Re: Bush AC34, no sound.
 

If it has two transformers it's an AC only model and won't have a live chassis.

Re: Bush AC34, no sound.
 

Hi Graham,

Got a few pics, hope they are useful

Bill
Attachment 60634

Attachment 60635

Attachment 60636

Attachment 60637

Attachment 60638

Re: Bush AC34, no sound.
 

That's an AC only model, so won't have a live chassis. The wiring looks to be in very good condition to me, assuming that the bits of red tape are labels that is.

I can see a waxy mounted on the screen between the RF coils and on the underside chassis is a can capacitor which if not polarised (ie not an electrolytic) will have a paper dielectric.

Take some voltage readings when you feel confident to do so.

Re: Bush AC34, no sound.
 

I suggest before you get going you do a few continuity checks with it unplagged from the mains:
1. The primary of the output transformer. (it should measure about 300-500 ohms)
2. The secondary of the mains transformer. If it is the same as the AC34 then looking at 'radio knobs 026.jpg', connect one end of your DMM to chassis, then the resistance should increase as you measure bottom left, bottom right, top right, top left. Middle left and middle right should show no continuity.

If these come out OK then it's time to check voltages. With the radio on and -ve lead of your DMM on the chassis measure the voltages on the output valve, UL41 grid (6), cathode (7), screen (5) and anode (2).

This is going to be hard work without a circuit diagram. We are probably going to need you to clean up the components on the tag strip and take a picture showing the connections as best as you can.

Re: Bush AC34, no sound.
 

Hi all,
The link below gives the model I am working on,as mentioned it was sold in Ireland as BS35
Bill





http://www.mike.izycky.dsl.pipex.com/ebs35.html

Re: Bush AC34, no sound.
 

Not quite...
EBS35 AC only using E series valves
EU35 AC/DC using U series valves
BS35 AC only using U series valves

Re: Bush AC34, no sound.
 

Hi pjl,
Following your line on the photo I got the following readings ,1.6, 3.4, 40.2, 115 and no readings on the middle 2 lugs. All the valves in this set are U series.
Bill

Re: Bush AC34, no sound.
 

Oops, I should have asked you to pull out one of the valves first! Apart from the values it looks OK though. What about the output transformer primary? It should go to the anode of the UL41 and one of the electrolytics in the can.

Re: Bush AC34, no sound.
 

Not sure if I am doing this right, measuring from one of the lugs at the base of the UL41 to the lugs at the base of the can the max I get is 85
Bill

Re: Bush AC34, no sound.
 

Looks to me as though the electrolytics (and maybe some of the tubular caps?) may have already been changed?

What does the team think, difficult to tell, but the earthing of the "can" neg tag looks redone to me, from original?

Not sure if this helps the OP, but may be worth knowing (if I'm right! ;D)

Good luck with the set.

Colin

Re: Bush AC34, no sound.
 

Yes Colin ,
The can is new and some wax capacitors have also been replaced along with 3 valves.
Bill

Re: Bush AC34, no sound.
 

Bill.

I think the output transformer is mounted on the speaker and therefore easy to get at. Measure the resistance of the winding on the primary side, which is the side that isn't connected to the speaker.

Re: Bush AC34, no sound.
 

The anode is pin 2 and has a blue wire connected.

Re: Bush AC34, no sound.
 

The underside of this set looks very similar to the Bush AC34.

I've attached the circuit for the output stage. PS1 looks like a potential (no pun intended) source of trouble. It's also a useful test point for the O/P transformer.

Re: Bush AC34, no sound.
 

Hi lads,
Between the anode on RL41 and cap I get a reading of 1.8
on the small transformer mounted on the speaker I get a reading of 85 with a bit of crackle from the speaker

Re: Bush AC34, no sound.
 

OK. For the moment I'll assume that the circuit is similar to the AC34 and that your readings are in ohms.

85 ohms seems low for an output transformer primary. The transformer in a Bush AC34 is quoted as 500 ohms.

If you were measuring from the anode to one of the smoothing caps the reading should be at least 85 ohms, as the output transformer primary should be between the two points. Please could you confirm which side of which cap you're measuring to. It should be one of the two caps in the largest can.

It might be an idea to reverse engineer the output stage and draw up the circuit. If it doesn't match the A34 at least we'll have something to work from.

By the way. What model meter are you using? We've been mislead before by someone using a continuity tester rather than a DMM.

Re: Bush AC34, no sound.
 

In post 34 Graham shows a small clip of the circuit (or a very similar one).
I would suggest you find C37 (or whatever it would be called on the correct circuit) and for now snip it out unless it has been swapped. Try measuring resistance across it.
If you really have got 1.2 (ohms?) here, between anode of the UL41 and the reservoir capacitor this C37 could be shorted.
As many of the capacitors have been replaced by someone else, you could have a man-made fault and need to check this part of the circuit for mistakes... there could be a short somewhere due to an error. The measurements you have made don't seem to add up to what they should.
If you unplug the speaker transformer and dial lamps, there should be open circuit reading from UL41 anode to reservoir capacitor (red terminal which goes to UY41 cathode).
When you plug it back in this should change to the primary resistance of the transformer... should be about 500 ohms but seems to be reading 85 on your meter. What sort is that meter?

Pete

Re: Bush AC34, no sound.
 

Hi Graham,
the large cap in the middle of the chassis has 3 terminals, 2 plus and 1 minus(which is earthed to the chassis). the reading is between the anode and one of the plus terminals.
I am not sure what model meter i am using....it was bought for me in B&Q and has different scales on the face...dc volts, ac volts, ohms, continuity.If you could recommend another meter I could possibly get one so we are on the same wavelength
thanks
bill

Re: Bush AC34, no sound.
 

Bill.

I'm wondering if you're measuring on the right pin. Looking at your pictures, there appears to be a red lead on pin 5 (Screen Grid) of the UL41 connecting it to one of the caps (C35) in the can which would be correct. Pin 2 (Anode) appears to be connected to a wire which I assume goes to the output transformer via PS1 if PS1 is fitted.

The other cap in the can (C36) is connected to the rectifier pin 7 (Cathode) which is correct.

I can't really comment on your meter as it's not familiar to me, but if you could get 85 ohms on pin 2 at least things would be consistent.

Re: Bush AC34, no sound.
 

Bill. Regarding your meter. Try measuring some of the resistors in your set and see if you get the correct readings.