Commercial Gainclone kit- building instructions

[NareshBrd]

Thermal shut down, maybe power supply diode / transistors need heat sinking.
At worst, it was used over its limits, and the chips are permanently damaged, need replacement.
Check the voltages, any above 80% in supply are too much, they means supply volts should be around 80% of max. continuous rating.
Also, see if the capacitors are failing, but the result of that is not consistent.
Check for dried heat sink compound too.

 

[bullittstang]

First thing - check supply voltages, should not be over +\-35Vdc and for your 4-ohm speakers better to be 28-30Vdc.
Second, is this both channels or just one? If only one, then disconnect the one with a problem and test the other channel to ensure it is working properly.
If it is, then use the good channel to compare voltages on the bad board and replace burned/shorted parts to get it running.

 

[bullittstang]

Also Google DBT (dim bulb tester). This will save you if you slip a probe while testing as well as limit current and keep any other parts from burning up.

 

[Cavergrace]

Main filter cap sizing

I built my LM 3875 amps about 8 years ago. Absolutely love it and it has been solid for 8 years! My main filter caps back then were 1000UF at 50V. I recently had some issues with one channel and changed the caps out and the noise went away. I am changing all four out now but saw on here that 1500UF caps were being used. What is the difference and what will the effect be on the sound and does it matter, 1000UF or 1500UF?

 

[Ixnay]

I must apologize for my lack of knowledge as where to post this simple question. >>>I have ordered the LM3875 deluxe kit from AudioSector and there has been no reply in 6 days. Is Peter Daniel still in business, or overwhelmed? Thank you all for your understanding.

 

[Peter Daniel]

I’m still around but my supply of LM3875 chips is running out and at this point I might not be able to fill out the complete kit orders.
Contact me either through website or forum mail to discuss your order

 

[pisi]

I’m still around but my supply of LM3875 chips is running out and at this point I might not be able to fill out the complete kit orders.
Contact me either through website or forum mail to discuss your order

I've been trying to contact you about my order for almost a couple of weeks now, but still no luck. You still there, Peter? :'(

 

[Peter Daniel]

Sorry for delay, I didn’t notice your emails. I just issued a refund for your order.

 

[Ixnay]

I might have been one of the last customers who got his order filled. Pretty fortunate. I built the amp with no real problems and have been listening for about 10 days now. I am glad that I built this amp. I haven't completed a chassis for it, since I wanted to listen for some time before I went further.
Thanks Peter for a memorable product

 

[jerin513]

Are they going to get more in the future or should I plan on a different amp? Planning on building mine in about a month or 2...

 

[soundsmith]

Hi Peter, can you still supply Patek Integrated?

 

[1202_ProgramAlarm]

Peter, are lm3875 orders being cancelled due to lack of chip supplies? Also, info on the LM4780 kits is pretty lacking on your site, are the assembly instructions more or less the same as the 3875 amps? Thanks very much!

 

[Ixnay]

I don't know if the LM3875 that Pete had in stock were matched to each other or not, but I suspect so. I am currently waiting on LM3875 for another build. It is supplied by another source, as is the circuit board. There are some differences that I will have to figure out when it all arrives.
It doesn't look like Pete will be stocking more supplies at this point, and I think that I was the last order filled.

 

[Peter Daniel]

The instructions for LM4780 kits can be found here: https://www.diyaudio.com/community/threads/audiosector-chip-amp-kits-dacs-chassis.51381/post-636565

l‘m out of chips right now, so only pcbs are available presently.

 

[Ixnay]

Thanks, Mr. Daniel, for the clarification. I didn't realize that you had more circuit boards available. I'll keep better score in the future.

 

[schumany]

By stereo version I mean the use of a single transformer powering both channels. You could still use two separate rectifiers boards, but depending on wiring it may produce hum in some systems, so I always stick with a single rectifier board when using one transformer.

For demonstration purpose, I will install all the boards inside 3 x 1.5" U-channel, 1.25" aluminum extrusion. For normal listening, this is enough to dissipate heat from the chips, and when things get hot, you can always attach it to larger aluminum panel.

I will show a version with a potentiometer, and without, so stay tuned.

Hi Peter. I am confused about the dimensions of the Al extrusion. I'm getting ready to order the kit and I'd like to order it also. Thanks!

 

[NareshBrd]

Find the chips first, supplies are erratic.
Without them, the kits are not useful.

 

[chuck55]

How is the bass response on the LM3875? I have read that is the weakness. The only similar digital amp I haved heard was Cryus "The One". While very clear, clean and detailed, the bass was much less than my Parasound Zamp.

 

[JDawg]

I need to replace one of the 1500uF Panasonic FC capacitors on my amp board. It was accidentally damaged when it got pushed towards one side. This capacitor is no longer in stock at digikey and Mouser. Is it ok to replace this with a 1800uF Panasonic FC capacitor instead? Are there any other capacitors I should try instead?

 

[NareshBrd]

Elna, Nichicon, Nippon, Keltron, Panasonic, Sprague, Taicon, TDK, Vishay, any standard brand, just stay away from Chines, and preferably 105 C rated.