So I'm having to rebuild an old, old PCB board - dated around 1968. Now, luckily, I have schematics!
However, something interested - there's two caps on it that looks like a chocolate drop upside down, and in the schematics they're listed as:
Capacitor Mylar 0.1MFD
Capacitor Mylar 0.047MF
A *mylar* cap? So, what would be a good replacement for these? 
I think you can still get them. Try "metal polyester film caps" when looking them up. They are the same if I understand it right.
Hm, thanks!
I'm actually finding a LOT of parts that - are no longer made (of course!) but.. references are almost nil online.
Hah - ever hear of a MM2266 transistor (Motorola)? Apparently, Google hasn't either. 
Redoing this board is going to be rather.. interesting..
Quoted from Coyote:Hah - ever hear of a MM2266 transistor (Motorola)? Apparently, Google hasn't either. Redoing this board is going to be rather.. interesting..
The MM prefix may be the manufacturer (Fairchild) and this be an NPN 2266 power transistor.
Quoted from krivoap:The MM prefix may be the manufacturer (Fairchild) and this be an NPN 2266 power transistor.
Did Fairchild com from Motorola? That one is listed as:
Transistor - Silicon (NPN) (Motorola MM2266, Texas Instruments SGB2321)
It IS an NPN.. Unfortunately the TI part no has NO hits on google - literally.
Quoted from Coyote:Did Fairchild com from Motorola? That one is listed as:
It IS an NPN.. Unfortunately the TI part no has NO hits on google - literally.
Nope, Fairchild, Motorola and Texas Instruments were distinct manufacturers. For old parts that I don't get an immediate hit on using Google, I tend to search the prefix separately from the remainder of the part number. Good luck.
Quoted from krivoap:Nope, Fairchild, Motorola and Texas Instruments were distinct manufacturers. For old parts that I don't get an immediate hit on using Google, I tend to search the prefix separately from the remainder of the part number. Good luck.
Thanks man - appreciated! It's an interesting learning experience, at least. The final test will come once I get a new board made and plug it in. 
Quoted from Coyote:Thanks man - appreciated! It's an interesting learning experience, at least. The final test will come once I get a new board made and plug it in.
By the way, it looks like the MM prefix may have been shared between Motorola, Fairchild and National Semiconductor: https://en.m.wikibooks.org/wiki/Practical_Electronics/Manufacturers_Prefix
Great Plains Electronics part numbers
CPR-0.1uF-100V-K
CPR-0.047uF-250V-J
For the transistor... could be something like...
http://pdf1.alldatasheet.com/datasheet-pdf/view/268697/ISC/2SC2266.html
Do you have a package type / picture/ how it is drawn on the shcmatic may help determine.
Wow, thanks guys. Will post a picture in a little bit -
It's called an "amplifier" board - all it contains are a butt-load of resistors, a few transistors and caps - it amplifies a signal from a tape recorder head to 'useable' signal values to send to what the call the 'logic board'.
The logic board is nothing but a bunch of gates and inverters with the right caps to trigger three outputs - motor forward, reverse, and a third 'acceptance' output.
This setup was used to detect 'valid' $1 bills inserted into a jukebox. The two motor outputs are for the bill motor assembly (suck in or reject back out) and the acceptance was used to start a wiper on a PCB to give the mechanical credit unit 7 clicks. (4 quarters, plus configurable bonus!)
In my 'amplifier' board, ALL the larger caps have swelled and leaked; they're toast. There's been several attempted repairs to the logic board as well, it's questionable. I'm currently working up a new replacement board so that I can solder in 'new' pieces and get it working.
You know, because my TZ rebuild isn't taking up *enough* of my free time.
Here are pics.
Hand-drawn traces, one-sided. A lot of work went into these..
Front and Back of the Amp board.. No logic, just amplifying and filtering signals:
IMG_20151025_132001.jpg
IMG_20151025_132009.jpg
Front and Back of logic board:
IMG_20151025_132019.jpg
IMG_20151025_132030.jpg
Close up of two Mylar caps. Note that they even use color codes.. (They're the black "blobs" standing on leads..):
IMG_20151025_132124.jpg
Close up of the two MM transistors. Note the very odd case size and look:
IMG_20151025_132151.jpg
And finally, for kicks, the wiper board. Since the credit unit runs on 30vac, I'm thinking it was easier for them to do it this way rather than power transistors. The output on the logic board activates a relay, which then powers the motor to turn the wiper on the board:
IMG_20151025_133201.jpg
Pretty ingenious, considering the date - and here we used technology like this to get during to the moon.
