T Rex Room-Mate [gutshots]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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Zokk
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Post by Zokk »

Hello
I've got one for repair (reverse polarity incident) so it's not functional, but I thought some gut shot may be interesting :wink:
The owner uses this outdoor with a small motorbike battery which is about 6A so the hit was tough, and the pcb has completely fried under a diode (M7 rated to 1A)...
I hope I can fix it :hmmm:

The regulator is a 7805 and the xformer is labeled "DT 16280-9 TRex 08/43", the tube is of course a chinese rebranded to TRex (pay attention to the glue on the socket) :wink:

So here it is:
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And the best for the end:
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If you want a special picture please let me know as it's still open on my desk, I think I won't like to re-open it later :wink:

0xPIT
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Post by 0xPIT »

Hi,

thanks for the gut shots!

Would it be possible for you to add some large detailed pictures of the raiser board (with the tube on), front and back?

Thanks

- pit

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Zokk
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Post by Zokk »

Hi

you're lucky: the pedal is dead but not yet buried :wink:
The transistor beside the xformer is a BC639... ICs are 7805CT, 78L09A and NE555.

Hope this helps.

Cheers.
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Zokk
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Post by Zokk »

Well edit button has gone away...

There's also an orange LED soldered just under the tube socket, it fits a 3mm hole inside the socket so it makes the tube a lot more "mojo-ish" 8)

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Post by 0xPIT »

thanks a lot!

iefes
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Post by iefes »

Hey! Just wanted to ask whether you managed to fix this pedal?
I'll get one defective pedal soon too and would like to ask if you have some suggestions, what I should check? The pre-owner told me he used it on a gig and from one moment to the other it didn't work anymore. He didn't drop it or anything. Any ideas what the reason could be?
And can sb tell me what kind of tube is working in the Room Mate?

Thx a lot! cheers

sinner
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Post by sinner »

I'm happy to trace this pedal if you'll fail to fix it. I will have to desolder most of the components to measure resistance/capacitance of passive components so the pedal won't be any good after that

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Post by Zokk »

Hi iefes
sorry the board on the one I had to repair was too damaged for me to manage to fix the problem. I admit this kind of digital FX with complicated multi-layer pcb is way beyond my poor skills in electronics.

Concerning the one you have to repair: first I'd suggest to check the regulator and the PSU part of the circuit... then post a topic with pics here to ask for help :wink:

The tube is a cheap chinese 12AX7.
Remember this pedal has a small transformer on the daughterboard, you should check it too.

@Sinner, yup mate I still have the pedal on my shelf and I won't spend more time trying to fix that... I'd be glad to send you what you need.

Just send me a PM and we will talk about that 8)

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Post by iefes »

Thx man! I will check these things first and let you guys know if I have any further questions. Tracing this one would be interesting I guess, but do you think it's an effect which can be built DIY? Arent there some "special" parts in there like DSP-Technology or something?

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Post by sinner »

No, I don't think it diy-able pedal as well, but some information can be gained like how valve is used, why PSU dies in that pedal like crazy - I'm more hoping to learn something on the way than build straight clone. Workalike can be done, there's few reverb projects out there where the core can be adopted. Little transplant job should take us close enough to be satisfied

@Zokk - I will PM you today, thanks

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Post by ppluis0 »

sinner wrote:...some information can be gained like how valve is used...
Hi Sinner,

There is another thread where another TRex pedal was traced: http://www.freestompboxes.org/viewtopic.php?f=1&t=22942

Also, analyzing that unit, I concluded that this manufacturer only put an 12AX7 inside their pedals merely for mojo. I think that the same can be suspected to actually happens in this unit.

But in the thread linked you can see how the PSU was implemented.

Cheers,
Josè

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