(Topic ID: 229354)

Meteor Resets – With Rottendog Solenoid Driver Board


By oldschoolbob

11 months ago



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  • 315 posts
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  • Latest reply 9 months ago by oldschoolbob
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There are 315 posts in this topic. You are on page 3 of 7.
#101 10 months ago
Quoted from oldschoolbob:

...I know how valuable time is for a working man with family. (been there)...
Bob

Actually, I'm an old fart nearing retirement.

Our basement is our date room. Theater, bar, and the pins. Pretty much got all the bases covered for a good time. Friday and Sat are almost always pinball tournament night between us. Problem is, spouse has most the high scores. Oh well, I guess I'm just destined to be the pin maintenance man.

2K resistor: As always, it's your call. I just try to point you in the right direction. Won't hurt anything if you don't. If the +12V doesn't appear to work, then add it. At 2K, you can use a 1/4W resistor, it will only dissipate 72 mW (that's the reason I picked 2K). A 2K resistor would only draw 6mA - but plenty to turn on Q1. Even a voltmeter has a large amount of resistance...that might be enough to turn on Q1, just not very well.

I drew the schematic with TinyCad, an open source program. Never used it until 5 min before I drew your schematic. Very easy. You can get it here: https://www.tinycad.net/

#102 10 months ago

The Hantek current probe is neat since it gives you current vs. time. Current meters, like the analog or the digital one you picked out just give a steady state value. Was just pointing that out as an easy option that doesn't require modding your power supply. Rather spiffy. Here's a screen shot of Houdini flipper current, you can see how it varies w/time. 1mV = 100mA
Capture (resized).PNG

#103 10 months ago
Quoted from oldschoolbob:

On the addition of the 2K resistor. Quench said a while back that he sometimes has problems with his computer power supply (something about the VR1 being out of spec) If he manually resets the MPU it will start up fine. I’ve never had that problem with this supply. Maybe (just maybe) it’s because my 12 volt is not fully energized until it sees a load. I really don’t know, but maybe Quench or someone could give an explanation. For this reason, I’m a little reluctant to add it at this time.

Some other pinsiders have had issues with PC power-supplies for bench testing Bally/Stern boards like I have during my time here. But the 2k resistor mbwalker is suggesting isn't an issue in this regard. It's a good idea and I would add it.
However I'm of a differing (oldskool) opinion that the 10,000uF smoothing capacitor needs to be on the rectifier output, not the transistor output. You could move the 2200uF capacitor on the transistor output if you like.
Also if you're changing transformer to a slightly lower voltage unit, the 15V zener diode is too high. It should probably be a 13V zener and the support resistor adjusted accordingly.

At the end of the day it depends how you decide you want to build it. Something tells me you're going to stick with the original design since it worked.

#104 10 months ago
Quoted from Quench:

...However I'm of a differing (oldskool) opinion that the 10,000uF smoothing capacitor needs to be on the rectifier output, not the transistor output. You could move the 2200uF capacitor on the transistor output if you like...

I'm good w/that. It actuality, the caps serve two very different purposes. The one at the bridge, like you said, cleans up the input to Q1 and the LM323. No sense in having a messy voltage to start with. The ones on the output (and Bob doesn't have one on the +5V, darn it) of the regulators allows for transient currents to be drawn out of the cap first while the regulators try to catch back up (if they can). The regulators all have a time constant, meaning there is a finite amount of time that it takes the regulators to respond. Plus under large transient load, the output cap really does all the heavy duty current work, taking the burden off the regulator. One of my designs at work uses a 0.3F (yes, F! not uF) for that very same purpose. The power supply can't supply enough current. My circuitry turns ons, draws a serious boatload of current...but mostly out of the monster cap. My circuitry turns off...and the power supply slowly charges the cap back up - ready for the next time. It would be impractical to design a big power supply if you didn't have a big cap. Plus the power supply leads are, of course, an inductor with a some wire resistance...providing a double whammy w/respect to why it is impractical and would limit performance if a big cap wasn't there. I know, too much info , but Bob's power supply is the same thing, just on a much smaller scale.

