SCC7 & 8 Bench Testing

[paradisecs]

Thanks Ron. When I was checking it to take the picture I noticed the original soldered fuse fell apart in my hand. My guess is it was bad and rather than removing and replacing they just shoved the dual socket on there as a jumper. At least I can understand the rationalization behind doing so even if it is lazy and stupid.

What came out was a 1/8 slow blow. Shouldn't this be a fast blow? Looking at the schematics and the parts list from the LS-1 service manual it doesn't designate fast or slow on any of the three fuses on the SCC-7.

I changed F3101 from 15 to 7.5. F3103 parts lists says 1 1/2 amp but on the schematic is says 15 amp, is safe to say this should be a 1.5? Schematics on F3102 are in fractions 1/8 but F3103 is not so I'm not sure which way to read it.

Stephen

[robnyc]

Stephen,

F3101 spec'ed 15 should be no more than 5-slow, This supplies the latch and trip solenoids and through resistors some small lights.

F3102 is 1/8th Fast. This is the high voltage doubler ckt that supplies W-I and R-O.

F3103 is 1-1/2 Fast. Some transistors and coils in the stepper and the trip relay.

In electronics where fuses protect solid state devices as in the two lower instances, fast blow is recommended as these items have no tolerance for extended overloads and can short instantly potentially ruining a transformer winding.

RobNYC

[paradisecs]

Thanks. None of the three fuses had the correct value in them but I was surprised the manual didn't state slow or fast.

Stephen

[Ron Rich]

Stephen/Rob,
The 1/8 can be either a fast or slow blow-Seeburg used a GJV fuse there---Later models used a "regular" fuse, and they found that a fast would blow for "no reason", and changed it to a slow blow.
On the 15 amp--I think 5 is too low---7.5 is required as several things can happen, at once, drawing more then 5 amp. Ron Rich

[robnyc]

Ron, regarding the 15 vs 5 amp fuse. This is the LVAC and serves the same functions as it does on the older machine (which Seeburg didn't fuse) on those I measured worst case load with drum turning (V-VL-K) latch solenoid and credit unit writing and it didn't reach 5 amps.

There is less drain on the later machines.

Either way, that winding is robust.

"The 1/8 can be either a fast or slow blow-Seeburg used a GJV fuse there---Later models used a "regular" fuse, and they found that a fast would blow for "no reason", and changed it to a slow blow".

Given Seeburg's history re; fusing I'd still go with a fast. if that blows then consider higher.

Rob

[Ron Rich]

Rob,
Yes--the LVAC serves the same function on all E/M phono's, however when the changed from a subtract coil to a subtract solenoid,in the pricing units, and had a motor drive subtract in some units, a 5 amp FB would not hold. My personal preference is to split the 25VAC, and use a 1 amp FB fuse on the latch bar solenoid. The 7.5 should be a FB. Ron Rich

[paradisecs]

I've seen many posts where both of you talk of adding fuses that aren't on original schematics. Do you have a write up of those somewhere? Or can you add them to the sticky on fuses? I'd love to update mine where recommended, especially on the digital boxes.

Stephen

[Ron Rich]

Stephen,
IMHO, none are needed. Do you have a copy of my "Seeburg MicroLog Trouble Shooting guide ? If so, look at the DCC notes. Ron Rich

[paradisecs]

Yes, I have both guides and Tony's books. I've just noticed many times where extra fuses are suggested and I can't keep track of them.

Stephen

[Ron Rich]

Hi Stephen,
Didja ever READ the "stickies" above ?? --One titled "fusing" MAY interest you- but it's not for the MicroLog series phono's. Ron Rich

[paradisecs]

Yep, read them. I thought I'd read of more than that on various threads here and on the phonoland archives.

Stephen