Lots of carbon comp resistors. Those tend to absorb moisture over the decades and change resistance value. Check them while you're at it. 40+ years - the electrolytics are probably all dried out.
And lots of NLA transistors and IC's - be careful with those!
Hmm, there was this topic about old capacitors with color code, those black cap's may use the same coding as the tropical fish ones.
Useful (and also some useless) information here:
https://pinside.com/pinball/forum/topic/i-need-a-old-man-to-help#post-1962491
Quoted from G-P-E:Lots of carbon comp resistors. Those tend to absorb moisture over the decades and change resistance value. Check them while you're at it. 40+ years - the electrolytics are probably all dried out.
And lots of NLA transistors and IC's - be careful with those!
How worried should I be?
I mean, from the looks of it, they're all NAND or Interters.. couldn't I just get another NAND chip (with same pinouts if using the old board) and drop it in?
Note that I'm NOT an EE. I can read schematics, and understand basic voltage, current, etc, but anything more advanced, I have to learn. So for one of the chips, for example - one of the chips is a NAND gate, two input, 4 circuit. I tried to pick one that was the closest in voltages to it, which was an SN74LS00N. (I'm not worried about pinout, as I'm redrawing the board.)
Edit to add - the logic board has a stuck output - either bad cap or a bad resistor, as it's credit output is stuck high (giving you a LOT of credits on the machine!) so that added to the fact that previous repairs on the boards.. I don't trust, decided to get new ones made to plug in.
Quoted from Coyote:ever hear of a MM2266 transistor (Motorola)? Apparently, Google hasn't either. Redoing this board is going to be rather.. interesting..
The crosses to an NTE 128
Quoted from Coyote:How worried should I be?
I mean, from the looks of it, they're all NAND or Interters.. couldn't I just get another NAND chip (with same pinouts if using the old board) and drop it in?
Note that I'm NOT an EE. I can read schematics, and understand basic voltage, current, etc, but anything more advanced, I have to learn. So for one of the chips, for example - one of the chips is a NAND gate, two input, 4 circuit. I tried to pick one that was the closest in voltages to it, which was an SN74LS00N. (I'm not worried about pinout, as I'm redrawing the board.)
On the logic board - probably not a problem. Analog areas is where I would be checking resistors.
Ya know, looking at those pictures. Roughly 50 year old boards and they all have the original caps -- and I cannot see where a single one of them hasn't leaked it's electrolytic puke on the board. Says something about how they were made back then compared to today's caps.
Quoted from Shoot_Again:Package sent good luck with repairs.
Thanks!
Quoted from G-P-E:Ya know, looking at those pictures. Roughly 50 year old boards and they all have the original caps -- and I cannot see where a single one of them hasn't leaked it's electrolytic puke on the board. Says something about how they were made back then compared to today's caps.
Yeah - none have completely leaked - ALL of the axial ones on the Mag Amp board are swollen, and have .. uh.. the soft puss around the leads. Some are bad, some are hardly swollen at all. Definately quality. Most of them are likely out of spec by now, even with the lack of leaking or swelling.
I have the schematics now captured for the Logic Board, and will be laying out the board this coming week.
Those epoxy transistors were usually made by Fairchild as I recall. Mostly low speed with low gain, so you could find a suitable replacement for them.
The resistors are all 1/2 watt 10% so you can cheaply replace them if you find any out of tolerance. The electrolytics do degrade with time.
The IC's are early DTL and TTL logic with non-conventional pinouts so it's pretty unlikely you would find a pin-for-pin compatible replacement. Also unlikely they're defective unless they took heat.
Definitely old-school PC boards there.
Wow, been a while since I've seen those boards. Basically, the guts of a Rowe BC-8 changer. Isn't there a third "power supply" board? Nothing but caps and diodes? Even back in the '80's all the caps and diodes had to be replaced when the boards came back. You said you had the schematic, did you happen to get the changer manual? There a whole circuit explanation and logic detail in the BC-8 manual. Good thing $1 bills haven't changed or all your work would be for nothing. That model basically just checks size and the frequency pattern of the portrait.
