TSPP Machine Buzzes (Hum) In Attract Mode

[Shmuel]

So this is my first Stern game. I often like to have my games on when
I'm at home. It brightens up my little city apartment. My two
Williams games make no noise, but my Stern game makes buzzing noises
when the lights flicker on the playfield and when the DMD changes
during attract mode.

I checked to see if the boards were secured to the backbox and they
were. I also checked the ground wire and they seem to be fastened
securely.

I noticed something odd though, my power driver board is "SEGA" and
not Stern. The CPU board is Stern though.

Any help in making my machine less noisy will be greatly appreciated.

Brian.
TZ, TAF, MM, T2, FH, TSPP

[Rare Hero]

In my experience, an early run TSPP w/ the BMST2000 sound chip will
hum. A later run game with the emulated sound chip won't hum.
However, the emulated board makes a weird "beep" or "honk" sound
instead of a small bit of music that plays normally on the original
board. Personally, I'd rather have the hum than the weird beep. :)

Greg

[stangbat]

My TSPP hums like crazy. Same with my JP. My TSPP has the BSMT setup.


--
stangbat
This USENET post sent from http://rgparchive.com

[Pinboy]

It's nothing to worry about, but GREAT to obsess over ;)

[skippy church]

Do you have that Moe's Tavern lighted sign? That thing made
buzzing/humming noises like crazy, and I finally had it and took it out
for the original.


--
skippy church

[phishrace]

On Nov 15, 12:48 pm, Shmuel <bwaldma...@gmail.com> wrote:

If the buzz changes with the DMD, it's likely the DMD itself. Remove
the speaker panel and listen closely to narrow it down. Whitestar
sound may be crap, but it shouldn't buzz noticeably at typical home
volume (2 or 3), or change pitch with the DMD. If it is your DMD,
there's not much you can do other than replace it.

-phish

[Stack15]

Mine does the exact same thing. I have had it for over a year with no
problems. I just figured that was what it was supposed to do.

[Daniel Tonks]

Standard issue with older Sterns such as Monopoly and TSPP. The problem is
the amplifier is way overdriven and picks up all sorts of interference from
the light matrix, and the volume control is purely digital - so no matter
how low you adjust the volume, the amp is still cranking at 100% all the
time.

The solution, however, is simple. You need to modify two resistors (R110 &
R106) on the sound board that control how hard the amplifier is driven.
Instructions have been posted in the past how to do this - there was even a
Stern service bulletin released for Monopoly, which believe it or not was
WORSE than TSPP, but if you go that route I would suggest using much higher
values than they suggest.

On my machine I made up two clip-on POTs that bridge the existing resistors,
allowing me to fine-tune the volume to where I want (including how strong
bass is) without any permanent modification. The goal was for my normal
playing volume level to be around 15 on the digital scale, as going below 7
or so starts clipping the sound.

- Dan


"Shmuel" <bwald...@gmail.com> wrote in message
news:d0a532fb-24e0-4a91...@a5g2000vbb.googlegroups.com...

[Rossz]

Very interesting! Do you have any pictures / values for the POTs you
used Dan ?

[Mike Schudel]

"Rossz" <ross...@gmail.com> wrote in message...

> Very interesting! Do you have any pictures / values for the POTs you
> used Dan ?

This is a write-up I did almost 10 years ago for Monopoly. I assume this is
still valid for TSPP as well running on the Whitestar boardset.
http://thepaisleys.com/paisleypinball/monopoly/eliminate_backbox_hum_and_buzz.htm
Adding a pot with some clips sounds like a neat option too. A couple 5K
pots would probably work just fine.

--
Mike S.
Kalamazoo, MI
Gameroom: http://tinyurl.com/yxzavc
W C S Owner's List: http://tinyurl.com/8ua2n
Gameroom Video: http://tinyurl.com/y8vmz6k

[Daniel Tonks]

"Rossz" <ross...@gmail.com> wrote in message
news:1357e9da-12b1-4df9...@i6g2000vbe.googlegroups.com...

> Very interesting! Do you have any pictures / values for the POTs you
> used Dan ?

It's been about 7 years since I made them. I took a look and the code is
T20YP 103C237. Google doesn't turn anything up on that (odd), but a T20YP
103D06 seems to be 10K ohm.

I can post a picture later if anyone needs it, but it worked perfectly to
quiet the humming.

- Dan

[stangbat]

My TSPP has the "Monopoly" service bulletin fix: 10k at R106 and 33k at
110. I'm going to try the modifications and I'll report back.


--
stangbat

[Daniel Tonks]

"Daniel Tonks" <dtonks@sunstormADD-DOT-COM> wrote in message
news:4ec3cfc2$0$2612$892e...@auth.newsreader.octanews.com...

>
> It's been about 7 years since I made them. I took a look and the code is
> T20YP 103C237. Google doesn't turn anything up on that (odd), but a T20YP
> 103D06 seems to be 10K ohm.
>
> I can post a picture later if anyone needs it, but it worked perfectly to
> quiet the humming.

Pictures for anyone who is interested:
http://www.sunstorm.com/stuff/tsppbuzz1.jpg
http://www.sunstorm.com/stuff/tsppbuzz2.jpg

- Dan

[Rossz]

Great link and explanation Mike, thanks!

I'll do it on my TSPP as soon as possible.

[stangbat]

As I stated earlier, my game has a 10k at R106 and a 33k at R110.
Mike's Monopoly had 22k at each location. So I need to add different
values than what he detailed.

After reading through the other posts, what seemed to be settled upon
was paralleling a 4.7k ohm resistor at R106 and a 33k ohm at 110. This
gives you a final resistance of 3.2k ohm at R106 and 16.6k ohm at R110.
For reference, R106 controls the gain for the backbox speakers and R110
is the cabinet.

For R106, I did not have a 4.7k ohm resistor on hand, so I installed a
3.9k ohm resistor. This drastically dropped the hum from the backbox
and I can live with it.

For R110, I had a 33k ohm resistor so I installed it in parallel. I'm
still getting quite a bit of hum from the cabinet speaker. Much more
than the backbox. So I think I'm going to have to reduce the resistance
of R110 even more. I'm going to wire in a pot like Daniel did, play
with the resistance until it sounds right, then measure what I dialed in
and install the appropriate resistor.

[stangbat]

I ended up going with 6.9k ohm for R110 (22k ohm + 10k ohm in parallel).
The cabinet speaker volume is a little weaker than I'd like, but I had
to make a trade off for volume vs. hum.

There are a few options to try to help equalize the volume. I could
install an L-pad on the backbox speakers to tone them down a little. Or
I could look for a more efficient cabinet speaker. Or I could use a 4
ohm speaker for the cabinet (existing is 8 ohm). I doubt the amp will
have a problem with a 4 ohm speaker at the volume levels we are talking
about.

We'll see. It it much better than it was. The machine still hums, but
it is the transformer that is the biggest offender now.