Diagnose real-vintage Strong-Hammer arcade machine

[edugimeno]

Hi there!
My friend wants me to help him repair his old-real-vintage strong-hammer machine. Well it's only 90% real as the force applied doesn't lift the weight itself but it is measured and it moves a motor that lifts the weight

I am attaching several pictures of the machine.
It basically has 2 sides, left side has

• 2 x 220->12+24v transformers
• 2 relays (1 moves motor UP, other moves motor DOWN)
• IGF and breakers for safety

Right side is shown on pictures. It has 3 boards ( top-down)

• Logic board. Receives 24AC and recitifies it into DC. Contains a uC (M80C85) with RAM/EPROM/ other chips. Contains an external board which seems to be a music generator (Chip AY...) and some EPROMS for probably midi or song samples, etc. Provides output to speaker, receives signal from "blow detector" board...
• Power board: Provides output for all the decoration lights and powers the coils of the relays
• Blow detector board. Has a small NTC at the right side, right in front of a plastic tube that comes from the "anvil", thus letting some air be blown into the NTC when the hammer impacts onto the anvil. Left side is the only connector to the logic board, which has 6 pins but 1-2 are GND, 5-6 and +12V (fed into an 7805 inside the board) and 3-4 are a little unknown to me. They are 2 signal lines, that are fed to-from the PIC uC in this board, Other IC's in this board are a quad OpAmp LM3204, 2 transistors, and a TC548 which is a AD Converter.

Also it has an added remote receiver board that allows you to fake the effect when you push the remote button the thing goes up, to catch the attention of the bypassers or to simulate a higher force when a small child plays. The NO-COMM leads of this board are connected between the 24AC and he COIL of the MOTOR-UP-relay.

The machine starts, makes lots of noises and plays music, lights up all the side bulbs up and down, and encourages to play with silly messages. It had already been configured to work coinless, so the coin adapter is disabled
One day during transportation it stopped reading strikes, and this is when I got called...

If I push the remote fob, the thing does go up, so from the relay and above this works
But when I strike the hammer into the anvil it does nothing (no new sound, no lift). Also if I remove the plastic pipe and blow hard into it it doesn't do anything.

My main problem is not understanding what "protocol" goes between the blow and the logic board. If this is analog voltage meaning "force", I tried feeding variable voltages to both 3&4 leads and nothing happened. Also I measured voltage on these leads while blowing onto the NTC and it remained stable at 0.XX volts. Maybe it's a digital signal like RS232...I don't have an oscilloscope with me.

I measured the voltage across the NTC while it was powered and it had 7.8v and then as soon as I blew air onto it, even from 1,5ft away, it jumped to above 8.1V

Does anyone know these machines or these boards to figure out how this works? ANY, ANY hint would be greatly appreciated.

Thanks in advance!

[redwire]

Don't just apply power to random pins, that is a bad idea.
Sensor (bottom) board, I can see it uses a hot-wire mass airflow sensor 470R PTC. So a blow must push air out of the blue hose over it. PTC should be warm at rest with several volts across it to heat it, unless it needs a trigger signal to turn on.
Post clear pics of the Blow Board.

[stj]

R6 on the sensor board looks fucked - maybe corosion.
and you could meter the inputs/outputs on the opamp while messing with the sensor

[redwire]

I would pull the sensor board, it has a lot of corrosion and water residue somehow, the backside could be pretty ugly.
The NTC J0 should measure around 470 ohms. It does look a little beat up and cracked.
The power transistors might be to control current to it for heating it. It's a weird way to measure a whack, using airflow.
The board has a PIC microcontroller, 5V regulator, ADC and the quad op-amp. A lot of stuff.
The PIC socket and the ribbon cable connector is surely corroded too.

[edugimeno]

Sorry I missed all posts here, for some reason since tha last forum platform update I don't get emails for subscribed posts, maybe it's me..

Yes the blow sensor board has some corrosion, but looking closely I haven't been able to identify shorted pins, but it needs further investigation..

I did measure the PTC while unpowered and it does get around 470-500 and this resistance changes pretty quickly with temperature. I believe I had to warm it with my fingers to get it to something close to 470 and when I left it at room temp (it was a really cold day) it would quicky go UP. I never saw a resistance value under 470. Long time since I don't work with PTC but don't they provide the stated R at 20 or 25ºC? That's probably the temp I provided with my fingers.
It's a little cracked as the operators thought that pushing the PTC closed to the hose would increase the sensitivity, so that's why the leads are bent everywhere, but they're not in short and they are not cut for now

R6 was a 1Ohm resistor feeding the PTC that I measured and was fine.

Would anyone imagine the general-blocks of this circuit? Having a custom programmed PIC makes things a little complicated. I would say the PIC is alive as the LED pulses like at like 1Hz all the time and probably, just probably, would change the pulsing when a blow is detected, which never happens.

Checking the LM324 voltages while blowing? Yes but not knowing the schematic I wouldn't really know what to expect on each Op Amp? I gues some would be used as non inverting signal amplifiers and probably one should be used as differential amp to find the ramp (speed) of the voltage change, but that's it... and just a guess....

