[batman7349]

The two TDA7297's that I recently purchased are the JHDZ-002 boards. Does anyone happen to have photos of their ver.2 modded boards?

[batman7349]

Well I'm going to attempt this myself, but I'll pause along the way and ask for help. So hear goes!!!

First off i purchased two of the amps. Here they are side by side, one virgin and one stripped.


Second picture of the bottom of both boards

[batman7349]

After stripping the board I jumped the diode(D1)

[batman7349]

Now I installed the new power capacitor (C1) with a new 661-EKZH250E222MK30S - EKZH250ELL222MK30S - 25Volts 2200uF sourced from Mouser.

[batman7349]

According to the TDA7297 build guide these are jumped so I did that next


I hope this is correct.

[batman7349]

In the version 1 build the Shunt Mute cap is replaced with a Mouser 661-EKY500ETC220ME1 - EKY-500ETC220ME11D - 50volts 22uf, but in later in the post it states "C4 can be changed but doesn't matter". I have the cap, but the C4 cap on the board is 10uf and the replacement is 22uf.

Question 1 should I replace C4 with the new 22uf?
Question 2 "Remove C2, the little yellow bypass cap". So just leave it out of the circuit with no replacement?
Question 3 C3 & C5 are the 1UF caps that are mounted on both sides of the board. Do they mount long lead to long lead or Long lead to short lead?

I'll continue when i know which way to proceed.

[batman7349]

Corrected a mistake in the previous step. After further reading and studying traces I have now removed the jumper and added wire to the input's.

[batman7349]

Further reading on various post's and I determined as I had previously thought that the input caps are installed electrically opposite of each other top & bottom, so now I have the input caps added.


At this point I'm waiting for someone to chime in regarding the shunt / mute cap being replaced.

I have a Little Bear RIAA phono preamp modified and ready.


I'm waiting on the preamp to arrive and I'll be able to test everything out.


I'm looking forward to hearing my vinyl collection again through my GR Research LS Encore's.

[Folsom]

A lower impedance cap will provide a little more noise attenuation. It's up to you, it won't affect the sound nearly as much as the larger cap.

The jumper you had on the ground could have been where you attached the ground as they connect on the board to the same plane. No matter, but for the next one you can use one wire and save a little.

I'm thinking about updating the build guide with a different power cap, or suggesting two.

The input cap configuration is still the cheapest way to achieve extremely clear sound from DC coupling (input) cap I've found - for thousands of times less than some film caps!

The only fault I found in this amp is the fact that the chips are the lowest grade from the manufacturer, and hence they don't pop after playing over voltage, they pop right at it or before they reach 18v. Put a good PSU on one and it'll rock! They can drive pretty inefficient speakers of somewhat complex loads.

[batman7349]

I finally had time to get everything hooked up. I am running the TDA7297 off of a car battery and it sounds pretty good. After about 10 minutes somewhere between 1/8 and 1/4 volume I noticed the highs dropping out. The amp was pretty warm. I'm not sure if that is an issue with running off of the 12V battery or maybe I was just driving it too hard. I'm going to get out the VOM and check out the operating voltage. Maybe I need to build a power supply.

[Folsom]

It's probably an issue with the fact that all the chips on these smokin deal boards are seconds. A little unpredictable, and often ready to pop at 18v for a microsecond.

I've come up with a few other power caps I think are suitable. My initial recommendation is a decent cap, but I think sound will be improved if one is willing to go through the challenge of close-proximity mounting of a few other caps.

For example one might be able to squeeze 4x of these in, with some serious creativity. Yes they're only slightly over the "operating voltage" but I assure you, as it's happened on numerous chips, 18v isn't an operating voltage it's a dead chip voltage usually.

With a painful effort of trimming the leads and using the hole for the diode, this capacitor might be able to work. It's 10mm lead spacing instead of 5mm... but it's a superior (for the price) cap.

The land of 5mm cap lead spacing isn't overly exotic since the BlackGates faded out.

[batman7349]

Well I've go three more on hand, so I'll try another one and see what it sounds like. This one would be good for the wife pushing a pair of LGK's in the kitchen!

[batman7349]

I'll order up 4 of the Panny's and 1 of the Nichion's and see what happens. This is too much fun! Any recommendations for a cheap and cheerful power supply instead of the 12v battery?

[Folsom]

The Astron's everyone is using on the 3116 amplifiers would be a great match. You can PM me if you want a schematic to bread-board your own with a transformer etc. (more of a project)

[gychang]

I'll order up 4 of the Panny's and 1 of the Nichion's and see what happens. This is too much fun! Any recommendations for a cheap and cheerful power supply instead of the 12v battery?

has there been any update on Panny caps, your thoughts?, any pictures of final pot connections etc?