Leon Borre Bally Extension to test memory chips
Extended Bally test method version 3.
For the newest version go to ; Version 4 on this page.
This is an extension of the repair method of Bally and Stern cpu boards, which is available on this site for already some time. The test eprom has been extended, but the initial test still works as described. To execute this additional test, all you have to do is press the button which is on top of the cpu board. The memory test will then start and give you two flashes on the control led. Check the initial test method for information on how to connect the board.
This test has been added on the downloadable version of my eprom since April 3, 2002. Downloads of this eprom before this date do NOT contain this test. If you are not sure, check the file you have downloaded. You can open it with Word(pad) in Windows, between all the special characters you will find this text: " memory test U7, u8 en U13" This text does not appear in the old version...
ATTENTION; the memory test hes been improved again since 29 july 2003!! Visualise the contens of the test eprom using WORD and you will find among some strange signs , a text giving the date 3 august 2003 and VERSION 3 . This is the latest version! The text looks like this..
0000B0 01 C1 00 2C 03 7E 58 A4 7E 58 00 FF FF FF FF FF .
0000C0 54 45 53 54 50 52 4F 47 52 41 4D 20 42 41 4C 4C TESTPROGRAM BALL
0000D0 59 20 53 54 45 52 4E 20 4F 75 74 70 75 74 73 20 Y STERN Outputs
0000E0 55 31 30 20 61 6E 64 20 55 31 31 20 6C 6F 77 20 U10 and U11 low
0000F0 61 6E 64 20 68 69 67 68 20 2B 20 66 75 6C 6C 20 and high full
000100 6D 65 6D 6F 72 79 20 74 65 73 74 FF 76 65 72 73 memory test vers
000110 69 6F 6E 20 33 20 61 75 67 75 73 74 20 32 30 30 ion 3 august 200
000120 33 20 43 72 65 61 74 65 64 20 62 79 20 4C 65 6F 3 Created by Leo
000130 6E 20 42 6F 72 72 E9 20 20 75 73 65 72 73 20 6D n Borre users m
000140 61 6E 75 61 6C 20 73 65 65 20 68 74 74 70 3A 2F anual see http:/
000150 2F 77 77 77 2E 66 6C 69 70 70 65 72 2D 70 69 6E /www.flipper-pin
000160 62 61 6C 6C 2D 66 61 6E 2E 62 65 20 20 6D 61 69 ball-fan.be mai
000170 6C 20 3D 20 6C 65 6F 6E 2E 62 31 40 70 69 2E 62 l = leon.b1@pi.be
000180 65 FF FF FF FF FF FF FF FF FF FF FF FF FF FF FF
There are some restrictions to this test, which I'll explain..
Although Bally and Stern cpu boards can be interchanged, there is a major difference: Stern boards type -200 have one memory chip extra at U13. To make both types of boards use the same test, I've had to use some tricks in programming the test chip..
If I hadn't done this, and you're testing a Stern board without U13 (or with a bad selection of this chip), it would be reported as ok, because a regular Bally board doesn't contain a U13 chip.....
So what you'll find is this...
When the test is started, the led will start to light in rythm, this is the regular test. Now push the little button. The control led will dim and after one second it'll light a first time. This means the test of U7 has succeeded. Again a second later the led will light again. The test has run on U8 and U13 and has succeeded. If the led lights a second time after 2 to 3 seconds, this means the test has succeeded but only for U8 !!
So on a Bally board both flashes have to be about 2 to 3 seconds away. On a Stern 200 board the second flash has to be one second after the first. If it comes 2 to 3 seconds later, then U8 is fine but U13 is not ! This way we can make a difference between cpu boards with and without U13. this was the only way to do it, as the only indication available is a led and timing. So when testing, if U7 or U8 is defective there'll be no or only 1 flash. If you have a Stern 200 boards and you find 2 flashes with 2 seconds between them, then U13 is not or bad selected. Remove U8, and the test will keep on running on the U8 U13 test. now it's easy to find out where the problem lies, by checking the selection and data signals.
