Rockola 440 Update

Ron,

From the videos I've seen on the 440, the home position is between the large gap in the magazine. Mine stops at F1 or E1. The selections are also a few off consistently. I'm guessing there is an adjustment for this? Maybe on the read out arm?

Also regarding my sound issue with the right speakers working only, if I reverse the input cable from the cartridge to the amp the left side is still out. However if I select Mono on the amp, all speakers work.



Robert

Robert,
Isn't there a screw on the side of the read-out arm for adjustment ? If I recall right, it pulls/pushes against the arm to change the relationship of the wiper blades, to the arm position----
As for the amp--you have a dead channel---
Ron Rich

Page 17 of the service manual has the details how to make the adjustment to center the gripper arm over a record, but this won't help being off a few positions. Maybe the basket needs to be loosened and adjusted. Not sure if the basket is slotted as it slips on the shaft or if it can be rotated a couple of positions. Sorry, I had a 440 once and sold it.

Hey Robert

Well done finding the mechanical fault with the microswitch alignment.
From what you say now however, it sounds as if there are more alignment issues.
As Ron says there should be adjustment screws on the carriages either side of the pin bank.

The one to the outside of the pin bank is for read out. you should I think adjust this first. Then rather than making a selection via the system, flick the actual pin of the
record you wish to play then make sure that the correct record is selected. The magazine should then stop at the correct "Home" position too.

As for the amp. I think the fact that you verified that when switching to MONO, both speakers worked. This would normally indicate a PRE AMP fault in one channel.
In most cases the Stereo/Mono switch shorts the two channels together just after the preamp stages, check the schematic for amp to verify exactly.
I am not sure about the amp used in your machine. But the later amps are completely modular, and it would be possible to swap the pre-amp PCBS to verify if the fault moves.

When I rebuilt the amp in my machine, I noticed that the preset adjustment controls were in a bad way. These needed to be replaced along with all caps, then the amp needed correct re-alignment for BIAS and levels etc.

Replacing presets can be a bit worrying particularly those affecting BIAS conditions. It is good practise whenever you replace a preset to set the replacement at about half travel first.

I had a similar fault with mine relating to one of the presets on a pre-amp board.

Hope this helps.

Pete

Hey Guys,

I sorted the amp issue out. Since both output channels worked the problem as Pete pointed out was in the preamp. Which was good since I don't know where to get those Delco output transistors.

I replaced the two 2N3417 transistors in the left channel preamp but that didn't solve the problem. Since there appears to be another stage in the AVC circuit BEFORE the mono/stereo switch, I decided to replace the two 2N3417 transistors (Q3 and Q5) on the left channel in the second stage. I'm not sure if one or both were bad, but I figured replace them both as I already had the thing apart. ( If this didn't work my next step would have been to replace the 2N3405 transistors.) Plugged it in and both channels and all speakers are working.

Now all I have to do is get the magazine aligned and I'll be all set.


Thanks again guys!