Tandberg 2055 resistor help

[Scripps66]

Hello friends, I'm trying to get a 2055 up and going and I've found a cluster area where the readings are way off on resistors, one in particular I'm going need help finding a modern equivalent,
The location is R851, the schematics read:
40 mv
0.68 ohms (I'm assuming, says in spot that normally reads ohms)
6w
Next to it is a 2w 10 ohm odd looking resistor and below that is a carbon resistor that is visibly fried, all the readings in all 3 are way off, I'll post a pic
Any help greatly appreciated

 

[mrwasabihead]

Hey Scripps66, The "40mV" you mentioned is measured over R853, but you asked about R851. And both are 0.68 ohm / 6 W. Obviously you'll have to replace the toasted resistor but I'd do that first and measure the other resistors you're concerned with with one leg out of the circuit before continuing. You can just lift one leg of the resistors in question and measure that way if you haven't already. If you have, did they measure way out of spec? I'd be surprised if the 10 ohm 2 W were bad. And is that a melted C825 I'm seeing there also?
I just finished a 2075 with many of the same components.

 

[Scripps66]

Hey Scripps66, The "40mV" you mentioned is measured over R853, but you asked about R851. And both are 0.68 ohm / 6 W. Obviously you'll have to replace the toasted resistor but I'd do that first and measure the other resistors you're concerned with with one leg out of the circuit before continuing. You can just lift one leg of the resistors in question and measure that way if you haven't already. If you have, did they measure way out of spec? I'd be surprised if the 10 ohm 2 W were bad. And is that a melted C825 I'm seeing there also?
I just finished a 2075 with many of the same components.

Thanks for chiming in, that C825 is the toasted resistor I was talking about, those (Carbon?) Things are sometimes listed as resistors sometimes capacitor, I ended up keeping the 40mv 0.68 ohm component resistors in, there were two 10 ohm 2 watt wire wound resistors (R855 and R856) along with melted C825 (carbon cap? Resistor?) the 2 watt 10 ohm resistors measured 12.5 ohms and 13 ohms out of circuit, with burn marks on both sides of the PCB for both resistors, I have another 2055 I pulled them out of just to insert to test out, along with almost a dozen caps (caps are new) seems to be ok now except phono outputs are noisy, but I guess I need to figure out what caused those resistors to crap out, I haven't checked voltages with multimeter yet so far just going by ear on this,..all the transistors checked out fine, along with all the 1/2 watt resistors, two zener diodes in same general area as fries 2 watt resistors and toasted C825, we're shot d801 & d802 (1N5245b's) replaced them.. I'll take another crack at it after Thanksgiving with the phono outputs, those phono outputs seem to be isolated to the input amp board and the program select/voltage reg. Boards ...I'll use the multimeter and check voltages and see where I'm at with it, but so far sounds great through tape 1 & 2 outputs, FM as well.. ... Those 4 big power caps look ok with ESR meter, haven't pulled to use capacitance meter, I'll post more next week for an update on progress (or lack of) but sounds better so far

 

[mrwasabihead]

C825 should be a 0.1uF film capacitor. That's what it shows on the schematic. I'd replace it. I would also test C815 and C829. All three are on your positive voltage rail and considering C825 is melted something isn't right. Do you use a DBT? (Dim bulb tester) If not it'd be a good idea to make one. Having your unit plugged into the DBT will allow you to test voltages while limiting the current to the unit, and if some component isn't up to snuff or fails while it's being repaired it will limit the damage. Lot's of info here on AK and online about how to do this and why. Have a good Thanksgiving and be safe.

 

[Scripps66]

Hey thanks and yeah I've got a Variac I can use to reduce voltage, great idea... C825 I pulled off a spare power amplifier board, and those (film?) Caps are pretty popular in Tandberg reel to reels and I've got lots of spare PCBs with those same components... And I'll double check c815 and 829 again, I may have already replaced one or both already but I'm out of town for the weekend so I just have my phone with schematics and a few pictures, on the program select/voltage regulator board there were some frakko caps and those burgundy looking old caps that were cracked and leaking maybe those were the cause? I'll send a picture, and happy Thanksgiving to you as well!

 

[Scripps66]

 

[mrwasabihead]

Oh yeah, those burgundy caps have to go, bro. Especially in the amp and power supply sections. That 2055 is another great Tandberg unit so it's worth the time spent to recap and restore to your liking. Take your time, keep good records of your tests and parts replaced. Caps and resistors are cheap and replacing the ones that need it is a LOT less expensive in time and money than having to deal with a catastrophic failure. Working on these old European receivers is a little bit of a challenge but it's doable if you're organized and patient. Hang in there.