Factory amplifier upgrade to 3700

[Zymurgy]

There is a factory upgrade that was generally done in two steps that was supposed to improve the overheating and stability of the amplifier.

My question is I was going to have the amplifier taken to a professional to have it improved. It is currently working but from what I have read the sound can be improved.

Should this work be done first and would be in addition to their work or is this essential the whole improvement?

The factory recommended improvements replaces a handful of resistors, couple of diodes, add a couple slow blow fuses, 4 capacitors and 5 transistors.

[Ron Rich]

Hi Mike,
As I understood it--it was a "Mandatory" factory up date, done at no charge ? I don't recall that it had any bearing on sound quality. If it were mine, I would do it NOW--for sure ! Ron Rich

[Zymurgy]

Now it all makes sense thanks Ron.

My local guys used to be Seeburg technicians. Am I to understand they would be well qualified to work on my Wurlitzer amp as anyone. They have a very good reputation, the two people I know personally both have Seeburgs however.

He told me he could rebuild it and work on any system of my Wurlitzer. I just want to make sure there isn't anything odd about it, which should make me look for a Wurlitzer tech.

[Ron Rich]

Mike,
I am not a "WurliTzer tech"-- All I know is what I was told by a very good WurliTzer factory tech., that I worked with after WurliTzer closed shop here. Ron Rich

[Zymurgy]

Well I guess I jumped the gun on planning to rebuild the amp.. I went through the phonograph section of adjustments this weekend and got everything into spec. The last thing I was going to do was change my needle. It wasn't coming out that easy, and it was getting late yesterday so I just left it until today.

Much to my surprise all the sound issues I was have was from a completely shot needle. It sounds great, nice punchy bass, the mids are bright and clean. During the beginning and end of a nice 45 it is crystal clear, no hum just completely quiet.

The only thing other than the needle that I changed was a new set of caps on the midrange speakers.

Couldn't be happier, all it really needed was some love and alot of cleaning.

[randyinnc]

I am a new jukebox owner and new to Jukebox Addicts.  I bought a Wurlitzer 3710 at an auction sale and I am in the process of cleaning and checking out the operation.  Surprisingly, it is in pretty decent shape, not knowing the history of the machine and what I was getting myself into.

One problem I am having is that there is a lot of static noise from the speakers prior to playing any records.  The static static sounds like the pop, crackle, and hiss on a dirty vinyl record.  The volume knob is missing and the "post" the volume knob was attached to is very touchy (large increase in sound with small movement of the post).  I haven't checked to see if my machine has the amplifier upgrade noted in this thread, but according to Rich, the upgrade doesn't affect sound quality.  I did my reading in the newbie folder, but couldn't locate any related information.  I am planning to buy a new volume control (any recommendations regarding parts would be appreciated) with the hope this may resolve the static problem.  Any thoughts?

Thanks everyone.

[Ron Rich]

Your phono probably never had a "knob" on the VC-- Have you tried "cleaning" the VC-- If the mute is working, and you get "static" when it's starting a record-- shut off that phono, and get it fixed --NOW-- Check our FAQ's for suppliers of parts -- Ron Rich

[randyinnc]

Thanks Mr. Rich. I'll try cleaning the volume control one night this week or this weekend. I haven't located a mute switch so I don't know if that is working or not. One point I was not clear on is that the static noise starts when I turn on the phono, not when initiating a record selection. Although the static does not go away when making a record selection either, it stays constant throughout. Any additional thoughts as to what the static could be?

Also, you are right about the VC knob. There is only a slot for a screwdriver. The existing small radiator hose screw clamp attached to the knob threw me off.

Thanks,

Randy

[randyinnc]

I have some new updates to my amplifier noise, but I still have the same problem.

Even though the thread above indicates the factory upgrade may not affect the sound quality, I decided to remove the amplifier to see if my cards had been upgraded. Once I removed the amplifier, I noticed that one of two 5A fuses was missing from the the AC input circuit that connects to three large capacitors. (This would be fuse F4 if you are looking at the 556 amplifier wiring diagram on card 139892. The other fuse, F3, was installed and intact). I figured the missing fuse was the solution to my problem. I installed a new 5A fuse and turned on the machine and, POOF, the new fuse F4, plus the existing fuse F3 blew out. No sound whatsoever. I then installed a new 5A fuse on F3, no fuse on F4, and now I have sound again, plus the original static noise is back even when not playing a record. Note, I can hear the record playing, but the quality is poor. I am at a loss of what to do next. Like I mentioned, these fuses are connected upstream to three large capacitors (2000, 3000, and 3000 Mfd). Could I have a bad capacitor? Also, I have determined that my cards have not been factory upgraded. Will the upgraded cards solve the problem?

It would be easier to post a picture of the circuit diagram to clarify what I have described, but I understand I cannot post a picture. Any help would be appreciated.

Thanks,

Randy

[Ron Rich]

Randy,
You need to have the amp repaired by a qualified person-- "messing with it" by installing new fuses, will only worsen (more $$) the condition ! I doubt that an upgrade at this point in time is all it needs ! Ron Rich