Determining the size of the caps: The limiting factor in Bob's case would be the amount in-rush current is required to charge the caps (which can be a lot), and if it stressed any components in doing so. Don't have an answer for that. Larger caps mean larger in-rush currents. The bridge is probably the weakest link. But I'm on board with you about 2000uF on the regulator output. After all, it is just to test pinball boards. LOL

#105 10 months ago

My original idea was to build an exact copy of this power supply and leave this one alone. But I'm beginning to realize that's not possible. The Q1 transistor is unknown and Quench just indicated if I change the transformer I'll need to change the zener and resistor. So I decided to reuse the transistor and transformer from the old unit. Once we get the new one working I can go back and mess with the old unit.

This is my first PC board layout. I'm already working on the second version because this is a bit big. One of the problem areas is the two 1000uF caps. I found a 2000uF cap at Mouser but the deal breaker is 8.00 shipping for a 2.00 part. GPE has 2200uF in stock. Will one of those work?

Thanks

Bob

pcb layout 06 (resized).jpg
#106 10 months ago
Quoted from oldschoolbob:

...Mouser but the deal breaker is 8.00 shipping for a 2.00 part. GPE has 2200uF in stock. Will one of those work?
Thanks
Bob[quoted image]

Arrow has free shipping: https://www.arrow.com/en/terms-and-conditions/free-overnight-shipping

They are a very large electronic supplier, just like Mouser. Major corporations use them. I bought some transistors a week or so ago...yep - free shipping for a couple of dollars worth of parts.

Regarding the cap, FYI: standard derating practice is double the actual working voltage. 17V out of you bridge rectifier, buy a cap rated for ~30V or more.

#107 10 months ago
Quoted from Quench:

...15V zener diode is too high. It should probably be a 13V zener and the support resistor adjusted accordingly...

Ditto on the zener. A 1N4743 would be a better choice - 13V.

#108 10 months ago

Mark, thanks for the lead on Arrow. I've never ordered from there before. They have 2000 uF caps. I just ordered a bunch of caps from them.

By changing the two 1000 uF caps for a single 2000 uF I was able to reduce the size of my PC board to 4 x 6. Much better now.

Bob

pcb layout 08 (resized).jpg
#109 10 months ago
Quoted from mbwalker:

Arrow has free shipping: https://www.arrow.com/en/terms-and-conditions/free-overnight-shipping
They are a very large electronic supplier, just like Mouser. Major corporations use them. I bought some transistors a week or so ago...yep - free shipping for a couple of dollars worth of parts.

Hey!
Gotta realize that many of the existing suppliers started out as small suppliers.
Jameco started out small company servicing hobbyists (many corps don't consider Jameco as a viable distributor but I won't go into that).
Mouser was started by a teacher who wanted to obtain electronic components for his students.
Digikey also started out as a very small company. As their name suggests - they started by selling parts to ham radio operators. If I remember right, they first started by selling digital keyers (keyboard to ham radio codes) using small ads in ham radio magazines.
Even Arrow started out as a small store but has become corporate distributor which has eaten other distributors (e.g. Pioneer and others).
These companies have been around for 50 to almost 90 years.

GPE has only been around for over 17 years with $M's in sales and has sold to many major corporations including Japan Airlines, Intel Corp, Cisco and several others. Unlike one of the companies listed above, we don't buy parts from Chinese sellers (such as UTSource & others) or through ebay or aliexpress. We are pickey about our parts sources in an effort to keep quality at a good level. We do represent a handful of companies (some of which are not yet on website) and have more companies coming (will be adding in another major manufacturer this month). So why has GPE not become a larger company? Answer = purely motivation. I feel that we're in a big enough market size where I'm kept busy (too busy) and have no motivation to grow larger at this time.

But that overnight shipping that Arrow is offering - now that is pretty dang good.

#110 10 months ago
Quoted from G-P-E:

Hey!
Gotta realize that many of the existing suppliers started out as small suppliers....