Should I focus on the blow detector board?

If you had to repair this machine which way would you go? I don't see any way to either find an schematic of this board or find a replacement board....

Thanks everyone here!!

[edugimeno]

I would pull the sensor board, it has a lot of corrosion and water residue somehow, the backside could be pretty ugly.
The NTC J0 should measure around 470 ohms. It does look a little beat up and cracked.
The power transistors might be to control current to it for heating it. It's a weird way to measure a whack, using airflow.
The board has a PIC microcontroller, 5V regulator, ADC and the quad op-amp. A lot of stuff.
The PIC socket and the ribbon cable connector is surely corroded too.

Yes, thanks. NTC does measure around that. See my other general reply
NTC has 7.7v across when powered on
7805 reg works fine, it gets 5v and PIC is sending a heartbeat pulse to LED
I measured ribbon point to point and there's continuty on all leads

[edugimeno]

Don't just apply power to random pins, that is a bad idea.
Sensor (bottom) board, I can see it uses a hot-wire mass airflow sensor 470R PTC. So a blow must push air out of the blue hose over it. PTC should be warm at rest with several volts across it to heat it, unless it needs a trigger signal to turn on.
Post clear pics of the Blow Board.

Yes, good point although I used a series resistor to apply voltage
I don't have access to the blow board now but I may get it some day next week, thanks for your help!

[edugimeno]

I forgot, I have the machine manual. It has some schematics (basic blocks, not inside boards) but someone screwed with the PDF contrast and its not too clear
Thanks

[stj]

can we get good pictures of both sides of the sensor board.

[edugimeno]

can we get good pictures of both sides of the sensor board.

Yes, I will try to get to the shop sometime this week, thanks for your interest!

[edugimeno]

Ok I got some pretty clear pictures from this board, which I brought home.
Some details in case it can't be seen:
Looking at full-side-component photo, from TOP to BOTTOM:

• NTC J0 is a PTC that's used to sense the blown air from an impact anvil driven thru a plastic hose "470R". The bracket above holds the hose in place
• Q1&Q2 seem to drive the current fed to the PTC. Probably a fixed current source
• R6 (large 1Ohm) seems a little overheated but multimeter checked and fine
• Left of the 3 caps, there used to be a component (probably labeled DR3, value inside "10K" (zenner?)) that has been replaced by a small transistor+Diode and bridged to R25 thru another resistor in shrink wrap. Not sure why they did this (but this board has worked fine for years with this mod)
• U1 is an LM324 (quad Op Amp)
• U4 is PIC16C54 (with a custom program that who knows what it does)
• U2 is TLC549 is "8-BIT ANALOG-TO-DIGITAL CONVERTERS WITH SERIAL CONTROL"
• U3 is not used, a 2K I2C EEPROM
• Then a LM7805 regulador, tested to get 12V and put out 5V

Socket at the bottom "CIN", like mentioned above, has 1&2 forGND, 5&6 for +12V, and 3&4 are 2 signal lines using an unknown protocol

It's a little hard to follow all the traces as it's dual side and large components, sockets, and dust dont allow much understanding.

At this point my main goal is determining whether this board is working fine or not. The manufacturer told me they have spares for this, so I need to make sure this one is bad

Thanks!

[stj]

the 7805 needs to be resoldered,
the hole board needs a clean, and i would replace the chipsockets.
maybe the caps too - given the age

[edugimeno]

Ok I tested the 5V output and it's fine everywhere at the board. I would like to know a good way to try the board and check if it actualy does its function, rather than going blind to redo stuff that may be good
If this helps, my friend said that this machine was stored in his warehouse, it worked fine tha last time they rented it out, and then one day they had to move it to a show thru a large and rocky road and when they put it up it didn't work anymore, so whatever happened could be due to vibration, or could be something it happened the very last minute of the last show...
Who knows...

[stj]

the solder joints on the 7805 are cracked.
probably because it's not bolted to the board like the other large packages, and it go moved a lot.

[edugimeno]

the solder joints on the 7805 are cracked.
probably because it's not bolted to the board like the other large packages, and it go moved a lot.

Thanks but that part is 100% tested, I have continuity from GND to socket GND, from IN to socket Vcc, and from OUT to all IC's that use 5V. Tested in continuity mode and in working state getting 5V
Im going to redo all the solder points as they have some corrosion, its hard to measure them with the multimeter, I need to push the MM leads hard to get them to test ok

[redwire]

Is R6 OK? Part of the feed to the PTC. Do you measure 470R across tne PTC? It should be making heat if the sensor is enabled - I guess that is when you put in a coin to start the game? I don't think the PTC is powered and hot all the time.

[VoicesFYC]

STRONG HAMMER is a Chinese Knockoff of the Andamiro KING OF HAMMER DX machine. i've had both

[edugimeno]

STRONG HAMMER is a Chinese Knockoff of the Andamiro KING OF HAMMER DX machine. i've had both

I just checked those abut they don't really seem much alike, neither the external appearance, nor the internal circuitry. I've seen all the boards and they don't relate at all

Thanks!