Author Topic: Mechanical noise from F-1X transformer (delamination rattle). (Read 1030 times)

remo · « **on:** March 05, 2006, 05:49:05 PM »

Hi.. my F-1X's transformer has quite a loud electric humm to it.. the preamp sounds wonderful and there is no static, hum or noise on the main outputs but when is switch the unit on the actual hum coming from the transformer resonates through the case of the unit and it's really quite loud. At gigs and in rehearsal this is no issue but when I use the preamp in my studio it's quite annoying..

I am in Australia (50Hz 24VAC) and I have correctly switched the internal jumpers to suit 240VAC.

I'd like to know if any US F-1X owners have experienced this transformer hum coming from their units or are all other F-1X's dead (I mean DEAD) quiet and there is a problem with my transformer causing it to hum?

cheers, Guy

David Houck · « **Reply #1 on:** March 05, 2006, 08:13:11 PM »

Hi Guy, welcome to the board. My F-1X is quiet. Sounds like you have a problem. I'm not an electronics person, so hopefully someone with some knowledge will notice this thread and respond.

David Houck · « **Reply #2 on:** March 05, 2006, 08:18:28 PM »

A couple questions that might be helpful. How long have you had the preamp? Has it always made this hum? Is the preamp in a rack with other components? If it's sitting by itself with no cables attached to the jacks, does it still make the hum when you switch it on?

remo · « **Reply #3 on:** March 05, 2006, 10:47:03 PM »

I have had the preamp for 3 months now.. I purchased it used from a guy in the USA. He said the unit was quiet when he had it. The preamp is racked with a Mackie 1400 power amp.. The preamp hums in or out of the rack. It also hums whe it is sitting by itself with only the IEC power cord attached (and with the unit switched on of course).

I'm thinking I might need the new transformer board inside the unit.. I'm a photocopier technician by day so swapping this would be very easy for me.

So no-one else has a mechanical hummmm from their transformer... Mine's quite loud as it resonates through the casing of the preamp.. I LOVE the sound of this unit and would really like to get this fixed..

I'd like to hear from some non-110VAC F-1X users in the UK or in Australia if possible to see if this is a 110VAC 60Hz vs. 240VAC 50Hz issue...

kmh364 · « **Reply #4 on:** March 06, 2006, 06:06:06 AM »

Good on ya, mate!

Just my two cents:

You might wanna ck and make sure every nut/bolt is tight in the chassis, xfmr and case covers especially. You could also isolate the xfrmr from the chassis with bits of rubber. Just make sure the xfmr is electrically grounded to the chassis if you isolate it. You can run a pigtail (jumper) from the xfmr mounting bolts (at the flange to the nearest chassis bolt. Make sure the connection is free of powdercoat and is clean and tight (use a star lockwasher). If possible, tin the connections with solder. Keep the grounding jumper a short as possible as well. If none of that works, then I'd try replacing the xfmr next.

Cheers,

Kevin

remo · « **Reply #5 on:** March 07, 2006, 01:22:47 AM »

thanks Kevin, all your ideas are good and I have checked all nuts and screws are tight. The problem with isolating the xfmr with rubber is there is hardly any clearance above or below the unit. Above maybe 3mm and below it is hard up against the 4 threaded mounting lugs.. so rubber pads are out of thw question as I don't want to make any modifications to how the PCB mounts in the unit.

I'm guessing a straight up replacement xfmr PCB would be the best bet.. the part number is 170-049. Is there a possibility I could either return my faulty xfmr PCB to Alembic for a replacement? I will pay shipping both ways.

I have previously emailed Alembic about this but I recieved no reply.

Can anyone help out?

David Houck · « **Reply #6 on:** March 07, 2006, 06:55:25 AM »

Guy; the folks at Alembic get a lot of email on top of all the other things they have to do, like build instruments, so it does happen that some messages get overlooked. Try them again; or give them a call.

kmh364 · « **Reply #7 on:** March 07, 2006, 03:59:24 PM »

Guy:

No worries, Mate!

Looks like you're on the right track. Have a little patience and Mica and Co. will take care of you.

Cheers,

Kevin

BTW, I spent two months in Oz back in '03. I have a bunch of friends in the Melbourne area as well as the gold and sunshine coasts (i.e., Surfer's/Main Beach and Brisbane areas). My biker/bike shop owner Mate from Brisbane is coming over this summer for the Sturgis Rally and to buy bikes (H-D's and custom choppers). Another biker /truck repair shop owner Mate from Melbourne was supposed to join us, but he spent all his vacation/bike money on a '69 SS Chevy Camaro, LOL!

mica · « **Reply #8 on:** March 07, 2006, 06:17:59 PM »

You can order replacement parts from us, but let's first determine what is the source of the problem you are observing.

The laminations are varnished in the transformer, shouldn't really hear anything from the transformer itself.

Take the lid off (mind the high voltage!). Can you still hear the noise?

With the lid on, if you hold your hand on top of the lid, is the vibration noise reduced enough to be satisfactory? If that's the case, then you could put some rubber-like material between the transformer winding and the lid to damp the vibration like you hand does.

remo · « **Reply #9 on:** March 07, 2006, 09:12:23 PM »

Hi Mica, I have listened to the noise with the lid off the unit and the hum is %100 coming from the transformer. I can slightly reduce the noise by pressing firmly on the lid of the unit I will try some rubber-like material as you suggested tonight and let you know the result. btw what is the estimated cost of a new transformer pcb?

I realise there is no direct warranty on mine as it was purchased used but the unit it in fantastic physical condition and looks hardly used (no rack rash, the contacts in the input jacks look hardly marked, all pots are firm and turn as new etc..) Would Alembic consider replacing the transformer under an non user specific good faith warranty arrangement? I would be happy to pay shipping both ways (I will send you my noisy one for inspection).

Otherwise could you please let me know what cost I would be looking at for a new 170-049 transformer PCB assembly?

mica · « **Reply #10 on:** March 08, 2006, 04:15:20 PM »

We can take you at your word about the testing and the results you've found - we've not heard of a transformer having this problem before in one of our preamps.

I can send you the transformer for you to replace yourself under warranty. Click on my username and send an email to me with your mailing address.

If you prefer to have us service it, you can send the board to us and we can solder the transformer.

remo · « **Reply #11 on:** March 08, 2006, 04:39:03 PM »

thank you very much Mica, I have just emailed you.

bassdr · « **Reply #12 on:** March 08, 2006, 05:43:04 PM »

This is another example of why we LOVE the folks at Alembic and the incredible instruments they hand craft! Michael (Flame Koa Essence)

remo · « **Reply #13 on:** March 08, 2006, 08:05:25 PM »

yes.. top shelf service.. thanks again!!!

Bradley Young · « **Reply #14 on:** March 08, 2006, 10:21:51 PM »

Guy,

Hey I'm in Melbourne at the moment. Nice town.

Brad