Apologies, wasn't thinking about that when I posted. Honestly, I didn't even see the GPE comment - I focused on 'Mouser' and I immediately thought of Arrow since I recently placed an order.

I had to a buy some transistors and ran into the same problem...$1 part, $7 shipping. Ughh..again. And I needed it right away. I usually build up and order so shipping is minimized.

Sorry!

#111 10 months ago

Why 2000uF on input of series pass transistor and 15000uF cap on output of series pass transistor?
Just put the 15000uF cap on output of bridge and forgo the 2000uF caps.

Any idea as to what the 12V load current is intended to be? What is the transistor type. An NPN darlington can allow smaller base biasing which alleviates part of the power dissipation across R1.
With the way it is currently shown, that series pass transistor has to dissipate heat from that load current in addition to whatever load is for the LM323K. Normally you run these in parallel as shown in post 76. But don't place caps as shown in post 76. One 10000uF to 15000uF cap on input, period. Smaller caps at loads. Never hang a large electrolytic on the output of an LM323K without installing a reverse biased diode across the regulator to prevent capacitor from discharging into LM323K when power is switched off.

#112 10 months ago
Quoted from G-P-E:

... Never hang a large electrolytic on the output of an LM323K without installing a reverse biased diode across the regulator to prevent capacitor from discharging into LM323K when power is switched off.

I looked for that specifically when Bob mentioned the LM323 since it was missing. Surprisingly, the data sheet never said it was needed. I was aware of the reason, and even tried to find other LM323 data sheets to see if it was mentioned - but to no avail. A fair amount of the linear regulators require that, but from my surfing around, I can't say I've seen that mentioned for the LM323. It is a valid concern tho, and I've seen a fair amount of other regulators call out a diode is required. Apparently the LM323 is immune from that issue.

Here's the data sheet: http://www.ti.com/lit/ds/symlink/lm323-n.pdf

#113 10 months ago

The main reason I buy from Ed is I know I’m getting top quality parts at a reasonable price. When I’m forced to buy from other suppliers I’m always concerned about the quality of what I’m getting. Also Ed’s shipping has always been reasonable. And the parts are nicely packed and well marked.

Ed, the reason for the rather odd location of the capacitors is I’m trying to replicate my old power supply. It started 40 years ago as a 12 power supply to run auto radios without a battery. Six months ago I added the 5 volt section copied from a Bally solenoid driver board. It’s worked very well for testing MPU’s. The original transistor (Q1) is unknown – no markings.

I hate to change the design but now I’m thinking maybe I should change. The problem is I must get my order into GPE tomorrow before he closes for the year.

I got a real problem now.

Bob

#114 10 months ago

Maybe my problem isn't too big. Everyone (and I do mean EVERYONE) has told me to remove the 2000uF and to move the 15,000 to it's place. Would that change make any difference to any of the other components?

Maybe I shouldn't be so bullheaded especially when I don't know what I'm doing.

Here is the latest board layout. Please, everyone, look this over - I'm ordering parts tomorrow.

Thanks

Bob

pcb layout 09 (resized).jpg
#115 10 months ago
Quoted from oldschoolbob:

I’m trying to replicate my old power supply. It started 40 years ago as a 12 power supply... Six months ago I added the 5 volt section copied from a Bally solenoid driver board. It’s worked very well for testing MPU’s.

I'm not so sure it's worked that well, this whole power-supply upgrade started because your "regulated" 13V line was reading 10 volts when you were hooking it up to the Meteor MPU board early in this thread

What's parts are in you order list?

#116 10 months ago
Quoted from Quench:

I'm not so sure it's worked that well

I chuckled when I read that. You're right - a month ago I was happy with my power supply. But look at what I've learned and all I will learn if I ever get it built. Besides that, it'll give me something to do.

Here's my parts list from GPE. Plus I got parts from Amazon (case and stuff), Jameco (PC boards, rectifiers, etc.), Arrow (more capacitors), and meters from Ebay. The first few items are for other projects or parts drawer.

It'll be a fun project.

Thanks

Bob

parts 1 (resized).PNGparts 2 (resized).PNG
#117 10 months ago

Mark,

I added the 2K resistor to the layout. Is this where it should be installed?

