Volume problem replaced transistor

armyaviation

Member
Joined
Nov 19, 2008
Messages
323
Reaction score
0
Location
Enterprise, Alabama
I know it's not a video game but I need repair info for my clown roll down redemption game. The volume is extremely low. When you turn the volume control pot the volume doesn't work unless you turn it all the way up and it is still low. Replaced the volume pot, checked wires, speaker is ok. I was told by baytek that it was an amplifier problem on the sound board. I took it to a repair shop and they told me it was a transistor, tip 122, that was bad and one of the leads was burnt. Replaced it and still not working correctly
 
I know it's not a video game but I need repair info for my clown roll down redemption game. The volume is extremely low. When you turn the volume control pot the volume doesn't work unless you turn it all the way up and it is still low. Replaced the volume pot, checked wires, speaker is ok. I was told by baytek that it was an amplifier problem on the sound board. I took it to a repair shop and they told me it was a transistor, tip 122, that was bad and one of the leads was burnt. Replaced it and still not working correctly

Pics of the board and the parts you changed out. I don't have a schematic for it but may be able to look at the pics to help you better. I also would like to see if there is an audio amp, it would have a metal tab or a large metal fin type thing attached to it.

Also did you put in the transistor in correctly?

This it the transistor you replaced and put it in the same way as the other, Right?

http://www.fairchildsemi.com/ds/TI/TIP120.pdf
 
Last edited:
yes thats the part. the board was burnt around it and i was told it tested bad. i was told by the manufacturer that it was an amp problem. is that piece an amp. i will get some pics tomorrow
 
yes thats the part. the board was burnt around it and i was told it tested bad. i was told by the manufacturer that it was an amp problem. is that piece an amp. i will get some pics tomorrow

It is very probable. Most transistors are either switching or amplifier. The next thing you need to look at is what else would have fried when that thing let the magic smoke out. Here is a basic circuit of the NPN common emitter amp and some of the probable parts the you need to look for and at.

http://hyperphysics.phy-astr.gsu.edu/hbase/Electronic/npnce.html#c2

EDIT:

You can look around there for common Collector and common Base circuits also.....
 
Last edited:
I seriously doubt that any modern (last 20-30 years) arcade game design used discrete transistors in the audio amp. Pretty much everything uses an ingrated amp IC. They're often SIPs. Look for something with 5 to 10 pins, and a heat sink. Reasonable chance it's labeled with something that starts with "TDA..."

If you had a burnt TIP122, it was probably used to control a solenoid, or lamp, or coin counter, or something. Decent photos will help a lot.
 
Yes that's the game. I will get pics, but there is a main board, a smaller one with sound ICs on top of the main and a small board on the side of the box with two of the transistors, one burnt, and some other things. Pics coming. Sorry
 
OK... looking at this pic:

attachment.php


I see a part that looks like the transistor you replace... but is on that small board mounted on the CPU board. What is the part # on it?

Also, what is the part # on the 8 pin chip on the other corner of that board.

Another thing to check... That transistor was a current pass transistor for one of the voltage levels. Is that IC chip right behind it OK? If it's not good then the transistor won't pass the proper voltage... if any.
 
The 8 pin chip ,4 on each side, is M9218 LM 380N-8


You see the two transistors how they are different styles. The bottom is new. If you looks at the bottom board under the red and white wires, you will see more of them. I just found one that, the black part, was crumbling apart
 

Attachments

  • image.jpg
    image.jpg
    97.8 KB · Views: 7
LM 380N-8

There's you audio amplifier: "LM380 2.5W Audio Power Amplifier (Rev. B)"

The other board, the one with the transistor you replaced, is a power supply board. Sounds like channelmanic's thinking the problem my still lie on it...

Thing is, most digital logic only needs 5V. However, audio is often a special case, and amplifiers often run on 12 (or 15 or 18) volts. So your power supply likely has at least two DC outputs: 5V (for most of the main board) and 12V (or a little higher) for the audio amp. If your audio amp voltage is way low... you won't get much for audio output.

Schematics would be nice. Have you searched around inside the thing for a manual or schematic or any documentation?
 
Which ic chip are you asking if its ok, the 8 pin on the sound board? If so I have no clue. Can those be purchased, do you think it's bad since the volume is low. Baytek informed me it was the audio amp, I guess because its a common problem. Is that the ic chip in question
 
There is another transistor on the main board labeled Q2 or O2 that looks bad. JP2 is the audio plug... I can't make out the tip number but above it is 99205. Other ones have 99205 and tip 122 after looking better. Should I replace that one as well
 

Attachments

  • image.jpg
    image.jpg
    94.2 KB · Views: 7
Back
Top Bottom