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148 audio chip HOT
- Thread starter Sarcasm
- Start date
I was informed by a experienced tech that NTE components aren't up to snuff like the better quality components. That's why I didn't put any in my 959 but let DTB do the work with his components.
Well, I wouldn't use the NTE finals since their specs are not even close to the originals. But some of the other NTE transistors used for different applications worked out just fine. The NTE-152 is considered by many to be far superior to the 2sc1419. I have no argument with that, they have always worked out well.
After ECG parts (Sylvania) became hard to find almost everyone everywhere in all repair shops ( not just radio but electronics in general) started to use NTE parts. That has pretty much become the defacto standard cross reference. I have used hundreds......no probably a few thousands of NTE replacements in commercial electronics and as long as the specs are the same they should be good. The problem comes from someone trying to a part that is "close enough" for them while it may not be quite close enough for the application.
BTW where does DTB get his parts? I don't mean a supplier I mean manufacturer.
I've had good and bad luck with NTE, the audio, and reg chips are doing well. The rest not so good, like diodes, small transistors and electrolytic caps being leaky.
Right now TR 17,18 & 52 are getting warm to hot, when the RX starts acting up. They all test good even when hot. So I'm thinking there is a problem in the AGC section, since when its cool the radio acts like it has a lot of gain. It's like the volume is turned all the way up, then when its warmed up I have to turn the volume up almost all the way to hear. I think the crackle is from shorting, but haven't found anything yet. Hopefully ill have more time tonight. Thanks
DTB uses some NTE parts, the last 29 had NTE diodes in it, and it actually has a much higher noise level than the stock one of the same model I have, but that could also be variations in those LX's.
I prefer Custom for work on most radios , since ive had the most consistent and best results from them, but a 148/2000 I will only send to Rick in CT.
Right now TR 17,18 & 52 are getting warm to hot, when the RX starts acting up. They all test good even when hot. So I'm thinking there is a problem in the AGC section, since when its cool the radio acts like it has a lot of gain. It's like the volume is turned all the way up, then when its warmed up I have to turn the volume up almost all the way to hear. I think the crackle is from shorting, but haven't found anything yet. Hopefully ill have more time tonight. Thanks
DTB uses some NTE parts, the last 29 had NTE diodes in it, and it actually has a much higher noise level than the stock one of the same model I have, but that could also be variations in those LX's.
I prefer Custom for work on most radios , since ive had the most consistent and best results from them, but a 148/2000 I will only send to Rick in CT.
2sc1419 >>> TIP41C >> TRANSISTOR NPN 100V 6A
Pin 2 capacitor should be 4.7uf / 25v instead of 2.2uf / 50v (C180).
Check C-179 (22uf / 6.5v) Tantalum.
C-176 should be 47uf / 10v, replace with 47uf / 16v or higher.
:drool:
Greetings from the Caribbean!!!!
Pin 2 capacitor should be 4.7uf / 25v instead of 2.2uf / 50v (C180).
Check C-179 (22uf / 6.5v) Tantalum.
C-176 should be 47uf / 10v, replace with 47uf / 16v or higher.
:drool:
Greetings from the Caribbean!!!!
Last edited:
Making small progress. I don't know what " motorboating" exactly sounds like when it comes to the cb version. But when the RX goes out it starts clicking, sounds like engine exhaust idle. Don't know how to describe it exactly. Only TR 18 & 28 get warm to hot. Replaced TR 10,11,14,21,31,35& fet2. So now it takes longer to act up. TXing or going to ssb will make it act up quickly. Radio tx and RX awesome till it warms up. Freeze spray individual TR's and waiting found nothing. Wondering if its a diode.
It's working a lot better now after replacing TR 33&48 and the varactor D12&13. I did find C30 had a broken leg and that fixed the changing gain issue in the AGC. It still has a fading or drop out RX but no more crackle. It takes almost an hour to act up now. Weird thing is just blowing on the audio chip will make it go for a few seconds. I did find a couple cans that were touchy when aligning on the scope. L19 being the most sensitive, just touching it made the vpp jump. Make me think the cap in it might be bad. Checking c179&180 now. Thanks