What size (watts) should it be?

Thanks

Bob

pcb layout 11 (resized).jpg
#118 10 months ago
Quoted from oldschoolbob:

I added the 2K resistor to the layout. Is this where it should be installed?

What size (watts) should it be?

The 2k resistor connects between common (ground) and the emitter of Q1, basically across the 12V output.

BTW, check the connections on your Q1 transistor above. The line going up from ZD1 should go to the base, not the emitter. And the base shouldn't be connected to the collector.

To work out power rating for the resistor, you need to know how much current is going through it and what voltage will be across it.
You know voltage will be about 12 volts.
Ohms law says:

voltage = current * resistance

To work out current, transposing the formula current is voltage divided by resistance: 12V / 2000Ω = 0.006 amps
Now that you know voltage and current, power dissipation is calculated as:

power = current * voltage

So: 0.006A * 12V = 0.072 watts.
That 2k resistor will consume 72mw. For margin, use a resistor with double the wattage rating so it doesn't run hot. In this case just get a 1/4 or 1/2 W resistor.

Now if you use these calculations you will see that 100ohm 10w resistor you have is way over rated... There is only 3-5 volts across that resistor. BTW I think that resistor value is too high and isn't drawing enough current through the zener.

Skip the 13V 1/2W zener, 1/2W seems too low. Get a 13V 5W zener instead.

#119 10 months ago
Quoted from Quench:

Ohms law says:
voltage = current * resistance
To work out current, transposing the formula current is voltage divided by resistance: 12V / 2000Ω = 0.006 amps
Now that you know voltage and current, power dissipation is calculated as:
power = current * voltage
So: 0.006A * 12V = 0.072 watts.
That 2k resistor will consume 72mw. For margin, use a resistor with double the wattage rating so it doesn't run hot.

As Quench eluded too, a 1/4w (standard size) is fine, which is the reason I picked 2K. A higher wattage is also fine.

#120 10 months ago
Quoted from Quench:

The 2k resistor connects between common and the emitter of Q1, basically across the 12V output.

I think that's what I have - the black lines crossing (just left of F1) are all the same continuity.

Quoted from Quench:

BTW, check the connections on your Q1 transistor above. The line going up from ZD1 should go to the base, not the emitter. And the base shouldn't be connected to the collector.

Wow, did I screw up there. I think C2 is also suppose to connect to "B". And R1 connects between "B" and the + of the rectifier. I gotta re-do that whole area - what was I thinking?

Quoted from Quench:

Skip the 13V 1/2W zener, 1/2W sees too low. Get a 13V 5W zener instead.

Out of 4 pages of zeners GPE don't list a 13V 5W. Only 1 watt and 1/2 watt. Those zeners are pretty cheap. Can you recommend a list of them that I "might" need for this project? I'd hate to have this project stall because of some zener I don't have.

I just added some 2K 1/2 watt resistors to the list.

Thanks guys

Bob

#121 10 months ago

Thanks again for finding that mess up on the Q1. That would have been a disaster.

Here's the latest layout.

Any ideas on the zeners?

Thanks

Bob

pcb layout 12a (resized).jpg
#122 10 months ago
pcb layout 14a (resized).jpg
#123 10 months ago
Quoted from oldschoolbob:

Out of 4 pages of zeners GPE don't list a 13V 5W.

13V zeners are a bit of an uncommon voltage to use so they aren't so common. 1N5350B is a 13V 5W zener.
Without knowing what the transistor is it's a bit hard to know what power rating on the zener you need.

#124 10 months ago

Do you think we could find a new transistor that fits this situation without changing too much of everything?

#125 10 months ago

GPE doesn't have that number - but Arrow has 1N5350BG and 1N5350BRLG. I ordered 2 of each.

#126 10 months ago
Quoted from mbwalker:

...Also, the 10W 100 resistor near Q1? That only needs to be about 0.5W ish. Just using really rough calculations tho.