Tests to do when a memory chip is bad
With a defect or bad selection of the memory chips, the test will keep on running on this one chip, by always selecting him again. This select is at the highest address of the chip, which results in all data and selection signals present and easy to measure. For U7 you have to find:
- pin 1 = 0 volt
- pin 2 to 11 = 2 to 3 volt
- pin 12 = selection signal, don't measure this with a normal voltmeter but use a probe or o-scope
- pin 13 = 2 to 3 volt
- pin 14, 15 and 16 = 3,5 volt
- pin 17 and 18 = 4,5 volt
- pin 19 = 3,5 volt
- pin 20 to 23 = 2 to 3 volt
- pin 24 = 5 volt
For U8 and U13 you should measure this:
- pin 1 to 4 = 2 to 2,5 volt
- pin 5 = 1,5 volt
- pin 6 = 4,5volt
- pin 7 = 2,5 volt
- pin 8 = 0 volt
- pin 9 to 16 = 2 to 2,5 volt
- pin 17 = 5 volt
- pin 18 = selectrion signal, difficult to measure with normal voltmeter, use probe or o-scope.
- pin 19 and 20 = 3,5 to 4 volt
- pin 21 = 2 volt
- pin 22 = 5 volt
When signals are missing or different, then you've found the problem. Follow this signal back to it's source using the schematics, until you find where it's blocked. If the signals themselves are ok then the memorychip is bad.
Good luck !
A restriction of this test is that you cannot use the adaptor socket. When you use this socket it's not possible to place U7 (check the repair manual for Bally Stern cpu boards). To check the memory use the regular game roms, they also check the memory chips. If you only get 2 flashes out of game roms, there's a reference to a problem with memory chips, unfortunately they don't say which one. So if you don't want to adapt your cpu board to use eproms, you cannot use my test eprom for the memory test (only) but still have some indication about memory chip problems in the game roms...
Version 4.
To be shure you have version 4 , read out the test chip on the eprom programmer . You will find the version number in the chip.
When the normal test is running , to start the memory test , push once on the pushbutton on top of the CPU board.
The Bally board has two memory chips U7 and U8. Stern has one more U13.
If both chips U7 and U8 are ok the LED on the CPU board will restart blinking afther a very short stop.
If U7 is bad the the blinking will not restart but the on board LED will stay "on" If U8 is bad the blinking will not restart but the on board LED will be " off". That way we know wich of the two memory chips is faulty. In case you have a Stern board on the bench, and the first memory test passes ok , switch U8 and U13 to test U13 now in the socket of U8.
When one of the memory chips tests "bad" and the blinking does not restart, in all cases the memory test keeps running and wil try to write and read the " bad" memory chip continously , this gives us the possibility to check all signals that arrivent on the pins of that memory chip.
The first chip tested is U7. As in most cases U8 is bad, a stop indicating that you have a "bad" U8 indicates also that U7 is ok as it was tested already before U8.
Tests to do when a memory chip is bad
With a defect or bad selection of the memory chip, the test will keep on running on this one chip, by always selecting him again. This select is at the highest address of the chip, which results in all data and selection signals present and easy to measure. When U7 is defective you have to find:
- pin 1 = 0 volt
- pin 2 to 11 = 2 to 3 volt
- pin 12 = selection signal, don't measure this with a normal voltmeter but use a probe or o-scope
- pin 13 = 2 to 3 volt
- pin 14, 15 and 16 = 3,5 volt
- pin 17 and 18 = 4,5 volt
- pin 19 = 3,5 volt
- pin 20 to 23 = 2 to 3 volt
- pin 24 = 5 volt
For U8 and U13 you should measure this:
- pin 1 to 4 = 2 to 2,5 volt
- pin 5 = 1,5 volt
- pin 6 = 4,5volt
- pin 7 = 2,5 volt
- pin 8 = 0 volt
- pin 9 to 16 = 2 to 2,5 volt
- pin 17 = 5 volt
- pin 18 = selectrion signal, difficult to measure with normal voltmeter, use probe or o-scope.
- pin 19 and 20 = 3,5 to 4 volt
- pin 21 = 2 volt
- pin 22 = 5 volt
When signals are missing or different, then you've found the problem. Follow this signal back to it's source using the schematics, until you find where it's blocked. If the signals themselves are ok then the memorychip is bad.
Good luck !
A restriction of this test is that you cannot use the adaptor socket. When you use this socket it's not possible to place U7 (check the repair manual for Bally Stern cpu boards). In that case to test the memorys, use the regular game roms , they also check the memory chips. If you only get 2 flashes out of game roms, there's a reference to a problem with memory chips, unfortunately they don't say which one. So if you don't want to adapt your cpu board to use eproms, you cannot use my test eprom for the memory test (only) but still have some indication about memory chip problems in the game roms...