Author Topic: 200-A Low & distorted output  (Read 3919 times)

Offline Abraham

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200-A Low & distorted output
« on: September 07, 2011, 10:28:00 AM »
I just got my quite not "new" toy just to find out it doesn't work... so there's an amp which hardly outputs some signal at max volume, sounding heavily distorted.

The volume knob doesn't work as it was supposed, it doesn't affect volume, you turn it on and the led glows but you can't hear any sound until 3 o'clock, once you got there there's no volume increase... just on-off

My knowledge on electronics are very basic, even if the circuit board doesn't seem complicate for someone with proper skills... At first newbie sight nothing seems to have been replaced... I only noticed green ground cable close to transformer was disconnected. Also, one of these grey somewhat long horizontal things (we have 3 of them on the right, pictures to be uploaded later) seems to have dropped out some silicon-like waste, I don't know how relevant this might be...

Any help appreciated, I would like fixing it myself better than taking this to a tech, as this is part of the fun (and cheaper!)

Thank you!
1976 Rhodes MKI '73 Suitcase
1976 Wurlitzer 200-A EP
1981 Casio VL-Tone (Yeah!)
199x Kawai CX-21D Upright
20xx Clavia Nord Electro 2

Offline adcurtin

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Re: 200-A Low & distorted output
« Reply #1 on: September 07, 2011, 11:11:28 AM »
Pictures would really help. Are you sure you have a 200A and not a 200? I think the 200 is the board with the 3 capacitors horizontally like that. If one leaked or cracked or anything, then it will need to be replaced, and is possibly the cause of the problems.

Post a picture asap, as it will help a ton.

Are you any good at soldering? Have you soldered before? How about desoldering?

Offline Abraham

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Re: 200-A Low & distorted output
« Reply #2 on: September 07, 2011, 11:56:58 AM »


Here you can see what Im talking about. Yes Im pretty sure its a 200-A and I guess those big can-shaped things behind are capacitors, but the component Im saying is the one on the picture reading "33 +- 10%", grey with the red line

Yeah Im skilled with soldering, I just dont have the knowledge to identify components or understanding how they work. On the other hand I dont have the proper tools for de-soldering but I think I wont mess it up

Thanks for your help!
« Last Edit: September 07, 2011, 12:00:27 PM by Abraham »
1976 Rhodes MKI '73 Suitcase
1976 Wurlitzer 200-A EP
1981 Casio VL-Tone (Yeah!)
199x Kawai CX-21D Upright
20xx Clavia Nord Electro 2

Offline Electric Nostalgia

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Re: 200-A Low & distorted output
« Reply #3 on: September 07, 2011, 01:34:52 PM »
I am having a similar problem with a wurlitzer I am working on. I'd check the output transistors to see if they're ok. (the big plastic things with three legs screwed in on the heatsink) They blow fairly often. Get your voltmeter and check to make sure TR11 is putting out around 22v on the base (B) and 22.5v on the Emitter (E) on TR13 make sure you're getting -22.5v on the Emitter.  Also do a resistance check on the transistors too and make sure none of them are shorted.

Like I said, I'm in a similar situation, so if I find anything else that might help I'll let you know

Offline Electric Nostalgia

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Re: 200-A Low & distorted output
« Reply #4 on: September 07, 2011, 01:54:30 PM »

Offline Abraham

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Re: 200-A Low & distorted output
« Reply #5 on: September 07, 2011, 02:58:11 PM »
SOLVED!! It was as easy as reading the service manual  ;)

Just located two fuses on the main preamp then added a jumper and now its working... now I would replace them with similar new ones... a non working one proves they're are there for a reason... I just don't want to find out why...

thank you thank you thank you!! now I have my working 200-A which I bought cheap because of a non working amp :)

btw the volume pot is broken and Im ordering a new one... if any of you could recommend where to buy, Im about to check ep-service or vintage vibe...

Thanks everybody for reading!!

thank you electric nostalgia... Im guessing your problem might be another, because fuses would be so obvious for someone knowing the matter as you seem to do, but anyway I wanted to share this just in case, as it might help others as well
1976 Rhodes MKI '73 Suitcase
1976 Wurlitzer 200-A EP
1981 Casio VL-Tone (Yeah!)
199x Kawai CX-21D Upright
20xx Clavia Nord Electro 2

Offline Electric Nostalgia

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Re: 200-A Low & distorted output
« Reply #6 on: September 07, 2011, 03:36:48 PM »
Way to go!