Oldschool: Quick update since I don't want to steer you wrong. Quench mentioned to me the beta of Q1 might be quite low, so my 0.5W comment would be low. I was thinking the Q1 beta was well over 100, which he pointed out that likely isn't the case being an old transistor. I don't think you changed it anyways.

#127 10 months ago

Update - all the parts are ordered (5 vendors) and shipped. Hopefully things will be rolling in this week.

In the meantime I'm back on the Meteor. I removed the bottom right flipper coil to replace the diodes. Once on the bench I noticed the coil sleeve was stuck. Usually a sign that the coil got hot. I checked it with an ohm meter but it checked OK. Is it possible that the coil gets hot, the windings expand and cause a short that resets the game. Then the coil cools and the windings contract and the short goes away?

I found a matching coil in my parts box and replaced it. It works now but I only played a couple of games. We'll see if that fixes it.

Thanks

Bob

#128 10 months ago

I been playing the Meteor everyday for the past 2 days and so far so good - time will tell.

All power supply parts are here except GPE. Looks like USPS shipped it 100 miles past my house today. Maybe tomorrow.

One of the parts that arrived is the new transformer. Seems that someone suggested I reuse the old transformer but I can't find the post. I'd rather use the new one than mess with removing the old one. The old one is 12.6 volts - 3 amps. The new one is 12 volts - 4 amps. I measured both today. The old one measures 13.1 volts and the new one is 12.1 volts. Would it hurt anything to just use the new transformer?

Thanks

Bob

#129 10 months ago

At 12.1V on the new transformer, the transistor (and 5V regulator depending where you wire it) will dissipate a little less heat.

Question about your old transistor, what voltage did/do you measure across the emitter and base pins? Curious whether it was a darlington or not.

#130 10 months ago
Quoted from Quench:

At 12.1V on the new transformer, the transistor (and 5V regulator depending where you wire it) will dissipate a little less heat

That's a good thing right?

0.602 volts between B & E.

Bob

#131 10 months ago
Quoted from oldschoolbob:

That's a good thing right?

Yep.

Quoted from oldschoolbob:

0.602 volts between B & E.

Ok, if that's what you read with some sort of load on the 12V rail then it's not a darlington transistor (a darlington would have had twice that voltage). Don't suppose that transistor has markings on the *side* of the can cover?

#132 10 months ago

The only load is the 5 volt section. Nothing connected to the outputs.

I cleaned it with a brush. I even looked on the edges of the case. No markings. I looked over it's cousin with the same blue paint and no marking on that either. Who would make a part and not have any markings.

#133 10 months ago

I'm not a big fan of headers and connectors but looking at the layout of my power supply, installing or replacing the transistor and regulator is not going to be easy. They'll be hardwired to the PC board. I could add headers to the PC board and use connectors wired to the transistor and regulator. But this adds a point of failure.

If you were building this would you use headers and connectors?

Thanks

Bob

box 02 low voltage (resized).png16513 (resized).jpg
#134 10 months ago
Quoted from oldschoolbob:

If you were building this would you use headers and connectors?
Thanks
Bob[quoted image][quoted image]

No... not good for this application with a steady state load.
I would wire direct. If you need connector-ized -- look more into something like a Keystone Electronics 7691 or 8191.
I use these all the time, you can't beat this type of connection.

8191 (resized).jpg
#135 10 months ago

Thanks Ed, I've never seen those before. If you use them all the time - I'm sold. They should work for the other PC board connectors also. I just ordered two dozen. The only down side is they take up a lot of space but I should be OK.

Thanks

Bob

#136 10 months ago
Quoted from oldschoolbob:

I'm not a big fan of headers and connectors but looking at the layout of my power supply, installing or replacing the transistor and regulator is not going to be easy. They'll be hardwired to the PC board. I could add headers to the PC board and use connectors wired to the transistor and regulator. But this adds a point of failure.
If you were building this would you use headers and connectors?
Thanks
Bob[quoted image][quoted image]

Bob,

You might want to beef up the traces on your board that supplies the high currents, they are a tad on the thin side for a few amps of current. Ditto on the grounds too. How are you going to make the PC board?

