I’ve Joined the Tate family!

[Owen Smith]

"If it ain't broke don't fix it" is fine for your own equipment. But I'm currently re-capping a DAB tuner for my parents. There is only one bulging cap, but while I'm in there I'm replacing all the other decouplers that are clustered around the heatsinks meaning they run hot. It's a 3 hour drive to my parents, I'm trying to avoid a sudden call out to fix it.

 

[par4ken]

"If it ain't broke don't fix it" is fine for your own equipment. But I'm currently re-capping a DAB tuner for my parents. There is only one bulging cap, but while I'm in there I'm replacing all the other decouplers that are clustered around the heatsinks meaning they run hot. It's a 3 hour drive to my parents, I'm trying to avoid a sudden call out to fix it.

Yes, I agree in a case like that replacing everything is the best/only approach. A lot of equipment is unreliable due to excessive heat build up. Important to use 105° caps rather than the regular 85° ones. I remember the old Uniden satellite TV receivers that would regularly cook nearly all the capacitors in a very short time, they ran very hot with everything crammed into a smallish case.. You either bought a new one or recapped the entire thing.

Thankfully vintage decoders run cool. The Tate decoders use heatsinks on the DES output chips, they run warm not excessively hot. Likewise the op-amps in the Composer are being run class A necessitating heatsinks: they run warm not hot. Most heat is from the power supply regulators. All the Tate decoders have the components spread out nicely, no real place for heat to build up.

 

[Owen Smith]

Yes, I agree in a case like that replacing everything is the best/only approach. A lot of equipment is unreliable due to excessive heat build up. Important to use 105° caps rather than the regular 85° ones.

I am using 105C caps for all the replacements. It's not the entire tuner that is the problem (probing with a thermocouple just after removing the lid), and there would be a lot of caps to replace if I did that. It's just the ones warming their cans huddling around the linear regulator heatsinks that I'm replacing. Here's a picture of them in another Arcam T32 tuner, the bulging cap in mine is the largest. It's a 105C part 4700uF 16V, it is on the output of a bridge rectifier of a 10V AC transformer winding, so is marginal on ripple voltage. 14.14V is a lot for a 16V cap, so I'm uprating that one to 25V. The rest are OK on voltage, mostly already 25V.

The largest heatsink is barely warm, that's the 5V digital rail. It's the second largest supplying the 3V3 to the DAB module that's the problem, it gets so hot it is too painful to hold continuously. Thermocouple shows about 70C with the caps near it sitting at 60C or a bit more, mostly due to radiated heat I believe. The rest of the tuner is a good 20C cooler as soon as there is any distance from that bank of heatsinks.

 

[par4ken]

Just examining the board in my 101A I notice 4.3K resistors around each audio stage op-amp. They do not show in the schematic but appear to be pull-up resistors used to force class-A operation. I had previously thought that only Audionics did that (with 2.2K resistors), so that would explain the need for the heatsinks on those op-amps.

The pots are all miniature Alpha branded, replacements are readily available. I see many listings on eBay most from China but almost all have the knurled type shaft rather than the solid round shaft of those in the 101A. The Composer uses similar type Alps branded pots .

The pots in the 101A are of higher value than those used in the Composer. The remote control of the Composer is selected internally by means of a DIP jumper plug. With the remote connected and jumper set you can not use the front panel controls.

The Fosgate approach is different. The unit accepts the remote via the front or rear jack but warns not to use remotes connected to both, as that could short the power supply. The Fosgate remote is not as versatile only providing front to back balance. While I don't have the remote or the schematic I can say that it works by using a much lower value pot so that when plugged in the setting of the front panel control is overroad by the setting of the lower value remote pot, rather cool! It is easy to unplug the remote if you want to use the front panel controls.

As I said before I'm in no rush to re-cap the unit. All the capacitors look factory fresh, especially the power supply filters. Counting the capacitors for future reference, the board contains Qty of 7 220µFd 16V caps that decouple the supply at various locations. There are Qty of 6 0.47µFd 25V caps filtering the detector RA-402 output, there are Qty 4 0.33µfd 25V coupling the signal into the detector chip there are Qty of 6 2.2µfd 25V connected to the CMOS switch used for the bypass function. There is a 3.3µFd 35V and a few other odd caps that I can't read due to their mounting location. This in addition to the Qty 13 4.7µFd 50V capacitors that I mentioned previously. The main power supply capacitors are axial types 2200µFd on the positive rail and 1000µFd on the negative rail. I find that a bit odd that the negative rail has less filtering but I guess that is due to having less current draw from the negative rail.

 

[par4ken]

Here are a few pictures of my Tate II unit.

I replaced the input jacks and in my usual fashion ran a bit of my favourite Epoxy glue around their backs to keep them from ever coming loose. I want to do the outputs as well but that will entail some cutting or drilling so I will save it for another day.

I spray painted the top and bottom panels as they were scratched/scuffed up a fair bit.

The plastic bottom feet only had the mounting tabs left so they were removed and replaced with self adhesive felt furniture pads.

I added rack mount adaptors but might replace them with a more attractive pair.

I replaced all the knobs as two were missing and I like the sleeker style of these replacements!