(Topic ID: 292500)

System 3 - mpu LED is stuck on

By torpedo

5 months ago


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  • 12 posts
  • 3 Pinsiders participating
  • Latest reply 4 months ago by torpedo
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W65C02 W65C22 (resized).jpg
6522 (resized).jpg
P10428-153433(1) (resized).jpg
P10427-192713(1) (resized).jpg
mpu LED is stuck on  (resized).jpeg

#1 5 months ago

Hi all,
I'm trying to restart an 1812 but I have the MPU LED stuck on. Reading the various posts and suggestions I tried to make various changes but without success. The only doubt I have is the ROM, in reality I don't know if it is corrupt, I tried to download the rom from VPforum but it doesn't work.
Unlike what Clay says, the LED on my board will turn on the same even without GPROM and without battery, I have no other ideas, I need your help.

What have I done:
- potentiometer 500ohm (A2)
- replaced R5-R6 with 680k
- replaced C20-C21 initially with 1uf50v ceramic capacitors and subsequently with two 10uf35v tantalum capacitors (still soldered).
- replaced U11 - U5 - U4

I have 3 roms (I don't know if they work, I'd like to know the correct cecksum):
Original Rom - Rom A - Rom B (vpforum)
I've tried all 3 but the results are still the same except for U7 pin6:
- Original rom = 5v LOW-pulse quickly __________ pressing SW1 = 5v LOW-no pulse
- Rom B ____ = 5v HI-pulse quickly ____________ pressing SW1 = 5v HI-no pulse
- Rom A ____ = 0v LO-pulse slow (6,5sec.) ______ pressing SW1 = 0v LO-no pulse

What I see:
- 5v perfect

- U6 (pinball on) pin1=5v ______pin2=3.20v ___ pin3=5v
- U6 (pinball off) pin1=3.20v ___ pin2=3.20v
- U6 (without battery / GPROM) pin2=4.75v

- U16 pin1=5v(no pulse)____pin2=0v(pulse slow 6,5sec.)____pin3=5v(pulse slow 6,5sec.)
- U14 pin4=5v(no pulse)____pin5=5v(pulse slow 6,5sec.)____pin6=5v(pulse slow 6,5sec.)

- U1 pin40=5v (pulse slow 6,5sec. with 10uf35v tantalum capacitor - instead it pulses fast with 1uf50v ceramic capacitor)
- U1 pin39=2.5v LO-pulse
- U1 pin38=5v HI-no pulse
- U1 pin37=2.5v LO-pulse

- U13 pin9/11 =no activity (HI-no pulse)
- U18 pin11 =no activity (HI-no pulse)

- keeping pressed the reset key SW1 no change:
U1 pin40 lowers from 5v to 0v
U13 pin4 lowers from 5v to 0v
- releasing the reset button SW1:
U1 pin40 immediately returns to 5v
U13 pin4 immediately returns to 5v

- U11 pin/volt
1/0 9/0
2/4.95 10/4.95
3/5 11/5
4/0 12/0
5/5 13/5
6/0 14/0
7/0.7to3.2(continuously) 15/0.7to3.2(continuously)
8/0 16/5

next checks?
Cesare.

(forgive me for translation errors)

mpu LED is stuck on (resized).jpeg
#2 5 months ago

I noticed VIA U5 has been replaced by a non- CMOS type. The Gottlieb system 3 board runs at a 2MHz clockrate. The designation at the 6522 chip is a bit confusing and I am not sure but I think it could be a 1MHz part. If I read the datasheet correctly, the designation for a Rockwell 2MHz VIA is R6522AP where A stands for 2 MHz and P stands for Plastic housing.

#3 5 months ago

are you telling me it might be incompatible? U4 was also replaced. I add a larger photo.

P10427-192713(1) (resized).jpg
#4 5 months ago

this is the original

P10428-153433(1) (resized).jpg
#5 5 months ago

That one is a 2MHz part and CMOS technology. I would go for that one or the Rockwell 2MHz CMOS variant R65C22P2.

#6 5 months ago

I'll try to get it, thanks

2 weeks later
#7 5 months ago

I finally got both the G65SC22P2 and the R65C22P2 and tried them both.
The result, however, does not change. The led is always stuck on and the measurements are basically the same as I wrote in the first post.
The only difference is U7 pin6, before it was 5v (HI-pulse quickly) now ranges from 0V to 5v and when I press SW1 it sometimes goes to 0v and sometimes to 5v. (watch the video).