ExpressPCB has free software to layout a board and order. You can layout a board, order (very inexpensive), and within no time professional looking boards show up in the mail. Software has a pretty easy leaning curve too. https://www.expresspcb.com/

Capture (resized).PNG
#137 10 months ago

Yes, ^ What he said. On a power supply - bigger is always better.
But in addition to that, always put the high current traces on the *bottom* side of the board.
And watch out for vias when transferring a trace from one side to the other, high current signals should have multiple, paralleled vias.

#138 10 months ago

I thought about having the board made but I only need one. (if I get it right the first time). But I bought three boards just in case.

I plan to make the traces as large as possible. Not only makes it heavy duty but also less copper to etch off. I made a couple of PC boards but that was years ago. I’m sure I’ll have questions as I go. I was going to layout the components, drill the holes, then mark out the traces with a magic marker and sharpie. Then dip it in etchant. I got some powdered stuff that makes a pint of ferric chloride.

This is only a single sided board. Trying to keep it simple so no vias. Maybe my next project will be more complicated.

I still don’t have parts from GPE. GPE is only 400 miles to the west so I usually get my stuff in a couple of days. This time USPS shipped my stuff 150 miles to the east – then sit on it for a day. Then it went to St. Louis (30 miles to the west again). I understand my order is now at the local post office. If they don’t lose it in the next 5 miles I should get them Monday.

In the meantime I been working on the case. The bottom of the case has a bunch of nubs to mount stuff. But my transformers don’t fit the nubs. So I made a plastic mounting plate for the transformers and will attach it to the nubs. The back panel is done. I had to modify the heatsinks to get space for the line fuse and line cord. I started laying out the PC board but I really would like to have the actual parts in hand.

Also I been playing the Meteor. So far it hasn’t reset but I’ve seen that before. I’m not much of a pinball player and I’d rather be working on my projects.

Bob

IMG_2933 (resized).JPGIMG_2939 (resized).JPGIMG_2937 (resized).JPG
#139 10 months ago

Today I remembered I have one of these transistor testers.

amazon.com link »

Is there anyway to test a TO-3 transistor with this? Maybe we can find out what the unknown transistor is.

Thanks

Bob

#140 10 months ago
Quoted from oldschoolbob:

...I made a couple of PC boards but that was years ago. I’m sure I’ll have questions as I go. I was going to layout the components, drill the holes, then mark out the traces with a magic marker and sharpie. Then dip it in etchant. I got some powdered stuff that makes a pint of ferric chloride...

One thing you can do with a simple layout is grab a exacto knife w/a decent blade, using a straight blade score the copper deep enough to cut the copper on the edge of where you would etch but not go into the material much. Then take the exacto knife and peel up an edge of the cut copper. Next, just peel up the copper you don't want. Instant board. Did many a RF boards like that in my younger years. Only catch is (besides only being appropriate for simple boards) if the board substrate (the stuff between the copper) is a softer material, it can be tough to peel the copper. But I would suspect you are using what they call 'FR4' or 'G10' which is basically fiberglass.

I've etched plenty of boards too. Not a thing wrong with etching. Might be getting hard to do as a home project given the chemicals and the EPA nowadays. Years ago a person could buy tape and etechant at Radio Shack to put on the board that would prevent etching in those areas. Worked pretty good, as I recall.

#141 10 months ago
Quoted from oldschoolbob:

Today I remembered I have one of these transistor testers.
Is there anyway to test a TO-3 transistor with this? Maybe we can find out what the unknown transistor is.

It can tell you some of the transistor specs. Below readings from a bog standard 36 year old 2N3055 transistor. The transistor image below shows it's a standard bipolar NPN. The hFE is its current gain.

IMG_0017b.jpg
IMG_0018a.jpg

#142 10 months ago

This might help identify what we got. Does it make a difference which way the B and E are connected? I'm guessing the white clip is connected to the E.

Also can it be in circuit?

Thanks

Bob

#143 10 months ago

Mark, the last board I made (for the 5 volt section) I just used a dremel tool to sand away the copper. Crude but it worked.

