Reddish 500 EQ

[JMan]

Agreed.

I can probably do a Zoom call sometime tomorrow, I just need to get the day's schedule sorted. Let's connect via PM.

 

[Forcemusicgroup]

https://www.jlmaudio.com/shop/dual-to-2xsingle-dip8-adaptor.html?display_tax_prices=1


Thoughts on this??

 

[JMan]

Cool item but won't really help here. For sockets, just a simple DIP-8 socket like this will be perfect.

 

[JMan]

Just an update for anyone who has been following. Forcemusicgroup and I spent some time on Zoom poking around on his PCB. We found two issues that explain what we've been seeing over these last few pages. The op amp was fried and passing V- to its output, which in turn popped C29. There is also something funky with the connection on J1 of the input transformer's pin 2. We're trying just connecting up a wire directly to see if that does it. Once these fixes are in place, hopefully we'll have a working unit!

 

[capacitorless]

That's awesome.

Is there a reason the OPA2134 would fail, or is this more likely to be a bad part to begin with? I'm thinking specifically of something like more than the opamp's supply voltage being on one of the inputs. I know this is really unlikely with a transformer in the way.

 

[JMan]

I would say there are two simple explanations for why a DIP-8 op amp like this would fail. One is it was just a faulty part to begin with. That can happen, though it would be a rarity, although if the part was purchased from eBay or the like, that's a whole different gamble (I'm not sure where this particular IC was purchased). The second reason might be that the pins saw too much heat from the soldering iron, whether that was when he was first populating the board or when he was touching up solder joints later. He's going to socket the replacement IC, so we will confidently avoid that hazard this time around.

The supply voltage was spot on, so it wasn't an over-voltage issue. Some internal component of the op amp failed and so the negative voltage rail was passing through to other pins where it shouldn't have been. That V- made its way to the positive side of C29, hence the popped cap.

Edit just because: I omitted a very obvious third possible reason, which is the IC being oriented incorrectly. That was not the case here, though.

 

[Forcemusicgroup]

Cool item but won't really help here. For sockets, just a simple DIP-8 socket like this will be perfect.

Old opamp has been removed ready for the new op and socket when it arrives in the mail. New cap put in. Jumper wire has been made with confirmed connection.

Was just a thought about afterwards a completed unit. "Hot Roddish" EQ

 

[JMan]

"Hot Roddish" EQ

Love it!

 

[JMan]

I heard from @Forcemusicgroup - after all that troubleshooting, we have a working unit!

 

[capacitorless]

That's awesome, congrats to both! Was there a final determination for the root cause?

 

[JMan]

It seems that the final piece of the puzzle was a couple of missed solder joints on J1 where it connects to the mounting board

 

[capacitorless]

This was a useful exercise to avoid problems with my own builds, so thank you to everyone involved. Among other things I learned is that I should socket my relays, and possibly/probably op amps, as a precaution and for easier maintenance. I don't mean just on these EQ boards, I mean in general

 

[MidnightArrakis]

[I should socket my relays] -- >> "SOCK IT" TO ME!!! <<.....



/

 

[Potato Cakes]

For the push button switches, I can only find the FLT (light touch) version. https://www.mouser.com/ProductDetail/CK/FLT2UEETB?qs=cygERTaPE9CiYZEuMsUViQ==

Could someone share a link to the push button switches that they used on their project?

Thanks!

Paul

 

[JMan]

This is what I have used in this project. A few photos in the thread show that others have found acceptable substitutes (perhaps even better, as I've seen at least one where the switches don't have the solder lugs opposite the PC pins).

 

[Potato Cakes]

I didn't check Digikey. I cannot just find just F2UEE switches on Mouser in stock. They are non-stocked with a 10 week lead time. Only some of the special variants are available. Thanks for the link.

Thanks!

Paul

 

[thelivingroom]

I didn't check Digikey. I cannot just find just F2UEE switches on Mouser in stock. They are non-stocked with a 10 week lead time. Only some of the special variants are available. Thanks for the link.

Thanks!

Paul

I just searched my email because I couldn’t remember where I bought mine, and found my Newark invoice from 8 months ago. I bought 30 of them for $.98 each, and now they’re $2.98 and out of stock with a 15 week lead time. Ugh.

 

[Potato Cakes]

I will make sure to get them from Digikey soon.

 

[inf0]

I just searched my email because I couldn’t remember where I bought mine, and found my Newark invoice from 8 months ago. I bought 30 of them for $.98 each, and now they’re $2.98 and out of stock with a 15 week lead time. Ugh.

I need to rethink mouser's convenience... I paid 10$ for each for the gold ones since it was all they had. DAMN

I'm gonna be building my 2nd one soon and they are out of the 2.2 mH as well