CEI Hot Slot Restoration Ques 1 Capacitor Selection

[tryingtolearn]

Starting off with the visual inspection I had two areas burnt up and 1 was missing all together . (Fortunately whoever was in here before wrote some values on the board - I hope they are accurate)

The small caps at C82 C83 and C89  are  what burned up, The larger electrolytic caps are no good (according to the meter)
C81,C84,C85, C73,C76

The ceramic caps on the rest of the board are marked .1M (Underlined)(Like in the last pic
I am Assuming thats 0.1uF +/-20% but there is no voltage rating -

Is it safe to at least double the rating of the larger electrolytic when selecting the replacement ceramics in this situation? 

Hope that makes sense.

[shortrackskater]

I'm not sure about doubling the rating; maybe someone else will chime in. I'd think slightly over the rating would be sufficient.
Have you checked the traces? I see some possible trace damage where that heat occurred.

[tryingtolearn]

Definite damage yes, just wanted to get the parts ordered - fixing the board will be happening while waiting on shipping lol.
Then have to determine what the cause was to burn all three ceramic caps out...

Turning out to be an interesting project - noticing issues with the game and reel EPROMs now as well - only half seated and 1 missing lead broken off.

Little bit of everything on this.

[shortrackskater]

I'd check out those voltage regulators too!

[tryingtolearn]

Looks like all 4 have been previously replaced , but yes did that, they all checked out good. 

Read in a different post if the Voltage is off on VR5 (The LM350) To check U52.
Going to trace that down in the a.m. and see what all it is connected to.

[Chris-socal]

Be sure to check the tantalum capacitors for ESR/short. They are the ceramic looking ones but they are polarized like an electrolytic. They can be replaced with electrolytic of same value. They are notorious for shorting or blowing their tops.

You might be able to find another.1M cap on the board and read its voltage rating, manufacturers tend to use the same components for ease of inventory management.

One thing you might consider is buying a electrolytic capacitor assortment from Amazon or Bob Roberts. You might spend $20–$40 but you will have most of the common caps. I have no issues with Bojack from Amazon or the caps Bob Roberts sells. Some people insist on paying for a name they recognize….but in many cases its those we are replacing. I check every new cap before installing and never get a bad one, nor have I had one fail. On the flip side I work on boards all the time that have 40 year old no-name caps that are perfectly fine. That doesn’t mean every no-name brand is good, Im just saying I use those with no problems.

Bobroberts.net has great shipping rates, but you need to email your order and mail them a check. Alice is fast to reply with a total and ships quickly.

Chris

[tryingtolearn]

Thanks - Great info.  Just kind of going through things systematically since I don't know any history on the unit or what was working and what wasn't.  Then seeing the things hacked together here and there decided its best to just go over the entire machine. 

Turning out to be way more than a quick job for a regular but oh well - learning more on slots...