IMG_2916 (resized).JPG

Here’s a photo of my PC board so far. The big squares are the connector blocks that Ed suggested. They take up a lot of space but should make removing the board easier. I had enough room on the right side to add in the 24 volt rectifier for the zero crossing. The minimum size of the traces should be about 3/16 inch.

IMG_2959b (resized).jpg
#144 10 months ago
Quoted from oldschoolbob:

Does it make a difference which way the B and E are connected?

Makes no difference - the tester will even tell you which pins are base, collector and emitter. See the transistor symbol and the last line identifying the pins on my display.

Quoted from oldschoolbob:

Also can it be in circuit?

Probably not. The tester needs to determine what device you've hooked up and with capacitors and stuff in that circuit, it won't be able to tell what is it.

#145 10 months ago

I gotta take it out sooner or later - may as well do it now and get over with. I'll take it out tomorrow and report my findings.

I have a hunch that its cousin (with the same blue paint from my parts box) will be a match. I'll test it tomorrow too.

Thanks

Bob

#146 10 months ago
Quoted from Quench:

It can tell you some of the transistor specs. Below readings from a bog standard 36 year old 2N3055 transistor. The transistor image below shows it's a standard bipolar NPN. The hFE is its current gain.
[quoted image]
[quoted image]

That's rather slick. An looking on ebay, it looks like there's newer versions (color) for only about $20, I think I'll snag one. Rather slick, darn Chinese makes stuff so cheap - hard to believe at times.

What does it indicate for a bad transistor? Just garbage numbers or does it give more insight (i.e. "EB shorted, "EC open")?

#147 10 months ago
Quoted from oldschoolbob:

Mark, the last board I made (for the 5 volt section) I just used a dremel tool to sand away the copper. Crude but it worked.
[quoted image]...

The electrons don't care what it looks like!

Been working for 30+ years, so you did something right!

#148 10 months ago

First I hooked up the mystery transistor from the old parts box. Don't seem to be much info here. I have no idea what this is.
IMG_2962 (resized).JPG
IMG_2963 (resized).JPG
Then I removed the transistor from the power supply. Definitely not the same part. I looked this up and it seems to be bipolar NPN. Other than that I'm clueless.
IMG_2967 (resized).JPG
IMG_2969 (resized).JPG
Is this a part that is available today?

Hope someone can shed some light on this.

Thanks

Bob

#149 10 months ago
Quoted from oldschoolbob:

First I hooked up the mystery transistor from the old parts box. Don't seem to be much info here. I have no idea what this is.
[quoted image]
[quoted image]
Then I removed the transistor from the power supply. Definitely not the same part. I looked this up and it seems to be bipolar NPN. Other than that I'm clueless.
[quoted image]
[quoted image]
Is this a part that is available today?
Hope someone can shed some light on this.
Thanks
Bob

No clue, but the beta (hfe) sure is awfully low.

#150 10 months ago
Quoted from mbwalker:

What does it indicate for a bad transistor?

If there's shorts, it won't detect it as a transistor rather eg. as a diode and low resistance resistor.
I use this tester mostly for checking capacitor ESR, sometimes SCRs, sometimes the current gain of transistors.

Quoted from oldschoolbob:

First I hooked up the mystery transistor from the old parts box. Don't seem to be much info here. I have no idea what this is.

It could possibly be (or similar to) one of those TO-3 rectifier packages found on the Bally Kiss/Future Spa/Space Invaders rectifier board. See the diagram below (RP1 and RP2):

Quoted from oldschoolbob:

I looked this up and it seems to be bipolar NPN.

Quoted from mbwalker:

No clue, but the beta (hfe) sure is awfully low.

It's got an anti-parallel diode built in across the collector-emitter.
Yeah you really want something that has a higher current gain.
The tester doesn't tell you the maximum current or voltage that transistor's rated at so without those basic details and from a choice of hundreds of transistors it could be anything.
But the low current gain is telling us it's not a good choice in this circuit.

RectifierBoard_RectifierPackage.jpg

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