Teac DR-H300DAB Volume Control Steps Problem

newcoppiceman

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Here's another funny to add to the list of observations about this unit:

I recently bought a spare unit and we've had it in service for a couple of months - it's been used daily for DAB radio and Freeview TV (via AUX 1) and from time-to-time for CDs, DVDs, cassettes and the VCR (via AUX 1) and the Wii (via AUX 2). It's behaved fine, except for the fact that it wasn't possible to set the normal listening level very easily as the volume increments - at least at low-to-medium levels - were very coarse compared with our original unit (now back in service and offering a very smooth change in volume level). The same remote was used throughout, incidentally.

Followers of various threads such as:

http://www.avforums.com/forums/all-one-systems/1054589-teac-dr-h300dab-design-faults-problems.html

on the DR-H300DAB and its design flaws, replacing the OPU, etc may know that I have a service manual. This reveals that the unit uses a PT2314 4-channel input audio processor chip from Princeton Technology Corp for source selection, volume/loudness, frequency shaping and muting. The chip spec says that the volume control is in 1.25dB steps which should be fine - 1dB is usually taken as an audio JND (just noticeable difference). So either I've a dodgy chip, or there's something amiss with the Teac host software which controls the chip via the ubiquitous I2C (that's actually I-squared C) bus.

Page 55 of the owner's manual states that in DAB or FM mode pressing the INFO/REPEAT button for more than 2s will display "System Reset" and pressing it again will display the software version, so I'll see if they're different between the two units.

Anyone else suffer from coarse volume control?

I will report back.
 
Well,...

Both DR-H300DABs, on interrogation, say they are running "Customer vC3.4" software, but whereas my original unit indicates 64 steps between (and including) minimum and maximum volume, my spare unit shows just 32. That means its volume increments are 2.5dB, hence the problem setting the volume to just the right level.

More anon.
 
Hi newcoppiceman,
did you ever manage to fix that coarse volume control problem?
I got a DR-H300 (no DAB) and have the same problem with coarse steps at low volume.
Well, it was annoying the past 15 years but finally I decided to try to fix it. I searched the web but only found your posts here.
I couldn't find any information about hidden service menus nor about firmware updates.
I was thinking about a 10 dB attenuation between the R/L IN and OUT pins of the PT2314, but that is tricky.
Any tips for me? :)
Greetings
Joachim
 
Hi newcoppiceman,
did you ever manage to fix that coarse volume control problem?
I got a DR-H300 (no DAB) and have the same problem with coarse steps at low volume.
Well, it was annoying the past 15 years but finally I decided to try to fix it. I searched the web but only found your posts here.
I couldn't find any information about hidden service menus nor about firmware updates.
I was thinking about a 10 dB attenuation between the R/L IN and OUT pins of the PT2314, but that is tricky.
Any tips for me? :)
Greetings
Joachim
I fixed this problem by replacing PT2314, in case someone is wondering.
 
Thank you. And that solved the coarse steps low volume issue?

The PT2314 is a SMD IC?
Is the replacement tricky? How long did it take you?
(Got electronic and soldering experience, but not much with SMD.)
 
Yes, it solved coarse steps. Yes its smd, 28 pins. You can either only desolder with hot air and solder with iron after cleaning pads or do both with hotair. Its rather easy for someone who does solder more than once or twice a year ;-)
 
Thank you. I see, they are available in China via ebay for a few Euro.
Are those ok or would you recommend a special brand or source?
 
Id recommend PT2314E, its upgraded version but fully compatible with older ones. I got mines from china and those are OK.
 
Oh, precious hint. Glad I asked. Thank you!

Just ordered via AliExpress. :thumbsup:
 
Last edited:
I was alerted that this thread was still active yesterday (sorry, I missed Sunburn's earlier post this year).

My old DR-H300DABs are long gone - sold-on years ago after we ditched the speakers and opted for a Canton DM55 soundbase. So I can't add much here, but Sunburn might gain some insight on working on PCBs with SMDs from a hummy.tv thread I joined last year when our Humax PVR started playing-up. I chronicled my journey to find the troublesome component starting at post #67 here: Start Up Fails When HDD Connected If you follow the thread through to date you'll see that many others have likewise fixed their PVRs - but with varying degrees of elegance/damage to the board. And that's the big risk. There are many, many tips on how to avoid lifting tracks, etc if you plough your way through the thread (while you wait for your shipment from China). The short story can be found at Hardware Fixes.

