Okay, so I replaced the PTC in the left channel. I played it for a few minutes and it sounds great again. I started checking voltages, but it's very confusing with the assortment of possible combinations. Should I be checking with the KT170s in or maybe KT88s? Any help with proper configuration for troubleshooting will be appreciated.
ELEKIT TU-8850 SE KT170 SET AMP
- Thread starter vkung
- Start date
Okay, I finished testing everything using KT170 tubes. The numbers don't match the manual, but they are consistent side to side.
| TP | L | R |
1 | 0.74 | 0.75 |
2 | 16.5 | 16 |
3 | 18.75 | 18.8 |
4 | 18.2 | 18.3 |
5 | 60.9 | 60.8 |
6 | 97.9 | 97.9 |
7 | -15 | -15 |
8 | 0 | 0 |
9 | 0 | 0 |
10 | 0 | 0 |
11 | 112 | 111.9 |
12 | 112 | 111.9 |
13 | 112.4 | 112.2 |
14 | 126.6 | 126.2 |
15 | 360 | |
16 | -46.9 | |
17 | -15.5 | |
18 | -69.2 | |
19 | 7.7 | |
20 | 7.48 | |
21 | 52.6 | |
22 | 264 | |
23 | 127 |
Argh, I am such a moron. After going through all the parts I had left over I realized I installed the circuit board for the 100V power instead of the 115V power. I've removed all the parts and am in the process of installing them onto the correct circuit board. However, I noticed the pins on the 9 pin box VH connector are now irregular. I'm assuming they've shifted from the heat of soldering/desoldering. Is this ok to use? If not any idea where to get another one?
Alright, circuit board swapped and here are the voltages. Left channel is right where it's supposed to be. Right channel is consistently 30% low across the board. Any help on what would cause that will be greatly appreciated.
| TP | L | R |
1 | 2.29 | 0.71 |
2 | 60 | 17.6 |
3 | 66 | 19.4 |
4 | 64 | 18.8 |
5 | 178 | 53 |
6 | 305 | 89 |
7 | -37 | -13 |
8 | 1.18 | 0.073 |
9 | 0.003 | 0 |
10 | 1.18 | 0.072 |
11 | 348 | 103 |
12 | 346 | 103 |
13 | 354 | 103 |
14 | 370 | 118 |
15 | 370 | |
16 | -45 | |
17 | -15.2 | |
18 | -59.3 | |
19 | 6.4 | |
20 | 6.42 | |
21 | 45 | |
22 | 222 | |
23 | 108 |
Looking at the circuit diagram, voltage is good at TP15 (370V). Then voltage is good at TP14L (370V). Voltage is low at TP14R (118V). The original problem was PTC 103 burned up. Is it likely that the same issue caused PTC 203 to go bad but not burn up? If PTC 203 is bad I think it would affect all the voltages in the right channel.
I tested PTC103 and 203 in circuit (cold). PTC103 was ~7ohms. That's in spec according to info online. PTC203 was 133ohms. Definitely not right. Elekit has these parts in their online store. Is it okay to order direct from Elekit? Never mind, Elekit won't let me order. Not sure why because I don't speak Japanese and Google's not translating the whole page. Any chance I can get another PTC UN600 200 from you Victor?
Just curious how you would compare 8800 with 6L6/EL34 to 8850 with KT170. I have a 8800 and a pair of full range open baffles (no box) with 100 dB sensitivity.