6522 (resized).jpg
#8 5 months ago

I see a couple problems with the photos of the parts.
First, as MarAlb stated, the board is running at 2MHz so a 2M or faster part is needed.
The R6522P is an NMOS version rated up to 1MHz and might or might not work in this circuit. Based on specifications, it will not work.
The R65C22P2 as shown in last photo is a 2MHz part (Rockwell changed their speed marking with this part to show speed as the last digit) BUT the parts you show are clearly counterfeits. Those can be anything but are probably not what you wanted.
The G65SC22P2 parts are properly marked California Micro Devices parts for a 2M part (CMD was bought out in 2009).
However, all the parts are shown packed on white foam. If they weren't dead before, there is a good chance that they are dead now. Throw that white foam away!

NEW 65C22s can be purchased today. W65C22N6TPG-14 made by Western Design Center. These are good all the way up to 14MHz.

Is U1, pin 40 really pulsing as mentioned in first post? If so, I would focus on verifying or getting proper ROMs because the CPU isn't clearing the watchdog timer. If you are trying to run this board with an U2 socket empty, then the watchdog timer is behaving properly and nothing will work.

#9 5 months ago

Damn! I don't know if they are original or fake.
Really foam damage the chip? I didn't know, now I've got rid of it all over the place, thanks.

As for pin 40 of U1 I made two short videos, the first was made with C20\C21 tantalum 10uf35v the second with C20\C21 ceramic 1uf50v (new of course).
With new G65SC22P2 installed, if they are not already dead.

I don't have the possibility to try the rom on another machine, the cecksum is 88FB and according to my information it's correct.
(I confirm that the tests described in the first post were made with U2 inserted even if there is not in the photo, in Clay's guides it says that without U2 the LED would not even light up so I tried and it lights up anyway) .

#10 5 months ago
Quoted from G-P-E:

Vedo un paio di problemi con le foto delle parti.
Innanzitutto, come ha affermato MarAlb, la scheda funziona a 2MHz, quindi è necessaria una parte da 2M o più veloce.
L'R6522P è una versione NMOS classificata fino a 1 MHz e potrebbe o non potrebbe funzionare in questo circuito. In base alle specifiche, non funzionerà.
L'R65C22P2 come mostrato nell'ultima foto è una parte da 2 MHz (Rockwell ha cambiato la loro marcatura della velocità con questa parte per mostrare la velocità come ultima cifra) MA le parti che mostri sono chiaramente contraffatte. Possono essere qualsiasi cosa ma probabilmente non sono ciò che volevi.
Le parti G65SC22P2 sono parti California Micro Devices contrassegnate correttamente per una parte 2M (CMD è stato acquistato nel 2009).
Tuttavia, tutte le parti sono mostrate imballate su schiuma bianca. Se non erano morti prima, ci sono buone probabilità che siano morti ora. Butta via quella schiuma bianca!
I NUOVI 65C22 possono essere acquistati oggi. W65C22N6TPG-14 prodotto dal Western Design Center. Questi sono buoni fino a 14 MHz.
U1, il pin 40 pulsa davvero come menzionato nel primo post? In tal caso, mi concentrerei sulla verifica o sull'ottenimento di ROM corrette perché la CPU non cancella il timer del watchdog. Se stai cercando di eseguire questa scheda con un socket U2 vuoto, il timer watchdog si sta comportando correttamente e non funzionerà nulla.

I'm buying a couple of W65C22N6TPG-14 and I wanted to take a new cpu, this is correct W65C02S6TPG-14?

#11 5 months ago
Quoted from G-P-E:

I see a couple problems with the photos of the parts.
First, as MarAlb stated, the board is running at 2MHz so a 2M or faster part is needed.
The R6522P is an NMOS version rated up to 1MHz and might or might not work in this circuit. Based on specifications, it will not work.
However, all the parts are shown packed on white foam. If they weren't dead before, there is a good chance that they are dead now. Throw that white foam away!
NEW 65C22s can be purchased today. W65C22N6TPG-14 made by Western Design Center. These are good all the way up to 14MHz.
Is U1, pin 40 really pulsing as mentioned in first post? If so, I would focus on verifying or getting proper ROMs because the CPU isn't clearing the watchdog timer. If you are trying to run this board with an U2 socket empty, then the watchdog timer is behaving properly and nothing will work.

I am buying a pair of W65C22N6TPG-14 and I also wanted to get a new cpu to keep as a spare, is this correct W65C02S6TPG-14?

W65C02 W65C22 (resized).jpg
1 week later
#12 4 months ago

I'm still, what do I do?
I can't understand why the led is always on.

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