SHP-1 Driverboard cooking resistor R76

Hello All,

Recently my SPS2 Matador’s right speaker channel went out and started humming. I opened up the amp and noticed that the R76 resistor was blown in half. This amp is stock right out of the 70’s never been touched. It’s a wonder it lasted me a year without doing anything to it. I have replaced all the caps in the amp except for the big 3000uf paper caps on the back of the amp. I have also replaced R76/75 and R98/99 with new 100 ohm 1w resistors. Upon placing everything back together and turning it on R76 still smokes. I know I need to do the jumper mod, would that make R76 burn up or is it the big roll of quarters looking cap in the back that’s making this happen. I also read about moving C46 to where the traces start, that also has not been done, would it cause my problem? I am ordering Tony Millers book as I type but would like this fixed asap as I have a party cumming up in 5 days. Any info would be much appreciated.

Thank You

Due to the fact the untouched amp was ignored before this happened, I suspect that now transistors have fried.
Incomplete or ignored restorations often wind up costing more - down the road.

After repairing 1000's of them, it would be my guess that you have blown outputs, a bad bias transistor, both pre-drivers, and possibly the one previous to them--( on Tony's book--see above about known errors) Ron Rich

Ron Rich wrote:After repairing 1000's of them, it would be my guess that you have blown outputs, a bad bias transistor, both pre-drivers, and possibly the one previous to them--( on Tony's book--see above about known errors) Ron Rich

Ahh, Guru Ron, if that's the case, it's the same as consumer stereo receivers - A chain-reaction caused by a fault.
In the case of speaker coupling capacitors, once they get leaky or short, POW! - there goes the ouputs!

So what you’re saying is that I’m in for some fun? Is there anything I can check or look for while I’m waiting for my book to arrive? I also have the caps to replace the big 3000uf paper ones, should I do so? If so can someone tell me what the positive post is and what is the negative, could not figure it out on the schematics. If anyone could give me a list of common parts that fail, I can order in advance so I can install everything right when my book shows up.

Thanks Once Again

"Center connectors" are pos. on the caps--no such thing as "common failures"--
Ron Rich

Ron Rich wrote:"Center connectors" are pos. on the caps--no such thing as "common failures"--
Ron Rich

Aren't electrolytics marked?
Plus and Minus?

Matt,
No, not these--these are "cans"--One is pos. supply--other is neg. supply
Ron Rich

Ron Rich wrote:Matt,
No, not these--these are "cans"--One is pos. supply--other is neg. supply
Ron Rich

Any electrolytic I know of is obvious as to polarity.
Even with no markings.
The rubber/seal side is poz, duh.
I'll use my cap-checker to determine value, and the PS rails or schematic can help with that.
Ya gotta have the right "tools" and experience.

Bi-polar supplies are nothing to wonder about either.

I have not done thousands of SHP amp repairs like Mr. Rich or others on this forum. I have done some in the last year so I am learning as a hobby - not as a juke repair specialist. Learning and making my share of noob mistakes as I learn.

Ron Rich and Tony Miller have authored excellent Seeburg guide books however I am a visual learner. I like youtube. When I started learning about Seeburgs a year ago March, I searched youtube and found a few bad seeburg videos. I figured I could make better videos - and correct mistakes in my videos as viewers make me aware of them.

To help other novices, I make my novice videos as I work on these SHP1 and SHP3 amps - unscripted unedited and drinking a beer. My youtube videos are not from an EXPERT but I think you can learn a lot. Just search youtube for Seeburg SHP and you will find them.

You may want to watch a few as you wait for Tony Millers book in the mail...

Make a Dim Bulb Tester DBT and use it on any SHP amp PRIOR to plugging it back into the Seeburg. Also have a speaker load hooked up to the shp before powering it with the DBT. I made multiple videos as I test SHP amps I am working on. Here is a vid showing how I made my DBT: http://www.youtube.com/watch?v=L3gJwrJgYBY

The two 3000 TNT looking caps on top C66 and C67 need to be replaced with 3300uf. It is easier to get to them if you remove the driver board. Important: the positive on one cap and the negative on the other cap go to the same terminal. Do not get this wrong. More Important: the two1500uf Non Polar Caps need to be replaced with NON POLAR Caps but nobody sells new 1500uf NP Caps so you have to make them with 3300uf caps. Here is my video explaining how I did this: http://www.youtube.com/watch?v=MQ6PHm4IpdE

Obtained two SHP1 amps recently that did not have the 4 jumper wires on the driver board. These 4 wires are critical IMHO to install. Here is my video showing how I installed the jumpers. http://www.youtube.com/watch?v=DI-HzCwt84A

I made excel spreadsheets for the SHP and DCC which you might find helpful. I uploaded them to the FILES resource section of the Yahoo group called Seeburginformationclub. Join this yahoo group so you can access the files.

As always - Constructive comments posted on the individual youtube videos are welcomed - just make the comments on each youtube video itself so others can read it.

Thanks MarkHits, I will take a look at all your videos and excel list after I’m off of work. Anything at this point will be very helpful. I have all of the other books on my Seeburg just never bought the amp one until now. I am very confident that I can make the necessary repairs, as I have worked on arcade games before. Once my book comes in I will update this post with my findings and any questions I might have.

Alright,
I received my book, ordered parts, and installed the parts. The right channel is up and running, after replacing Q14-Q18. The new problem that I ‘m having is a lot of static in the right channel. I tried reseating the needle cartridge and checking for loose wires, but no luck. I have also adjusted the bias on the left channel, but the right channel won’t give a reading even after being on for an hour, Can anyone point me in the right direction?
Thanks Again

Faulty capacitors leaking DC can effect transistor bias, or even tubes.
Something caused the initial problem, and if not addressed, will take out any new parts soon, making the job a waste of time.

It has all new caps in it, any place I should look in particular?

Mehlonhead wrote:It has all new caps in it, any place I should look in particular?

Being an experienced tech, it's virtually impossible for me to diagnose a fault from miles away.
The bias issue could be lurking within dozens of parts, one being off value - who knows?
I'm not there in front of this thing with my test instruments able to check voltages, etc.
I'd find the problem in a few minutes if that were the case.
The internet just doesn't cut it for some things, sorry.

I can appreciate one attempting to repair their own stuff in order to save money, but, some things simply cannot be diagnosed over the internet... it creates endless threads of "is it this - is it that?"