Phonoland

Hey guys
I have an old Antique Apparatus RB8 Bubbler and getting no sound coming through the speakers. You can very faintly hear the song if you put your ear close to the needle but that's it.
I changed out the needle itself and then hooked up a small external amp with a speaker to the terminal that the needle wire harness plugs into. Music come through just fine.
Could the amplifier all of a sudden gone bad, had been working great up until a week ago. The heat sink is hot to the touch but there are absolutely no lights or error reading for the amp itself.
Before I send the amp in for testing is there anything else I can check.
Below are some pics of my setup, any help would be greatly appreciated..or anyone know a good service tech in Phoenix AZ

Hi,
You have an "Antique Apparatus" RB-8, equipped with "Rowe components". Yes, these amps, as well as all amps fail--just like that !
If you have the skills, you can repair it yourself--if not, you can remove the Amp, and send it out for repair--I would strongly suggest it be sent to someone with experience in these-- I do offer re-building services for them, PM me if you wish to send it to me. Ron Rich

Ron
I took the amp out to get ready to ship and noticed one of the 5A glass fuses on the right driver board was blown. The other 3 fuses look good. I replaced the fuse and plugged everything back in and the fuse popped again.
My only concern is getting a new amp and when i plug it in it does the exact same thing.
If the output transistor has gone bad will that keep causing the fuse to blow and the amp to heat up like that?
I will happily spend money to repair/replace the amp if that's all that causing the no sound issue but understand it could be something else!!

Pics of the fuse that keeps blowing..








Looks like this output transistor corresponds with P1 on the driver board. Should I change just the one out or do you recommend changing all 4 to avoid this down the road?

Hi,
You probably have more than just that fuse, and output blown--can't say from here--very unlikely something outside the amp is a problem--
Ron Rich

Copy that Ron, will get this Amp packed up and sent your way.
Thanks very much!

It's never just one transistor.
Other components can cause transistor failure, and vice-versa.
Leaky caps, out-of-tolerence resistors...
Then also the driver transistors can also become defective..
Best to let proper troubleshooting procedures be handled by a pro.

Probably one of those electrolytics on the driver board. Almost guaranteed.

Hi djmaincheese,

When you get the repaired amplifier back from Ron, before you plug it back in you need to correct the wiring to the output package going by your pictures. The pink and violet wires ideally need to go to the same levels on the tag strips yours are are on E4 on the left channel & E7 on the right so the sound will be unbalanced I would connect to E6 left & E6 right.

Regards
Alan

Alan Hood
ami-man
UK

Hey Alan,
Funny--I get no photo of the out-put transformer package ??
Sure do agree with you on wire placement-as log as no "aux speakers" are attached to the jukebox.
Ron Rich

Hi Ron,

There are a couple of shots of it in the early part of the topic. The output package is one of the CD types but for the amplifier fitted it should been one of the 4-06336-06; we of course are both well aware of the issues with the AA builds for using different none standard parts.

Regards
Alan

Alan Hood
ami-man
UK