In the early days of ICs it used to that snipping an IC's leads was the way to go, followed by removal of the lead remnants, then solderwick/defluxer to tidy-up the pads before fitting the replacement. That was in the days of decent-width traces that could withstand the mechanical stresses when snipping. Might still be worth a try - you'd have to assess the board - but the number one thing to bear in mind is avoiding damage to the board.

Our PVR has worked fine since fixing it and recently I've started doing some research on Canton's products, so that I'm prepared in case our DM55 dies. More info here: Canton DMxx Soundbar/Soundbase - "Stuck on Green" Fault

Good luck with your SMD adventures!
 
Thanks for your reply, newcoppiceman, and for the helpful tips.

I got an IC-desoldering tip for my old Weller iron and I hope I can somehow make use of it, although it is for 16 pin regular old fashioned ICs.
If that doesn't work I might cut the pins of using the Dremel, rather than snipping them with the side cutters in oder to apply minimum mechanical stress to the pins and the PCB.

I will report ...

I was also thinking to replace the Teac with some state of the art device, but couldn't find anything similar as powerfull, nice and compact.

Some years ago I had trouble with the DVD-drive, as the drawer would not move any more. I found that the motor was dead, but fortunately was able to replace it with some motor of an old common PC-CD-drive and everything was fine again. :)
 

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I got an IC-desoldering tip for my old Weller iron and I hope I can somehow make use of it, although it is for 16 pin regular old fashioned ICs.
If that doesn't work I might cut the pins of using the Dremel
Hmm... don't think that IC-desoldering tip will be any use; will only effectively transfer heat to the IC package it was intended for, I suspect. Two things with the Dremel - risk of cutting into board, and flying fragments (could cause shorts elsewhere). Maybe hook-up some dust extraction scheme? Two other top tips: Flood the area with plenty of light; some SMDs have little spots of glue under them to prevent something called "tombstoning" in production.
 
Thank you. Meanwhile I went to youtube school and found a trick to desolder these ICs using a wire:


... or I will buy myself a heat gun soldering tool. Will probably be the best idea.

And yes, you never can have enough light when working ... especially when you are > 60. :)
 
I went to youtube school and found a trick to desolder these ICs using a wire
Thanks for the link. There's a guy on YouTube who has posted about his repairs to Canton soundbases. At the heart of these units is a 128-pin DSP/System-on-Chip; it has a pin pitch of 0.4mm. He has fixed some issues by replacing this chip, so maybe he uses this method (not without its risks however). I would have pre-fluxed the pins using a flux pen (a handy toolbox addition) and possibly added fresh solder. Our German friend didn't show the just-as-important step of cleaning up with solderwick/flux remover - again, has risks. Flux removal after soldering is always a good idea.
 
The chips arrived 3 weeks ago and today was surgery day. Mission accomplished successfully, though it took two attempts.

I unsoldered the chip with my Weller iron going over the pins while pulling on the chip. Soldering the chip was no problem, the flux pen is essential.

When done, it worked fine with Aux and Tuner, but with CD and USB the left channel was dead. I traced the signal up to pin 14 of the chip (left input for DVD/USB) and figured that I have ruined the chip probably with too much heat or machanical stress.
Fortunately I had ordered two chips (one spare) so I did the replacement all over again and this time all works fine. Yes, volume control is much better now. One problem less. :)

Thank you guys for your tips, support and encouragement!

Joachim
PXL_20220929_113035918.jpg
PXL_20220929_105327381.jpg
 
The chips arrived 3 weeks ago and today was surgery day. Mission accomplished successfully, though it took two attempts.

I unsoldered the chip with my Weller iron going over the pins while pulling on the chip. Soldering the chip was no problem, the flux pen is essential.

When done, it worked fine with Aux and Tuner, but with CD and USB the left channel was dead. I traced the signal up to pin 14 of the chip (left input for DVD/USB) and figured that I have ruined the chip probably with too much heat or machanical stress.
Fortunately I had ordered two chips (one spare) so I did the replacement all over again and this time all works fine. Yes, volume control is much better now. One problem less. :)

Thank you guys for your tips, support and encouragement!

Joachim
View attachment 1759669View attachment 1759670
Glad I helped!
 

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