MP-1 no display or LED's

[Iperfungus]

Yes, it's trying to read from RAM and it gets garbage in and crashes.

I've seen these fail before that's why I wanted to see the signals because I was already pretty sure this was the problem.

I won the bet.  :lol:

[MarshallJMP]

 :thumb-up: 

[Iperfungus]

An issue with a cheap solution!

[andtimebegins]

Thank you so much MarshallJMP!!!

Is this the correct part to order?

The only number thats different is the "549". On the original part it says "741". Will that make a difference?

[andtimebegins]

Actually, found these for .39 cents.

Just want to be sure before I buy:

https://www.jameco.com/shop/ProductDisplay?catalogId=10001&langId=-1&storeId=10001&productId=45583   

[Iperfungus]

I think this one would be good as well:

https://www.mouser.it/ProductDetail/Texas-Instruments/CD74HC20E?qs=xFfolx0DHx3Po1GpIhjG1w%3D%3D

Or:

https://www.ebay.com/itm/CD74HC20E-SN74HC20N-DUAL-4-INPUT-NAND-GATE-74HC20-IC-1-pcs/133272187753?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D225086%26meid%3Dd0694875b7534d95a3b0034ee007b987%26pid%3D100623%26rk%3D1%26rkt%3D5%26sd%3D174142942335%26itm%3D133272187753%26pmt%3D0%26noa%3D1%26pg%3D2047675%26algv%3DDefaultOrganic%26brand%3DRCA&_trksid=p2047675.c100623.m-1

[andtimebegins]

I think this one would be good as well:

https://www.mouser.it/ProductDetail/Texas-Instruments/CD74HC20E?qs=xFfolx0DHx3Po1GpIhjG1w%3D%3D

Or:

https://www.ebay.com/itm/CD74HC20E-SN74HC20N-DUAL-4-INPUT-NAND-GATE-74HC20-IC-1-pcs/133272187753?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D225086%26meid%3Dd0694875b7534d95a3b0034ee007b987%26pid%3D100623%26rk%3D1%26rkt%3D5%26sd%3D174142942335%26itm%3D133272187753%26pmt%3D0%26noa%3D1%26pg%3D2047675%26algv%3DDefaultOrganic%26brand%3DRCA&_trksid=p2047675.c100623.m-1

Thanks dude!:I'm gonna get it ordered asap and will report back my results!

[Iperfungus]

Thanks dude!:I'm gonna get it ordered asap and will report back my results!

GO!!!!!  :thumb-up:
Revive that unit and make it scream again as it deserves.
An ADA MP1 has no equal.

[rnolan]

An ADA MP1 has no equal.No but it has a better (MP-2  >:D ) LoL...

[MarshallJMP]

I guess you made your order by now, so let us know the results.

[Iperfungus]

An ADA MP1 has no equal.No but it has a better (MP-2  >:D ) LoL...

Pfffff....WHO came first???  :lol: :lol: :lol:

:banana-upsidedown: :banana-upsidedown: :banana-upsidedown: :banana: :banana: :banana:

[rnolan]

(Pfffff....WHO came first???) Too true my friend and it was a really good prototype  :lol: .  That's a bit unfair though, the MP-1 totally changed my world, I've hardly used my '73 Marshall 50 since I bought my first MP-1 which I loved dearly and used for many years.  When MP-2 came I bought one as soon as I could, I love the extra features, they do sound quite different though.  One of my MP-1s seems to have similar issues to andtimebegins, hopefully my tech can read this post and it will help get it sorted.  My other MP-1 works but has midi issues changing programs  :facepalm: .  I must say when I first got them both and tried them out, albeit quite quickly, I had a good measure of nostalgia and wanted access to those tones again.

[Iperfungus]

(Pfffff....WHO came first???) Too true my friend and it was a really good prototype  :lol:

ADA did great stuff in the '80s and '90s.
Starting from the original MP1, through the Classic and MP2.
That's just a matter of taste.

I personally prefer the direct, raw tone of the original MP1...but you've to know it was the very first tube MIDI preamp I could afford (used from a friend) when I was 20.
I forgot those stuff for decades, and when I started back to collect rack stuff....the ADA MP1 has been like coming back home.
I know, I'm not very objective...  :lol: :lol: :lol:

I really want our friend andtimebegins to have his MP1 alive again.
About yours...you could suggest the same fix to your tech. Why not? Easy and not expensive. No risk.

[andtimebegins]

Well, bad news guys.... it didn't work.

I ordered 2 of the same chip. Both with the same results as before.

MarshallJMP would there be something else I could try? I appreciate your help so far, I feel like we are very close to getting this fixed.

[MarshallJMP]

Oh that's to bad, put in the new ic and do the measurement again, see if the results are the same on the scope.