02 worth as it makes my inner engineer shout no! As you pull them out. Still like to see computers younger than my PET 4016 being fixed. As I jumped from the pet to pc's due to working on custom embedded systems.
Adrian saved lot of C64! Satisfaction.
That RF sield was not there without a reason. I don't know why everyone gets rid of those. Maybe heat issues?
The reason they shields were there is because they provided a crude way to block RF interference in order to meet FCC regulations. These days, RF interference from our retro machines is basically a non-issue, and all the cardboard does is trap heat, which will cause an early death to our precious vintage microchips. Unless you really really want your C64 to be 100% original... #DitchTheCardboard
@Adrian's Digital Basement
You need a bigger "Dead Parts Bin"...
Another question to the Basement Community , if I may ? On the same C64 Rev. B I found Q1 Transistor D880 . It is just below the cassette port . The first time , I oscilloscoped no signal on the Collector , just a flat voltage . The same on the Base , which is what I expected of the Base . While I found signal on the Emitter . So I thought , the transistor must be faulty .
Then tonight , I looked at it again , and I found the Collector had oscillation 50 Hz , the Base had oscillation 50 Hz and the Emitter had the same oscillation with extra roughness .
My question is ; is this due to more breakage ? or is this transistor using AC power ?
Thanks for reading .
my online handle is Kasran so the mention of the "CAS RAM" line startled me
What about a FPGA replacement for the VIC2 chip or go for broke and replace all custom chips with FPGA replacements for the broken chips. What about using 74AC*** chips for all 74LS*** chips.
I am kind of confused over why some of the machines came with a bunch of sockets from the factory and why some did not. Wasnt there any consistency or quality control?
Had a moment of panic with my tablet. There is a bit of wire on the bench that made me think I had a cracked or scratched screen!