Offline adcurtin

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Re: 200-A Low & distorted output
« Reply #7 on: September 07, 2011, 06:56:57 PM »
I would check your transistors. My 206A amp worked alright, then fried a fuse, I'm pretty sure one of my transistors was blown, it may have caused others to go. And yes, that is definitely a 200A. Those caps on my 206A were red.

For the volume knob, I'd say VV would be your best bet for an original one, or one that's an exact match. Otherwise just any old 10K pot with a switch on the back should work.

Those grey things are also capacitors, they're just not electrolytic, they're polyester film. They shouldn't leak stuff like that, that is probably hot glue (like what's on top of the screw right there). Those caps are .33µF 200V caps, and can be replaced with modern ones. Here's the ones I put in my amp: http://www.mouser.com/ProductDetail/Panasonic-Electronic-Components/ECQ-E2334KB/?qs=sGAEpiMZZMvOcEq4GH1AAnaCoOhkJpOzBr3OznZFAcs%3d

Offline Abraham

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Re: 200-A Low & distorted output
« Reply #8 on: September 07, 2011, 09:26:52 PM »
thanks for the info adcurtin, it seems that someone intentionally isolated the screw right close to that gray non-electrolytic capacitors using some silicon or glue alike... it was just the fuse, Im checking if any of those or compatible ones are still available, so I still got my board protected from shocking.

Right after the jumpers were placed the piano started working normally (apart from the knob, which is 14.00€ at www.ep-service.com) so by now Im done with electronics, that was the part I was less scared of, now Im fixing action and some other stuff, but Im opening a new thread for this

Thank you guys, I really enjoyed doing it myself (of course, with your valuable help) and it was a really good deal as It was bought cheap just because amp was "not working"!!!
1976 Rhodes MKI '73 Suitcase
1976 Wurlitzer 200-A EP
1981 Casio VL-Tone (Yeah!)
199x Kawai CX-21D Upright
20xx Clavia Nord Electro 2

Offline adcurtin

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Re: 200-A Low & distorted output
« Reply #9 on: September 08, 2011, 11:47:32 AM »
I don't know about the UK (or the EU, not sure what the currency symbol is), but radioshack in the US has more generic fuse holders and fuses (rated for 250v instead of 125v, but that's ok). My 206A had 2 amp fuses, I think the 200A uses 1.5 amp fuses though. Any inline fuse holder should work, just make sure it's 1.5amp and at least 125v (might be different in 240V models, look at the service manual).

Offline NoahScotia

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Re: 200-A Low & distorted output
« Reply #10 on: March 02, 2016, 07:06:50 AM »
Hi Everyone,

New to the forum, first post actually, and recently picked up a 200A that's been living in a barn for 25 years and had a "blown amp" for close to no money.  Thanks so much for this old thread - along with dirt and cobwebs, a blown fuse and one of the big silver capacitors being loose seems to be the bulk of distortion and crackling problem. Did the fuse jumper test, and boom, Wurlitzer came to life.  I've only got basic soldering and diagnostic skills, so I really appreciate this info while I move forward with fixing these issues! Hopefully a new fuse doesn't blow, but if it does, I'll look here...

Offline seanny_keys

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Re: 200-A Low & distorted output
« Reply #11 on: May 13, 2019, 10:01:55 AM »
Wanted to revive this thread for some clarification about the two fuses on the main PCB.

In the service manual it states you can replace the two fuses with some jumper wire as the "the fuse has been eliminated on later models".

I've got a blown fuse on an early 200a model (1974) & I am wondering if I am better off replacing the fuse or just using a jumper line. It sounds like the Original Poster of this thread had success just using jumpers, but I am a little paranoid and don't want to fry my piano.

I've provided a few screen shots of the manual to show what I am talking about.

Hope to gain to some knowledge from anyone's experience here.

Thanks
-Sean

Offline seanny_keys

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Re: 200-A Low & distorted output
« Reply #12 on: May 16, 2019, 09:25:23 AM »
Just following up to my own post.

I played it safe and replaced the fuses with great success. Found some replacements online that cost next to nothing.

My wurly is singing once again!