faulty Wurlitzer EP

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faulty Wurlitzer EP

Postby what_noise? » Tue Sep 28, 2010 11:39 am

hi, picked up a Wurlitzer 206 student model, its in really good nick, i wired it up so it runs of mains power, it turns on but theres no output out of any headphone jacks or the speakers, it just hums when set on whatever output its set on. ive checked there are no cracks in the circuit board. what else should i check/ replace? im in Perth and dont know anyone local who has a clue about them, and ive spent all night searching for info on the net with little luck.

Ive rebuilt the amp with the deluxe rebuild kit from vintage vibe. But its still the same, a constant hum, only a lot louder now. I have no idea what it could be any more. Ive checked all the reads with a feeler gauge and non are touching, vacuumed them all and am pretty sure there's no short there. I also tried the amp in the second wurli, with no luck.

I did have a few problems during the build though, as i first thought the problem was with TR9 and 10, i replaced them first and tested the amp with the same result. I ended up soldering them in backwards as that was the wrong info I got given. I soldered them the right way round and added TR8 and TR1, This time the fuse just blew. I think this was due to me making a rookie mistake and not bolting the circuit board in and i think it shorted something on the screw mounts.

Not wanting to make any more stupid mistakes I got someone to help me build the board entirely. I replaced all the capacitors and transistors and am pretty certain there in right. would of wiring the output transistors wrong killed them? I didnt replace the 2 diodes that came with the kit as im not sure which ones they are meant to replace, not sure if they could be part of the problem?

Theres such a small amount of electronics in these things and was sure rebuilding the amp would of solved my problem. Any help would be much appreciated and without anyone local with any knowledge of these things, and not having enough cash atm to buy a new amp i need to try and sort this out myself (if I can sort this out ill be getting another kit to fix the second one). Is it possible the transformer is the problem? and where and how should i test sections of the amp, I wanted to plug something into the RCA to make sure it was receiving an input signal but am worried about the 150V killing whatever i plug in. how is that usually tested? The hum gets alot quieter when the reed bar is disconnected. Seems very weird to have 2 with the exact same problem.

If anyone knows anything about these or anyone that can fix them or especially part numbers for replacement transistors, that would be great, really stuck here
cheers
Oliver Horn
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Re: faulty Wurlitzer EP

Postby Chinagraf » Tue Sep 28, 2010 3:10 pm

I only have a Rhodes, but it sounds like it could be a pickup problem.
The manual here may help. You could also speak to Vintage Vibe in the US, they know a lot about old EP's.
Good luck.

http://www.hallofelectricpianos.co.uk/wurlymanual.html
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Re: faulty Wurlitzer EP

Postby Thirteen » Tue Sep 28, 2010 8:04 pm

Resolder all of the joints on the board, particularly large caps, the solder joints fail all the time. I would do this before looking for electronic faults. Other common issues are cracked resistors.
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Re: faulty Wurlitzer EP

Postby what_noise? » Tue Sep 28, 2010 8:23 pm

Chinagraf wrote:I only have a Rhodes, but it sounds like it could be a pickup problem.
The manual here may help. You could also speak to Vintage Vibe in the US, they know a lot about old EP's.
Good luck.

http://www.hallofelectricpianos.co.uk/wurlymanual.html



have a rhodes, unfortunately quite a bit easier to fix than this, wurlies have an active system but ive checked for any shorting.

Thirteen wrote:Resolder all of the joints on the board, particularly large caps, the solder joints fail all the time. I would do this before looking for electronic faults. Other common issues are cracked resistors.


cheers, ill give that a go,
is there any way of testing the amp is getting an input? Ive thought about plugging something into the rca but with the 150volts I dont really want to fry what i plug in
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Re: faulty Wurlitzer EP

Postby Thirteen » Tue Sep 28, 2010 11:25 pm

If all you get is hum, have you checked the power supply rails for ripple? Check the rectifier diodes to see if any have failed, and replace the filter caps.
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