Oh, forgot what attracted me to this topic in the first place. The Mylar caps. As long as the value is the same and the voltage rating is adequate you should be fine. Today's caps probably hold a more consistent value anyway. But there is a difference. There are mylar film capacitors where the mylar is the insulator between sheet of foil. The metalized film capacitors have the conductive material deposited on the film which acts as the insulator. No big deal until a transient comes along. Transients will blow holes in the metalized film destroying the capacitor from the inside. I've seen metalized caps that weren't caps anymore, or very weak anyway. The mylar film caps were tougher, they didn't degrade anywhere near as quickly. The ones you really have to be careful about are the tantalum caps - when those fail they like to turn into little roman candles and spew hot junk out the side. On boards that old replace all of them.
Quoted from 64bsstp:Wow, been a while since I've seen those boards. Basically, the guts of a Rowe BC-8 changer.
Close! This is older - BC-2!
Quoted from ramegoom:Those epoxy transistors were usually made by Fairchild as I recall. Mostly low speed with low gain, so you could find a suitable replacement for them.
The resistors are all 1/2 watt 10% so you can cheaply replace them if you find any out of tolerance. The electrolytics do degrade with time.
The IC's are early DTL and TTL logic with non-conventional pinouts so it's pretty unlikely you would find a pin-for-pin compatible replacement. Also unlikely they're defective unless they took heat.
Definitely old-school PC boards there.
Thanks! Yeah, I went ahead and decided to re-do the boards altogether - I need the experience in designing anyways, so this is good practice. And since the original boards HAVE had work done, including some really horrible trace patching, and other traces lifting, I figured I'll just rebuild them. Once I finish laying out the boards, I'll post here the replacement parts I think I found, and see what everyone thinks.
Since ya'll've been a great help, here's two more questions. One is kinda silly. The second I'm having issues finding a compatible item. Trying to narrow down replacement bits..
First - All the caps are listed with 'MFD'. Am I correct in assuming the 'M' stands for Micro (u), and not mega? Because those mega caps are HUGE...
Second - One of the items listed is, and I quote: "Inductor, Variable 0.975 - 1.025 H". In the scematic, it's labeled as "0.975 - 1.025 HY" There's no 'M', no 'u', etc in front of the H. However, when I go to look up 1H inductors.. those things are HUGE. Like, the size of a small transformer. The one on the board is about the size of a quarter round, and an inch high. Small, compared to what I find online. What am I missing?
Thanks guys..!
Quoted from Coyote:Since ya'll've been a great help, here's two more questions. One is kinda silly. The second I'm having issues finding a compatible item. Trying to narrow down replacement bits..
First - All the caps are listed with 'MFD'. Am I correct in assuming the 'M' stands for Micro (u), and not mega? Because those mega caps are HUGE...
Second - One of the items listed is, and I quote: "Inductor, Variable 0.975 - 1.025 H". In the scematic, it's labeled as "0.975 - 1.025 HY" There's no 'M', no 'u', etc in front of the H. However, when I go to look up 1H inductors.. those things are HUGE. Like, the size of a small transformer. The one on the board is about the size of a quarter round, and an inch high. Small, compared to what I find online. What am I missing?
Thanks guys..!
MFD = uF micro
To answer 2nd question.
Really big hash chokes could be in Henry's. This would be small to medium transformer sized bugger - don't see them often anymore.
Small chokes, crossover inductors, RF and various other types of inductors are typically rated in uH.
Not exactly a high failure item. If it looks good and isn't open or burned - leave it alone.
Quoted from barakandl:MFD = uF micro
Quoted from G-P-E:To answer 2nd question.
Really big hash chokes could be in Henry's. This would be small to medium transformer sized bugger - don't see them often anymore.
Small chokes, crossover inductors, RF and various other types of inductors are typically rated in uH.
Not exactly a high failure item. If it looks good and isn't open or burned - leave it alone.
Thanks guys.
Can't keep the original choke - since the whole board's getting replaced. It's unfixible, so I'm re-developing the boards. I could take this inductor off the old board, but I'll need to measure and layout the drill file for it for the new board. I'd prefer to use a newer component, but, it's doable!
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