The Multi Amp aka Dynalo Mk2

[mypasswordis]

Added benefit is you can sous vide some eggs while you're listening

[ruslanch]

I assembled dynalo mini and that340 chips on my board is very hot. Is it normal? Thanks!

[Pars]

I assembled dynalo mini and that340 chips on my board is very hot. Is it normal? Thanks!

I don't think so. Double check all components, check for solder bridges, etc. And this is both THAT340 chips are getting hot? How hot?


Sent from my iPhone using Tapatalk

[ruslanch]

40 minutes ago, Pars said:

I don't think so. Double check all components, check for solder bridges, etc. And this is both THAT340 chips are getting hot? How hot?


Sent from my iPhone using Tapatalk

Thanks! 65-70°C on that340, both. But works fine. Now I checked all the components of the strapping - it's all right. But hot.

[kevin gilmore]

that is hotter than I expect, what voltage rails and what voltages on the led's

[ruslanch]

16 minutes ago, kevin gilmore said:

that is hotter than I expect, what voltage rails and what voltages on the led's

20v psu , 1.60v on the led's

[Helium]

It might be transistors are heating THAT340 thru copper layers. Are they soldered directy to board, or plugged in sockets?

[ruslanch]

7 minutes ago, Helium said:

It might be transistors are heating THAT340 thru copper layers. Are they soldered directy to board, or plugged in sockets?

In sockets

 

 

[kevin gilmore]

I was thinking the other board.  Yes that board gets that hot due to the transistors

you can add heatsinks

[GrindingThud]

47 minutes ago, ruslanch said:

In sockets

 

 

 

 

Nice!, what heatsink is that on the outputs? I'm so far behind...I still need to build mine. I never found the pot either, is there a source? 

 

[Pars]

^ There was a group buy awhile back...

 

[cspirou]

I got lucky and was able to make a small order. Minimum order is 1000 pieces. If there was a group buy with a minimum of 20 each we might be able to reach that. A lot of people bought multiple pots so maybe someone is kind enough to sell one to you.

otherwise it’s probably better to do the version with the TKD pot, which you can order direct. Or air wire an ALPS pot like someone else here did.

Edited November 8, 2017 by cspirou

[GrindingThud]

1 hour ago, cspirou said:

I got lucky and was able to make a small order. Minimum order is 1000 pieces. If there was a group buy with a minimum of 20 each we might be able to reach that. A lot of people bought multiple pots so maybe someone is kind enough to sell one to you.

otherwise it’s probably better to do the version with the TKD pot, which you can order direct. Or air wire an ALPS pot like someone else here did.

I'll keep my eye out for an "extra"   I already have a pair of the boards. In the mean time, I may just adapt an ALPS like you mention.

[ruslanch]

8 hours ago, kevin gilmore said:

I was thinking the other board.  Yes that board gets that hot due to the transistors

you can add heatsinks

Thank you! I hope that this is indeed so, not my mistake.

8 hours ago, GrindingThud said:

Nice!, what heatsink is that on the outputs? I'm so far behind...I still need to build mine. I never found the pot either, is there a source?

Thanks a lot! Heatsinks from the nearest radio parts store, noname ). I bought a pot on ebay. I found a seller with a similar product and asked him to order from the manufacturer for me. It took 3 months but I got what I ordered.

[Bespav]

Hi, Kevin!
Your site is down or moved somewhere?

[Pars]

Kevin retired. Look in the stax mafia thread


Sent from my iPhone using Tapatalk

[jose]

I have a doubt with the LEDs. In the BOM there is one of Vf 2v (Ref. 351-5001). it is right? 

 

[Pars]

Which Dynalo are you talking about Jose?

For the regular Dynalo Mk2, in my BOM I show

859-LTL-307ELC for D1, D2 (this is from the thru-hole BOM)

For Kerry's Dynalo Mini, I show LTST-C170CKT (4, Red D1, D2) and VLHW4100 (1, White D4)

Edited November 13, 2017 by Pars

[jose]

Thanks Pars, I´m doing a regular Dynalo MKII. I guess that I have the last pcb´s (Rev 1.2, blue pcb with through hole resistors and SMD sand).

I supposed that I could use the LTL-307 (It´s the "standard" ) but in the BOM that I found there behind pointed to the ref. 351-5001. I don´t know why. 

So if I can use the LTL-307ELC, better. I have a ton of these leds.

 

 

[Pars]

Yeah, I just use whatever I have around for 1.7V red LEDs... FLV110, others through the years.

[jose]

Guys, I´m working on my Dynalo SS and I finded this: 

 

 

 

Pad of 24.9K is on the border of track.Yes, I know that is OK and work but there is enough space to move the track and center it with the pad so for future PCB´s I guess that is better change the gerber file ¿no? 

I have rev 1.2 PCB´s

 

[astro]

Hello, everyone. Sharing some phots of my recently built Dynalo mini. I have to thank Kevin, Kerry, and johnwmclean in the first place.

My machine is pretty hot compared with others on the forum.

The transistor heat sink temperature is 88c with 20mA bias(R14/R29 237ohm), 84C with 17mA bias(R14/R29 220 ohm)

The IRM 15-24 power module is 16~18C cooler than the fin. The derating of it starts from 50C and shut down at 70C (ambient temp)

This already makes me feel the amp working on the shutdown margin, though the sound is still fine.

 

The forward voltage of D1/D2 LED is 1.794V and the R1/R3(increased to 453 ohm) cross voltage is 1.307V after warmed up which

means the constant current 2.8mA.

I remember the default constant current is 2.5mA, the Max bias current is 20mA and the normal bias is 15mA? Correct me if I'm wrong.

Having no ideas about why my dynalo is hotter than other nearly 25C. Could it just cause by the higher hfe of the PZTA/MMBTA transistors?

There are only minimum hfe value shown in the data sheet and no maximum is shown.

I'll try 200 ohm and 180 ohm in the next week to see if I can lower the temp to 6xC. 

[gepardcv]

That looks pretty nice, @astro. I don't have an answer for your question, but I have another question for the wider audience: shouldn't the Mean Well PSUs use fuses on input for this circuit? I know these IRM units have some protection built in, but I don't understand how robust it might be.

[cspirou]

There's a fuse near the switch.

Nice work @astro! Where did you do your casing? Are those temperatures inside the enclosure? Are there holes underneath?

Edited November 25, 2017 by cspirou

[GrindingThud]

38 minutes ago, cspirou said:

There's a fuse near the switch.

Nice work @astro! Where did you do your casing? Are those temperatures inside the enclosure? Are there holes underneath?

Ye, very nice job! I'm also interested in that case.